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Anquan7
 
  2005 G.Caravan with crazy heater/overheat issues - Posted: 12-03-2011, 11:46 PM
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Post #1

This thread is actually an entire update to an earlier thread. I have to update the whole story so helpful folks can advise properly. Thanks in advance.

2005 Grand Caravan, 3.8L engine. Heat started fading and returning back and forth while on the road. I replaced the thermostat, water pump, radiator cap with new. The radiator was brand new when I put that in 4 months ago after a small front end collision.

Then, 2 weeks ago, the temp. needle would start shooting to HOT randomly on the road, and throwing in in Neutral and gunning engine to 3K or higher would make: 1) the heater blow hotter, and 2) temp needle return to normal!! Go figure. It was like there was a clog in the coolant line and higher RMPs blew past it. I should also mention I kept the radiator and reservoir topped off every day.

So I took it to a dedicated radiator shop. They pressure cleaned/tested the system, and said it was doing good, great heat. Yeah, but they didnt drive it. Paid them $90. They said if the problem persists, I had either a blown head gasket or leak at the intake manifold. But he admitted the engine was 'running like a top' and seemed fine. No white smoke out exhaust....no continuous bubbles up radiator neck, and power while highway driving is normal and strong. No water or extra moisture coming out tailpipe. When I left the radiator shop, not 5 minutes later, the heater went lukewarm.....then hot again in a minute or two, then cool.

But then I started noticing from that point on, I was having to add 1/2 GALLON OF COOLANT to the radiator every trip out. If I topped everything off and then drove it on the road for just 15 minutes, the radiator would be down 1/2 GALLON again. Thats a major loss!! No leaks under the car. No leaks at the draincock, waterpump, or anywhere we can see. Going out the tailpipe? 1/2 gallon that quickly? Is it possible? I dont know, seems like water should be dripping out the exhaust at that level. Its not.

I even added a can of heavy-duty radiator stop-leak just to sure. Made no difference.

I have flushed and flow-tested the heater core. Its fine. I was hoping it was JUST a bad core to replace. I dont think so.....

I really need to mention that the past few days I realized when it started to overheat, and I GUNNED the engine to bring the needle DOWN, I would always hear sloshing sounds from the core an instant before the needle dropped AND the heat blew hotter. And I confirmed this several dozen times. Heat would start to blow cool.......Engine temp would rise....put it on neutral, gun engine up to 4K RPM, keep it there until I hear the SLOSH from the core, THEN, every single time without fail, the engine temp dropped to normal, and heat started INSTANTLY blowing hot again. That told me there is a FLOW problem. But I had the system professionally cleaned and tested, and said its good. Then I flushed the core and whole system, and it was good.

Any thoughts? Thanks
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wally59321
 
 Posted: 12-04-2011, 12:47 AM
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Post #2

Did you see anything flush out of the core.
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Anquan7
 
 Posted: 12-04-2011, 02:23 PM
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No, nothing flushed out of the core that I could detect.
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StandOnCliff
 
 Posted: 12-04-2011, 05:17 PM
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The coolant loss should be addressed first. Not all times a bad head gasket or intake gasket, will blow it out the tailpipe. Make sure your oil isn't tan colored and creamy. A radiator pressure tester will help you find the coolant loss. Pump it up to recommended pressure. It should stay there all day. If it doesn't, there is a leak for sure somewhere. If none is on the floor afterwards or inside the vehicle from a leaking heater core, it's either going into a cylinder or the oil. Which is either a head gasket or intake gasket. They should of seen if this was the problem or not when they pressure tested it. They stated if it continues it's either the head gasket or intake, sounds like they didn't pressure test the system. Maybe they just pressure tested the radiator.

Fill the system on an incline with both heaters on hot. The rearend of the vehicle on the lower part of the hill. This will make any air pockets flow to the front, into the radiator and out of the system. An air pocket in the system, will cause the radiator cap to open and loose coolant out the overflow. Have it running and goose the throttle a couple of times to move the coolant around and keep it topped off. This sounds like the problem. It would explain the slosh sound your hearing, air trapped in the system.

If you have a bleeder valve on the thermostat housing, open it until no bubbles come out. The intrepids have one. If you fail to open it to get the air out through it, they suffer the same problem. The temp gauge will go to hot and no heat will come out. The overflow opens and it blows the coolant out.
As far as I know the Caravans don't have one.

Is the thermostat installed correctly? It has a bleeder valve on it that is supposed to be in the 12 o clock position. If it's not installed correctly, the air is trapped in the system. It should have a tab on it, so it can't be installed incorrectly, but some brands may not.

Getting the air out of the system is crucial. Air trapped in the system causes the coolant to boil. Boiling creates more air, making it worse.

Last edited by StandOnCliff : 12-04-2011 at 05:23 PM.
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Anquan7
 
 Posted: 12-04-2011, 10:02 PM
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The oil is clean and maintaining level, not going up, not creamy or frothy. The thermostat is correct with the jiggle valve at top. I have flushed and filled the system several times and got the air out.

I should mention that it had stopped withdrawing coolant from the reservoir upon cooling like it used to, to make up what it lost, but I put on a new reservoir hose, and a new radiator cap, and now it works right. But the fluctuating heat issues continues, as does the 1/2 gallon of coolant loss every trip out.

But check this out. Bear in mind I check and top off everything before each trip. Now, some days, it won't start to overheat and go to 'H', and the next day it will over and over. Then it wont. Then it will. Sometimes the coolant doesnt seem to go down as much, next time it will. Its mind-numbing...

I guess what I really want to know, is with that much coolant loss (1/2 gallon if I drive it 20 highway miles or less), would there not be either engine power loss to some degree, or at least alot of steam or drips out the tailpipe? I mean 1/2 gallon for a trip to the grocery store and back seems ALOT of water going into a cylinder in a short time. But the engine runs fine, smooth, and full power. If its a head gasket, and its NOT leaking into oil (its not), where else would it leak to? Could it be leaking into ALL 6 cylinders at the same time?? Then I could see such a rapid loss and no perceived lack of performance. Thanks
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StandOnCliff
 
 Posted: 12-05-2011, 12:50 AM
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Post #6

There has to be an explanation as to where the coolant is leaking. A proper running system very rarily needs coolant added. If your using coolant and have no evident leaks in the system, it has to be the head gasket, cracked head or intake gasket failing.

A head gasket can fail many ways. It can leak oil outside of the head and down the block. It can leak coolant out of the head and down the block.
A head gasket can fail around a cylinder, connecting two cylinders, or connecting a cylinder to a water port, between the two cylinders. If it blows out, it can now blow cylinder pressure into a water port. The one way a head gasket fails is the water port itself begins leaking into the cylinder or crankcase. When it goes this way, coolant comes out the tailpipe or mixes with the oil. This is not the only tell tale sign of head gasket failure. When it goes the other way compression from the cylinder enters the water port. The cooling system runs 18 psi, or what your cap states. The cylinders run over 100 psi. It won't take long this way for it to blow the coolant out. Each cylinder is going 700 revolutions per minute, just at idle. Pumping over 100 psi with each revolution. So it is possible for just one cylinder to blow out a half gallon very quickly. When it goes this way, the weakest point leaks. The weakest point is the radiator cap. Anything over 18 psi, it opens and coolant comes out the overflow. This is really easy to find out. The coolant in the reservoir always stays full, until all the coolant is blown out. To put a temporary catch jar over the overflow tube, will verify if this is whats happening. If after a drive that container is full, it may be whats occuring. The other way to know if this is whats happening, is after the drive you hear it hissing out the overflow for a bit. The cap will remain open until the system blows out the extra pressure.

I had a head gasket go this way. I couldn't drive it to town without it running out of coolant.

A compression test can help verify which cylinder is problematic, if this is occuring. The cylinder(s) affected will have low pressure.

The most effective and accurate diagnostic test to determine if the cylinder head gasket is sealing combustion gasses, is to check for the presence of combustion gasses in the engine coolant. This must be done with the engine warm and the radiator cap removed. This can be a bit tricky so be careful when warming the engine with the radiator cap removed or removing the cap when the engine is warm. With the radiator cap off and the engine warm, place a funnel where the radiator cap would normally be. Start the engine and let it run. Watch the coolant as it circulates. It is normal to see the presence of some bubbles in the cooling system, but the presence of lots of bubbles in the cooling system may be a sign of cylinder head gasket failure. Be very careful when running the engine with the radiator cap removed. Hot coolant may be expelled from the radiator unexpectedly.

With the engine running, a tool (pictured) is used to draw fumes from the cooling system through a chemical that checks for the presence of carbon monoxide (CO) in the cooling system. Carbon monoxide will only be present if the head gasket has failed or the cylinder head itself is cracked. The chemical starts off blue in color, but turns green or yellow in the presence of carbon monoxide. This test is known as a “block check."
http://www.arrowheadradiator.com/hea..._leak_test.htm

Another method is to use the gas analyzer that the shop uses to check vehicle emissions. When this machine is used, the presence of hydrocarbon (HC) gasses escaping from the coolant will be measured and if the HC reading is over 50 PPM, then the headgasket is leaking.

If it has to be torn down to replace a head gasket, do both while your there.

Heres a picture to help explain. The second picture is your head gasket. Notice the red circles around the cylinder. Those are water ports.
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StandOnCliff
 
 Posted: 12-05-2011, 01:05 AM
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Post #7

Catastrophic cylinder head gasket failure can be easy to determine. A large stream of white smoke billowing from the exhaust and an overheating engine are sure signs. However, more subtle cylinder head gasket failure signs may be more difficult to diagnose. The engine may experience mysterious coolant loss, or only lose coolant when the engine is driven under heavy load. You may even experience a rough running engine when you first start the vehicle.

An initial inspection of cooling system components and a comprehensive test drive may be necessary to confirm the customer's complaint of coolant loss or overheating. Check for the presence of white steam/smoke coming from the exhaust. Steam coming out of the exhaust may smell slightly sweet as the steam gently dissipates into the surrounding air. (It is normal to see drops of water from the exhaust of a modern car as it is warming up.) Another sign that the head gasket may be leaking is the presence of oil in the cooling system. Check for oil residue in the coolant reservoir.


It is important to confirm actual engine running temperature and accuracy of the temperature gauge. This can be verified by using a non-contact infrared heat detection gun. It is a non-intrusive method used by most repair shops to verify temperature gauge accuracy and actual engine running temperature.


Pressurizing the cooling system (to eliminate coolant leaks as being the source of coolant loss), checking for proper operation of the cooling fan, and checking radiator efficiency are important before jumping to the conclusion that the head gasket is defective.
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wally59321
 
 Posted: 12-05-2011, 02:14 AM
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Anquan7

“Pressurizing the cooling system (to eliminate coolant leaks as being the source of coolant loss), checking for proper operation of the cooling fan, and checking radiator efficiency are important before jumping to the conclusion that the head gasket is defective.”

The easiest thing to check is the cooling fan. Raise your hood, start your van and let it idle. Watch you temperature gauge. When it gets up to normal operating temperature or just over your fan should start and you should see your temperature gauge drop down.

The next test requires the use of a pressure tester, but if you are like me it costs more than i could afford when i had heating problems. If you do not have one you have to inspect every clamp and every hose in the heating system. I have had 2 hose clamp failures on my vans. To give you an idea of bad clamps look at pic 1. It shows a 5/8 radiator hose with a clamp around it. It looked tight and no sign of rust. It turned out the clamp was rusted in half on the bottom side. I had the same problem with the heater hose going down from heater core between the engine and the firewall to the rear heater. It looked tight and not to rusted but it was rusted in half on the bottom side. I could only see this by jacking up the van and getting under it and looking up.

The second pic is another example of how hard it can be to find all clamps and inspect the hoses. This is a pic of 3 radiator clamps hidden by the oil filter. In other words, not having or buying a system pressure tester requires a LOT of work to be sure you do not have any leaks. And by the way, like you, i never saw a drop of water leaking anyware.

Speaking of radiator clamps. Many people do not know the dirty radiator clamp secret. There are 2 kinds of clamps, plated steel and all stainless steel. The stainless steel clamps will be stamped “all stainless” on the body of the clamp. Our local auto stores sell the cheap plated steel ones. To get all stainless, check ACE hardware and True Value hardware.

This is a good deal on a pressure tester. I toughed it out without one, but it took a l o n g time to get the system fixed.

http://www.harborfreight.com/radiato...kit-65053.html
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hcmq
 
 Posted: 12-05-2011, 06:59 AM
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Post #9

water pump. who put yours in? you or the shop?

They will seem fine but they are not.

Mine would leak a good bit and I couldn't tell where it was coming from.

The 05's are famous for water pump issues that are very hard to detect and for leaky radiators.

Catalytic converters are so good now that you have to have a really bad head gasket leak before you see white smoke.

Last edited by hcmq : 12-05-2011 at 07:04 AM.
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StandOnCliff
 
 Posted: 12-05-2011, 12:28 PM
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Post #10

You should be able to rent a pressure tester from your local autozone. It'll cost you the price of the tool, but on return you get all your money back.

This is how I get one, since someone borrowed mine and never returned it. Been so long, I forgot who I lent it too.


Never buy hose clamps from Harbor Freight. They are made in china and are cheap. Trying to tighten them will strip them out. Stainless is the best bet as wally stated.

Last edited by StandOnCliff : 12-05-2011 at 12:43 PM. Reason: spelled best gest
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Anquan7
 
 Posted: 12-05-2011, 04:33 PM
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There is another problem I also just discovered, and I am SURE it is related. With it in PARK or Neutral, you can raise the RPM up to 4K very smoothly, but once it gets a hair over 4K, the needle wants to fluctuate back and forth, and the engine makes some swooshing sounds, and you can hear a slight 'bonk----bonk' from the tailpipe (I think) and the whole van shimmys a hair with each bonk, like a very small muffled backfire, but it does it like every 2 seconds, over and over, once you try to push it over 4K RPM. But while driving, just today, I gunned it many times to prevent overheating (3K-4K RPM) , and when passing cars, the tach will jump to 5K without any noticable issue, though its only for a second or two. While cruising on the highway today, doing 60 MPH for about 20 minutes each way, the van runs smooth, engine purs, taching at its normal 1900-2000 RPM for that speed. Would such a drastic coolant leak of 1/2 gallon per trip not affect performance?

As for other comments and suggestions from you all, I replaced the water pump myself, and the old pump was not leaking, and looked pristine inside, I just changed it to rule-it-out. I have changed water pumps about 7 times in 3 Caravans, so I know its in right. The radiator is only 4 months old from brand new, and shows no sign of leaks. And I have bled the air out of the line countless times, topped everything off, and still the heater core will make squirting trickle sounds minutes after hitting the road, when no coolant could have really leaked/burned out yet. I flushed the core from its nipples and firewall hoses, and the water ran clean and consistant both directions...

Thanks for the tip on the RENTAL of the pressure tester. Bingo, thats just what I needed and I I didnt know you could do that. But IF the leak is the head gasket or intake manifold, how will I know it? I know a pressure drop will mean a LEAK somewhere, but how do you know just where?
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StandOnCliff
 
 Posted: 12-05-2011, 04:51 PM
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You'll find drips coming out of where it's leaking, if anything is leaking. If the pressure drops and you can not find a leak anywhere, then you'll want to get the block check kit to test if carbon is found in the radiator.
The bonk sound from the tailpipe almost sounds like a misfire, which would be caused from a bad head gasket.
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wally59321
 
 Posted: 12-06-2011, 12:23 AM
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The swishing sound he hears from the heater core bothers me. I do not see how a head gasket can cause this noise. He said it was in a front end collision. Could the water tube from the water pump to the heater core be bent or crimped. This is a picture of my hot water tube from the water pump to the heater core as seen through the radiator. My van is a 1992 so yours will probably be a little different but it is worth looking at.

Hmm, just as i was posting this i had another idea. With your loss of coolant so fast and your refilling the radiator everyday how can there not be air in your system everyday. Getting all the air out takes a little bit, like cycling the overflow tank several times with normal engine heating and cooling. You can not do this because your system is not working. Or you have to park on a hill and idle the van until the thermostat opens and then slowly fill the radiator until it is completely full and there are no bubbles, and the heater must be on to let the hot water in the core (later years do not have a heater core vacuum valve i do not know what the cut off year is though).
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Anquan7
 
 Posted: 12-06-2011, 09:34 AM
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*** UPDATE ***

I rented a pressure tester. The directions say if it holds the pressure for 2 minutes, there are no major leaks. It does hold pressure...and maintains the 16 PSI I put in it for 6-7 minutes before is slowly drops. An hour later, its down to about 9 PSI. According to the manual, this is fine.

Then to test for internal leaks, it says to attach tester, run engine to normal temp, and see if pressure rises quickly for a head gasket leak. The pressure does NOT rise, but holds steady. Then it says to look for a pulsating needle for head gasket issues, but the needle stays steady.

Checked the oil and trans fluids again, no froth or cream. Looks normal.

So what about an INTAKE MANIFOLD leak? The manual does not mention what symptoms that causes. Anybody know? Shouldn't that show up somehow with the pressure tester?

I am glad I rented the tester ($75 at Autozone, 100% refunded when you return it within 90 days), but it left with just as many questions as I had before using it.
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Anquan7
 
 Posted: 12-06-2011, 10:13 AM
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UPDATE. When I mentioned above the pressure very slowly dropped over an hour, well I tried it again, and this time it is holding the pressure for over 45 minutes now. Just a few pounds of pressure drop over an hour

Last edited by Anquan7 : 12-06-2011 at 11:16 AM.
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StandOnCliff
 
 Posted: 12-06-2011, 03:18 PM
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Post #16

Did you by chance wiggle and move hoses around as the pressure was applied?
Some leaks may not appear with it sitting.
The engine vibrates, moving hoses around and may only leak when this is occuring.
Keep the pressure at the caps max reading as much as possible. Max reading is where the system runs when load is applied. Have the system topped off before applying pressure. You don't want air coming out of the leak, or you'll never find it. Keep looking around for leaks. Keep smelling around as your going through your hoses and such. If you get a wiff of a sweet smell, there is a leak somewhere. The longer you keep it pumped up to pressure the better the chances at finding a leak. A puddle or a drip will appear. If it is an intake leak it'll run rough the first start after keeping your pressure up for a while. The intake will fill with coolant and suck it into the cylinders on first start. It will also have a sweet smell coming out the tailpipe.

Check over very well any steel lines that may have got bent, causing a resriction from the accident. Make sure your cooling fans are kicking in with it warmed up.
If everything is checking out fine, it has to be air is trapped somewhere. Fill it on an incline with heaters turned to max hot setting, take it for a quick ride, let it cool down a bit, then top it off again.

The only other problem could be the engine itself has a bunch of buildup inside, a flush would fix this. It would of been evident when you pulled your water pump though. You would of found a bunch of buildup behind it.
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StandOnCliff
 
 Posted: 12-06-2011, 03:36 PM
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Post #17

Cooling System Flow
1 - HEATER - REAR (3.3/3.8L OPTIONAL EQUIPMENT)
2 - HEATER - FRONT
3 - ENGINE
4 - THERMOSTAT
5 - ENGINE OIL COOLER (3.3/3.8L OPTIONAL EQUIPMENT)
6 - WATER PUMP
7 - RADIATOR
8 - COOLANT RECOVERY/RESERVE CONTAINER
9 - COOLANT FLOW - PRESSURE CAP VACUUM
10 - COOLANT FLOW - PRESSURE CAP RELIEF

You want to go over all these connections and hoses as well as the component itself while pressure is applied. A leaking heater core is found if you smell coolant inside the vehicle when the heater is on or the windows fog up when the heater is turned on.
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wally59321
 
 Posted: 12-06-2011, 04:28 PM
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After you recheck the system for leaks per Cliff’s instructions if you find none then this may apply.

There is only one explanation that makes sense to me and it explains all your symptoms. You have air in your system. That explains why you hear the swishing sound from your heater core and why it over heats. Depending on how much air you have the water pump will not pump or pump very poorly. That would explain why when you rev it up you get better cooling.

Some cars/vans are just known as a beach to get all the air out. I suspect thats what was behind the other post you got about changing the water pump the right way.

I have a top secret code one method for getting the air out of difficult systems. It involves drilling a 1/8 inch hole in your thermostat and tilting the car front end up to help force the air to the radiator.

Look at the pic of the thermostat and see the 1/8 inch hole drilled on the side. This will let trapped air get passed the closed thermostat. You have to be careful were you drill the hole, not to close to the edge were it will cause a leak, and not to close to the center were it will ruin the thermostat mechanism. My other classified secret for the thermostat is using wheel bearing grease instead of RTV to seal it. I clean up the housing and cylinder block one time using a razor blade and or wire brush. From then on when changing the thermostat i grease up the housing, block, and gasket with a thin film of wheel bearing grease, and it always comes apart easily for the new thermostat, and in 10 years i have never had a leak.

After the thermostat is in then find a steep hill or if you have a floor jack raise the front of the van at least 6 inches. Start the van let it idle with heater on and slowly fill the radiator giving the air time to work its way out. Fill every bit of the radiator except the filler neck. When no more air bubbles come out go to the overflow tank and make sure it has fluid up to the minimum mark, this is important or as the van cools it will suck air back in to the system. Put your radiator cap on. If your system is working properly you should not have to remove it again. You keep the system topped off by adding to the overflow tank making sure when the system is cold you are above the minimum mark. If you keep checking this and keep it at the proper level then any remaining air will work its way out of the system naturally.
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wally59321
 
 Posted: 12-06-2011, 04:37 PM
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Post #19

I should say this to. A bad radiator will cause your problems. I know its new, but when i was looking for a new radiator for my van i found you could buy undersized radiators as well as oversized ones. The outside dimensions are the same on them, its the number of cores that is different. My van comes with a 2 core radiator but you can get a low performing 1 core radiator for it for less money. It would not surprise me to find out a shop cinched out and put in a 1 core. Did your cooling system ever work right after it was repaired?
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Anquan7
 
 Posted: 12-06-2011, 06:30 PM
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Post #20

First, THANKS to everyone's comments so far. The pics and diagrams are great, too! I am reading it all and trying most things. So please, for those following this thread and my plight, I will try to update and clarify things up to this point.

The radiator, about 4-5 months old, was working fine when it really counted, this past summer and the AC blasting most days. It was the first radiator and fan job I ever did myself, and was so proud it worked flawless.....

Alot of people, as well as alot of websites, says trapped AIR may be the problem. But shouldn't the reputable radiator shop (Glenrock Radiator, Norfolk VA) have figured that out and filled it/bled it right? And I have forward/backward flushed the entire system 3 or 4 times now, took off the core hoses too, you name it....and keep filling it.

If it is AIR trapped, why does 2 quarts or more vanish every trip out? Where does it go every day, every trip, if it is AIR trapped in the system? I have no idea here, I am not a mechanic, I am just asking question to try and learn my beast Caravan

If its a closed system, and the pressure test shows no leaks, then even if there is air pockets in there, and even if the water pump is not moving the water well, and the water in the block and head were boiling, it still can't go anywhere if there is no leak, so where is my coolant going to?

As soon as I come home from a drive, I run out and check to leaks, steam under the hood, and then underneath to see any traces of reservoir overflow wetness or drips, as well as water pump.....pipes....rear heater core, etc. Everything is always totally DRY....

I did let the 16 PSI sit in the system today with pressure tester for 2 hours. It started up immediatley and ran smooth, so I dont see signs of coolant leaked into a cylinder, but it still could have...

The think getting my goat the most now, is why it stumbles and stammers now when you rev it up to 4100 RPM or so. In Park, it really doesnt want to go beyond 4100 RPM, it starts really bonking and gently swaying the entire van with each rythemic bonk every 2 seconds or so. It never did that before. However on the road, in passing gear, it will jump to 5000RPM for 3-4 seconds, and seems fine, cant hear/feel any misfires.

No check-engine lights. I checked for any OBDII codes. ZERO codes...

So before I really try the parking on a hill, and that COOL idea about drilling a hole in the thermostat (thats neat, I like that, I want to try that!), before I do any of that, can it be explained to me why/how it can be losing 2 quarts each trip, with no leaks, because of air? How does air in the system make 2 quarts vanish? Where did it go? How can it get out?
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