DodgeTalk Forum banner

Status
Not open for further replies.
1 - 12 of 12 Posts

·
Registered
Joined
·
23 Posts
Discussion Starter #1
Did a tune-up today on my 03 Quadcab 4.7L with 103,000 miles. First thing I did was seafoam by using the vacuum line, some in oil and the rest in the gas tank. Followed directions, smoke, drove it about 10 miles then changed the plugs. Was original plugs and went with ngk iridium 6441's and put in a k&n air filter. Changed the oil from penzoil 10w30 to mobil 5w30 (not synthetic) and am using a fram hp-1 filter. Also changed the pcv valve. Took the truck for a test drive and after a few miles it sounded like a gust of air under the hood and a slight stagger in performance then normal( a little noise like the fan was loose or something just after the air noise). Drove it another short distance and the same thing. Also on my overhead mileage guage it has dropped from normally about 14-15 mpg to 8-10. What has happened? Anyone else ever experience something like this?
 

·
Ramistered User
Joined
·
6,420 Posts
Sounds like the fan clutch stayed engaged. That would explain the rush of air sound and the gas mileage suffering. It doesn't sound like anything you did during the routine tune-up. Maybe just a coinciedence that the fan clutch went out at the same time as the tune-up
 

·
Ramistered User
Joined
·
6,420 Posts
Did you attach the brake booster line back up?
 

·
Registered
Joined
·
23 Posts
Discussion Starter #4
Yeah all the lines were hooked back up. The brake booster line, had to remove the air box and all and removed the hose hooking to the back of it, those were the only lines that were removed...the short hose that the pcv valve hooks to was a little worn (small cracks) and when pressed you could hear a light hiss but we put electrical tape around that hose to help seal it off just in case. The engine runs smooth except we broke the end of the electrode of one of the spark plugs (the ngk tapers down pretty small) but we believe it is firing as no pull down in engine when plug is unhooked from the coil so ill call that good. That was the only issue or problem during the tune up. We let it idle for about 10 minutes and the fan ran with no problem the whole time with no abnormal noise. Truck seems to run fine except for the couple of times it did that.
 

·
Ramistered User
Joined
·
6,420 Posts
Well if you broke an electrode, still running your truck and your wondering why you had a abnormal noise then I cant help ya. Maybe i'm not understanding.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #6
The tip of the electrode on one plug was broke. Sounds and runs normal. Drove down the road, normal, after a few miles sounds like a releasing of air (not a miss like a sparkplug) and then a sound like something rattling like the fan but all that lasted for just a few seconds and during the air sound the enging lagged just a bit, not a big lag but a tad noticable, then it did it again after a couple more miles...did this about 5 times total out of about 10-15 miles of driving...drove it a few more short distances and it hasnt acted up anymore, even let it idle for about 10 minutes..about the sparkplug, we think it is firing because the engine doesnt pull down, you have to unplug 3 of the coils for the engine to pull down anything noticable and when we plugged the broke plug coil back in the engine leveled out as if it was firing. Big difference in a sparkplug missing and a spew of air and a clang.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #7
Another thing I noticed...before when driving 70 mph the rpm's would be around 1800 and now they are running around 2-2100 rpm's...dont know why it would be different.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #8
I just thought about this, I had the a/c running on low the whole time and I had came across a couple of older posts about a loud hissing or something with the air conditioner. Wonder if this is related to what I heard? Anyone else?
 

·
Registered
Joined
·
1,617 Posts
Revvv said:
change the busted plug
Absolutely!!! Even though you’re not experiencing any drivability problem due to the broken plug your just asking for disaster! When you broke the tip you also undoubtedly cracked the remaining porcelain insulator. The cracks are likely microscopic and unable to be detected with the naked eye. But never the less the extreme heating and cooling of the plug could cause the crack to expand and cause a portion of the porcelain insulator to break off in the combustion chamber...THIS WILL RUIN YOUR MOTOR!!! It will be well worth the $10 and 1/2 hr to replace the plug.

As for your pull down test; this really doesn’t work very well on today’s computer controlled engines. The computer will since the disconnected plug and will do it's best to optimize the system. Theoretically and without computer correction, if the plug was firing correctly when disconnected the engine idle should DROP or pull down by about 1/8th (idling at 800 before disconnecting the plug, 700 after) this isn't happening because the computer is adjusting the other cylinders to compensate for the misfire.
 

·
Registered
Joined
·
1,882 Posts
^^ ditto. ac will cause some nice seat of the pants power loss. when mine kicks on you can hear a thud as the clutches engage. sounds normal minus the mpg lost. oh and possibly a worn o2 sensor. they dont like havin carbon being blown through the exhaust as they clog easily. although its questionable as to if its carbon or seafoam that makes the smoke show.
 

·
Registered
Joined
·
380 Posts
Spark plug Porcelain plays hell on the tops of pistons and combustion chambers. We replaced the head and #3 piston on my brothers 94 BMW 3series after he over torqued a spark plug, broke the porcelain on it and ran it for about 5 minutes. Its amazing how strong porcelain is. All due to a $10 plug.
 
1 - 12 of 12 Posts
Status
Not open for further replies.
Top