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Draining Coolant

44K views 17 replies 12 participants last post by  spun360 
#1 ·
I'm changing my radiator tomorrow. What is the word on taking out the coolant plugs on the block?

My Haynes manual says do it, and that the holes may be rusted over and need a good poking to open them.

1.Is their a risk of this poked rust clogging my new radiator, or will all the loose stuff come out once the coolant starts flowing from the hole?

2.I read that on some vehicles removing the plugs is not advised because they are often so corroded that they break off, is this a problem on our trucks?

I've never done this because I didn't know the plugs were there.
 
#2 ·
I wouldnt do it. When you have the hoses off just flush it real good.
You stand a good chance of creating a lot of unneeded work by pulling the freeze plugs its not worth the chance.
Flush it good with clean water, mix up some new anti-freeze, with a 50/50 mixture and be done. You could change the bypass hose, just to be safe, and maybe your upper and lower hoses, and T-Stat, if needed. Thats all I would do, if I was only changing the radiator.

barracudadave67 aka Dave C.
 
#3 ·
Not the freeze plugs. According to the manual there is a bolt on each side of the block specifically for draining coolant.

I was thinking about flushing too, but I don't plan to dig in and take out the thermostat, so it would be pointless, right? I know I should, but this is sort of a band aid repair until I get everything amassed to do the plenum fix and all the little stuff that goes with that.
 
#4 ·
umm i have never heard of a ''coolant drain plug'' on a motor, there are only freeze plugs, there is however a coolant drain plug on the bottom driverside of the radiator
 
#6 ·
There most certainly are drain plugs on each side of the engine, usually right above the oil pan mounting boss. They are usually a brass pipe plug. They drain the coolant out of the cavities that surround the cylinders.

I would definitely pull these out and drain all the old coolant. You can take a small brush and scrub the holes a bit to get the corrosion out, then with the plugs still out you can flush with some fresh water. Then let it all drain out, replace the plugs (maybe with some petcocks for the next time?) and refill with antifreeze mix. Done.
 
#5 ·
Yes, there is one. I just took mine out today for new antifreeze. Its on the drivers side betweeen the freeze plugs. Its a 9/16 bolt and you will probably need a small breaker bar to get it loose. I would take it out as long as it comes out fairly easy. It took about 75 pounds of torgue to get mine out. Take it out if you want to get all of the old antifreeze out.
 
#7 ·
ehh learn something new everyday, im new to the mopars
 
#8 · (Edited)
i have a rubber plug in my 99. was leaky when i first got it and had to tighten it up a tad, so already knew about it.




if your going to use something like prestone super radiator flush, id back flush to help prevent ur heater core from clogging (if your system was dirty) id probably rid my air hose maybe at 20psi to give it more agitation (bubbles) and little more pressure but not too much air, might stress the gaskets
 
#9 ·
i replaced mine when i rebuilt my engine, they were petty corroded but i replaced them with brass instead of galvanized steel and i probably wont worry about it for another 150k. But i just put a water hose in the lower hose on my jeep and ran the engine without a t-stat and let the water run out of the upper hose.
 
#10 ·
That rubber plug isn't OEM, it's a replacement for the front right freeze plug.
The drain plugs near the back of each bank of cylinders. They aren't bolts, they're 1/4"NPT plugs and if the coolant is flushed they won't corrode in.
Use pipe sealant on them rather than over torquing them and they will come out easy next time.
 
#11 ·
The driver side one is behind the starter, so I didn't even bother. The other one was fairly easy to get to, but it wasn't budging even with a 2' breaker bar, and I wanted the swap to go smoothly(didn't want to risk breaking it), so I ended up leaving it too.

The thread wasn't a total loss though, those two guys found out about the drain plugs.
 
#12 ·
can u guys see this pic? if not ill move it to photobucket.



and yes to above, going by the picture, it does look like oem would be brass/steel freeze plugs, and my rubber one is aftermarket replacement (dunno may vary by mfg year, I cant really read the plug to see if the mfg is an aftermarket name or not)

but i do like the convenience of the removable plugs, for flushing.
 
#13 ·
Good info, learn something new all the time.
 
#16 ·
prestone flush is 75% glycol and 25% bs. use pyroil, in a little black pint. it packs a punch! run it for a week then drain. yes remove the block plugs. driver side is behind the starter which you will have to remove to get to. in the least remove the passenger and when you reinstall plugs, apply teflon or plumbers pipe dope to allow easy removal next time. yes they are hard to get out," a six sided socket only, so as not to round them off."
 
#17 ·
With as many times as I've pulled the engine on my 96 you'd think I would have heard of this. I have a 360 hanging on the cherry picker in the garage Im gonna go look at those things!!!
 
#18 ·
the driver side is behind the starter and the pass is above and slightly forward of the engine mount, at least on my 96 360.
 
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