GM 3.4 Leaking Anti freeze, need temporary fix

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Hi Guys
thx for all the previous help I've received.

Today's problem: 3.4 in Chevy Venture leaking anti freeze, appears to be from rear bank. It's probably the typical intake gasket problem. What stop leak do you guys recommend to slow this down until warmer weather arrives? Used my Stant to pressurize system and leak is dripping down block near tranny pan. Impossible to see where it's coming from-V6 in a minivan is a tight fit. Can't get van into my garage to fix due to the "garage queen" Chevelle!
thx in advance for any suggestions/help
Joe
 
It could be head gasket too. The 3400 cooks under/in the small engine bay of those vans. You could try some sort of stopleak but I wouldn't recommend it.
 
Can you drain the radiator? Whatever you use, drain the radiator, add the sealer, then refill the system. That way the sealer has a chance of making it into the engine block. I've used Bar's Leaks many times on GMs; if you add it when the radiator is full, it tends to sit in the fins in the radiator.

Although I've used the regular Bar's Leaks, I'd try the premium head gasket fix. It claims to fix head gasket and other leaks better then the regular Bar's Leaks.

The cooling system will end up somewhat gummed up with sealer after you use it, so subsequent drain and fills aren't a bad idea.

I've had good success using the basic Bar's Leaks on 2 GM vehicles.
 
As beast says it could be a headgasket. The stop leak I prefer are ones that are dry powered. The one exception to this is from the company that makes restore engine treatment. Its called radiator restore. I have used that with good results. The ones with Liquid contain something that attacks/swell hoses after continued use.

Almost every time I take one of these apart the gasket is also leaking into the oil. Just not in large enough quantities to be seen with the naked eye.

John
 
Stop leak may clog more than just your leak. And do you know if it's leaking in to a cylinder. The water jackets can be very narrow and you may end up with bigger problems than just this leak.
If you are going to put in stop leak please drive around for at least an hour after you put it in. It will get the coolant to cycle thru many times and eliminate or lessen the chances of a blockage somewhere in the system
 
thx for the replies Drew and Beast,

This thing is a bear to work on. Can't even change rear plugs w/o removing dogbones. Looks like a multiple day job changing intake and head gaskets. Weather here in NE Ohio makes it tough to plan any major outside jobs. Ever use the GM tablet sealers that are made by Bar's Leaks? Just looking to slow this down until spring. Will then pull apart to do correctly.
 
Originally Posted By: Clevy

If you are going to put in stop leak please drive around for at least an hour after you put it in. It will get the coolant to cycle thru many times and eliminate or lessen the chances of a blockage somewhere in the system


+100 This is very important. Do it with the heat on high so the product doesn't clump up towards the heater core valve.
 
Last edited:
Originally Posted By: Joe72Mart
thx for the replies Drew and Beast,

This thing is a bear to work on. Can't even change rear plugs w/o removing dogbones. Looks like a multiple day job changing intake and head gaskets. Weather here in NE Ohio makes it tough to plan any major outside jobs. Ever use the GM tablet sealers that are made by Bar's Leaks? Just looking to slow this down until spring. Will then pull apart to do correctly.


I've used the Bar's powder, which many say is the same thing as the tablets, just ground up. Fixed a leaky heater core in my Dad's Blazer and it never needed replacing after many years.
 
Try k&w head gasket stop leak. It worked for me on an old cavalier almost instantly. And when I did tear it apart almost a year later you would have never known it was there. I highly recommend that its priced well to
 
thx again for all the replies

Friend worked at at GM plant and claims they dropped a couple of tablets into each car on the assembly line. I looked at Bar's Leaks MSDS and a couple of the active ingredients are ginger and walnut shells??
Can't be sure if head gasket is intact, can't get a compression gauge near plugs due to tight fit. Oil drained seems OK, never had analysis done. No white smoke out of tailpipe. No CELs. Van seems to run OK.
Joe
 
The GM tablets may work for an intake gasket leak. Don't know about a head gasket. GM does recommend the tablets (made by Bars).
I've used the Bar's Leak in my daughter's 2002 Grand Am with the 3.4. Holding so far after a year but it's a temp fix. Whatever you use, I smashed the pellets before putting them in.
 
I'd get the Bar's powder that is actually crushed walnut (like the GM tabs).

In reality it is poor practice to bandaid something like this for months. Get it fixed. If the chevelle is that scared of getting wet, pay someone to do it and have a proper engine again. Dont take chances as it could propagate into worse things.
 
I had a leaking intake manifold with this engine in an Alero. I had assumed it was the intake manifold gasket being incompatable with Dexcool, but after repairs, don't think that was the problem (yet). The intake manifold leaked from the mounting bolts loosening up, and from the thermostat bypass tube, which appears to just be pressed into the manifold.
The GM fix is to reinstall the tube with sealant (there's a GM part number for this, but I think it's just red Locktite) and install new intake manifold bolts that come pre-equipped with Locktite to keep them from loosening up.
For a quick fix (if you don't have the thermostat bypass tube problem) you might try just retorquing the manifold bolts. In the Alero, one or two required a 10mm crow's foot wrench to use with the torque wrench. In your van, I'm not sure of the accessibility.
 
thx Philly

I'm leaning toward using the GM tablets. Thx for the tip of grinding them up. I'm hoping this is just an intake seal issue and hopefully the tablets will at least slow this leak down to a manageable level. If the tablets don't work, will drain and flush and try one of the above recommended sealers by Bitogers. I've read that Subaru also has some leakage issues in some of their cars, they also sell tablets to solve the problem IIRC.

The van was purchased by a friend from a low budget used car lot. I've already fixed multiple problems that have occurred. Last owner must have known about previous problems and just traded it in.
 
Originally Posted By: JHZR2
I'd get the Bar's powder that is actually crushed walnut (like the GM tabs).

In reality it is poor practice to bandaid something like this for months. Get it fixed. If the chevelle is that scared of getting wet, pay someone to do it and have a proper engine again. Dont take chances as it could propagate into worse things.


LOL "Chevelle getting wet" : ) Right now it's on 4 five ton jack stands with enough stored underneath/next to it to fill a shed! Probably take me longer to dig it out than to fix the van! When I clean my garage every spring, I have so much stuff pulled out of the garage and onto the drive, that people stop and ask if I'm having a garage sale!

Van belongs to a friend who's working at a minimum wage job w no bennies. I'd guess the repair bill would be about 1k. Not affordable in his circumstance. I agree with you totally JHZ, job should be done correctly and ASAP.
 
Nope, checked that. Not leaking from pump or drive belt side of engine. Thermostat housing dry, no leaks at any visible hoses. Felt heater hoses-dry.

Leaks from somewhere in the rear bank. Drips hit the ground near middle of van, near the trans pan. Really hard to see where on this van, very limited access to rear bank and firewall. Next step may be to put in on ramps and pressurize it with my Stant, then check underneath. Doubt if the view down there is any better tho, tranny, steering rack etc blocking a clear view.
thx for the response
Joe
 
Take it for what its worth but I have a 2001 Grand Am GT with the 3400 V6 that also starting leaking coolant back in 2006 from where the trans pan is(typical GM LIM leak) and I just put Bar's leak(liquid aluminum kind) into the coolant overflow bottle and it sealed it up. I added a second bottle in 2009 when I noticed it starting to leak very slowly again and soo far it has been holding ever since. I have never changed the coolant on the car and I am very afraid to do so at the risk of messing up the engine.

If you only plan on keeping the car a few more years the Bar's Leak is the way to go.
 
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