GM 4.3L air in coolant

[segfault]

My grandfather has a 1996 Chevrolet S-10 with the infamous 4.3L engine. A local mechanic replaced the Dex-Cool with Prestone. Now, there is a distinct gurgling sound from the heater core area, whether or not the heater is running. Is this cooling system self-bleeding? I could have sworn I saw the 4.3 on a list of engines that must have the radiator cap elevated to properly bleed, but can't find any links that indicate this...

Is there a special procedure to follow when changing coolant in this engine, and what course of action would you guys recommend to get rid of the gurgling sound? I ask here because it seems like we have quite a few members with GM 4.3L V6's.

Thanks...

 

[Chris142]

Did the guy that flushed it remove one of the heater quick connect fittings on the engine?

Those stupid things are made from pot metal and always break off. But they have a restricter built into them so if someone replaced one with a regular pipe nipple the restricter is gone. This will cause weird noises in the heater.

 

[2004 F150 4x4]

When I changed my radiator hoses and added some coolant a few years ago I noticed the same thing? Has'nt seemed to cause any problems on my 96' GMC 1500 that now has 108000 miles on it. Not sure wht you called the 4.3L V6 "infamous" It is a good engine. Basically a 5.7L(350cid) with 2 cylinders shaved off. Same bore, stroke etc... These are great motors.
My .02 anyway.
Dave

 

[ikeepmychevytoo]

Just in case... if your antifreeze concentrate wasn't at least %50 I'd raise the concentrate first.

My 2.8 V6 GM just wasn't working right with a lesser concentrate. When you stop the engine and circulation stops rad. cap alone cannot handle the pressure requirement not to boil for the portion around the hot cylinder walls hence creating some air bubles, and even rushing coolant out from the bowl if it is not a newer pressurized bowl system. During the process there might be some air left in the system. Next time I start, the heater was sounding like a waterfall for a while. On my open-to-air bowl coolant was boiling creating a gurgling sound. 50/50 coolant and no coolant loss or boil anymore. A little unnoticed boil might be unavoidable though.

 

[frankiee]

Take a carefull look at the top heatercore hose that it is not to high. Use a level if need be. It should be lower then the height of the rad cap.
I think you will find that it is higher and has air in it.
Bleed that line.

 

[segfault]

I called it infamous because I thought it was one of the engines afflicted with the gasket problems. Thanks for the tips, I will forward them.

 

[Chris142]

quote:

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Originally posted by motorguy222:


I think the 3.1 and the 3.4 are the ones with intake problems.

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I see plenty of 4.3's with bad intake gaskets. It's a Dexcool thing.

IMHO GM V engine + Dexcool= trouble regardless of engine size.

 

[motorguy222]

The 4.3 liter is basically a 5.7 liter(350)with two cylinders cut off.

They are a very good engine.

I think the 3.1 and the 3.4 are the ones with intake problems.

 

[motorguy222]

The 3.1 nad 3.4 have a bad intake design(plastic)and fail a lot.It isnt really a gasket problem but a design problem.

I havent heard about the Dexcool causing gasket failures.

I dont refute it either.

I have learned something new.

 

[BlazerLT]

quote:

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Originally posted by segfault:
I called it infamous because I thought it was one of the engines afflicted with the gasket problems. Thanks for the tips, I will forward them.

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Same 4.3L here and your rad cap needs replacing.

It allows air into the system due to the crappy fibrous rubber gasket it uses.