Hey all,
I'm new to this forum, joined today to help out a friend of mine.
(He has a 2000 S10 Blazer with 4.3L V6.)

Few weeks ago blown radiator has been replaced. I don't remember if he said the engine was overheated, I remember that he said massive steam was coming out of the hood. Other than that, nothing needed to be replaced according to him.


Here are the symptoms..

1) Coolant does not leak when the engine's off. But a stream of coolant leaks when the engine's running.

2) Heater on/off engine off= Doesn't leak.
Heater on/off engine on= Leaks.

3) It's leaking from the left(passenger)-rear side of the engine, right by the firewall, above the starter. (Pics below)


So far I have checked..

1) Front of the engine and heater hoses.
Thermostat, waterpump, both radiator hoses, radiator itself. There was a bit of leaked coolant around the t-stat, but I don't think it was actually leaking from t-stat and went all the way back of the engine.
And the heater hoses weren't leaking at all.

2) Drain plugs, freeze plugs.
At first I thought drain plugs on GM engines might have washers as well like my car. But they weren't leaking, just rusted. Freeze plugs were in place as well.

3) Possible point of leak.
I had to remove the starter to get a better view. Around the exhaust manifold was soaked by coolant, that white thingy(blue numbers written, 605) wasn't soaked.

(Left side of the picture is rear of the car)



Here's what I'm suspecting..

1) Some by-pass hoses I never heard of. I've only worked on German/Japanese cars..Some mentioned an existance of by-pass hose, I never heard that in my life.

2) Gasket..Well the only gasket related to cooling system would be a head gasket, right? I sincerely hope it's not head gasket. No milky engine oil and white smoke, btw.


Can anybody give me an idea what could cause leak in left-rear side of the 4.3L V6 Vortex engine??? Haynes manual doesn't say anything about it, it doesn't even have a diagram. So disappointed.

Any tips would be helpful..Thanks in advance!

 

Does it look like it my be seeping up from between the valve cover and intake manifold? Very common for the lower intake manifold gaskets to fail in these trucks. If that's what it is, the gasket is about $90 and you'll want to fix it before coolant mixes with the oil.

 

Another vote for a leaky LIM gasket. A leak at the passenger rear of the LIM gasket can look exactly like what you described.

 

Thanks for replies! This is quite new to me actually. Coolant related to inletfold system..Phew, much more to learn.

Thankfully he bought a Haynes manual, this seems to be helpful for inletfold R&R. Looks like coolant passage holes of inletfold gasket is our prime suspect! I will keep searching for pictorial DIYs. (Quick DIY link assistance would be very awesomely greatful lol! )

Thank you very much again for leading me to right track!

 

How To Replace Intake Manifold Gaskets On A GMC Jimmy 4.3 Liter V6 To Fix A Coolant Leak - GM Truck Engine Repairs

That's what i used. I don't know if some things may be a little different or not, but that should cover it pretty well.

 

Here is the one for this site.
https://blazerforum.com/forum/tech-a...-4-3-v6-46168/

 

This is why I love American car forums, so many great DIYs, informative and knowledgeable members! Thank you again for all your helps, I'll keep it posted

 

My .02 is the lim also. When he replaces the gaskets be sure to get the felpro brand. When I did mine I could only buy a kit that came with valve cover and upper intake manifold gaskets and some others. I used them all.

 

No problem.

Is this the one you used? It's what I put in mine a month or so ago.

Felpro/Intake Manifold Gasket (MS98002T) | 1996 GMC Jimmy 4WD 6 Cylinders W 4.3L SFI | AutoZone.com

Comes with valve cover seals, grommets, plenum, lim gasket, throttle body and other stuff.

 

Tell your friend this is a normal and EXPECTED repair on these engines. If it has never been replaced of late suggest that he considers replacing the water pump while he as it torn down to save future time/money. With new quality intake manifold gasket materials it should not be a repeat failure point. We developed a dripping leak at about 175K miles and before that had to replace the heater core (Dexcool issue) and since the radiator.

His gasket started to fail long ago. Some do have the spider fuel injection system tested/cleaned when it is all opened up. Actually exchanged remanufactured ones are only about $200 while one is there.

Our 2002 Blazer is at 193K with no injector problems since we have owned it. The 1998 that we just purchased and blew up was still running when we got it with 524K real miles on it and nothing was mentioned about the injectors ever being replaced but there was a miss at higher RPM's that became a full time miss after a valve train wreck.