Hi All, and thanks for your contributions.
I've done my research as best I can. Just want to verify and ask a few questions.
2002 2dr, 2wd blazer 4.3. Runs good. No odd engine noises, water in exhaust after (probably prior to) intake gasket replace.
GF's son brings me the blazer for "a coolant flush because I can't keep the coolant level up". Strong coolant odor as soon as he pulls into my shop.

I read on here about changing the intake gasket. Did that due to obvious leaks and loss of coolant. I used the felpro gasket set.
The old intake gaskets were the plastic type and showed clear signs of leaking externally. All intake seals appeared to be doing their job. Only one small area from coolant MAY have possibly been leaking into the plenum area. Oil was old - due for a change and appeared to be only oil. I cleaned my oil drain pan very well prior to draining oil and found zero traces of any coolant in the oil. I changed spark plugs and all 6 were in identical shape and color was good.

Got the intake gaskets done and found that while doing a flush the coolant had bubbles in the radiator, exhaust was cloudy and water was dripping from the tail pipe and puddles under the muffler. The coolant will not fill to the top of the radiator for more than several seconds. I can hear it draining internally.

I know I may have an intake gasket that didn't seat properly. But, the design should have held them in place and the manifold sat right back into place.

This brings me to the head gaskets. I'm sure the vehicle was overheated on several occasions.

Anything else I should check prior to digging back into the engine? I should have inspected more carefully prior to the intake removal. Live and learn...

From my research I see it's possible to pull heads while motor is in the vehicle.
I'll take the heads to a shop to have them tested.
I see a cyl psi test is often recommended. But I know I have to dig in anyway. And, based on the plug inspection would a psi test tell me anything that may help diagnose?

Sorry for the long post. Am I barking up the right tree?

 

One of the byproducts of a catalytic converter is water, so a certain amount of water from the tail pipe, while running, is normal. Obviously if there are clouds of steam, there's a problem. If coolant is entering a combustion chamber, the engine will misfire. Another clue is if the radiator hoses pressurize and become rock hard just after starting the engine. There are a few ways to tell if coolant is leaking internally, ie head gasket or cracked cylinder head. One is a gas analyzer inserted into the radiator and check for hydrocarbons, (there should be less than 50ppm). Provided the analyzer is 100% acurate, the results are 100% acurate. You can also pressurize each cylinder seperately with compressed air and watch for bubbles in the radiator. There are also chemicals that will check for the presence of HC and CO in the coolant. Pressurizing the cooling system is great for visually locating external leaks, but does nothing to pinpoint an internal leak. A compression test is used for checking piston rings. A cylinder leakage test is used for diagnosing intake and exhaust valve leaks.

This article goes into detail: How to Test for Head Gasket Failure


Blown head gaskets are not a "common" problem on the 4.3L but, if the engine has been overheated, the heads can crack, as they will with most engines.

 

I always take a whiff of the exhaust on a suspected head gasket that is watery/ steamy exhaust. If I get a instant sore throat I will to the HGs. I did em on my 04 after the ol lady overheated it on a 107* day, the temp gauge was pegged at 260* and was so hot you couldn't open the hood. I love crappy thermostats. They are not a pleasant job to do on a s10 but they aren't too bad.

 

That's a new one on me. But I do test my tools by taking a solid whack at my thumb with a hammer. If I my thumb hurts instantly then I know my screwdriver is bent.

 

Thanks for the replies! And the link. Part of me says the leak is so obvious I should just tear into it. But, I'll do the reasonable thing and do some tests. Besides, I just got a new mityvac for my chainsaw hobby that does pressure and vac.

I can pressurize the cylinders via air compressor. How much pressure should I shoot in there? 220, 221, whatever it takes?

I assume the coolant system should be around 12 PSI as indicated on the rad. cap?

 

Your Mightyvac isn't going to help you with this one You'll need a cooling system pressure tester. Remove the radiator cap, hook up the pressure tester, pump it up to ~15psi and look for leaks.

Pressurizing the cylinders, (Mr Mom ) only needs 150, 151psi 220, 221 is a bit of overkill, but won't hurt it. If you put the cooling system pressure tester on the radiator, you can watch cooling system pressure. If it rises, you got a leak!