95 Blazer Coolant Leak, Intake or Head Gasket?

[nova72]

Hi, I have a ’95 Blazer with a 4.3L Vortec V6. The engine has developed an internal coolant leak. No external leaks are visible. A considerable amount of white smoke comes out of the exhaust. The coolant level drops and there appears to be coolant dripping out where the right exhaust manifold mates to the Y-pipe. I pulled the right side plugs. The #6 plug appeared to have a little more buildup on it but all appeared dry. I cranked the engine over, but nothing came out of the plugholes. The question I have is, could this leak be from the lower intake manifold gasket or a head gasket problem or worse? Thanks!

[MT-2500]

Originally Posted by nova72

Hi, I have a ’95 Blazer with a 4.3L Vortec V6. The engine has developed an internal coolant leak. No external leaks are visible. A considerable amount of white smoke comes out of the exhaust. The coolant level drops and there appears to be coolant dripping out where the right exhaust manifold mates to the Y-pipe. I pulled the right side plugs. The #6 plug appeared to have a little more buildup on it but all appeared dry. I cranked the engine over, but nothing came out of the plugholes. The question I have is, could this leak be from the lower intake manifold gasket or a head gasket problem or worse? Thanks!

Any external leaks on top/rear/front of intake?
Has intake gasket ever been replaced?
Does engine heat up fast or overheat on a pull?
To make sure it is not a head gasket they make a chemical block test for exhaust gas from headgasket leaking into rad coooling system.

If you plull lower intake gasket you should be able to see if it is cracked out or leaking in that area.
If you replace it use only the felpro problem solver hard rubber/steel intake gasket.

[Rick Norwood]

In my humble opinion, (which is subject to change without notice) is that the cloud of white steam (not Smoke) coming from the exhaust pipe is usually a head gasket, but not always. (That was a big help).

The Exhaust Gas test as MT2500 mentioned is a good thing, but a compression test might also tell you something.

[toddman67]

A combustion leak detector test tool in the radiator would rule out the head gasket. A coolant leak pressure tester hooked to the radiator might help as well. If the guage increases quickly and seems high would also indicate a problem as well.

[nova72]

Well, I finally got around to replacing the upper and lower intake manifold gaskets. The right rear area where the lower manifold mates to the head appeared to be damp along with the #6 intake runner, but nothing conclusive. The intake manifold gasket appeared to be deteriorated but not through to the water passage. I finished the job and started it up. The truck continued to smoke for 20 minutes so I thought that I had not solved the problem. I drove it and after about 1-2 miles, it stopped smoking and ran fine. No problems after about 100 miles and the coolant level is steady.

[MT-2500]

Thanks for posting back how it went.
Good luck