Hi all!

'95 4x4, Vortec V-6.

If I had a leaky intake manifold, what symptoms would I be noticing? How would I go about positively diagnosing it?

Thanks for your help!

 

My experience:
- Dexcool turned to mud (brown and thick) due to exposure to the air in the radiator
- Trickle of coolant running down the front of the block
- Coolant level falling in the radiator with no other signs of leaks (water pump, hoses, radiator, etc.)
- Heater may not work because of air in the system

I was lucky, the gasket broke between the coolant passage and the outside of the block instead of inside where it would mix with the oil and effect lubrication.

I'm sure there will be others with symptoms.

 

You would be getting coolant in your engine oil, so a used oil analysis would pinpoint it with high levels of sodium from the DexCool. I have used http://blackstone-labs.com/, but there is also http://www.dysonanalysis.com/. Blackstone is less expensive, but Dyson gives more in the way of explanations. Either is well worth the small cost to see what is going on inside your engine.

 

With a lot of these, they leak to the outside. Mine leaked on the driver's side front of the manifold and could be plainly seen. If it is leaking into the engine, it is obvious... Your dipstick will look like someone replaced all of your engine oil with 5qts of chocolate milkshake.

As far as intake manifold gasket replacement goes, I found the link below to be a great tutorial on replacement.
GM 4.3L Intake Manifold Gasket Replacement

Good luck!!