Manifold Gasket leaks

[MarkStrobel3367]

I own a 1998 GMC Safari Conversion van. It appears that the Manifold gaskets need to be replaced as they are slightly leaking.

1) Short of replacing the gaskets which can be quite costly, is there some product that I could use to effectively stop or slow down the leaks without negatively affecting other parts of the vehicle?

2) With leaking gaskets, can the coolant spill into the oil?

Thanks.

[Blue Bowtie]

A replacement gasket set for both the upper and lower intake is only about $40.

Leaking intake gaskets can allow coolant into the sump. Coolant in the oil is very, very bad, since the coolant has an affinity for the soft metals on engine bearing shells, like the tin, copper, and antimony. Running with coolant in the oil for any length of time is a fairly sure was to destroy the crank, rod, and cam bearings.

[Steve47]

I just had my intakes gaskets replaced in May 08 - Apparently I have just spun a bearing.

Any sure fire way to know 100% if the intake gaskets are leaking /gone?

Mine is still under warranty from the dealer that did the job. I may have a case here.

[old_master]

Pressureize the cooling system and watch pressure, if it drops, there's a leak somewhere. Coolant can leak internally and/or externally. If there is coolant in the oil, most likely the intake gasket is leaking internally. If the pressure doesn't drop, pressureize each cylinder with compressed air and watch for bubbles in the radiator. If bubbles are present, most likely a head gasket is leaking.

[astro44]

I have a '98 (190,000 on engine and 80,000 on transmition) as well and have just expierienced loss of anti-freeze internally. In the past 1.5 weeks I have replaced almost 2 gallons of anti-freeze. I assume internally as I have not seen any puddles.

I took it to my mechanic and he confirmed it is leaking internally and with out tearing it apart is thinking, from his expierience and my explanations, the bearings are shot ?? This would require new engine. He has a small shop and doing this work was not something he wanted to takle. I took it to another shop here's where I'm looking for opinions...

This shop drained the oil\anti-freeze put new OIL in and apparently the motor has no knocking. They could not pressurize the system as the bad gasket would not allow them to. In their opinion it ran smooth and this is a sign that bearings probably are not shot and replacing the in-take manifold gasket could be all I need done.

I'm struggling with my limited mechanical knowledge, do I spend the $600 and get the in-take manifold replaced and hope this fixes it? Do I get a rebuilt 4.3 and put it in (pay someone) or cut my losses get rid of it as is and move on.

I hope this makes sense but I'm trying to decide what to do next. Any opinions or expieriences would be appreciated.

[Steve47]

There's a test you can have the mechanic do. It's the sniffer test. They can remove the cap on the radiator reservoir and check for CO2. If they detect it you have a leaky gasket. Due to the mileage I'd get rid of it if it's within your budget to do so. I did. Even after I had the dealership replace mine further problems cropped up. Just my opinion. Good luck.

[old_master]

Typically the "sniffer" test will determine if combustion gasses are present in the coolant which would indicate a faulty cylinder head gasket. If an intake manifold gasket leaks coolant internally, it will drain into the crankcase. Pressure test the cooling system, and watch for external leaks. If there are no external leaks and the pressure still drops, the intake gaskets would be highly suspect, (very common on 4.3L engines).

Provided the oil pressure is within specs, there is no internal damage to the engine, and the basic engine is in good condition, it may be a worthwhile investment to replace the intake gaskets.