Not A Truck Question Intake Coolant Leak.

dreamingmuscle · September 21, 2009

I know its not a truck but I can't find a decent forum for GM mini vans

Any way I have a 98 Olds Silhouette With a coolant leak. The vehicle was running rough with a misfire code coming up. Then it started using lots of coolant. Pulling the oil filler cap confirmed where the coolant was going. Momma said the temp ran up to the red but never got entered it. She turned off the A/C and it went down, then would climb again when she had to stop at a light. All this happened with in 10-15 minute period. Thank God I got one smart enough to know only to drive the car as far as she needs to get to a safe place and call me.

At first I thought blown head gasket. Then I remembered these were problematic for intake coolant leaks. Well I have pulled the intake and examined the gaskets but I can't find a problem with them. Not that I'm a Intake Gasket guru or anything. Went ahead and changed the spark plugs. First time at 167000 miles I believe. They still looked pretty good, not wet at all, only a very slight film of build up and the gap was still close to 0.60

I also don't see any oil in the water jackets in the heads either.

Anyway where do these intakes typically leak from?

And what are the chances that it's a head gasket and not the intake gasket?

Since I have the all the rocker arms and push rods off could I do a cylinder leak down test to tell if its a cracked head gasket?

Thanks Glen

mtm700 · September 22, 2009

Most times a cylinder leak down test don't show crap with these engines as far as diagnosing a head gasket. They are very well known for head gasket failure, done more than my fair share of these. Most times, the cylinder heads are cracked between the valves. Once the heads have been cleaned in a parts washer, the cracks are quite visible. You can buy reman heads at a Carquest auto parts store, or even possibly at NAPA, for around $350 per head. So, you might as well keep tearing it down, sounds like a head gasket to me, probably the rear head. If you do one head, might as well do 'em both. Don't forget to buy new head bolts, you absolutley cannot reuse the old head bolts. While its apart, replace the oil pump drive o-ring and thermostat.

dreamingmuscle · September 22, 2009

I was hoping someone wouldn't say that. I don't have the capabilities or facilities to lift the vehicle high enough to get the engine out. So getting the exhaust manifold bolts and other misc exhaust shield bolts out is going to be a real pain on that rear head. I might just put it together and hope for the best. And yes the might as wells will be replace as I go.

Glen