We have a 2000 suburban with 160K miles. Recently we've been going through a bunch of coolant and oil. Probably about a half gallon of coolant and a quart of oil per week, but it's not ending up on the ground. The driveway under the car is always dry. Even though everything is running fine we are at the point where it's time to get this repaired. I'm assuming this to be a head gasket problem, but what are other possibilities? Could it be an oil cooler issue? Cracked block (which obviously would be worse than a head gasket)? What kind of tests can be done to pinpoint the problem before we jump into solutions?
Thanks - Drew

 

check the condition of oil and coolant. if oil is milky it could mean blown gasketked head/block. check coolant for brownish color. also, pull plugs to see condition.

 

Thanks. I'll do that. Oil seems thinner, but I wouldn't call it milky. I haven't tried draining any coolant yet. Coolant in the reservoir doesn't look brown.

 

pop cap on radiator to check coolant. pull the dipstick, check for milky, or possibly water spots. when you first start rig, watch the exhaust for blue smoke or steam. the oil could be burning. plugs would tell ya this too. hope you can find issues.

 

Check the underneath side of the oil fill cap. If it has a gray, jelly looking substance on it, the coolant is going in the oil.

 

Read the spark plugs. What do they look like?

Here's a page on the various conditions -
http://www.ngksparkplugs.com/tech_su...qs/faqread.asp

 

I didn't have the time or energy today to check the spark plugs (I assume I'd be looking to see if it has a burned oil appearance), but the oil is not milky/foamy/watery and the coolant (via the "reservoir" as the radiator doesn't have a cap) looks like coolant. If this is a head gasket leak will a compression test show that? Or what will determine the problem? We have had coolant system pressure tests in the past and the system always holds pressure for hours (overnight). I don't want to spend the money on a head gasket replacement if that's not the issue, but it's better than replacing the engine - which is been proposed by a shop that hasn't fully diagnosed the problem? What else could this be?
Thanks - Drew