Found out my coolant leak was the intake manifold gasket and my mechanic said the engine ate a lot of coolant. How soon should I do a rebuild or how much longer does this engine have left and what's the typical costs involved? I'm more concerned about shop labor costs since rebuild kits look to cost 500 bucks at the most for a 4.3.

 

Do not run the engine again until you have the coolant leak fixed. Once the coolant leak is fixed and the oil is changed, listen to the engine. If you hear bad noises, you need to rebuild it. If it sounds fine and you have good oil pressure, drive it 'til it breaks and fix it at that point. You may not have done much damage. Have you shortened the life of the bearings? Probably. But you won't know to what extent unless you pull the engine and tear it down. Something I wouldn't consider until I had a good reason to.

 

Oh the coolant leak is fixed, though I had to drive my ailing Blazer 90 miles back home when it happened. After routine brake work i'm now down 800 bucks. He said the oil pressure was fine and the truck was great when he was finished and it runs great now. Winter time is the time when i'd have the funds for this, I just wasn't sure if waiting until its toast was the best thing to do.

 

I heard Blazers are "notorious" for coolant leaking into the intake manifold or engine. Is this true? What are some ways of preventing this problem? Checking the gaskets I assume?

 

I'll answer the question, but I don't want to delve off the original topic for too long. The intake manifold gaskets are known to be of poor design. Many people would atribute this to the coolant used (please, please lets not get into that in this thread), but it really is a problem with the design of the gasket and the materials chosen. The aftermarket gaskets now available should not have these problems. I know on some of the other engines with problematic intake manifold gaskets, GM has released an updated gasket that has an aluminum frame instead of the plastic frame that originally was used. I am unaware of this design change on the 4.3L gaskets.

My advice would be to keep an eye on your coolant level and on your oil. At the first sign of losing coolant or milky buildup on the dipstick, you need to have your cooling system integrity assessed.

To the OP (original poster), how is your engine running now? Does it seem to have good oil pressure? Does it make any odd noises? If not, I would drive it until it gives you a reason to tear things open. I've rebuilt many engines in the past ranging from I4s to Detroit diesels and D8 doser engines. If you want something on the cheap, I would look into getting a low mileage junkyard motor and maybe replacing the intake manifold gasket before you drop it in. If you have a bit more money, you could go with a remanufactured engine from a number of reputable sources (jasperengines.com to name one). If you have the time, tools and know-how to rebuild the motor yourself, then it is a very rewarding process, but it isn't something to tackle over the course of a weekend. If you are paying someone else to do the swap, the easiest way to get it done is to have a replacement motor there for them to swap in. This will really cut down on the labor costs.

You can typically pick up a low mileage 4.3L engine from a junkyard for under $750. I just saw an 4.3L out of an '02 S10 for $650 at the local pick-n-pull yard. Odometer showed 34k miles, but was totaled after being rear-ended.