97 Blazer Coolant Loss

ScottyBoy · February 28, 2009

I just got a 97 blazer and among other problems, I've noticed repeated coolant loss. It doesn't run hot (which may be simply because its cold this time of year) and no visible coolant leaks or puddles are seen under the vehicle. When the engine is running, I can smell a slight antifreeze smell. Every time I start it, I notice the coolant level is low, so I add more to fill it up yet it is low again the next time I start it and check it again. The radiator also has a muddy looking dark brown sludge/residue in it. The best way to describe it is that it looks like dark mud or used chewing tobacco. I got the blazer from my brother and he just had a new radiator and thermostat put in less than 3 months ago, and has driven it less than 500 miles since then.He had overheating problems before changing the radiator and he said it hasnt run hot ever since. He said the sludge was in there before changing the radiator, it must be something in the engine. From doing a bit of research on here, I've found that its common for the 97-99 5.7 liter vortec engines to have an intake manifold gasket leak. Now I'm wondering if this blazer has the same problem. It has the 4.3 votec v6. How would I find out if this is my problem?? Also, is this a big job to change out that gasket? Could the coolant loss and sludge all be connected to the same problem?

Operation Mindcrime · March 1, 2009

Your intake manifold gaskets are leaking, the dexcool has mixed with air causing the coolant breakdown resulting in mud. You need to reseal lower intake manifold, carefully check water pump for any signs of leak. Replace t stat

back flush heater core, clean the reservoir and replace rad cap 2X. And you will need extensive cooling system flushing. The radiator and/or heater core may be plugged depending on the extent. A simple flush will not clean it out. There is a TSB for this and the flush alone is 3+ hours

I usually run them for 3+ hours and them try to get it to run clean out of the heater core , radiator and the block drains, usually takes the remainder of the day. Failure to do this will result in the mud returning. The block drain is actually only accessable on the drivers side above the oil cooler lines and a real pain in the a$$ when hot. Don't believe the hype that is caused by dexcool alone. Buy the gaskets from GM dealer thay have been redesigned, not plastic anymore, metal gasket with neoprene lip seals.

ScottyBoy · March 1, 2009

Your intake manifold gaskets are leaking, the dexcool has mixed with air causing the coolant breakdown resulting in mud. You need to reseal lower intake manifold, carefully check water pump for any signs of leak. Replace t stat
back flush heater core, clean the reservoir and replace rad cap 2X. And you will need extensive cooling system flushing. The radiator and/or heater core may be plugged depending on the extent. A simple flush will not clean it out. There is a TSB for this and the flush alone is 3+ hours

I usually run them for 3+ hours and them try to get it to run clean out of the heater core , radiator and the block drains, usually takes the remainder of the day. Failure to do this will result in the mud returning. The block drain is actually only accessable on the drivers side above the oil cooler lines and a real pain in the a$$ when hot. Don't believe the hype that is caused by dexcool alone. Buy the gaskets from GM dealer thay have been redesigned, not plastic anymore, metal gasket with neoprene lip seals.

how much would a job like this cost at a shop?

MikeInCtown · March 2, 2009

Heck with the redigned GM gaskets. FelPro makes a high performance gasket set that is sworn up and down to be the best by guys on the S-10 forums. The intake leak is a very common problem and is one of the firstthings to check for when purchasing a used S-10 (besides hub bearings and oil line leaks)

ScottyBoy · March 2, 2009

Heck with the redigned GM gaskets. FelPro makes a high performance gasket set that is sworn up and down to be the best by guys on the S-10 forums. The intake leak is a very common problem and is one of the firstthings to check for when purchasing a used S-10 (besides hub bearings and oil line leaks)

True, I wouldn't have bought this blazer with all the problems it has. But it was given to me for free. The only $$$ I have into it so far is about 200$ to rent a trailer to tow it back here from my brothers house in Baton Rouge. Just trying to get all my ducks in a row to see if its worth fixing up. The cooling system is shot, intake gasket, the suspension is shot, something keeps draining the battery, the drivers power seat doesn't work, the power mirrors don't work, the AC don't work, and now the transfer case is possibly bad also. It will go into 4wd Hi, but not 4wd Lo. the way its looking, its cost me over 2k just to get this thing roadworthy.