Hey all.. I recently picked up an 89 Trooper for cheap.. I knew there'd be some issues.. just trying to figure em all out now

So, its loosing some coolant somewhere. There's no visible leaks and it doesnÆt seem to be the head gasket (I was told it was replaced 3 years ago) and the heater will work intermittently. Blowing hot for a while, then cold, then it starts blowing hot again.. And the temp gauge is a bit erratic staying a little blow half for a while then jumping up to above half for a while and going back down. This will happen while its idling with the radiator cap off making sure its topped off and while driving. So I thought maybe the previous owner put a bunch of stop leak gunk in there so I had the radiator flushed. DoesnÆt seem to have done much.

Im wondering if a bad thermostat might cause something like this? I was going to try that. If that doesnÆt do anything I not sure what to do other than replace the radiator.

Any thoughts or suggestions?


Thanks

Your symptoms _do_ seem to indicate a head gasket problem.

Do a compression check.

What are you? Some kind of Trooper junkie? An 88, an 91 and now an 89. All within 2 years? <img src="/forums/images/graemlins/smile.gif" alt="" />

Head gasket or cracked block/head. In addition to that compression test, having a leak down test is probably a good idea too.

Other than that, just look. One of the more common places for the HG to go is the drivers side of the block. Look very closely at the side of the block behind the exhaust manifold. It is hot enough in there to evaporate the coolant before it reaches anywhere to drip or puddle.

Check the underside of the pump and look at the weep hole. Other than that, it sounds like you have a head gasket issue. Are there bubbles in the radiator with the engine running? Does the radiator smell like exhaust? Pull some plugs and look at them.

Good Luck,
Michael

Hehe, well its not my fault See.. the 1st one got totaled, so I got another. This one is for my fiancÚ. Guess she caught my trooper bug and wanted one of her own.

So, I did a compression check. This is the 1st time I've done such a thing so I hope I did it right.. All of them were at 150 psi accept the 3rd which was about 140 psi. Is that bad? <img src="/forums/images/graemlins/confused.gif" alt="" />

I dont have a leak down tester so I couldnt try that..

So, I drove it to the parts store today after filling the radiator again.. By the time we got back the radiator is half empty and the overflow tank is well, overflowing

I checked for bubbles or coolant it the oil, it looked fine to me and its not blowing any steam out of the tail pipe.. thats why I didnt think it was the HG or cracked head.. But what do I know..

Sounds like a bad radiator cap. Could it be that easy? <img src="/forums/images/graemlins/ignore.gif" alt="" />

Unfortunately no, because it was just replaced yesterday..

List of "Could Be's..."

Air trapped in head. Cold engine: remove thermo-air valve from top of thermostat housing. Fill radiator until fluid comes out of housing. Pop thermo-air back in. Idle with radiator cap off until flow is present and look for oil globs or fine air bubbles (indicating leaking head gasket).

Bad Pump. Check belt tension. My alternator bracket broke a bolt and was bouncing free so the pump would grab sometimes and not others. Temp would shoot up and drop down over and over.

Leak on intake manifold. Not obvious. Coolant runs through the galleries of the intake and the throttle body (helps warming things up).
Easier to spot at night with a flash light if it's a little drip, or spread out a cheapy drop cloth with a paper face under the engine and leave the engine run for a bit. Some things leak when they warm up. Others when they cool down.

'Course it could really be you have a bad head gasket too.

Thanks for the suggestions. I will take a look at those things. As far as the compression check, is 140 to 150 psi a big difference? I guess its all dependant on how bad the crack or blown gasket is, eh?

I did take a look at the plugs when I did the compression check.. they all looked the same, a bit of a grayish brownish color..

Compression check won't isolate a gasket problem. It could just as easily be worn rings or a leaky valve. But! After reading the post about the fact that you have a full expansion tank and an empty radiator after a short trip it reminded me there was a comment back in October about exactly the same thing. Problem stemmed from a sticky check valve between the radiator and the tank. The fluid was all going out and never coming back in. Don't ask me the mechanics of it. Maybe the original poster will chime in and give details. I can't see where the check valve would be unless it's where the line goes into the tank.

I also once inadvertently reversed the two lines to the expansion tank. The effect was as you describe. Everything was being pumped overboard to the expansion tank and nothing could return.