In the last year - we figured our 98 Lumina had fallen victim to the dread faulty LIM Gasket issue that a lot of the GM 3.1 V6's have had.
We had the dreaded mud coolant, random lose of coolant and overheating. I got in there, changed ECT before realizing this, installed new gaskets and new thermostat - things were much better for most of the summer, and the temp was solid whenever it got to running temp. Sometimes running temp was a little higher, but no overheating. I had used primarily water until we knew this problem was fixed. We knew this was just part of the problem, as we were also not getting the fan relays to switch on during traffic. For the summer, I just used the A/C On to override, and run the fans constantly (we were getting a low coolant warning, just need to replace sensor, and all that might clear up.)
One of the issues we're experiencing NOW is, regardless of speed, stopped or going - there are random temp variations going all the way to 3/4 the gauge. Stays steady, and then will randomly come down. Coolant is evaporating in the overflow, but not in the radiator itself, it appears. Checked multiple times, during 1-2 week intervals - to only needing less than a cup to top off.
Checked a number of things:
Water pressure seems too light in return hose. When bleeder valve is opened @return, it spurts but not in steady stream, water intake bleed @ transfer case is nothing until fans turn off - water temperature stays constant, but it'll start spitting as if boiling, again not in steady streams, and then reverses if coolant fans are reactivated, until nothing is coming out again.
I'm at a loss. I'm about to just pull off the water pump and replace it - but what else could cause this? Much less fans not switching on, with 3 good relays. The low coolant light couldn't be triggering the PCM for that could it?
Wednesday, September 14th, 2011 AT 2:50 AM