: Just one glitch left '93 North* %$#@!!



Mountie
01-03-09, 02:39 PM
My gosh!! I solved the leaking fuel inlet inside the injectors using a replaced 'O' ring. The ISC got self adjusted by the computer ( pretty spooky).

The coolant tempeture is PERFECT while driving at normal speeds & conditions. The coolant ranges from 117 to 201 at cruising around, and sneaks up to 224 just before the fans cool it back to average temps, as expected.

I have been doing this for 3 weeks now.........

But..... when I finally floored it to 4,500+ rpm for about 15 seconds, up a long incline, getting to 105 mph, the temp jumps out of control!!!! It starts rising to 235, 240, 245, 250!!! When this is happening, I am already slowing, and even coasting downhill. ( It was 45 degrees outside)

The "Coolant Hot" comes on, then "Engine Hot" comes on. Computer wants to shut down the engine ( gets rough) I have to pull over and wait 45 minutes as the coolant drops down.

The over-flow is not that hot, ...no coolant spewing, no coolant bubbling and the engine seem with-in temp ( by touching ), the fans are working.

Even though the computer says it's hot, lifting the hood and just looking at the engine area, it seems normal.

After limping home ( not too far)..... I park it, ( and put it to bed)...

Next day everything is back to normal while driving 'normal' again.

So, could this be a bad thermostat? ( I hope?)

delatorre1986
01-03-09, 03:04 PM
Could be the thermo getting stuck how many miles on the engine, was the engine cold when you floored it up the hill? I had a car with a bad thermo because I replaced it with a cheap autozone thermo... usually when you have a bad headgasket the harder you run it the higher the temp goes because of exhaust gases, but you said there was no water comming out. Could be a bad radiator cap too. Or maybe the water pump belt was slipping when you ran it hard.

Mountie
01-03-09, 03:35 PM
Could be the thermo getting stuck how many miles on the engine, was the engine cold when you floored it up the hill? I had a car with a bad thermo because I replaced it with a cheap autozone thermo... usually when you have a bad headgasket the harder you run it the higher the temp goes because of exhaust gases, but you said there was no water comming out. Could be a bad radiator cap too. Or maybe the water pump belt was slipping when you ran it hard.

As I have mentioned in earlier posts, I replaced the North* with a 'good-used' one on simular miles. I used GM parts, for the waterpump, thermostat, etc. I didn't replace the water pump belt or radiator cap ( it seemed good), and I believe it is a GM thermostat.

Uh, yes, the temp was at 198 ( for 10 miles at 75 mph - cool evening) before excelerating.

As for exhaust gases, why would the temps be 'perfect' driving all day long every day for weeks, then ONLY spike during an aggressive exceleration for 10-15 seconds?

Maybe changing water pump belt & thermostat.... By looking you can't really tell if they are bad

delatorre1986
01-03-09, 04:01 PM
could be the water pump belt tensioner also. Someone will chime in with more info. Thats all I can think of for now...

Ranger
01-03-09, 06:04 PM
As for exhaust gases, why would the temps be 'perfect' driving all day long every day for weeks, then ONLY spike during an aggressive exceleration for 10-15 seconds?
That is the first symptom of a failing head gasket. I'm not suggesting that IS the problem. Just answering the question and mention it as a possibility to keep in mind.

Mountie
01-03-09, 07:11 PM
Well, I haven't found an exhaust contamination tester yet..... I'll ask a radiator shop of advice...

Even if this is evidence of a future HD disaster, just driving for a long while without flooring it is fine. ( cheaper than pulling the engine)

So, just by driving 'normal', doesn't allow the exhaust to impact the coolant temp enough to overheat.......

I got this STS as a play car. If I have to put it inside a friend's shop & buy a longblock & drop the engine, that is fine. I'd rather keep this car, rather than sell it & pay $$$$$$$ for another car that is anything close to the fun this car is.

Originally, the entire cost of this '93STS encluding the other engine, and my doing the R&R myself was only $2,400.00 - "out of pocket" cash. Also knowing the transmission has been already done before the swap.

Having fun with it for 4 years,....... not a bad expense.

The car will be wonderful with a fresh engine!! ( Maybe have Alan Johnson massage it a bit ?)

Taking the time to see if something as simple as a thermostat may be bad is a good risk.

Time will tell.

Ranger
01-03-09, 07:45 PM
Even if this is evidence of a future HD disaster, just driving for a long while without flooring it is fine. ( cheaper than pulling the engine)

So, just by driving 'normal', doesn't allow the exhaust to impact the coolant temp enough to overheat.......

IF it is the head gasket, it will slowly get worse.

Stand by, Destroyer will sniff this one out and be by shortly to pronounce a head gasket failure.


I got this STS as a play car. If I have to put it inside a friend's shop & buy a longblock & drop the engine, that is fine. I'd rather keep this car, rather than sell it & pay $$$$$$$ for another car that is anything close to the fun this car is.
If it does turn out to be a head gasket, there is no need to get a new block. Just drill, tap and Timesert or stud the bolt holes and will be fine for a long long time.