93 Overheating - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 07-13-2006, 10:13 PM   #1
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Default 93 Overheating

Well, my brother just recently picked up a '93 lesabre... L27, no important options to mention, other than a lack of gages... idiot lights abound.

His wife showed up today with the car barely running, stumbling under load. I took it for a short test drive and here'* the observations:

1. runs smooth at idle. Apply any load (>5% throttle), and the engine stumbles and tries to die. w/o a tach, I can only guestimate that it drops the RPM'* down to about 300... that bad.

2. that'* about it.

After I brought it back, I left the key in the run position with the engine off. The fans... they ran. Oh boy did they run. It took a full 15 minutes before they got the signal from the PCM to turn off. And it was kicking some serious heat off of the radiator.

After a cool down (now suspecting heat to be a major issue), we took it out for another drive, and as expected, it ran great... no problems at all. About 5 minutes into the drive (this was after a 30 minute cool down from before), it slowly started creeping up again... small stutters when you got into the gas.

So when we got back, I got out a coolant tester, and all 5 balls shot straight to the surface. Equivalent cooling capacity was some -40 or something. Looks to me like the coolant was either put in straight, or overmixed with a bias to coolant over water.

So now the question I pose is this:

Do you, the wonderful people of BC land, think this issue is...

a) completely coolant related
b) somewhat coolant related
c) something else in the cooling system
d) something else entirely

and if so, what?

The way I figure, it'* either the coolant, at an inappropriate mix on a hot day, or a bad water pump, just not moving the coolant fast enough. On that note, while running, the pump is running dead true... so I'm not convinced there'* an issue there, unless the pump was worn away on the inside. As an out-there possibility, I've heard that a clogged cat might possibly create the same issues... any thoughts on that?

And finally, is there any good way to check the WP for failure (other than visual inspection while running) without removing it?

thanks again!
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Old 07-13-2006, 11:10 PM   #2
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When I first started reading this my initial thoughts were a clogged cat. If it stumbles, especially when hot, that'* typically a sign of a clogged cat. How many miles on the car? Do you know if the cat has ever been changed? I'd get under there and try to shake it using a broom handle (if it'* hot). If it'* not hot, just grab it with your hands. Are you getting a check engine light?
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Old 07-14-2006, 12:19 AM   #3
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No check engine. 172k miles, original everything as far as non-routine maintenance is concerned...
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Old 07-14-2006, 01:25 AM   #4
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Cat sounds okay. We just diluted the coolant a bunch... still not quite where it should be, but better than it was. Gave it a go, but it'* a little cool out to see if it'll do what it did during the day.

The water pump feels pretty tight, and the pulley is moving straight and true, but you can see a bit of wobble in the path the belt takes over the pulley. We'll see what happens tomorrow, but I have a suspicion that the water pump may be slowly failing, internally. Just enough that the coolant doesn't move quick enough on a hot day to cool itself down.

Eh, we'll see. Wish I had something more than idiot lights to go by...
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Old 07-21-2006, 12:58 PM   #5
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FYI, waterpumps don't slowly fail. The only failure is bearing or seal failure, but they ALWAYS pump the same amount of coolant.
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Old 07-21-2006, 01:08 PM   #6
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Then I guess you have never seen the turbine part of the pump pit and degrade... I have seen a few do this... Its always a shock when you see one that has done this... But its usually due to acidity or an engine that has run straight water for a given amount of time...


I'd be tempted to do several checks right down to the thermostat to see if its sticking... The Coolant protects the metal and prevents boilover, Mixing the coolant with water is what gives the coolant its heat transfer abilities

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Old 07-21-2006, 01:16 PM   #7
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I've seen pitted turbines, etc., but never to the point that they pumped noticeably less coolant. I guess anything is possible, but i think it'* unlikely that it would cause a significant loss of pumping capacity, no? Seems that even if that was a possibility, it would occur over a very long period of time.
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Old 07-21-2006, 01:27 PM   #8
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I'm pretty sure that did occour over a period of time... Degradation like that will never happen overnite...lol And it did create serious overheating issues... I really wish I had a Digital Camera back when...lol

mkaake,

Pull that thermostat, and check it to see if its stuck partially open limiting flow when the engine is warm causing it to overheat or if it may be stuck shut altogether...

Once you get it out, clean the coolant off, toss it into a pot of water, throw a thermometer in there and watch the water temp and see what temp the thermostat opens at, and how much it opens...

That would be my first guess..

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Old 07-21-2006, 01:44 PM   #9
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Also, to answer one of your first questions; one way to tell if the water pump seals are bad is to look for the "weep" hole at the shaft. If the seals are bad, there will be either wet coolant or at least stains from where it has been leaking.
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Old 07-21-2006, 02:11 PM   #10
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Well, a week ago, when we were looking at this, we knew the coolant was pretty shody... from our tests, it looked like there wasn't any water in at all. So we put in a bit of water (though not enough, admittedly), but it took care of the problem for the most part.

Quick Q, that should probably be in it'* own thread... was 93 one of the years that baffles failed in the tanks? They started having problems with the car trying to die going around corners, with less than a 1/4 tank of gas. I told them to keep it above 1/4, as they likely had bad or failing baffles... but the damage to the pump had already been done. The car started choking and trying to die quite often... completely different than the temp related failures that started this thread. Threw a pressure gage on the fuel rail, and sure enough... the FPR is amazing on that thing (didn't loose 1 psi of pressure after 10 minutes of being turned off), but the fuel pump just couldn't do it'* thing - under load, the psi dropped by at *least* 20... which coincided with the stumbling perfectly.

Anyway, back on track. Not sure if the WP is bad or not... we need to get it up and running properly before I can find out more about the overheating issue now. The person who sold it to them (had owned for *many* years before) never drove more than about 15 miles with it - enough to get it warm, but not really hot, and not for any extended period of time. I think a lot of it has to do with the coolant not having the cooling capacity (JR, as you said, because the water is the primary means of heat transfer), so we'll start with a full flush, once we get the rest of the car back under control.
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