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Introduction and 94 Cutlass 3100 temp fluctuations


jmlee44

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Good morning everyone,

 

My name is James from San Antonio. I recently acquired a 94 Cutlass Ciera with 80k original miles. It has been well serviced by its elderly PO and runs\drives great.

 

If I believe the temp gauge though, it is being weird. It moves around a lot.

Leaving town yesterday it warmed up normally and climbed a tick past mid way (which is 220) then dropped back to about 1/4 then settled around 200...a tick below half. Cool

 

But it didn't last...I sped up to merge onto another hwy and it crept up again. Now for the whole 60 mile interstate drive it was running 200 to 230 by the gauge, varying the whole way.

 

Half way in stopped for gas and left it idling...the car got warm about 3/4 up the gauge getting close to the red. When I merged back to the highway the temp dropped rapidly to 1/4 ...them slowly returned to what it was doing before moving 200 to 230 and back.

 

So I dropped it out of overdrive to bring revs up...no change.

 

So it runs hot all the time ..at idle...at speed....sometimes I let it coast down a klong hill on the highway ...barely drops it at all.

 

None of the usual things seem to make sense...

 

Any thoughts. And yes water is full and looks fairly good. The PO was reminding me to check the battery water...I think its been fairly well serviced.

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Welcome! A cutlass ciera isn't a W, but I'm sure some of us can be of some help :thumbsup:

 

I'd swap thermostats first, and make sure it's topped off and has no bubbles. Sounds like what my Monte was doing when I had a pinhole leak and would get low on coolant

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I've suggested this elsewhere in another post.....

 

 

pick up one of these.......

 

 

http://www.amazon.com/Ckeyin-Handheld-Infrared-Thermometer-Temperature/dp/B00H2C6HDI/ref=pd_sim_sbs_hpc_5?ie=UTF8&refRID=0C31RPGRMJWXNPH24WJB

 

 

they are invaluable in diagnosing the cooling system....check the temp of all the coolant hoses, if the return hose from the rad back into the engine is *hot* then I'd suspect that the rad isn't doing it's job properly.

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Yeah I have one at home but I'm out of town visiting family. By touch the bottom hose feels hot like the top...but not quite as hot. A flat palm on the face of the radiator shows hot from top to bottom. I dropped a meat thermometer in the open radiator cap, when the gauge showed 220 the meat thermometer read 209...that's straight across the top but seems reasonable.

 

If I rev it when idling the temps do drop thouhh... About 10 to 15 degrees. It seems that when I accelerate the extra revs bring the temps down but the added heat from highway travel catches up with it after a minute and it climbs back up. If I pull a hill on the highway it will climb, if I let it drop back to idle on the highway it will not drop much, it will drop if I am keeping a little throttle in it but mainly going downhill...so higher rpm but light load.

 

With the cap off and revving it...it looked churned up and cloudy ( not oily ) but like lots of tiny tiny bubbles...no big ones...could the pump be cavitating ? Is that a thing? It reminds me of the bubble trail a boat propeller makes in shallow water.

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Cutlass CIERA is an "A" body. Doesn't really matter though, the 3100 is the same in all FWD GM cars.

 

Now, first thing you should do is check for leaks. You may have one, even if it's small. 2nd thing would be to change the thermostat and verify the water pump, although water pumps are very cheap nowadays that it wouldn't hurt to swap it. I'd also do a coolant flush. Use the green stuff, not the red stuff.

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thermostat. it will cost you $5, take roughly an hour if you can get your hands under the throttlebody and it will rule out something that is almost always going to be problematic with a 21 year old engine since there is a good chance it is the original thermostat.

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With the cap off and revving it...it looked churned up and cloudy ( not oily ) but like lots of tiny tiny bubbles...no big ones...could the pump be cavitating ? Is that a thing? It reminds me of the bubble trail a boat propeller makes in shallow water.

 

Don't like bubbles....that implies air, with the system full to the rad cap neck there's no place for air to get in, outside chance of a head gasket beginning to fail, that could explain the increased temps you are seeing but not to the point where this is an outright failure. One needs to do a coolant pressure test to see if the system holds proper pressure (both cold & hot), as well a cylinder pressure test with air pressure to see if one is leaking into the coolant system. The higher engine rpms under light load are pushing a larger volume of coolant thru the system, the coolant system is fighting to keep the temps down.

 

But do the simple tasks first,

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I agree. Sounds like a combustion leak in the cooling system to me. I had a '95 3100 Cutlass Supreme and a '94 Corsica 3100 which both acted exactly the way you've described, and both ended up having damaged blocks due to combustion leaks. I've found a block leak tester very helpful in diagnosing combustion leak issues. Here's a link to one for sale through NAPA: http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=BK_7001006_0361073538 Just out of curiosity, have you guys had luck doing head jobs on 3100s to fix failed head gaskets? I've had 3 cars with 3100s which had head gasket problems in my time. I did head jobs on all of them (had heads surfaced on all of them too), and it only fixed one of them. The other 2 I ended up putting engines in.

Edited by chevelle3504speed
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I was having similar issues in my 3100. My car would cool down to the lower end of the temp gauge on the highway and warm up when stationary. I had the thermostat changed and it all went away. Needle stays right in the middle now.

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  • 2 weeks later...

Wow have I been away ...sorry for the delayed response. I have a couple things planned. I ordered a delco tstat to be sure of things. Was gonna drop it in this weekend but life happens. I also gonna do the combustion gas test kit...its cheap enough ...and for the last and final play, I bought a cheapie endoscope camera off of eBay. Its waterproof and lighted , only 6mm across. He is going to go into the coolant hoses and look at the radiator innards and the pump impellar. I may also be able to move it around and make sure there isn't a bunch of barsleak or block sealer in the system ...I heard gm proscribed tablets or something similar in the past.

 

I suppose I could also use it for looking down in the cylinders to see if any show signs of being steam cleaned. It was only 15 bucks and after I'm done I'm sure it will come in handy around the house or just annoy the gf with pics from up my nose...

 

I will make sure to keep everyone posted as to the result once I figure it out...maybe it will help others. And thanks again i realized late it isn't a wbody car...but I hope the info is useful either way.

Edited by jmlee44
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