# 3.1L overheating



## herpfan

95 Chevy Lumina 3.1L 94k miles. Car will redline on short drives say 4mi or 10min. usually upper rad hose is cool and lower is warm. No vent heat. Have noticed if a quick sharp turn is made the temp will drop after a minute and gradually warm up again with some vent heat. After the temp drops the low coolant light eventually comes on, both rad hoses will be hot. reservoir has fluid so it shouldn't be low. Only have white exhaust when really cold, no water/coolant on dipstick but some beige gunk on oil filler cap. No external sign of coolant leak, minor oil leaking on engine - not bad enough for ground spots.

6mo ago quickie place flushed coolant. low coolant light would come on. some research caused me to bleed they system - they probably didn't. Fine for a while but had occasional warning in the last 3 months during a weekly long distance commute. I snapped the head off the bleed screw mounted above the water pump. It appears to be mounted in a bigger screw. Can I just unscrew that one to bleed or should I remove/replace the busted screw? 
The water pump looks simple enough but the thermostat housing lower bolt looks like it will be a pain. I would like to try these on my own although I really suck at repairs. Shop gave rough estimate for parts/labor water pump/thermostat $330 or head gasket (w/machined heads) $1300.
Any ideas on overall problem and bleed screw fix?


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## buddycraigg

since you do not have any heat i am leaning towards the waterpump.
if the thermostat was just stuck closed, you would have heat at the vents.
that is untill the water started to boil.

and could you give me a pic of the broken screw and the bushing that it goes in so i will have a better opinion?

the water pump is very doable by the average person. just take you time.


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## herpfan

ok a few pics and some more questions. I ask all these ?s because once I start it may be hard to get free help if things go wrong and I hate not having transportation. 
The thermostat has a built-in rubber gasket but does the thermostat housing need a gasket as well?

its blurry and 3am  The broken shaft is slightly below the top of the hex nut.
Side view 1) Does the tube need a gasket where it goes into the water pump?









As far as the serpentine belt tensioner. I can see the nut. Do I rotate it toward the rear of the engine until I can remove the belt or does it come off completely? Will I need a pulley removal tool for the water pump pulley or should it come off easily once unbolted?


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## Midnight Tech

Herp, that water pump bolts into the housing with 5 or 6 bolts-you don't have to remove the housing to get the pump off. Bleeder screw? Check the Chevy dealer or _maybe_ your parts store will have that bleeder. BTW that water pump part # is 58-323 in A1/Cardone.
You shouldn't have to remove that tube where the bleeder is in, but if you do, it does take a gasket.
The tensioner will rotate toward the back of the engine to remove the belt, and water pump pulley will come off either before or after you take the pump off.


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## buddycraigg

you do not turn the bolt to release the tensioner.
there is a squeare in it made to accept a 1/2" drive ratchet or brake-over bar.


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## herpfan

*thanks!!*

found it. I assumed it would be turned at the hub and not a hole in the arm. what a simple repair.


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## ANDYRISSO

herpfan said:


> 95 Chevy Lumina 3.1L 94k miles. Car will redline on short drives say 4mi or 10min. usually upper rad hose is cool and lower is warm. No vent heat. Have noticed if a quick sharp turn is made the temp will drop after a minute and gradually warm up again with some vent heat. After the temp drops the low coolant light eventually comes on, both rad hoses will be hot. reservoir has fluid so it shouldn't be low. Only have white exhaust when really cold, no water/coolant on dipstick but some beige gunk on oil filler cap. No external sign of coolant leak, minor oil leaking on engine - not bad enough for ground spots.
> 
> 6mo ago quickie place flushed coolant. low coolant light would come on. some research caused me to bleed they system - they probably didn't. Fine for a while but had occasional warning in the last 3 months during a weekly long distance commute. I snapped the head off the bleed screw mounted above the water pump. It appears to be mounted in a bigger screw. Can I just unscrew that one to bleed or should I remove/replace the busted screw?
> The water pump looks simple enough but the thermostat housing lower bolt looks like it will be a pain. I would like to try these on my own although I really suck at repairs. Shop gave rough estimate for parts/labor water pump/thermostat $330 or head gasket (w/machined heads) $1300.
> Any ideas on overall problem and bleed screw fix?


Did you ever get the fix on this? I ask because I am having a similar issue with a 97 Monte Carlo 3.1. Have replaced the water pump, thermostat and radiator. Have posted it under "andyrisso" as user.


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## herpfan

definitely had a bad intake manifold gasket. Could see some external leakage - coolant would bubble but no puddles on ground. Probably internal leaks as well. An ex-mechanic said this engine has problems with that. Took it to the shop because it was running rough and started dying. They said the coolant was gone. They also said the coolant leaked into the oil and would separate. Starting the car caused the coolant to be cycled instead of the oil and this caused the bearings to go bad. 
Long story short - its probably the intake or head gasket and better to replace before serious engine damage occurs. btw living car-free now and down 30lbs :grin:


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## ANDYRISSO

ALMOST SAME PROBLEM HERE, DID YOU FIND AND ANSWER??

Approx 2 weeks ago our 97 Monte Carlo with a 3.1 in it started overheating drastically. Nothing had been done to just prior to it that we think could've caused it. The next day I took it out around the block and in less that a mile it pegged the temp gauge. Upper hose was hot, lower hose was warm. Smaller hose coming off the "T" with the bleeder screw on the water pump was cold and no heat inside of the car.
I have since replaced the water pump, the thermostat, Had the system flushed (twice) and even replaced the radiator with a new one and am still having the same issues. It will blow hot hair for the first time it gets hot, but then cold air and the temp gauge still goes to the red.
I have bled the system numerous times and nothing, no fluids are leaking, no oil/water mix is apparent and plugs look clean when inspecting them. I also hear no leaks either by pressure or water. But since replacing the water pump, thermostat, and radiator have noticed that the bottom hose gets warmer now and if release some of the pressure from the cap, it blows into the overflow tank and thew water is warm.
Can my heater core be pugged?


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## herpfan

thought about that too. my recovery tank had oily film so I wondered if the oil had gummed up various parts of the coolant pathway. first time I had it flushed they told me it looked like the Maumee river. 
the car is a 95 and they wanted $3k to replace the engine. At first I decided I wanted a new car. Now that I'm really getting into biking have saved a ton of money and can't see spending $10-15k on a new car that I don't want or need to drive. May buy a beater for the really bad days and emergencies.


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## cardoc

Hi all.
Unfortunatly a very common problem on GM's 3.1 are bad headgaskets.Not to metion bad intake gaskets(we see them a lot).The intake ussually is just a leak but the head gaskets cause all kinds of games.Sorry to be the bearer of bad news but it's seems to be the way these go.
Cardoc


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## cardoc

Hi again
If you know somebody with a block tester it's an easy test for a head gasket.Fluid in tester changes color almost instantly in the presense of combustion gases in cooling system.This will peg it.
Cardoc


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## hardmonte

*Problem Found 3.4L overheating*

I Have a 1997 Z34 Monte Carlo, About a year ago my water pump Bearing went so i replaced it with a Re Manufactured water pump from Car Quest.
the water pump was different looking because it had a fan blades (6 Blades) on it that looked close to like a house fan and the old one looked more like a spiral blades (10 blades). the car quest pump came with a picture saying its a new design and will work just as good. my car started overheating about after 5 miles and my thermostat would pop and suck the radiator hose closed. Every time the engine was over heating i could stop and open the bleeder screws and just let the air piss out. 
I finally found that Napa carry's a Brand New water pump with the spiral blades (like ten blades) which makes the water pump faster. My car is running great again, wish i found that out sooner since i drove it for a year with it over heating


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## shadetree83

I have a 2000 lumina that runs hot and will overheat after about 4 mi (with coolant in radiator, otherwise overheats automatically) We replaced the thermostat (Wow!) and the water pump, and the upper radiator hose still runs hot and holds too much pressure, the coolant will run into the engine coolant tank fill up and overflow and I have to cool the engine release the pressure from the radiator cap and allow the coolant to flow back into the radiator, I also replaced the cap, we have also flushed the coolant system as well, whats goin on?


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## mack1

Hi Shadetree83,

Posting a new thread just for yourself is a good idea and will get you more help. Anyone looking at this thread will think you have had a lot of help (lot of responses) when in fact, no one has. 

Notice that hardmonte just above your post didn't get any responses, probably for the same reason.

Very best regards,
Mack1


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