engine running hot, then normal

kei9th

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i am the proud owner of a mini-van? i searched for about 6 weeks and found a good deal on a 2002 chevy venture 6 cylinder automatic 3.4 liter 67,000 miles very clean inside and nice paint, tires ect. they guy wanted $3800, was willing to spend $5000 took it for a drive around the block everything was up to par. checked fluids all clear looked like i was going to get a good vehicle for a good price. drove it home about 7 miles, no issues. took it to the mall and drove around, no problems. so i told the wife im going to drive it to work because i want to drive the new car plus i drive 100 plus miles a day and ill get to see whats doing. i noticed that the temp gauge stays about 1 dash below middle and goes up two dashes over middle. it is sporadic. i drove 23 miles one way to Miami with the gauge at i dash below middle go off the highway and sat through some traffic then i noticed that it went up to to marks above middle. its been doing that for three days. it has never gone any higher that the second mark after center. i am thinking that the thermostat is sticking closed? could the water pump be going bad? there is no weep hole on that pump. i am sure of that i just replaced a water pump on the same motor for my office manager. i bought the truck for 3500 so if i have to spend a couple bucks im not to unhappy. any thoughts?
 

bruceb58

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Mar 5, 2006
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Re: engine running hot, then normal

What is the electric radiator fan doing during all of this? For a test, you could hard wire it to be on and drive around to see what happens.

You have checked your coolant level right?
 

kei9th

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Re: engine running hot, then normal

has two fans run normal they have two speeds they seem to be on the lower of the two speeds although im not sure. coolant is where it should be.
 

Pascal

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Re: engine running hot, then normal

has two fans run normal they have two speeds they seem to be on the lower of the two speeds although im not sure. coolant is where it should be.

2002 GM = Dex Cool??? = problems???

Just bought a 2002 buick with a 3.1L that I'm not so sure about for the same reasons.

one other cooling symptom I've noticed is that a fluxuation in temp gauge like you describe has meant that the coolant in the block is low - no matter what the expansion tank says. It acts like an air lock in the system.
 

cribber

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Re: engine running hot, then normal

I'd check into an electrical issue. If you have two speed fans it could be your temp sensor acting up not allowing the fans to go to the higher speed based on engine temp.
 

kei9th

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Re: engine running hot, then normal

2002 GM = Dex Cool??? = problems???[/QUOTE said:
ya i know office managers son overheated his 1999 chevy lumina. she bought a used motor from the junkyard, against all odds same problem with the new motor. we ended up pulling the heads and that motor also had head gasket issues. machined the heads threw it together and it runs beautiful. i have no idea how to pull the heads on this motor its a van. i guess i got screwed. hopefully i can get it fixed for around $1000. i should have payed better attention to the motor when i bought it. ill never buy american again.
 

marlboro180

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Jun 23, 2009
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Re: engine running hot, then normal

. i bought the truck for 3500 so if i have to spend a couple bucks im not to unhappy. any thoughts?
Yeah, something about carts and horses....
Diagnose it first, condemn it after diagnosis shows it is gonna cost big bucks.
 

bruceb58

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Re: engine running hot, then normal

i guess i got screwed. hopefully i can get it fixed for around $1000. i should have payed better attention to the motor when i bought it. ill never buy american again.
Am I missing something here? How did we come to the conclusion that the head gasket is bad?
 

kenmyfam

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Re: engine running hot, then normal

Am I missing something here? How did we come to the conclusion that the head gasket is bad?

I will second this one.
Are we missing something Bruce ???
 

kei9th

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Re: engine running hot, then normal

tomorrow i will try bleeding the system, i already worked on another of the same motor with similar problems and had to redo the heads. i was hoping to read that it was something simple. the other car had 30,00 more miles. like i said before i am willing to spend a few bucks to get it up to snuff. its more my fault for not researching this vehicle farther. kelly blue book with the mileage and condition was right on with what i paid. to me it seems like a sticky thermastat. this weekend i am going to replace it and flush the system. i dont think it is the head gasket because when i get on the gas it dosent overheat. the gauge only moves about a quater of the whole sweep. i have hope still, at least its not a ford.
 

bruceb58

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Re: engine running hot, then normal

If the temp is going up when you are moving slow or idling and then goes down when you are moving at highway speeds, sounds like a fan issue, not a thermostat.
 

puddle jumper

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Re: engine running hot, then normal

I think Bruce is on the right track also. Just something to check is some of those V6 chev engines have air bleeder valves in the cooling system. If they are not bled can cause some goofy cooling problems. You may also want to wash out the out side your rad with the garden hose because if the rads fins are plugged up can contribute to low speed cooling problems.
 

kei9th

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Re: engine running hot, then normal

thanks everyone im going to try everything suggested. im hoping to solve the issues myself. i don't know how to make the fans run on high, i know there is a way to do that. i will keep you posted on the results.
 

TilliamWe

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Re: engine running hot, then normal

Kei9th (silent 9) I think you are jumping to a VERY big conclusion. All of my 3.1l/3.4l equipped vehicles (1999 Century, 2000 Impala, 2001 Impala, 2003 Impala, 2003 Impala, 2004 Impala, 1999 Montana Van) have had temperature gauges that fluxuated. It's normal.

Unless the coolant level is going down and the oil looks like caramel, you don't have the intake gasket problem. You may in the future, though. As far as the headgasket being bad, if it was, you would be pushing coolant out the reservoir bottle. And again the coolant would be low. One of the easier places to check for oil contaimination is the PCV valve. Very easy to get to.

But I don't think you even have a problem at all. It's normal for a temperature gauge to fluctuate with the opening/closing of the thermostat and with the turning on and off of the cooling fans. Remember, one is wired to the A/C as well. So turning the A/C on/off can affect it.
 

dolluper

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Jul 19, 2004
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Re: engine running hot, then normal

no codes.....possible coolant temp sensor[cts] has lost it's value
 

kei9th

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Re: engine running hot, then normal

if i replace the dexcool will it harm the motor or radiator?
 

puddle jumper

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Re: engine running hot, then normal

if i replace the dexcool will it harm the motor or radiator?

Make sure you flush the cooling system with water before you add a different kind of coolant plus bleed the air out of the cooling system.
 

TilliamWe

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Re: engine running hot, then normal

if i replace the dexcool will it harm the motor or radiator?

Nope, properly flushing the cooling system and replacing the fluid with anything BUT Dexcool will HELP it!
 
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