Overheating...is my fan ok?

[American_Muscle]

Hey guys

I recently have come across a serious overheating problem.
Temperatures have often gone into the red (!).

I tried something today...

I turned the car on..the temp was all the way at the bottom (I'm guessing 130 deg)
I let it idle for about 6mins.
The temp never changed.
I checked the fan..it was running the entire time.
The I back the car up and BAM...the temp immediately started going up.

Within 2 mins of VERY mild acceleration the temp was about 3/4 of the way up.

I already ordered a 180 deg t-stat and have a new water pump ready to go in.

But could this really solve my problem.
I mean overheating may be a problem but this is grotesque!

Thanks
Patrick

 

[bluevenom867]

More tests....

New sending unit for the gauge?

Worth a shot...

 

[American_Muscle]

I dunno...but why would the temp stay at the minimum while parked and running?
Which tests should I do?

 

[bluevenom867]

I dunno...but why would the temp stay at the minimum while parked and running?
Which tests should I do?

Yea that aint right,at idel it should warm up.

As for test,I would see if you can get a thermal sensor gun.

 

[American_Muscle]

Oh ok..I'll try.
It was weird how the temp started going up immediately after I started backing up.

How long could an engine run at MAX temp(all the way at the top of the guage...I believe 270)?
Because it has reached that temp but I had no opportunity to pull over....it was in the middle of traffic.

 

[bluevenom867]

Oh ok..I'll try.
It was weird how the temp started going up immediately after I started backing up.

How long could an engine run at MAX temp(all the way at the top of the guage...I believe 270)?
Because it has reached that temp but I had no opportunity to pull over....it was in the middle of traffic.

Yea see,that just dont seem right.

So your saying that the car doest warm up ideling,but as soon as your moving it starts warming up?And that it goes up faster as your accelerating,right?

 

[bluevenom867]

Oh,as for runing at max temp...very bad.

Dont do it unless you cant absolutly avoid it.

 

[HISSIN50]

I like the idea to get yourself a real gauge before doing anything.

It should take some minutes (takes me about 5) to start reading anything on my mech gauge, which starts at 130 (I could not tell you about the stocker - I dont look at it).

Get a real gauge and go from there. It sounds like a gauge issue (did you happen to have A/C on while it ran real hot? The computer shuts the A/C off at 242*F). If you still had air, I doubt you were running that hot.

I like a gauge or electrical issue.

Good luck.

 

[sgarlic]

Did you try grabbing the upper hose to the rad after the 6 minutes idling in the driveway? What I would do is just hold on to the hose for a few minutes until you suspect the engine should be at/near operating temp. then check the gauge. If the hose is hot but the gauge hasn't moved, it's the gauge. If the hose is cold then A) your thermostat isn't opening, replace that first, but if your gauge still hasn't moved, the gauge or sender is bad as well. The fact that it is overheating is a problem within itself, probably the t-stat from the sounds of it. The fact that the gauge isn't moving is a separate issue. Perhaps the needle is stuck.

In regards to the question about how long can you operate in the red, it's a matter of how much you're willing to allow your engine to become potentially damaged. Personally, if I were in traffic (even in downtown Tucson,) and the needle went in to the red, I'd shutdown. Even if it were in the middle of traffic. My cars health is far more important than a few minutes of blocked traffic.

 

[American_Muscle]

Ok I'll give that a try tomorrow.

Bluevenom:
Right, it started going up as I started acceleration.(it was very mild though..up to 15mph) and it was only 2 mins max.

Hissin50:No the AC was off.

But I can give that a try as well.
I do have an aftermarket gauge for water temp but the seller said it wasn't working. He never said anything about the stock gauge though.

 

[American_Muscle]

Ok I checked the top radiator hose today.
After about 8mins the hose got pretty warm.
The temp gauge was working however.
Temp was at about 200 deg.
That's when the hose started getting hot.

It didn't overheat at idle. I didn't want to drive it so I don't know if it would've overheated, but I don't see why it would change.

Hmm..so I'm stumped.....(?)

 

[ac09lude]

did you check to see if it was the fan clutch? spin the fan if it spins freely it is most likey the fan clutch..

 

[American_Muscle]

Yeah..it had some resistance when I spun it.
It didn't spin freely.

I'm thinking of looking to see if the rad is clogged.

Where do I open it up..at the top?

 

[tjm73]

My '90 GT runs between 190-220 all the time. If it's in the upper 80's and 90's, closer to 220. I have the OE rated 180 thermostat (it's practicaly new). I have a mechanical water temp guage too. My car has run like this for 5+ years. My coolant is fine, radiator is fine, hoses are fine, water pump is fine. I've asked several very knowledgable people about it and they all say that's pretty much normal.

Now my cooling fan is fine (but getting up there in age) and it's running more consistently in the 220-225 area in stop and go (cools to around 205-210 on the highway), so it may be time for the fan clutch to be replaced or maybe for an electric fan and alternator upgrade. But still nothign to be too concerned about. EFI cars run better and cleaner if they run kinda hot. Anything around 200 is perfectly normal.

 

[American_Muscle]

It's normal for driving, but I reached that temp after 10mins of idling.
It reaches 260-270(!) when driving.

 

[tjm73]

It's normal for driving, but I reached that temp after 10mins of idling.
It reaches 260-270(!) when driving.

WHOA!!!! Ouch.

This is gonna sound dumb, but check 2 things. When I swapped my engine out I put a new t-stat in it. The t-stat that came in the box ended up being wrong (right box, wrong part inside). I found this out when it was boiling over and my brother and I figured out the water neck was distorting the t-stat so it couldn't open. Then like a dumb as I put the new and correct t-stat in backwards and it boile dover again, but figured it out and flipped it over. Ran fine (ie didn't boil over) after I flipped it the right way.

Check that out on your car. It's simple but easy to do.

 

[American_Muscle]

I can try that too.

But if the t-stat were in the wrong way it wouldn't activate would it?

 

[1970 slantroof]

"GENERALLY SPEAKING" if a car has the proper size radiator in it and it runs cool at idle and overheats while driving, you have a plugged radiator. I have taken them apart and rodded them out myself but it usually pays to have it done by a radiator shop. I learned this by moving to Southern Arizona 28 years ago.
Good luck,
Howard

 

[HISSIN50]

"GENERALLY SPEAKING" if a car has the proper size radiator in it and it runs cool at idle and overheats while driving, you have a plugged radiator. I have taken them apart and rodded them out myself but it usually pays to have it done by a radiator shop. I learned this by moving to Southern Arizona 28 years ago.
Good luck,
Howard

Whoa Howard, bringing the thread back from the ice age.

I'd add one contingency to Howard's reply - it applies to aero Fox chassis GT's: The air dam needs to be in place since there is no grill. The dam helps divert air in front of the coil, while creating a low pressure zone behind the coil to enhance air flow for optimal heat rejection.

Without the air dam, one can keep it cool while stationary but heat up at speed. The lack of the air dam mimics a clogged coil because there's hindered transfer (though it's necessarily the fault of the radiator itself).

:OT: Howard, one of these days I still wanna make it over your way to see your wicked shop and rides, if the offer's still open.