Runs crazy hot with a/c - water pump?

[Liquid_force]

Earlier this summer I started noticing my temp gauge getting pretty high with the a/c on in slow moving traffic.
I flushed the radiator (found a pieces of tstat gasket stuck in the reservoir line). The water that came out didn't look very dirty.
Dealt with some other minor a/c issues, but eventually got it working well again.

W/o my ac on my temp gauge is never above 1/2 way regardless of the air temp. 95-100...no probs.
At hwy speeds and temps in the 90's the temp is at 3/4 at the min with the air on. It gets even worse with city driving. It was around 95 recently and I came into town after getting it good and hot on the hwy and it was basically right on the white line at "H". Switch from a/c to vent and it will drop back to 3/4 in a couple minutes.

What's the deal? Is the cooling system just maxed out in high temps with the a/c on?

I find myself wondering about the water pump.
I know the SLO pumps were known to deteriorate pretty badly over time. I checked my wp belt. It looks fine.
The symptoms I have make me think the wp just isn't getting the job done at the lower rpms of 0-40 in-town driving.

Most of the wp info I've found sounds like they're pretty worry-free.
Any thoughts?

 

[gmail]

Water pump is chain driver on v8 SHOs so leaves out belt slippage.. maybe the problem is electrical... anyway of knowing if the gauge is correct?

Heres a thought when the ac is on it will run the cooling fans more which helps in cooling the ac system but I know gen 2s will not run engine fan at speeds above 40 I believe stock.. if the ac is making the fan run at those speeds sometimes the fan is a rectriction when at highway speeds if the fan runs.

On my 92 when I got it there was a switch to turn the fan on and off.. the ccrm relay was fried sp the previous owner wired the fan in. At highway speeds it caused my car to run hot as it was actually restricting the airflow... shortly after thr wiring used got hot and melted dripping on my leg but anywho..

That dont explain at cruising speeds tho.. still check for proper cooling fan operation..

Also check restrictions between ac condenser and radiator leaves etc.

Pressure check radiator as a pin hole can cause the temp to rise when load comes on..
My 92 later on got a small crack at the filler neck of the radiator and never lost coolant but kept running warm under load and heat.. worth a look

 

[Liquid_force]

Water pump is chain driver on v8 SHOs so leaves out belt slippage..

it's belt driven off the back of the cam

 

[ctwrench]

With the a/c on, a single fan should increase in speed, or if a dual fan unit, the a/c will automatically turn the second fan on. Check fuses, relays and the fan motor.

 

[BamSHO]

Just check tensioner for the little belt that runs the water pump. Might be a good I idea to change out the thermostat, sounds likes it has failed in the open position. Thats where i would start.

Brian Michael
98 black Gen3

 

[gmail]

Agreed with bamsho.. I didnt relise they had a belt drive on them.. guess I should get to know the v8s first haha

 

[Liquid_force]

Just check tensioner for the little belt that runs the water pump. Might be a good I idea to change out the thermostat, sounds likes it has failed in the open position. Thats where i would start.

you mean failed closed?

 

[Liquid_force]

FWIW -- Drove it again on Tue in 96-97 degree heat with the ac on. Speeds of 75-80 for a while then a little stop/go. About 20 min into the trip the gauge was at 80-90% so I had to cycle the ac to keep it out of the danger zone on the gauge.

Today, it was 86-88 degrees when I drove home from work 1/2 hr 55-65mph. Set ac to 69-71 deg. Temp gauge was about 40% up on the hwy. When I got into town when it usually starts to climb the gauge barely moved, MAYBE 50%. That 8-10 degrees air temp seems to make all the difference. Maybe speed's a factor too.

I guess it could be the tstat, but I find it hard to believe it's even driveable in the summer if the stat's not opening.
Had the tstat out when I flushed it -- should have changed it then.

Fans seem to be working normally.

 

[BamSHO]

The one green Gen2 I had the thermostat failed in the open position. When the weather was warm the temp gauge needle ran high. Little or not heat in the winter. With it failed in the open position, the coolant just keeps circulating. Since the thermostats are fairly easy to get at on a Gen3, its an easy job.


Brian Michael
98 black Gen3

 

[Bull Geek]

How is the reservoir cap? Ford has done multiple revisions to the cap since they started using them. One of my cars had a failed cap.

http://www.youtube.com/watch?v=xM38rFuI_YE

I picked up a couple of new Motorcraft coolant caps at the stealer. The Stant cap he recommended in the video broke on the SHO as soon as I tightened it...

Motorcraft RS-527
Ford # 9C3Z-8101-B

 

[SHOZ123]

If the radiator has never been out it is probably clogged up externally. Both fans should run at the same time, be sure they both are running. Could also be the ECT but you would need some OBDII scanning hardware to read the ECT live.

If the coolant tank leaks off pressure this would also cause problems such as this.

 

[Liquid_force]

The tank's a 1-1/2 to 2 yrs old. It's the dorman tank. I'm guessing they aren't using the best quality cap.

Radiator clogged. Maybe.
But I had it opened up a lot last summer for Tq conv replacement and aux trans cooler install and I don't remember seeing anything that looked like a problem

 

[SHOZ123]

Radiator is clogged externally. If it is the original radiator and has never been taken out to clean the fins then it probably is full of fuzz.

 

[TimboSHO]

The tank's a 1-1/2 to 2 yrs old. It's the dorman tank. I'm guessing they aren't using the best quality cap.

Radiator clogged. Maybe.
But I had it opened up a lot last summer for Tq conv replacement and aux trans cooler install and I don't remember seeing anything that looked like a problem

You probably wouldn't see the stuff clogging the front of the radiator, because the condenser is in the way. I agree with SHOZ123.