Koenig-Specials 928

Yesterday in Toronto, Canada the temp rose to mid 30 degrees C. With AC on and only doing 60mph caused the temp to hit the red zone. No AC and it was ok at any speed (last white line). When the engine got cooled down I checked and the coolant level and oil levels were normal. I have no visible leaks on the car. Belly pan is also installed. Running new Ford dual 2 sp fans. Fans come on when called for (when hot or when ac switch put on).

Background info: 5 years ago intake refresh was done that included oil pump refurb, kevlar TB belt, Porkensioner, new water pump, thermostat and all seals in the water bridge. Been using Royal Purple 20-50 since.

Is this pointing to the 25 years old and tired rad?

Please and thanks in advance for your advise.

ROG100

Fred,
Did you replace the thermostat rear seal?
Are the flaps in front of the rad open or closed?
Are both your fans running?
Roger

Koenig-Specials 928

Yes & yes. all the seals in the water bridge were replaced. Flaps opened up and fuse pulled. Both fans running at high speed. I did not question the waterpump because without the ac on i drove constantly at 80mph for a while and then idled it for 15 minutes and no increase in the temp gauge was seen.

polecat702

Fred, ya need to check the temps with an infrared heat gun to get a true reading. A lot of debris will collect between the evaporator, and the radiator.

I had to replace my radiator, just shot after 25 years. Did every thing while I was in there too. Car runs nice and cool.

Koenig-Specials 928

great idea to check up on the temp gauge with infrared. Yeah, I figured too the rad may be shot after 25 years of great service. Thanks

69gaugeman

The only way the rad is shot, is if along its life there were extended periods where the coolant wasn't changed. This is the one single thing that does our motors and rads in. The corrosion is brutal.

My 90 GT is a DD and it never gets over the last line. It did for a while when I had a vacuum leak and it would lean out and run hotter, but since I fixed it it never goes over the top line.

I second checking it with an IR temp sensor and confirm the gauge is reading wrong.

auzivision

Surprisingly, even though I've completed multiple partial drains (radiator and hoses) practically annually for one reason or another... I found a huge improvement with cooling when I did a complete (block both sides and radiator) drain and refilled with Zerex G-05.

Not sure if switching from green coolant to orange caused this or finally eliminating any residual beer cooler water from a blown heater hose incident years ago. It was all I had handy coming home from a hot day at the Indianapolis Motor Speedway.

I diluted the Zerox nearly 50/50 with distilled water(error maybe on too much water) and didn't add any wetter this time. Temp gauge is level most of the time even with A/C and just reaches the upper line under spirited driving conditions and maybe slightly above spirited over mountains

Might be worth a try... it surprised me. Oh yeah, and I'm also running a non-stock fan setup... with all 5 fans running all the time.

69gaugeman

I have put VW/Audi G12 coolant in mine. While I am not sure if that makes a difference in cooling capacity, my years and many tear downs of Audi products and never seeing corrosion on a head, lead me to this decision. I am sure the Zerex - G05 is fine as well. Just wanted to add what coolant I was using.

Jetdriver69

My 82 runs just below the second line all the time. But actual temps are 190 going into the radiator and 180 coming out when the temp gauge is at the second line. So the gauge isn't super accurate. Same thing with my voltmeter, when it shows about 12.4 on the gauge it is actually 13.6 or so with a multimeter. I may take out the ashtray and put in an accurate VDO voltmeter and temp gauge. Bad gauge readings just bug me.

Koenig-Specials 928

With the engine very hot after a long run I got 205 degrees to the rad and 190 in. Fans were running at the time and the ac was on full blast. btw car gets really really cold so ac is running correctly. I change oil and coolant before putting to bed in the fall since I owned the car which is 13 years now.

So is 15 degrees across the rad enough? At 205 the pointer is almost at the red so I think the gauge is reading a bit too high also

I've ordered the alum rad from Carl. Obviously the OEM lasted 25 years (and still not leaking and holding 13 psi) but I'll like to try the alum for a change. I hope to become one of Carl's successful stats. Fingers crossed.

ROG100

For a hot run the temps are perfectly normal and a LONG way from over heating. Your rad is working fine.

Tails

Have you checked for debris between the A/C condenser and the radiator and also whether the fins on the condenser and radiator are clean and not blocked.

When the A/C is on and the fans are running at full speed the temperature should drop on the temperature gauge.

I have been in stop start traffic at 40 degrees C with A/C on and all operated satisfactorily with "flaps" operational.

Koenig-Specials 928

fins need to be 'combed'. will do that and flush debris between condenser and rad.
thanks for all the great ideas.

j.kenzie@sbcglobal.net

I was fooling around with a different fan once and accidentally wired it backward. When the a/c came on, the fan blew the wrong way and acted as an obstruction. My temp went through the roof. I turned off the a/c and it came down quickly. I felt stupid when I checked the fan rotation. It's not that obvious when you look at it, which way it should turn.
Just an idea, and I'm sure there is some other explanation for you.
Good luck,
Dave

MainePorsche

Dave,
Excellent pearl.

Hessank,
Have you done any work in the vicinity recently ?