ebs3349

I have a '79 shark U.S. spec, auto trans that loves to play with the upper portion of my temp gauge when sitting in traffic or at idle after the car has been driven after at least 15 mins. I've read all the tip sheets and troubleshot everything I think involved. Replaced w/new fan clutch/bearings. New electric fan. New thermostat. All sensors are cutting the aux fan when supposed to and aux fan is running when the AC is on or when the temp does go overboard. Car does great on open road with no problems at all. Recently took 300 mile non-stop trip on interstate in 90+F temps with no problem until I got to the first traffic light/traffic. Temp will flirt with near red part of gauge and scares me!! Start moving again, temp drops right down. Car has never "boiled over" though. Any suggestions?!?!? HELP!!!

Mongo

try a little of that pink Redline Water Wetter stuff. It will lower it a little bit, but my dad never really had a problem with our 85 like you had. If you got a new thermostat and everything the temp should stay lower. DId you replace the fan clutch yet? Sometimes the fan will underdrive if the clutch is going out on the fan

<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

ebs3349

Thanks, I'll try the Water Wetter stuff . And yes, I did replace the fan clutch.

John Struthers

EB,
Not 928 specific but related thru the wonders of radiator cooling.
About 2 years ago drove 6 hours to a place north of Dallas to actually look at a 928.
An 85' RED, Black Int. owned by a Honest to God 60 year odl woman.
On the way home my pick -up started overheating.
Pulled off for gas and a hose went...
Replaced hose, new fluid...
Overheated again, on with the heater , windows down ... thank God for Vent windows.
Home changed thermostat -hard pipe(hose)- all new hoses,fresh fluids.
Overheating on anything over a 15 mile run.
Fan good, new cap, more fluid.
Overheating...
No leak or squeal from pump. But out of options.
While cganging pump discovered bolts installed without anti-sieze compound. Five snapped off not a problem. pump off and access to remaining 5 studs with channel locks external to cam cover.
1st one broke off, used easy out. Same for 2nd, 3rd. last two inaccessable without removing half the front end. Flat bed to shop...$900.00 later ... new cam cover, gears/sprockets, water pump, power steering pump, all new hoses new thermostat, cap and fluids.
Still overheating in 20 miles .
Pulled thermostat again... still overheating <img src="graemlins/crying.gif" border="0" alt="[crying]" /> Added back flush kit, descaled 3 times...ovrheating.
Yanked radiator, new one $146.00 from Advance Auto. 30 min job
Engine runs cold <img src="graemlins/c.gif" border="0" alt="[ouch]" /> Feel free to drive around the country!
Moral of story...Use anti-sieze compound,
and probable cause of scale was tap water ...use distilled water with a low phosphate coolant.

Normy

-Sounds to me like an air-flow problem at lower speeds. Most likely, the fan clutch needs to be refilled. Check out Greg Nichol's site for the info on how to do this cheaply.

Normy!
'85 S2 5 Speed

WallyP

The normal engine operating temperature of the 928 is 85 - 90 deg C.

A 50/50 coolant mix at one bar boils at about 130 deg C.

The temp gauge on the 928 is not all that accurate.

A hot engine will smell and feel hotter than normal.

It is not unusual for a 928 owner to waste a lot of money trying to cure a nonexistent overheating problem.

If you are really concerned, you might be able to find an infrared temp gun to check the actual temp of the hoses and radiator.

Or, you can buy a cheap mechanical temp gauge with a sensing bulb on a thin capillary tube. Remove the top radiator hose, insert the bulb, put a little RTV silicone around the tube, and reinstall the hose. Put the gauge where you can see it, either under the hood, or tape it to the windshield wiper. Drive the car and check the temperature against your gauge.

ebs3349

Thanks, looks like a new radiator for X-mas!!

Greg86andahalf

EBStokes,

How well is the A/c cooling when you're in traffic and the temp guage is up?

If it's lackluster, carefully check the condenser for bugs, road stones, leaves, bent cooling fins, etc. Also check between the condenser and the radiator. Any blockage in the condenser airflow will effect airflow through the radiator. It doesn't take much debris to have a negative effect. When you spin the clutch fan by hand, it should move about 1/4 turn or less. If it moves more, the fan clutch is suspect.

If the A/C is ice cold in traffic and the engine temp reads high, airflow may not be the problem.
Too bad there is no way on the 928 to see circulation through the radiator. On radiators with a filler cap, you can watch the coolant flow with the cap off. Keep in mind that more coolant than a 50/50 mix will cause a negative effect on cooling. 45 coolant/ 55 distilled water is typical.

Greg

ebs3349

Thanks, Greg. A/C blows cold in traffic. seems not to be air flow. The only thing I can think to try is new radiator $$ <img src="graemlins/crying.gif" border="0" alt="[crying]" />

Dennis Wilson

EB,

Before you get anew one, try flushing yours. It may loosen up enough of the build up to keep you from over heating. Your local parts store should have flushing chemicals that are safe for plastic radiators and aluminum engines.

Dennis

ebs3349

People!! Ya'll won't believe this!! I was skeptical of using any coolant additive, but tried "Redline Water Wetter Super Coolant" additive and I think we may be on to something. Also, previous records indicate that a stock 92 C radiator sensor for aux fan was installed less than a year ago. Maybe previous owner was having same problem. First thing tomorrow AM, I'm going to replace with 75 C sensor. So far today, temp never went past second mark.

dr bob

[quote]Originally posted by EBStokes:
<strong>People!! Ya'll won't believe this!! I was skeptical of using any coolant additive, but tried "Redline Water Wetter Super Coolant" additive and I think we may be on to something. Also, previous records indicate that a stock 92 C radiator sensor for aux fan was installed less than a year ago. Maybe previous owner was having same problem. First thing tomorrow AM, I'm going to replace with 75 C sensor. So far today, temp never went past second mark. </strong><hr></blockquote>

Note that the 75c thermostat doesn't add any cooling capacity to the system, it only determines what the minimum temp will be. Fix your overheating problem for sure, then decide if you want it to run at 75c on the coldest days.

Just a thought!

johnb

hi

my '84 S2 euro did the same thing, until recently...

i tried everything, new stat, replaced fan clutch, flushed rad, replaced temp sensors, temp switch......no change still got toooo hot!

replaced the seal in the back of the thermostat housing (stat closes onto it) and no more problem!

simple as that.

the stat was not closing the cross head gallery, so the cooling water was not being pumped thro the rad properly. a couple of bucks, removal of the remains of the old seal, pushed in new seal, tapped home with a 32mm(?) socket, problem solved, gauge now stays in the middle, up hill down dale!

regards
johnb