HOT-SHU (a.k.a. Wes Shew)

led, how did you clean your rad? If professionally by a shop, what did they charge? What was the after effect?

Where/which grounds should I be looking for?

TIA

led

It was cleaned by a shop and they actually charged me more than what a new rad costs but I didn't ask for an estimate beforehand so I got stuck with the bill. The after effect was simple, no more overheating.
The grounds would be the ones behind the instrument cluster. Also, adding another ground from the engine to the grounding point for the DS light has helped a few people, I did it but it changed nothing.

EZRider

If you're going the radiator route I strongly recommend replacement instead of just flush/clean.

Lousailor

My early 85 had similar symptoms. Temp warmed up fairly quick and was always at least at the halfway mark. Went up while sitting in traffic, and fans kept it from going all the way, but no real reduction in temp. Even drivimg on the highway at cruising speeds didn't bring the temp down, and sometimes the fans would come on at speed (I knew that wasn't right). The fan temp controller is down toward the bottom driver side of the radiator and the hose from the pump (through the thermostat) to the radiator is on the passenger side. This is so if the water flowing through the radiator reaches the temp switch limits, it kicks on the fans to cool the water in the radiator and keep the engine cool. If adequate water is NOT flowing through the radiator, most of the coolant is recirculated through the engine, and the motor can overheat without typical symptoms of overheat at the overflow tank and radiator. The temp gage gets it's input from a temp sensor on the engine block. Sharp spikes on the temp gage can also be indications of coolant boiling off and pockets of hot steam.
I finally got tired of living on the edge, and was going to put a low temp thermostat in, but the #$%&@ng PO had broken off one of the tabs of the retaining spring and it took an entire day to twist the thing out. So without a new spring handy, I just buttoned it up and went commando (doable in balmy SoCal). Engine temp takes a while to even get to the first mark, when I slow down and the temp creeps towards halfway, the fans kick on and it goes right back down - COOL! I got a new spring, so one of these day I'll pop the thermostat back in, but if you're motors not behaving similarly, and it's not the water pump, it's the thermostat. And yes I've had a brand new one not work before - sucks.

Legoland951

Change the thermostat and flush out the radiator if that does not work. Poor ground has nothing to do with no heat pulled from the radiator fans. The fans work, then its not electrical. The sensor for the gauge is in the block while the sensor for the fan is in the radiator. If the fans are on and no heat is coming off, THERE IS NO HOT COOLANT CIRCULATING THROUGH THE RADIATOR. Bad thermostat, clogged radiator, or waterpump impeller is not turning (separated from the shaft or the timing belt is not turning the pump for some reason).

Rich Sandor

Wes - try these two things first before you do anything else. They are easiest and cheapest.

1: When the car has heated up, try turning your headlights and foglights on and off. See if there is any jump up or down in engine temp, If there is, you need to simply clean or replace your grounds.

2: Thermo-switch. If you have a spare, or a new one, replace it. Weissass has em for cheap too.

I had a very similar problem and these cheap fixes helped.

If they don't work for you, then I would replace the Thermostat and try to flush the radiator.

Cheers
Rich S

W88951

Spend 20minutes to make and install Supplimental grounds. The temp guage in my car bounced all over the place, never read correctly and bugged the hell out of me. I spent $10 at Home Depot to buy some cable terminators and wire loom, Used some spare 4awg Amplifier cable and made supplimental grounds. One goes from the gounding block by the battery to the top of the cam tower. And the other goes from the front of the drivers side balance shaft cover to the factory ground point by the drivers side headlight. Since I have done that my temp Guage reads normal.


While your Engine bay ground cables may look good from the outside they are most likely completely corroded on the inside and the only way to tell this is to split open the cable.

Add the supplimental grounds first and when you have a chance replace your Ground Cable and your Starter cable. It will save you time and pain!

Rich Sandor

Wes - I made my own ground cable as well - I think it greatly helped kill the electrical gremlins as well.

If you don't feel like buying the materials and doing the welding and so on - Iceshark sells a ground kit which is really good quality. Randy Jang has it on his 951.

ljd-924SE

i had similar symptoms and it turned out that the main ground at the bellhousing was faulty. a good way to check if this is the case for you is when the guage is reading hot, turn off the engine, then turn the key back to the on position until the temp guage works. if the guage is now reading normal temp, you know that the ground is bad and becomes overloaded when the engine is running.

Blue S2

Hmm...does anyone have a link to IceShark's ground kit???

Rich Sandor

Just do a search for Dan Wray's email.

TestDriver

Hello,

I'm trying to check my fan relay switch for proper operation following the routine from Clark's Garage but I'm having difficulty because of my company's web settings. I'm able to read the cached text but I can't see the graphics directly from the regular web page since it is FORBIDDEN by our system. Can someone post a copy of the thermofan switch diagram as it is shown on the Clark's Garage site? If not, how about a description of what is meant by numbers 1, 2 and 3 in relation to the terminal locations. Thanks.

Ramon

TestDriver

I forgot to post this link.

http://www.clarks-garage.com/shop-manual/cool-01.htm

It goes directly to the procedure referrenced above.

Ramon

hy944

Wes,
Sounds to me your thermostat. Your fan seems to be kicking in and working. Your temp gauge is going upand down, hot water vapor does strange things to a reading of temp sensor.Your very first post you indicated that the fan was working, engine was hot, but the air drawn through the rad was cool. Thermostat is located on the return side of water pump inlet. Feel the lower rad hose, is it cool or warm?If there is a partially opened thermostat, water coming out of head to radiator will be slow it will trigger the fans, but remember water circulation will be slow, so the fans will cool the water in rad quickly hence the cool air when you checked it. The interior fan is operating like your rad taking hot water from top of head, through interior heat exchanger, and back to inlet side of pump behind the thermostat.Your rad fans will still work because you still have some circulation flowing through rad through the partially open thermostat and triggering your fan switch. You probably won't have too much problem when idling but when you drive it, you need the extra cooling. I don't think it's an externally blocked radiator otherwise there would have been a gradual increase in engine temp over the months same with the internal rad blockage.Unless a big leaf blew up into the rad intake or a chunk of corrosion crud broke off, blocking the internal cores of rad, It sounded like it happened suddenly. Electrical grounds? Your fans are coming on at 97 deg cel, and turning off when cool, Thats OK. The temp gauge goes up and down relative to engine temp, thats normal. Check the top rad hose temp, should be hot like the engine, lower rad hose should be warm or less hot for obvious reasons if the hose is cold then you probably not getting water circulation. check the water inlet side of pump aluminum neck. if the neck is as hot as the engine cyl head and the hose is cool, then the thermostat is blocking the flow of water. Sometimes the mechanical things are easier to check then diagnosing electrical probs. If you suspect grounding problems, grab a good jumper cable and connect the batt ground to engine and see if anything changes. If it were a gauge sensor problem still does not explain why your fans are blowing cold air while the engine is hot. My 2 cents

PCMAX

There's some good info for checking out your temp gauge at:
http://www.frwilk.com./early944/
it covers early & late models.