93 240 coolant temp rises on high demand at 65mph and higher, replaced thermostat no help. While driving I turn the cabin heat on full blast and needle reads normal. Pump, fan and radiator seem to be working water circulates mixtures flows in and out of pump. Unplugged sending temp sensor (1 yellow wire) and gauge read zero. EEC shows 111 indicating eng coolant sensor no faults found. Please help.

Have you bypassed the temperature gauge "compensation" board? This is a small circuit board plugged into the cluster which changes the behavior of the temp. gauge so that it stays in the center most of the time. When it goes bad, it can cause all kinds of strange readings. Search the board for many posts instructing the bypass procedure.

It sounds to me like a clogged radiator, though. The rad in my '93 died only about a year ago, and it was pretty clogged with plaque. Ever since replacing it, the temp stays in the middle of the gauge in almost all conditions. Even if the radiator is not clogged, the mineral deposits inside can reduce cooling efficiency a great deal.

I would guess and jump the connector to the instrument cluster that connects to the temp gauge? And I'll also check the center of the radiator for the fins condition. Thanks

Radiator doesn't look too healthy I think I'll r&r the radiator any ideas on a site to order one for a good price?

Nissens I believe is the best around these days. FCP of groton usually offers free shipping. Get some hi-temp black paint ready to treat the bare metal. Your in NJ so you will have it next day as well most likely UPS ground so late in the day. As far as the temp.comp. board you have to remove the cluster and then the board and jumper pins 1 and 3 as I recall.Use a piece of household power cord and just slide it on the pins.

Ok thx. Today I found something else to the equation. After picking up my Mom at the airport the needle was climbing so I believe I regulated the temp with the cabin heater. When I got home I popped the hood to witness the aux cooling fan not working. Well I turned on the ac and no fan operation, so I jumped the fan connector from batt + ,fan works fine. I found the thermal switch jumped the conn with a 20 amp fuse, fan ops good. So the thermal sw is bad, the fan relay works as I cycled it by connecting and disconnecting it. My question is according to the Haynes manual in the 93 model is, does this fan turns on to auxiliate the engine cooling with out the aircond on? I need a wiring print that clarifies the cooling operation. I did order both coolant temp sensors because they are cheap enough in order to illuminate them from the equation. Thank You again.

Before you throw too many parts at it, next time you see the needle rise above nine o'clock, give the dash a good swat right above the instrument cluster. Watch the needle. If it begins to migrate down (or up) get your compensation board out of there.

Notes on the Temp Faker - Or That Temp Comp Board

If that does not happen, wash the radiator. If you have a temp switch in the rad with actual wiring, you have a modified car. The AC helper fan was controlled by a high pressure switch in the refrigerant line to the condenser when it left the factory. But some replacement rads come with a temp switch to plug the hole and make it more universal.

Notes on 240 AC wiring



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Art Benstein near Baltimore

Acupuncture is a jab well done.

Art I removed the compensator and jumped the pins with the old lamp wire method, plus I washed the radiator as you suggested. The wire did ohm out correct. So the final test will be when I hit the Turnpike tomorrow morning. Wish me luck. Thanks again.

The reason I said to check the fins on the radiator is because I had the same exact issue and the radiator was replaced 5yrs earlier, evidently with a cheapo POS. The fins just fell apart like burnt paper and all the ones in the center were gone, I assume it was the fan that pulled them through 1st. When I finally removed it I was shocked at the degradation that occurred in such a short time.

Same here joekidd. Rad crumbled. 5-year old Valeo:


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Art Benstein near Baltimore

When you've seen one shopping center you've seen a mall.

Art I replaced the water pump because it was leaking and the temp sensors by the #1&3 cylinders and now the gauge is reading high approx 11 o clock pos. Should I reinstall the gauge compensator or remove the thermostat for troubleshooting purposes?

Joe I drove this morning to work and the needle was ar 9 oclock position steady so as right now its a fix. Thx again

alright that sounds simple enough the malettize technique... will try that thanks

If the temp comp board is still in it must removed 1st.Always used distilled water in the radiator same as you would in your battery. Check that the fins are not gone on the radiator,especially in the center.

OK thx for your input I will check the center of the Radiator because I visually glanced at the upper portion and it appeared in good shape.