I bought the car two weeks ago, I put a new radiator in it. Since I was driving 1300 miles starting the next day I thought I would throw in a bottle of the Wetter cooler? its the same stuff IPD sells. Annywho I put distilled water and the wetter in. One the trip I noticed that if wind was hitting the radiator the temp guage would dip down to almost the 7 oclock possition.

Anywho Saturday I took my nephew to the nascar race and we had to set in traffic for two hours and I noticed it would heat up in gear but not in neutral. Any thoughts what might be causing this? I bought a electric fan to throw on this afternoon. Thanks in advance

If this happens again, try this: Set the cabin heater on full hot and full fan. That makes the heater core perform like a mini-radiator. If you see the temp gauge needle drop, then there is a lack of cooling capacity in the system. Old plugged radiator, maybe something else.

Also, tranny in gear might heat the ATF a little hotter than when in neutral. With the ATF cooler inside the radiator, and fan-only air flow, that might account for some of the heating up.

Definitely check/replace the thermostat. Labor to check = labor to replace, and they are inexpensive. If the removed unit is OK, you have a good spare.

Good Luck,

Bob

:>)

I think it's the charging system.

The temp gauge is just an idiot light; doesn't show anything except large changes in temperature. We'd all like it to be an accurate gauge, but it's not. It shows cold, okay and too hot. Everything else is voltage drops, sorry.

If you are seeing fluctuations it is from the voltage drops if accessories are on or if the alternator isn't fully charging up the battery. Happened to me.

--
Stef -- 1981 245 B21A SU M46 323000km my volvo pages

re: "...if wind was hitting the radiator the temp guage would dip down to almost the 7 oclock possition...."

With a proper thermostat (and assuming your temp gauge is working right), your temperature shouldn't be able to drop to 7 o'clock -- it's a sign that the thermostat, for one thing, certainly isn't working right (probably stuck open).

re: "...set in traffic for two hours and I noticed it would heat up in gear but not in neutral...."

In gear, your engine rpm is lower; out of gear, it rises. At lower engine speed you're not getting adequate cooling -- could be the fan clutch (not enough air flow) or water pump (not enough circulation of coolant), but probably the former (fan clutch), as water pumps don't usually fail this way.

Could also be a loose fan belt, allowing slippage that could contribute to both slower fan and pump speeds!

Try a new temperature compensating board on back of the instrument cluster (works like a voltage stabilizer between fuel and temp gauges).requires cluster removal and disassembly.

I have to admit that an erratic temperature gauge because of a faulty compensation board (found on '87-on 240's) could be the problem.

But before going to the trouble of pulling the instrument panel and either replacing the compensation board or substituting a jumper (the better solution, for future accuracy), let me first suggest how to confirm whether this is the problem.

There is a widely available, hand-held infra-red (i.e., remote reading)thermometer that is very accurate [I've compared it to my multithousands of dollars instruments in my biology laboratory, and it's close enough]. Made by RayTek, and sold by IPD, Griot's garage, etc. for about $80 to 90, you can aim it at the side tanks of the radiator, the thermostat housing, etc., to instantly determine coolant temperature to within a half-degree. Sure it's a bit costly, but you'll find countless other uses for it, not only in in your garage but elsewhere -- in the kitchen (tell your wife you bought it for her :-), around the house and garden (get air temperature, soil temperature), etc. It's a great diagnostic tool.

Anyway, you can confirm easily if it's an inaccurate temperature gauge or a cooling system problem.
Good luck.