Temperature Gauge Reads Hot!

[Shakedog]

Hello everyone! I'm brand-new to the forum and happy to have found this source of information. I'm hopeful some knowledgable members can help me out with a problem.

I have a '95 Accord EX with about 130,00 miles. It's been a great car and I've taken excellent care of it. However, just in the last few days I've noticed that after the car has reached operating temperature, if I throw the car into park, after about 30 seconds the temperature gauge steadily rises all the way up to the top. If I turn the engine off, the secondary cooling fan kicks on -- I've never before noticed it kicking on except perhaps on very hot summer days. The check engine light does not come on at any point and the car continues to idle normally -- (i.e. it doesn't run or sound like an engine that's overheating). When the car is in any gear other than park the temperature gauge reads exactly what it should - just below the mid-line.

I checked to see if perhaps the thermostat was stuck closed but the upper radiator hose was not cool so I don't think it's that. At this point I'm leaning toward thinking it's the temperature sending unit but I wanted to post on here and see if anyone else had any ideas. It has been almost 4 years since I flushed the cooling system and I'm planning on doing that this weekend. I haven't detected any coolant leakage around the car so I don't think it's lost coolant.

Also, one thing I have not yet checked to see is if after having the car in park and letting the gauge rise to the top, throwing it back into a drive gear and seeing if it drops back down. I'll take a look at that later today.

I'd really appreciate any advice!

[AccordCodger]

The cooling fan behavior, at least, is normal. (The part about it coming on after switching off the motor).

Are both your fans working? Put the A/C on (with the ignisiton on) and they should both fire up.

[mpumas]

So you are saying that the car in neutral and idling, the temp gauge stays in mid range?

[Shakedog]

I had a chance to investigate further this afternoon.

I understand that the secondary fan normally kicks in after the car is shut off but this Accord really hasn't done that much except on very warm days. I used to have an '89 Accord where the fan ran more consistently. Both fans are functioning.

As long as the car is in drive and moving, the gauge reads normal. If the car is in neutral or park it will start to rise up. Additionally, this afternoon I saw it start to creep up while I was idling in drive at a long stoplight. Once I started moving again it dropped back down immediately.

This just seems like odd behavior for a temp gauge which continues to lead me to suspect it's the coolant temperature sensor. I'm just not certain yet.

[blacknight]

Check the radiator fluid and makse sure it's topped off. Also, Check to see if there is any white smoke from the exhaust. If so, you may need to replace the head gasket.

[mpumas]

I don't think it is the guage. The temperature goes up when the engine isn't moving much water through the engine and radiator. When you increase engine speed, the temperature goes down. I think you need to flush the radiator. It may be partially plugged up with a goo that cleaner can dissolve.