Hello everyone, new guy here. I just purchased a 1988 Honda Civic HB with a 16V motor last week. Has 61K on it, but kids owned it, and they got it form their Grandmother when it had only about 27K on it. Anyways.... The temp gauge wire was disconnected. Not long after I start the car it goes overtemp. I changed the sensor for the gauge and its the same. Could it be the thermostat or are the impellers gone on the water pump. The upper radiator hose gets hot but the lower is cold. I'm thinking water pump and I hope the engine is OK. Any help would be awsome.

Signed,
Been had.

 

Change the thermostat first. Note that it is on the lower hose behind the engine. There is nothing in the upper outlet fitting on the front of the engine.

It may be time to do the timing belt if you don't know how old it is (years will degrade it even if it doesn't have many miles), when you do that you can replace the water pump for good measure.

 

OUCH... could be bad... personaly id go get my money back if that temp gauge was unpluged! they knew it had a problem overheating and they hid the problem!!!!!
with it overheating it could have already done some serious damage to the head!
it could be just a bad thermostat..... but if the water pump isnt making any noises i doubt its bad....
BUT problem with just swaping out the thermostat is you dont know how long its been ran overheating like that before you bought it! which could have warped the head which will easily trash the motor out.....

id go get your money back ASAP!!!!! and raise hell (with a few buddies with ya) and at least scare them to give back your money on this LEMON/FRAUD CAR!!!!

 

Not the thermostat as I tested it out of the car. Original owner called back and said he never had a problem with it overheating, and his mechanic said its doesn't have a problem. This just raises more ?? May just try an aftermarket gauge to see what it does for the hech of it. I doubt I running the car long enough for the thermostat to even open.
More soon.

 

Got a brilliant idea. Warm water in coffee cup. Original sensor with ground wire held to it with vice grips. Stick sensor in warm cup of water and gauge goes full scale! I purchased a Autometer temp gauge but the 1/8" sensor will not screw into the head, must be NPT vs. something else. The funny thing is I can take the original sender from the car and it will screw into one of the Autometer supplied adapters so its really close. hhmmmm.
Well, atleast it looks like this thing isn't overheating, but there is no way that the PO could have ever known if it was running HOT.

 

Probably running at normal temp then, if you've changed the sender to a proper one it must be the gauge in the cluster is reading wrong. I'll measure the resistance of the sender in my '91 tonight at normal temp and if you have an ohmmeter you can compare. That resistance value might also be in a book or on the web if you look for it.

 

be careful if it is actually running hot. My water pump failed on mine a week after i got it and it overheated one time, I shut it down as soon as It did too. But sure enough about a month later, after the t-belt and water pump, and radiator ahd been replaced, the head gasket was gone. three places blew out... it ran like absolute crap and overheated real quick... I was forced to drive it overheated for like four miles because there was no safe place to stop.

I got extremely lucky with it. we took the head off, and checked it out thouroughly, straight as it can be, no cracks, and surprisingly clean for the 199k miles it had at the time. stuck a new head gasket on the block and bolted it back on.... good as new... still running great today, a year and a half later @ 238k miles... most of the time though with aluminum heads you wont get that lucky if it is running hot. the head can warp or crack very quickly if it gets to hot.

I know that because I drove a ford escort with a cracked head for a year... it wasn't hurting anything, it just idled real rough and went through a bunch of water, but nothing was mixing in the oil and it was over cooling rather than overheating, so I kept driving it,.... ended up rebuilding it, and then sold it to get my honda... I'm a lot more happy with my civic...

 

The sender should be about 78 ohms with the engine at normal temperature. Warm up the engine, turn it off, disconnect the sender, and measure from the sender pin to ground. If that resistance checks out then the gauge in the cluster is going to be the problem, or maybe the wire from the sender to gauge has a short to ground.

 

Mine was at around 170 ohms. Hot water in the coffee cup prooved the sender was bad to me. Got the Autometer installed and the car is running around 190. I never looked at what thermostat was in it, but now that I've had it out I may just replace it as its pretty easy to get out. Thing I'll flush the coolant system out too. Feel a little better about things now. Started cleaning up the car, vacuuming, remove all stickers, clean windows, etc...
Funny thing has happened, the Mazda Miata that I was trying to contact a women about is up for grabs. She practically had it sold and it feel through. 85K on it, 1992 I believe, clean but the clear coat is peeling, has the hard top option, asking $3,000. Only thing is its an automatic.
I've got $600 into the civic and it came with loose snows that are practically new. Not easy being a car nut, so many cars so little time.