I’m having a problem with my 1993 Honda Civic which has me stumped. I’ve been driving it for 10 years. Up until recently, the temperature gauge reads about 1/3 of the way when the engine warms up and it sticks there. What’s happening now is, after driving for a half hour or so, the temperature gauge starts to rise when I’m idling, eventually getting as high as 2/3 before the fan finally kicks in. So, it’s not exactly overheating but it’s definitely behaving in a manner that is unusual and it’s nerve wracking. I’ve replaced the thermostat and fan switch and it’s still the same. I’ve checked both the fan motor and relay and both seem to be working. No coolant leaks, head gasket is good. Any ideas?


1993 Civic Hatchback DX
Automatic
No a/c
Engine type - D15B7

 

timing belt maybe jumped a notch?

 

Thoroughly bleed the cooling system. Then go from there.

 

Hmmm...hadn't considered that, but seems unlikely. I'll check that this weekend.

 

If after you bleed the coolant it's still doing that, I would suggest replacing the thermostat.

I tested a brand new thermostat that I had put in a car that did exactly as you described and found it was opening late/higher temp than the car requires. Your thermostat could be old and is now opening at a hotter temperature than the engine requires, then once the fan kicks in you see the temp drop back down.

 

Test the thermostat by putting it in boiling water and check temperature with thermometer and see if it’s opening at the right temperature.

 

I've replaced it twice now with the same result. I may try again this weekend.

 

That's clever! At what temperature is it supposed to open?

 

Bleed. There's a good chance that air is trapped in the cooling system.

It's critical that you quickly solve the overheating problem, which will destroy the engine, if this hasn't already happened.

 

180*F should be where it opens up I believe


here a videos in how to

 

Check if your coolants is low.

Here how I bleed my coolant:
Jack from of the car up so it’ll be incline a bit, then leave cap off the radiator and turn heat all the way up, once it gets up to temperature squeeze the bottom and top radiator hose to help get the air bubbles out. Keep bleeding till you stop seeing air bubbles from the radiator neck.

 

Additional important information:
The D15B7 has a bleeder bolt on the water outlet to remove air. Starting the bleed process with a cold engine, the process should continue until the radiator fan turns on twice.

 

180 is the VX D15Z1 only, all other 92-95 stock engines is 172. The 172 I bought didn't start opening until 180 and is why I believe the temp gauge would rise to 3/4 then drop when the fans kicked on. And would not overheat at all when driving, only idling.

 

Sorry for the misinformation guys I just went by how I did it.

 

Alright, so it looks like my weekend work is:
- check thermostat
- bleed coolant
I'm also going to pop a new relay in...I talked to a guy who's worked on a lot of Hondas and he said that it's possible that it's getting stuck and behaving erratically. I'll report back with results.

 

what about a clogged radiator?

 

Can you give me the correct Honda part number for the thermostat that opens at 172f for the D15B7 engine?

 

Enter your VIN and look up the part #.

https://www.bernardiparts.com/