Hi guys,

Wondering if someone can help me out here.

My car: 98 Civic Vtec 1.6 - stock standard, no modifications.

It all started last week sometime when I was driving along normally and heard a popping sound(almost as if something had exploded in the front of the car) followed by the car hunting. I switched it off and back on again and drove it a a little while and the car was fine.

Nevertheless I took it round to Honda to get it looked at and they noticed that the heat gauge goes up instantly. That is; it goes up(to normal operating temp) as soon as I start the car even if its been parked overnight.

The strange thing is that it does not go any further than normal, in other words its not showing that the car is heating up. Honda have no idea whats wrong however everything seem to point to an electrical fault, but they can't isolate the fault so they can't actually fix anything. The ECU had some minor error which they said was fine and they cleared it and it hasn't reported any error codes since.

They have confirmed that the car is not actually heating up and that the cooling fan comes on at the right time.

Anyone with any idea's?

Thanks
Sam

 

Ok, so you start the car from sitting overnight, it goes to the halfway mark, right? And no heat is coming from the vents?

And when the car has been driven for a while, the gauge stays the same and heat is coming through the vents? Have you touched the lower hose to see if it is warm after being driven?

Right now, I am starting to think the pop is unrelated, and you either have a sensor issue (cheap fix for a replacement), cluster issue, or a more serious wiring issue.

Just wondering, goes the gauge goes back down to "C" when you shut the car off and remove the keys?

 

Yep start the car from sitting over night and the heat gauge goes up to halfway mark instantly. No heat coming from the vents, the car is cold.

Yes, when the car has been driven for a while, the gauge stays the same(no sign of heating) and heat is coming through the vents if I turn the heater on as normal.

Honda say they've tested the sensors and the cluster looks fine.

The gauge does goes back down to "C" when I shut the car off.

 

Got it. Three things (IMO) that could be wrong:

1. Coolant temp sensor located under the distributor - doubtful
2. Cluster needing replacement - doubtful
3. The wire going to/coming from the temp sensor is grounding on the motor somewhere and causing your issue. However, I am not sure if the wire was grounded if it would make the gauge go all the way to hot, or if it would just simply make the gauge jump up to what you are seeing.

MK is a GREAT diagnostic helper. Hopefully, he can come in and help out by giving you pointers or having you check other things.

 

now that you mention it, I do remember seeing that the grounding wire from the engine to the body was not bolted on to the engine. It went if for a cambelt change recently and they must have forgot to put it back. Could that be the cause?

Just chatted to the Mac from Honda, he says he put that wire back and it still did the same thing. They putting on another cluster to test now.

Its the cluster. Needs to be replaced. Thanks CVCRCR99!!! Appreciate the effort.

Any idea on the "pop" and hunting?

 

There ya go. Glad I could *kind of* help. haha

BTW, I meant that the wire (one wire) from the temp sensor under the distributor could have been split open and touching a piece of metal or the motor, causing the wire to ground out, and the gauge to move. The ground wires on the motor to the chassis would not be a cause for this I wouldn't think. However, with enough of them removed, I bet you would have some trouble starting the car

 

If the wire grounds, the gauge goes all the way to hot. Going up only halfway is probably the cluster like they said. The test would be to unplug the sensor and make sure the gauge stays at cold.

You can also test all this by just turning the key on and not starting, that will ensure that there is no actual heat involved.

 

Thanks MK! I was feeling the the temp would go all the way hot, but I wasn't 100% sure on it. Thanks for the clarification on that