3rdman

94 si Bone stock 151k bought it from original owner (no longer available) no records left behind

i got no heat in the car, (not that its needed) but doesnt blow hot, and car is over heating and fan wont come on till needle is over 3/4 of the way up tword hot on the gauge. top hose gets very hot, lower stays cold. 4th thermostat installed. noticed alot of stop leak inside the housing that the stat sits in. thought i was getting bad ones, so tried 4 different ones, also changed the rad, and fan switch. still the same thing. you can drive it on the highway. seems to be fine, (must be the air blowing on motor) ones you slow down and hit a side road. it goes right up! then comes down, but most of the time stays up. what should be next.. other then the heater core clogged. (would that make me over heat?)

Former User

Check whether the heater hose valve on the firewall is stuck closed. If so, manually open the valve and then thoroughly flush out all of the junk out of the cooling system. Then install a new fan switch in the thermostat housing and refill and bleed the cooling system.

slow96lude

Also check whether the thermostat is stuck closed. Or just take it out all together

Former User

The thermostat must remain installed because removal can lead to engine overheating.

slow96lude

I have never ran a thermostat in any of my hondas and I live in a hot climate. I have never had a problem. The only reason the thermostat is there is to warm the engine up faster. It stops flow until the engine is at operating temperature then opens.

Former User

This is partially correct. When fully open, the thermostat additionally functions to slow the flow of coolant through the cooling system. This restricted flow cools the engine more efficiently because slower moving coolant is able to absorb more engine heat than is faster moving coolant. Therefore, running the engine without a thermostat will actually overheat the engine and reduce its life span.

chan1234

this was going on with my old civic and ended up bein a blown headgasket

3rdman

i can just bypass the heater core if its clogged till i get a new one by looping the 1 hose back into the motor correct?

Former User

Yes, but first try disconnecting the heater hoses and then flushing the heater core out with a lot of pressurized water from a garden hose. Do the same for the entire cooling system.