Cooling question

Hi everyone,

I have a problem and maybe someone here can help.

I have P2264, I have just under 10,000 miles on her and could not be happier.

That said, over the last month, I have had a problem with overheating.
My motor is a Roush 302 based 342R.

All last summer even on hot days here in California she ran cool, no problems!

Now I find that even on cool days the temp climbs steadally until it overheats. Oddly if I turn on the heater, even without the fan the temp drops almost immediately, quicker than the small heater core could do on its own.

I'm guessing that this may be a thermostat problem with the heater water somehow bypassing the thermostat?

Does anyone have any thoughts as it is getting warmer and leaving the heater on is problematic.

Thanks!!

I would guess a replacement thermostst could be fitted quite easilly and cheaply, give it a go.

Simon

Coulld be a thermostat. Can you borrow a thermal laser/infrared temperature gun? Check the temps at the hoses and at the radiator inlet/outlet.

The temps will indicate if you have proper water flow as a bad water pump can also cause issues. On P1116 we had a crap reman pump that the installer put on, had overheat problems consistantly except at steady cruise. replaced the pump with an alloy Stewart unit and the car could idle on a 90 degree day and never overheat.

Jim,

I'll bet it's your thermostat.

The heater lines bypasses the thermostat (at least does on my FE install with no pump bypass) so with the heater servo valve open you get water flow through the heater core to the radiator and back to the block even if the thermostat is not open or only a bit open.

BTW; with no pump bypass I warm up the engine with the heater servo open and get a gradual warm up not a thermal shock as if I waited for the thermostat to open.

Steve

Thanks everone,

It looks like I'll change the thermostat this weekend.

I'll try and find out which type from Roush.

Thanks Again!!

Check your coolant levels. Sounds like you have an air bubble in the system to me.

Jim:
You might want to look into a fail-safe type thermostat, Fails in the open position. The motor usually won't warm up fully, but you will get home without overheating.
Cheers
Phil

Potentially like the MGB V8 problem

With the cabin heater on there was such a clear run for the water that it all circulates vja the heater and that becomes a secondary bypass thus very little water flows through the radiator

If this is the case fit a restrictor in the cabin heater circuit

Oh yes and it was not the same on every MGB car - some worked well and others overheated

Ian

Well, it was the thermostat,

I changed it out and she now runs cool again, thanks everyone for your input!!