General Tech Running hot

[Trevor Triumph]

I replaced the radiator - and the engine gets to the "N", the midpoint of the needles's sweep. At idle at a traffic light of stop sign the needle moves toward the hot end of the sweep. Usually, the needle returns to the normal position after a short distance. Lately it seems to take more time. I have not adjusted the SUs in a while, and I understand if the fuel mixture is lean, the engine tends to run hotter. Also the number one cylinder has about 70 psi, the others are 110 psi. Also there is a the sound of exhaust leak. I tightened the manifold bolys to spec and it sort of cleared up. I was teaching grandkids to drive the car and the temp gauge went into the "hot" zone. I immedialtely took over and drove home the and needle returned to normal range. The "leaky" exhaust sound has returned. So... Warped head due to lean mixture / mis-adjusted SUs, timing problem?

T.T.

 

[NutmegCT]

What's the weather like when that overheating happens? Southern Arizona isn't known for a cool dry climate.

I'd bet a thermostat controlled electric fan would do what you need. Also, are the coolant passages through the engine clean, or full of 60 years of crud?

Hope this helps.
Tom M.

 

[Graham H]

Not likely to be a warped head due to a lean mixture but it could be a blown head gasket, run it with the radiator cap off and look for bubbles in the water.

Graham

 

[Mickey Richaud]

Not likely to be a warped head due to a lean mixture but it could be a blown head gasket, run it with the radiator cap off and look for bubbles in the water.

Graham

Yeah, with that low compression reading on #1 it sure is a possibility. How does the oil appear - any milkiness to it?

 

[bobhustead]

Mixture is not causing this. The number 1 cylinder is probably involved. Can you find a shop with an exhaust gas sniffer for the radiator?
Bob

 

[Sarastro]

Since you replaced the radiator, I presume you have replaced the coolant also. But there still could be rust and crud in the block. It might be a good idea to do a full flush, with stuff designed for that. I've used the Prestone in the past, and it removed a lot of crud, but there are others.

Also, as with any cooling-system problem, replace the thermostat.

Finally, there should be an orifice in the bypass line, usually where the bypass line connects to the pump. Some older TR water-pump bodies don't have one, and without it you can lose a lot of cooling capability.

I agree that you could have a leaking head gasket, but I think that should be second to making sure that the cooling system itself is doing its job.

 

[CJD]

The TR cooling system is airflow limited. The stock fan does not provide enough flow to cool when at a stop. The solutions are:

1) Check the ducting is installed properly from the cowl to the radiator.
2) switch to a "tropical" fan, which moves more air.
3) Add an electric fan, which will absolutely solve your problem, but it requires more power, so an alternator conversion is also required for this.

Here in 100 degree Texas, I simply shut down the motor if I am at a long stop light. It fires up instantly, and as long as the car is moving it has enough air to stay cool.

 

[Trevor Triumph]

Thanks for the suggestions.

I checked the radiator cap; sometimes the rubber is crazed so pressure can't build. It seemed to be smotth and pliable.

A friend uses the eight blade fan from a later Spitfire - his suggestion.

I'm not sure, but the thermostat could be malfunctioning - I think I replaced it when we rebuilt the engine in 2007.

I get the opinion is there may have two problems, perhaps unrelated - the cooling system and low compression.

T.T.

 

[Graham H]

A leaking head gasket will give you both problems, I had a similar problem because I didn't retorque the head after my rebuild, I think it may be head off.

Graham