Cool running

[Morgan33mike]

Don:

I have an A-4 in a 1971 Morgan 33 classic. My issue is that we can't seem to get the temperature above 110 degrees. We did a complete re-build (from main bearings, cylinders and valves) last year and replaced all gauges and sending units at that time. I have a fresh water cooling system with a water lift muffler. Any ideas on how to eliminate the possible causes such as gauge, solenoid and thermostat without purchasing a new one of each?

Thanks,

Mike

[Don Moyer]

Mike,

A couple items:

Are you running the engine under load? Depending on the temperature of your outside water, it's not uncommon for the temperature to take forever to come up with the engine in neutral.

If you replaced your gauges with Stewart Warner instruments, you will have to be sure to connect the "GND" terminal of the temperature gauge (not just the case of the gauge) to engine ground. You can usually ground this terminal to the instrument panel which is normally connected to engine ground via a ground wire from the engine block, but not always.

Don

[Morgan33mike]

Don:

I verified this past weekend that the gauges were connected properly. I have the ground wires connected which are lead to the engine ground. Even last summer when underway and our water temperatures were in the 80's, I could never get the temperature above 115 or 120. If the engine tends to run this cold what problems, if any, does it cause or should I not worry?

Mike

[Don Moyer]

Mike,

If your engine continues to run at 120 degrees or lower, you might expect to see some sooting of the plugs. If the plugs stay clean and dry, I don't see much of anything bad that is likely to result. On the assumption that your gauges are correct, the cause of your overcooling is most likely a thermostat that is stuck partially open or a restriction in the bypass loop.

Don

[jhwelch]

To see if your gauge is not reading correctly use a cooking thermometer,
the kind you jab into a fowl, to probe around the engine block. Just
make sure you buy one in the right temperature range.

-jonathan

[Morgan33mike]

Don:

What if any are the symptoms if an aftermarket thermostat was used in a late model without the conversion kit? By the way at the beginning of the thread I said this was fresh water cooled but the correct terminology would be raw water cooled because I do not have a heat exchanger.

Mike

[Don Moyer]

Mike,

The most glaring issue would be that the aftermarket thermostat wouldn't fit. They are just a bit longer than the OEM thermostat and will hit the floor of the cooling jacket in the head.

Don