Triumph Repair: 1975 Spitfire, temp gauge, wet test

Question
Engine overheated in July. Car stopped running. Pulled over and raised hood. Coolant is everywhere. dripping unto pavement. Never restarted after I had it towed home.
Engine is out of car on stand in garage.
What next ?
Is it true you need summer/winter thermo. for engine?
Driven the car under 1000 miles before this happened.
I may have overfilled with oil.
Thanks

Answer
Hi Michelle,

The over heating may or may not have done any major damage. To test it do this, first since you have the engine on a stand run a compression test and write down the results (throttle open). Now squirt about 3 or 4 squirts of engine oil in each plug hole and run another compression test. This is called a "Wet Test" and if it shows more then 10% to 15% higher then the first dry test, it is an indication that the over heating has taken the tension out of the rings and you will need to put in new rings.

Another damage that happens when an engine overheats is the #2 & #3 cylinders get so hot that the valve springs on those two cylinders loose their tension also. This is easy to test. Remove the valve cover and rotate the crankshaft so that all the valves on #2 & #3 cylinders are closed then with both thumbs try to compress a valve spring on #1 or #4 cylinder to see how hard it is to compress a spring, then do it to the 4 springs of #2 & #3 cylinder.

If the overheating has damaged the springs you will note easily the difference in pressure it requires to depress a spring.

This test probably should be done first before the compression tests because when an engine over heats enough to do damage, the valve springs go first then the rings.

Generally when a person is on an expressway and sees the temp gauge go high they have only minutes before major damage is done. (next exita) If one sees the oil light come on when driving you have only seconds before major damage is done.

It is generally accepted that if an engine overheats and still has some coolant in it that it may not receive major damage but as soon as the coolant is boiled out damage is in seconds.

The only way to know is to run these tests. All this has nothing to do with what caused the engine to overheat in the first place. The tests are ONLY to find out if the over heating has done major damage.

Let me know the results of these tests and I will give you the tests to find the orginal cause of the overheating.

Howard