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MG MGB Technical - Loss of coolant

Got the engine back in the car. Before I removed it the back core plug had blown out and I lost a considerable amount of coolant. Guessing there was only a quart or so left by the time I got it into the garage. But the engine was still running. Now the engine runs but it's not right . Also turning the engine by hand I can feel there is little compression. Actually I can't feel any although I haven't put a compression gauge on it yet.Is it possible that the loss of coolant caused the rings to go bad?

George
G.E. Bulwinkle

1. How far did you "move it" minus the core plug?
2. Do a dry, and oil, compression test and let us know the results.
Allan Reeling

I drove it about a mile when I noticed coolant was leaking onto the block resulting in steam coming out from under the bonnet. But I think it had been leaking for a while.

Compression tester is scheduled to show up tomorrow. I'll do dry and oil tests.
G.E. Bulwinkle

Dry 130 132 111 131

No. 3 was always a little low.
G.E. Bulwinkle

With oil - 132 140 120 140
G.E. Bulwinkle

George. Please define, and expand on: "Now the engine runs but it's not right."

The compression numbers you show are sufficiently high that each cylinder should be capable of running well. I have seen working engines, old but worn, with 100 psi and they still were capable of being driven at highway speeds. Your highest and lowest readings are slightly more than the 10% difference that is considered the ideal maximum difference, but the engine should be capable of running and providing adequate power for general use. It, simply, is less than ideal which is quite different than "bad" or "non-operational". The lack of significant difference between the dry and wet compression checks tends to indicate that the rings are in good condition.

So, please define, exactly and to the best of your ability, what you mean about the engine being not right. It would, also, be good to note the last time you did a major tune up, including resetting valve clearances. Knowing what distributor and what type of coil triggering system it employs would also be of benefit--moisture in the dizzy can damage the internals and cause several forms of problems.

Les
Les Bengtson

Thanks Les. Took the car out this afternoon , revved it up to 5500 and it runs fine. I don't know why it seemed not to run ok before. Maybe I didn't have the timing set right. It's been a while since i've adjusted the valves.

George
G.E. Bulwinkle

I have a digital voltmeter on the dash. Before I pulled the engine it used to rise quickly to 14.2. Now it struggles to get to 13. I ordered brushes, rectifier and regulator.

George
G.E. Bulwinkle

Did you check the voltage on the alternator output is similarly low? Low voltage on a plumbed-in voltmeter can be due to bad connections in a variety of places.
Paul Hunt

Slipping belt. Sprayed some belt dressing. Volts up to 14.2.
G.E. Bulwinkle

There you go. An ounce of diagnosis save ten pounds or parts.
Paul Hunt

This thread was discussed between 08/06/2014 and 14/06/2014

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