The Fordson Tractor Pages Forum

I have a Dutch barge that has a 1965 marinised Ford 592E industrial engine (which I believe is the same spec as the Fordson Major series of engines).

I'm in Belgium and am having work done on the engine that will include a compression test.

I have searched the forum in the hope of finding the answer to two questions that the mechanic has asked me: what is the best compression pressure that one can expect and what is a 'too-low' pressure (i.e. one where an overhaul would be advised).

I found conflicting answers to the first question. One post said the best pressure one could expect was 380psi but another said that after a rebuild the pressure was 300psi. Another post suggested that 300psi was 'not bad'.

There are no suggestions on what might be considered 'too low'.

Any help would be appreciated as the mechanic is returning tomorrow to set the valve clearances to the correct values - 0.305mm exhaust and 0.381mm inlet - before doing the compression test. He has already removed the injectors which will be tested, cleaned and replaced.

Regards

Well, after all that, I'm flummoxed. Compression test done and it's 440, 405, 420, 405psi.

Maybe the industrial engine is different.

There are several people wanting info on compression pressure, lately. I will post the numbers from my Fordson manual soon. Yours are considerably higher than the info in my book.
Let us know how she runs when you get the injectors back in.

It would be interesting to know if those quite high compression pressures were obtained after a dry or wet test. Squirting oil into the bores has the effect of raising the pressures quite a lot and is usually used to test the efficiency of the valve guides and seats after a dry run check for the sealing of the p/rings.

Pavel

The test was dry. He hasn't done a wet test - and may not do.

But he has tested the injectors and they seem to be the problem: they're 180, 150, 170, 170 ats and the three low ones are not giving a proper spray.

Have ordered four new nozzles - they'll be NL 141 to replace the current NL 123. I'm now away for a week so will report back when the new nozzles are set up and, fingers crossed, she starts on the button.

Meanwhile, any theories on such high compression?

Also, which may not be significant, the engine may not be 1965 but 56 or 57, as my engine block casting code, which appears to be three letters, the first obscured, ends in 2Z (the Z indicating 56). And the pump is a SIMMS SPE4A70S (pistons now upgraded to 7.5mm) with vacuum governor which apparently was used until June 1962.

Maybe the head and/or block have been machined in the past. The settings of the valve gap adjustment screws would give a fair indication of this. Very little thread left would be an indication of head machining.

Pavel

I don't know if the head's been shaved at some time, so can't help there.

But all works fine now. With new nozzles, valves adjusted and helpful, if strangely high, compression. Vroom.

Thanks for all comments.

And there's plenty of thread on the adjustment screws.