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Old 11-06-2020, 15:38   #16
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Re: Yanmar 2QM20 running issues

Curious mind wants to know...

You didn't try testing the existing injector pump in situ with one of the new injectors?

The logic pointing to faulty injection pumps sound good though. I hope the new injection pump fixes the problem.

The 200psi compression also sounds quite low to me but if it starts easy and runs well with the new head, injectors and injection pump, I guess it is good enough.

Looking forward to your next report!
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Old 11-06-2020, 15:49   #17
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Re: Yanmar 2QM20 running issues

How did you check the compression? You cant check 300 psi plus by hand holding the gauge in, you need a fitting and screw on gauge.
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Old 11-06-2020, 18:46   #18
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Re: Yanmar 2QM20 running issues

I was going to mention phase and calibration adjustments but if you’re getting a rebuilt pump it seems unnecessary because it will already be adjusted. Are you removing the delivery valve to do the timing?
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Old 11-06-2020, 18:49   #19
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Re: Yanmar 2QM20 running issues

The other thing I forgot to add is water could be getting in through a corroded exhaust manifold. Did you check that?

Edit: sorry see you said you checked it in OP
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Old 20-06-2020, 16:38   #20
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Re: Yanmar 2QM20 running issues

it took me a while to get my 2qm20 running reliably because; the tank taps were leaking air; the fuel hoses were leaking air; the fuel filters were leaking air; I thought the mech. lift pump wasnt working so replaced it (still dont know if it was faulty so i keep the old one as a spare); the bleed screw on the injector pump was leaking air. Thing is, all those things were cheap to replace but collectively they created a hell of a mechanical conundrum. I've noticed mechanics tend to be "man with hammer only sees nails" ie. tend to focus on the mechanical (and expensive ) end of the motor...most diesel engine problems tend to be due to air leaks (tho' your discoveries under the head suggest other problems as well..) hope you have success getting the eng. running - they are excellent little motors once they are set up.
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Old 20-06-2020, 16:49   #21
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Re: Yanmar 2QM20 running issues

Quote:
Originally Posted by charliehows View Post
it took me a while to get my 2qm20 running reliably because; the tank taps were leaking air; the fuel hoses were leaking air; the fuel filters were leaking air; I thought the mech. lift pump wasnt working so replaced it (still dont know if it was faulty so i keep the old one as a spare); the bleed screw on the injector pump was leaking air. Thing is, all those things were cheap to replace but collectively they created a hell of a mechanical conundrum. I've noticed mechanics tend to be "man with hammer only sees nails" ie. tend to focus on the mechanical (and expensive ) end of the motor...most diesel engine problems tend to be due to air leaks (tho' your discoveries under the head suggest other problems as well..) hope you have success getting the eng. running - they are excellent little motors once they are set up.
Too right re "man with hammer" but he has bad corrosion in 1 cylinder. Do you happen to know your 2QM20's compression reading in psi ?
Just OP's sounded way low to me.
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Old 24-06-2020, 16:14   #22
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Re: Yanmar 2QM20 running issues

yes, i was a bit flippant but i did acknowledge his comments on the internals - I've never tested my compression, had the head off a few years ago and the picture was very pretty so it got a new gasket and nothing else - tho' i regret not adding some liquid reinforcing of the gasket around the pushrod galleys - its still weeping a bit of oil, which was why i had a look at it originally. Doh!
I guess the point i was trying to make was - older engine can develop complex problems but its always good to eliminate the fuel sys airleak first.
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Old 24-06-2020, 16:37   #23
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Re: Yanmar 2QM20 running issues

Yep, multiple problems causing the same symptoms can be frustrating. You find and fix one problem and expect the engine to run but same problem. Multiple problems that cause weird symptoms are even harder. Don't let the little issues go and there is a lot less chance of that happening.
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