Hitachi EX60-5 pulsed air from air filter housing

[Art_H]

Hitachi EX60-5 5700 hrs, has a pulsed air burst from the air filter housing. (intake manifold)
The pulse speeds up with RPM. Is this normal for these engines?

Do I have a bad valve?
Lash set incorrectly?

I pulled the oil filler cap to increase the venting of the engine (4 cylinder normal crankcase air pressure) and the intake reverse air pulses did not change.

I want to check my valve lash, but don't have the specs. Anyone have the valve lash specs for a A-BD30 Nissan engine?

Where can I get a workshop manual that isn't a fake etc?

Also what compression test adapter do I need for the injector, or is the glow plug the preferred method?

Thanks,

Art

 

[willie59]

If you have an intake valve that is bad enough, whether improper valve lash setting or bad valve, to cause a noticeable burst of air coming out of intake piping, then you will most certainly have insufficient compression for combustion of that cylinder, you will have a cylinder with a dead miss. Start your engine, at idle, and crack open fuel lines at each injector. It will have the same result as pulling a plug wire on a gas engine, you will find your problem cylinder and get a clue of where to start checking.

 

[Art_H]

willie59,

Thanks for the advice. The engine seems to run smooth, and not lacking in power, though difficult to feel that with an engine running a pump and not a direct coupling. There does not seem to be a miss, but I'll check the fuel lines none the less, and see if it changes etc.

If the lash is set too tight on an intake valve, wouldn't it open early with a little exhaust pressure maybe coming back out the intake? Things behave a little differently without a butterfly valve and vacuum.

Thanks,

Art

 

[willie59]

If the lash is set too tight on an intake valve, wouldn't it open early with a little exhaust pressure maybe coming back out the intake?

I would say unlikely because even if both were adjusted too tight, the exhaust valve closes and intake valve opens with piston in area of TDC, likely little residual exhaust pressure at that point.

 

[John Shipp]

It's a while ago, wondering what the follow up might be on this situation. Cheers.