I have a Mitsubishi MS 120-8 Excavator it has a 6D14 mitsubishi 6 cylinder engine. It the same excavator as an early Cat 120. It blew a head gasket when it did so it started pushing out through the intake? I changed the gasket but it continues to push air out the intake. Any ideas on this? Any one see this before? Thanks
Did you pour diesel in the intake ports when you had the head off to see if the valves sealed good?
Not having any direct knowledge of your particular engine, I would only think you could get air back through intake with a valve train related problem. How did the head look when you had it off? Maybe something as simple as a valve adjustment. If it were my problem I'd pop the valve cover off and check the intake valve adjustments, make sure a valve isn't being held open. Just spitballing some ideas, good luck.
I did not. Could how well the valves are sealing changed after the blown gasket? It was a great running engine before it blew. Thanks
No obvious problems with the head it look ok. I did adjust the valves when I put it back together. Thanks
If valve adjustment is fine what's possibility your head is cracked somewhere weird
When this happened I asked a guy who works on equipment If he thought the head could have cracked he told me its rare for them to crack. I will look into getting it checked out Thanks
How does it run now? Defects on the head or valves/valve seats could come from over heating when your gasket blew, or if there was a problem in reassembly. If it's running rough and the valvetrain adjustment is good, then a compression test would isolate the problem cylinder. I can only see a cracked head or intake valve related issue allowing combustion gases back out the intake. The head gasket itself doesn't typically seal combustion gases from the intake manifold.
It starts very hard and runs rough. Thanks
What does the air leak sound like, like backfire? Run it with all the air intake pipes off, no air filter even, the sound may get louder and you can isolate your problems more. Sounds like valve train problem, burnt intake vales? Just educated guessing.
I would first double-check the valve lash. A miscalculation there could be the problem.
G'day, Is it overhead cam and did you therefore replace the drive chain in a different position which would make valve openings all wrong! Regards, MX45
Equally warped head = new gasket won't do a thing if head not checked for level plane!
Sounds like hissing Air. I did remove the intake hose and its louder and you can feel it. Thanks
I did Thanks
It is not a overhead cam. Thanks
I checked it with a straight edge Thanks
I think the head has to come back off. When it was off you should have had the head checked out at a machine shop, they would have at least vacuum tested the valves and surfaced the head. You may not have even had a leaking head gasket.
You could also try backing off all your intake valves completely so they are all closed and see of you can blow shop air thru the intake maybe just an idea maybe
Yair . . . This has got me confused (not that it takes much) . So when the O/P cranks the engine air hisses from the intake to the extent that he can feel it? Surely (as others have said) this must be valve related, burnt, cracked seat, maladjusted. It shouldn't be hard to isolate by dropping off the manifold. On another tack . . . does the engine have a decompressor or an exhaust venturi for evacuating the air cleaner? Cheers.
Confusing for sure, I thought it was blowing air when running? In any case, the head gasket has nothing to do with this, though it might help to know what the "bad head gasket" symptoms were in the first place. Go back to square one with a different mechanic than the one who did the head gasket.
There were 3 torn rings in the head gasket so it was definitely junk. I was told its rare for them to crack or warp this may have been bad info. I was also trying to to save money I do not make money with this machine. so I did not take it to get check out Thanks
It is blowing when running
Yair . . . Crikey I must be thick. I just don't understand how "air" can be detected (heard and felt) coming out the intake of a running engine . . . unless its running backwards and its exhaust . . . it could well be exhaust from a valve, it must be exhaust, but it beats me how the O/P can detect it with the induction air rushing in. I'm assuming a manifold with turbo removed. Cheers.
Its a non turbo engine. Intake hose was remove from the manifold but I could actually feel it just by removing the air filter. I have found nothing really similar to my problem searching the internet and asking around. If and when I figure it out I will post the info. Thanks