White Multifuel popping through intake

[M35a2 Driver]

Hey guys my first post on here, have been a member for some years now and have found the TM'S and posts on here helpful. Here is my situation:
Replaced the intake and exhaust manifold gaskets (it has a D turbo) and afterwards on start-up everything sounded great..go to drive down the road and after getting warmed up I start to get into it..all is fine until I notice it is obviously missing on one cylinder. The reason I say that is because i could feel the shaking at idle and while in gear under mild acceleration it misses until it reaches around 1800 RPM then smoothes out.

So I search everywhere I can, look at everything I can and so far we have pulled and cleaned the injectors, set the valves, and pulled the intake horn from intake manifold to turbo, the loudest I can hear is straight from the intake manifold. pop pop pop pop pop. I can't quite seem to understand what is causing it. Worst comes to worst I'll have to pull the head and see what Is going on.

Truck is a 1969 Jeep Kaiser M35a2 with a white Multifuel with 50,000 miles on it. Any advice is appreciated like I said it almost seems to be backfiring through the intake.

Thanks,

Harley

 

[rustystud]

This could be a number of issues. One, your valves could be burnt or no longer seating correctly. Perform a compression test and cylinder leak down test. Two, your head gasket has sprung a leak. Perform a compression test and cylinder leak down test.
Three, your cam has a worn lobe. This is harder to diagnose. You will have to measure you rocker arm travel with a dial indicator. There could be other issues, but I would start with the compression tests and cylinder leak down tests before anything else.

 

[M35a2 Driver]

Very much appreciated, I will do the tests and report back. Thank you

 

[rustystud]

Your welcome.

 

[Jeepsinker]

I bet on a head gasket blown between two cylinders. Hope not, but sure sounds that way. Any miss will usually seem to get better at higher rpm, as long as it is only a single cylinder miss, but don't be fooled. It is still missing.

 

[M35a2 Driver]

It very well could be considering it started happening out of nowhere, have to do the tests and see what comes of it. I just have that gut feeling I'll be pulling the head

 

[AZK9]

... have to do the tests and see what comes of it. ...

Hope things work out well for you. Good luck with it!

 

[M35a2 Driver]

Thanks for the responses guys!

Here's what I've gotten done so far..

Compression tested all 6 cylinders

1 - 450
2 - 435
3 - 450
4 - 450
5 - 450
6 - 50 - that's not a typo.

So a friend of myne had a bore camera that fit in through the injector opening and it looks as if it has a small scar that could be milled down but the cylinder walls looked to have normal wear in all 6. While compression testing I noticed when cranking over I could hear it pushing air back through the intake manifold, my best guess would be there is a valve not seating..time to pull the heads off and get to work!

I am going to purchase new head gaskets, intake/manifold, rings, studs?, and whatever else I may be forgetting at the moment. I am going to have a valve job done and have the Pistons replaced. If you guys can think of anything else I should do while the heads are off let me know! I appreciate the quick response and friendly environment you guys have provided.

Thanks again,

Harley

 

[donnerwetter58]

I am going to purchase new head gaskets, intake/manifold, rings, studs?, and whatever else I may be forgetting at the moment. I am going to have a valve job done and have the Pistons milled. If you

Harley[/QUOTE]


Pistons milled? That one has me curious.

 

[cattlerepairman]

I bet on a head gasket blown between two cylinders. Hope not, but sure sounds that way. Any miss will usually seem to get better at higher rpm, as long as it is only a single cylinder miss, but don't be fooled. It is still missing.

So true - I can attest to that. Really cool when you revv it up, let off the fuel and watch the flame shoot out the exhaust stack. Even if you were deaf, you'd realize that this is a massive misfire!

 

[M35a2 Driver]

I am not extremely familiar with these engines. Upon further reading, I'm better off to get a new piston, rings and sleeve for it.

Thanks again,

Harley

 

[gimpyrobb]

PM sent, I have some parts.