Running Problem

Subject at hand is an IH 650D, gas-start deisel.

When I start her up cold, there's a "phhht-phhht-phhht" sound out the exhaust, accompanied by corresponding puffs of white/grey smoke with each "phhht".

Once I start working her and get things warmed up to operating temps, the "phhht" sound is replaced by what's best described as a "pop-pop-pop" sound, and the white smoke clears up and if I don't touch the throttle it also gains RPM when the sound changes and the smoke goes away. After I'm done using it, I can let it idle and cool down and eventually the "pop" is replaced again by the "phhht" and the white smoke is back.

I can crack all the bleeders, and each one kills the cylinder and slows RPMs, so I know it's not missing on a cylinder. Bleeder number one kinda changes the "pop" sound too. I've checked all the valve lash and everything was in good shape there.

I'm pretty sure it's a "bad" valve on number one. Most likely an exhaust valve. But what exactly would be "bad" on it? You hear people all the time say "sounds like a bad valve" but never do they specify what exactly is bad. Not sealing due to a worn seat or warped head on the valve? Stem sticking in the guide and not closing all the way? Why does the symptom change along with operating temp? This tractor sat for several years before I bought it, by the way.

Or- could it possibly be a starting valve problem? Would that let it blow out the exhaust? I'd think that would be blowing back through the carb.

Anyway- thanks for reading and thanks in advance for any advice.

I知 thinking it is a bad valve (heard that one before I値l bet!).

What I知 thinking is that the exhaust valve has developed a small flat spot on the circumference of the face somewhere, probably because of a carbon deposit causing poor cooling in that spot. It might not have developed as far as Rusty mentioned yet, so it is just a small leak, therefore the phhht sound when it is cold.

As the engine warms up from working, the valve gets hot and it is possible that the valve may get hot enough in that spot to actually deform enough that it conforms a bit better to the seat, causing a slightly better seal, causing the noise you are hearing to change to a pop. (This is just a theory.)

I guess the bottom line is that the consensus here is that you have a valve train problem, most likely a leaking valve. If adjusting them did not eliminate it, then you will need to pull the head. The sooner you do this, the less work the head may need. Running burnt valves long enough will eventually cause the flat spot on the valve to worsen. If it gets bad enough, it can even cause the guide and seat to wear bad enough to need replacing.

Nick- you're right about Opheim. Their shop's about 28 miles from us. One of my earliest memories is that we had a 560D that the engine went bad on, and we took it to them and they put a gasser engine in it. His son in law(I think), Tony Booth, still runs the shop and still works on some red iron. Had a good conversation with him at an auction last summer when I was trying to get the injector pump on this 650 sorted out.

I thought all tractors in Cherry county ran like that??? :>)

Don't 'spose we got the old IH bad camshaft thing going on do you? That popping sure puts 'er in the valve train.

Allan

I have the same question about the burnt valve suggestion....I've seen burnt valves caused by the same thing Rusty mentioned...looks like they've been hit with a cutting torch, but can't figure why it would suddenly change so much once it warmed up? It really does seem to run better(gains RPM) when it warms up, and most cracks generally expand and get worse when they warm up...so I'm stumped there.

As for the head gasket suggestion- I'd have to figure that if it was leaking it would most likely be leaking into the cooling system too, right? And there's never been a sign of that. It has antifreeze in it, and the white smoke doesn't smell like antifreeze. Smells just like the white smoke that briefly comes out of my 6.5 Chevy diesel when it's started cold.

I guess it all boils down to the fact that the head's gonna have to come off, no way around it. I have an auction coming up in a couple weeks real close to me that happens to have three more 650D's on it, so maybe if the stars are lined up right I can come home with another 650 or two and wind up with a good head I can rebuild and just swap on to this one, plus alot of other parts that I'm needing.

check the timing of the punp and static timing first..

if it sat for a while, throw some additive in her that will lube the injectors and pump...

you just may have some old fuel that has jelled 4 or 5 times and it does not have what it takes anymore..... ..get old out and try some new???