1998 yukon Mystery p0300 and rough idle still

[OilBurner2003]

While you’re there, are any of the cap mounting tabs cracked or broken (yet)?

Looks like the factory original plastic distributor.

View attachment 385523

None located so far.

 

[OR VietVet]

Side to side play? If spins freely and the side to side play is tiny tiny, then likely ok but if is original, like @east302 says, I would replace while is out and dont cheap on it. If you have a GM cam sensor, get a reman dist without sensor, if not, get a reman with new cam sensor and may even come with cap and rotor. Discolored teeth? First I heard of that. Drive gear?

 

[OilBurner2003]

Side to side play? If spins freely and the side to side play is tiny tiny, then likely ok but if is original, like @east302 says, I would replace while is out and dont cheap on it. If you have a GM cam sensor, get a reman dist without sensor, if not, get a reman with new cam sensor and may even come with cap and rotor. Discolored teeth? First I heard of that. Drive gear?

It does have a little bit of side play, also, when it spins there is a very slight hesitation and a light clicking noise. I think it’s a GM sensor, no clue.

 

[OR VietVet]

When you spin without cam sensor in it, does it make the noise? That shaft should spin freely, no hang ups that can get worse with engine heat and no clicking at all.

 

[OR VietVet]

That hesitation and clicking noise could be the shaft bearing and when gets engine heat in it, it can swell and get worse. Hell, its not my money, get a new or reman dist assembly, cam sensor, cap and rotor

 

[OilBurner2003]

That hesitation and clicking noise could be the shaft bearing and when gets engine heat in it, it can swell and get worse. Hell, its not my money, get a new or reman dist assembly, cam sensor, cap and rotor

Might as well at this point! If I go any further I’m gonna start doing leak down tests. Well, I’m gonna get started looking for a kit. I suppose I can only resume when I get this part installed with new cap and rotor as well. You gentleman have been a fantastic help so far!

 

[east302]

I’d suggest reusing your cap and rotor if they’re new and Delco parts.

When were the lower intake gaskets last done? Slightly higher misfire count at #2 is in the right spot for a leak, but your counts are on both banks which should mean something that would cause a widespread issue. Or both gaskets being bad. And there are no coolant leaks at the intake/block seams or along the sides under the valve cover edge?

Knock on wood, never had the joy of a P0300.

 

[OilBurner2003]

I’d suggest reusing your cap and rotor if they’re new and Delco parts.

When were the lower intake gaskets last done? Slightly higher misfire count at #2 is in the right spot for a leak, but your counts are on both banks which should mean something that would cause a widespread issue. Or both gaskets being bad. And there are no coolant leaks at the intake/block seams or along the sides under the valve cover edge?

Knock on wood, never had the joy of a P0300.

Well sir, lower intake gaskets have never been done on this engine since it was swapped, I think 11 years ago now. I have no doubt they’re in crappy condition. I’ve asked about them in the past but I’ve never had hard coolant or noticeable coolant loss, or overheating.

 

[OR VietVet]

Remember, I said, smoke test is not always gonna show problems. I know and so does @east302, that sometimes you cant see what is right in front of you. If, a big if, you are gonna keep rig, then fix even something that is not the current problem. While you are in there and can afford it and gonna keep, do it so you dont have to guess later. The rig has time on it but is worth fixing, when it meets your needs and is paid for. Think of what you can do with just a portion of what newer rigs cost. Use quality parts and take the time to do it right.

 

[OilBurner2003]

Remember, I said, smoke test is not always gonna show problems. I know and so does @east302, that sometimes you cant see what is right in front of you. If, a big if, you are gonna keep rig, then fix even something that is not the current problem. While you are in there and can afford it and gonna keep, do it so you dont have to guess later. The rig has time on it but is worth fixing, when it meets your needs and is paid for. Think of what you can do with just a portion of what newer rigs cost. Use quality parts and take the time to do it right.

Probably a good idea to do the gaskets anyway, that way it can be ruled out regardless even if the distributor fixed my issues.