Odd case of Rough Idling and Misfires on my 96 FZJ80 (1 Viewer)

[hdj8081]

So I had the leak down test performed.

The mechanic said, they heard air escaping from the crankcase. They added some oil to the #4 Cylinder and now the Compression is now at 177 psi from its original test of 170...

They basically said that its an internal issue(long block) and that the rings are worn, and would recommend an engine replacement if I want to fix it. What are y'all thoughts on this? This is out my level of expertise so I'm not sure where to proceed

I wont do it.

 

[Miilkman]

This is exactly what should have been done prior to taking the engine apart, because this would have changed the entire scope of the service.

It was honestly my initial fear after seeing the condition of your cylinder walls.

You're in a very tough place now.

170 to 177 psi really means nothing.

What's the variation in each cylinder from the leak down test? Those are the real results of a leak down test, not compression.

I'll see what they specifically say about the variation from the leak down test. They were just saying that after 8 revolutions cold start, They said the cylinders were like:
1: 190
2: 190
3: 185
4: 177
5: 195
6: 190

 

[Miilkman]

I guess the question now is replace or rebuild?...

 

[rdcnj]

I'll see what they specifically say about the variation from the leak down test. They were just saying that after 8 revolutions cold start, They said the cylinders were like:
1: 190
2: 190
3: 185
4: 177
5: 195
6: 190

The compression doesn't worry me necessarily.

I mean, 170 to 195 variation isn't what anyone would want to see, but you could ride that out for quite a while.

Right now, you're seeing how much time you may have left with these tests.

As for fixing, the block needs to be checked by a professional rebuilder.

Won't know till it's all apart.

 

[ChaseTruck]

I guess the question now is replace or rebuild?...

Or LS-swap, or get a different truck altogether, or say the hell with it and take a vacation in Italy ...

I think it's time to take a step back.

If the compression number on #4 is correct, I'd venture to say that it is high enough for proper combustion IF there's a spark at the right time.
Several posts in this thread point out that this is likely an electrical problem. If that's the case, then that's what needs to be fixed.

I'd start at that battery, and specifically at that ground cable (for instance, our '93 is very picky about the ground cable making solid contact with the negative pole. Even if slightly loose - which has happened to occur after long washboard rides - the truck will be unhappy). Then I'd address potential issues with the main engine harness, at the EGR, and perhaps also in the cab. So, electron chasing first, and then, well...

 

[middlebay]

did you ever post the results from the leak down test?

It should be like a percentage- like 95%, 96% etc… with a leaky cylinder at say 35%.

Any updates?

 

[Miilkman]

did you ever post the results from the leak down test?

It should be like a percentage- like 95%, 96% etc… with a leaky cylinder at say 35%.

Any updates?

Some Updates:

So I asked them about it. They didn't provide much new info regarding the test % itself... They elaborated that cylinder 4 is pretty much a intermittent dead miss and will only get worse as I continue to drive the car due to the worn ring. Since they didn't provide the data, i took it to another shop