Knocking engine

[asmith]

What lead you to the conclusion there was 0 compression in one cylinder when you first cranked it?

This is my question too. Do you know for a fact there was zero compression in that cylinder, or it just sounded like it?

 

[IDIBRONCO]

Do you know for a fact there was zero compression in that cylinder, or it just sounded like it?

I'm guessing that it sounded like it which is why I mentioned low compression along with no compression.

 

[94f350]

Every cylinder had an even crank except for one which kinda sounded like it was firing but It wasn't, you could tell there was zero resistance on the starter.

 

[94f350]

Also, I don't understand how the engine would run good after it had just knocked like crazy. I don't understand what could've changed. I shut it off again after it was running good and I went to start it like an hour later and knocked, shut it off, turned it back on again and it ran fine. It really confuses me

 

[FrozenMerc]

Just so we are clear.

1. Cold Start - Engine knocks loudly, and seems to turn over easier, most likely at a higher RPM.
2. Restart after engine is off for only a few minutes at most - No knock, and it runs smoothly.

For these two symptoms, I would lead toward an injector problem. One or more are probably hanging up when cold. A bent push rod or similar valve train issue would cause a consistent problem that would not go away and come back.

 

[94f350]

But that doesn't explain the weird compression issue, I dodon'understand how that can happen and then go away

 

[Black dawg]

Also, I don't understand how the engine would run good after it had just knocked like crazy. I don't understand what could've changed. I shut it off again after it was running good and I went to start it like an hour later and knocked, shut it off, turned it back on again and it ran fine. It really confuses me

Have you ever heard the noise these will make with a bled down exhaust lifter, or exhaust valve not opening for whatever reason? It is a fairly loud noise that I have heard described as knocking many times. Sound varies anywhere from a pretty low pitched thump thump sound to higher pitched pop pop sound......but it is pretty loud.

Another thing that could knock and then go away is a lost glow plug tip.......

 

[Rdnck84_03]

Another thing that could knock and then go away is a lost glow plug tip.......

Wouldn't that be completely random though? I don't see any way it would stop bouncing around on the piston after being shut off and restarted.

Feel free to shoot holes in my train of thought, most of you guys know way more about these engines than I do.

James

 

[IDIBRONCO]

Also, I don't understand how the engine would run good after it had just knocked like crazy. I don't understand what could've changed. I shut it off again after it was running good and I went to start it like an hour later and knocked, shut it off, turned it back on again and it ran fine. It really confuses me

Have you ever heard the noise these will make with a bled down exhaust lifter, or exhaust valve not opening for whatever reason? It is a fairly loud noise that I have heard described as knocking many times. Sound varies anywhere from a pretty low pitched thump thump sound to higher pitched pop pop sound......but it is pretty loud.

I haven't heard the noise, but after reading both of these posts, I'm still leaning toward Black dawg's diagnosis and thinking that it's a bad lifter. That would also describe the temporary sounding like a loss of compression.
94f350, how long have you let the engine run when it sounds like it's knocking and did it change the way it runs any?

 

[Nero]

But that doesn't explain the weird compression issue, I dodon'understand how that can happen and then go away

Did you actually check for low compression? I think you're getting hooked on the idea that it might have had low compression, which isn't a fact yet.

 

[david85]

The engines are interference, but the valve points down directly at the piston (perpendicular), not at an angle like some other interference engines. This means that if the valve was hit by the piston, there is a chance it may not have bent the valve and simply been slammed straight up against the valve seat in the head.

 

[IDIBRONCO]

This means that if the valve was hit by the piston, there is a chance it may not have bent the valve and simply been slammed straight up against the valve seat in the head.

True, but I think that something else probably would have been bent or broken if this happened. If that had happened, then it wouldn't run right after a second start.

 

[ttman4]

1A. OK, dummy question.....what is "interference engines?" New one on me.

I learn at least one thing daily! Sometimes two things. I plan on living till I'm 150 yr old, got about 78+ more to go.....my point #2A, can you imagine how really, really smart I'll be at 150?

Back to point #1A....what does "interference engine" mean or what does one do?

 

[Rdnck84_03]

@ttman4 An interference engine is any engine that the piston is capable of hitting a valve if it is open for any reason when at TDC.

James

 

[XOLATEM]

You may just make it to 150...by my calculatons you must have been born in 1951 and that was the chinese year of the Rabbit...

And...according to my armchair tinhorn chinese zodiac wisdom...gathered from a restaurant placemat...that is the luckiest sign of all of them...so...I'm rooting for you to achieve your goal...

Besides...this place would not be the same without you...