Truck Quit Running

[DavidC]

I have done many a leakdown test. Minimal amount of labor and may ease the mind if blowing out the intake or exhaust or real depress someone if it's the crank case. If it's just the head the engine stays, if the crank case it comes out.

 

[cerberusiam]

It is even simpler than that if that hole is dead. Run it it with the oil cap off, puffing like a freight train engine has to come out, if not *maybe* just a valve broken and pull the head.

A quick look with a borescope will help also, but, blow by vs no blow by on a dead hole doesn't need a lot extra testing or tools to know what needs done.

 

[jghflys]

Run it it with the oil cap off, puffing like a freight train

If there is not enough compression to fire the cylinder the engine will not puff like a freight train. OP said there was no compression.

And, why spend labor money putting it back together to run it when you can do a 10 minute test?

 

[cerberusiam]

The compression already identified there is a problem, no reason to test that again with a leak down test that can't happen with zero compression.

Just exactly where do you think that volume of air that is normally getting compressed 17:1 is going to go with a hole in a piston? Pressurize the crank case and it is going to go out somewhere and be noticed, the oil fill hole would be quite noticeable. That would have already been checked BEFORE going any further, given they have a clue how to properly diagnose.

Doesn't sound like a piston issue unless the piston shattered or was blow torched badly. Usually by that time you are usually hearing a LOT of other noises, like the rod getting ready to come out the side of the block. There was no mention of squeaking or knocking. No compression, dead hole, no other noted problems, AND the fact he had another head put on it raise the chances it is a valve issue, probably exhaust valve(s).

At some point a look into the cylinder WILL need done, kicking that can down the road doesn't change what needs done. Analysis paralysis is the correct term for that.

 

[jghflys]

Analysis paralysis is the correct term for that.

Analysis paralysis for a 10 minute test? You crack me up. They have spent many times that so far and have gotten nowhere.

hat can't happen with zero compression.

Leak down tests can be done with zero compression. The supplied air will just go out through the leak location and you can hear where it is leaking.

 

[cerberusiam]

They have spent many times that so far and have gotten nowhere.

Why do you think we are saying get on with it? If by chance they cannot run a compression test correctly, they pulled the head and NOTHING is wrong who's tab is that on? At same point it seems they need goaded into doing SOMETHING conclusive.

Leak down tests can be done with zero compression.

Hmmmm, a leak down test consists of warming the engine up to the correct temp for the test, pressurizing the cylinder with a set amount of air, tracking the bleed out over time to compare to a spec. A leak down test on a no compression cylinder nets you ZERO set pressure over time to compare to a spec. Please explain HOW those results tell you ANYTHING more than a compression test?

What you are advocating is an air path test because the leakage route was missed on the compression test. Standard procedure with an initial ZERO reading means check the tool and do it again paying attention to where the air is leaking, if it is. It is pretty distinct with that volume and compression where the leakage is with ZERO compression.

If compression is off over the 10% mark THEN a leak down test can tell you more, but, ZERO compression means the engine comes apart. Period. One can pop a head off a lot faster than pulling the engine, and, pulling an engine minus a head is a lot easier if that is needed.

At what point are the symptoms conclusive enough to get on with the process? Rod out the side of the block? Water in the oil? Fuel instead of oil in the engine? C'mon, inject a little art into the process instead of rote going thru the steps.

 

[jghflys]

Hmmmm, a leak down test consists of warming the engine up to the correct temp for the test, pressurizing the cylinder with a set amount of air, tracking the bleed out over time to compare to a spec.

Nope, that is not a leakdown test. Educate yourself get the equipment and use it. You will notice that the air supply is continuous and the air out of the leak path is continuous. You will be pleased with what it will tell you and how easy it is.

 

[DavidC]

No more updates ?.

 

[HPSimpson]

No more updates ?.

Typical TDR folks help, then no feed back!

 

[jghflys]

I need y’all’s help please.

Any updates? Spread the knowledge.