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Rebuild about done

My son is a heavy equipment mechanic but doesn't have the right compression tool since his is for big excavators, however his boss thinks he has one with the attachment for the 6.5. Hopefully he can find it.

Just logically thinking of possible causes. Tell me if I'm wrong or missing something. valves/spring, ring failure, injector, IP.
 
Correct. Through the glow plug hole.
Yes, the issue is to the cylinder either fuel or compression.

You disconnect the wire to the fuel shut off solenoid.
Disconnected the control wire to the glow plug solenoid.
Remove all 8 glow plugs.
Pen & paper ready to write the numbers, install the tester into glow plug hole then crank engine a few revolutions (you will hear it and see it) and you’ll see the needle raise each time around. Usually the third cycle it is peaked and you stop cranking. Write down the compression number and how many cycles it took to get there.

As to checking fuel:
You could have the two cylinders fuel lines off, slip an empty and dry water bottle over the end of the line where it would connect to the injector. Secure with bailing wire or similar. Start the truck and let idle for a minute. Shut off and compare volume of fuel going to them. It’s gonna misfire bad with two cylinders not firing and set a code or two.
Just use opposing cylinders by firing order. What cylinder is giving you the issue?
 
1872
6543

So opposite of 1 is 6
Opposite of 3 is 2

I am referring to opposite load on the crankshaft. You would not want to do this with two consecutive cylinders firing, that would be the hardest on the engine.

You have to do them at the same time, not do one then another because you can’t run the engine for exactly same number of cycles. You will be comparing very very tiny differences in volume as to a clue if the ip is goofed.
 
Twisted Steel Performance said:
Specs for a compression test states 6 revolutions . FYI a 18:1 motor should be @350psi and up....
Click to expand...
100%. Thanks for adding that critical info.

I learned that when they peak by 2nd or 3rd stroke and maintain through the last ones things are awesome vs if it keeps climbing until 8,9,10 that there is usually heavy ring / cylinder wear or burned valve. When it falls part way short right away and never really increases that is a worse scenario. So I record how many cycles to peak in attempt to diagnose issues.

Obviously one low cylinder and the others all ok is what we are afraid of here.

For people wanting to pad their truck history from new engine and maybe doing over maintenance : each time you replace glow plugs every 3 years because I am paranoid… record compression test for future diagnostic records- see a trend in wear. It never helped me yet- each time i did this either something happened or I sold the truck. Haha
Yes- too much tinker-itis might be at play in my mind.
 
Lets hope it's rocker arm related and not a bad piston, rings, or cylinder wall. my last escapade with white smoke and missing ended up being the rocker arm shaft bolts backing out of the head causing the valves on the #2 cylinder not getting depressed. others told me that it was the plastic buttons holding the rocker arm to the shaft. I ended up replacing all the buttons with bolts, flat washers, and nuts along with some red never-come-off juice (lock-tite). that escapade scared the hell out of me when it happened. it started after a long drive out to the coast while on vacation about 150 miles away from home. For whatever reason, maybe my guardian angle helped hold the engine together for the homeward trip but it began to run smooth for our trip home. made it home and was able to drive to work the next day or so until it came back with vengeance.
Drove it baby like home, tore it down and found this....

IMG_4410.jpg
 
dbrannon79 said:
Lets hope it's rocker arm related and not a bad piston, rings, or cylinder wall. my last escapade with white smoke and missing ended up being the rocker arm shaft bolts backing out of the head causing the valves on the #2 cylinder not getting depressed. others told me that it was the plastic buttons holding the rocker arm to the shaft. I ended up replacing all the buttons with bolts, flat washers, and nuts along with some red never-come-off juice (lock-tite). that escapade scared the hell out of me when it happened. it started after a long drive out to the coast while on vacation about 150 miles away from home. For whatever reason, maybe my guardian angle helped hold the engine together for the homeward trip but it began to run smooth for our trip home. made it home and was able to drive to work the next day or so until it came back with vengeance.
Drove it baby like home, tore it down and found this....

View attachment 84697
Click to expand...
I hope it's something minor.
 
What should the compression be? My son just did the Driver side. The pressure is with 8 cranks. 1=240 and 3,5, & 7 are all with in 10lbs of 300 PSI. I know # 1 is lower than it should be. Additionally, all the glow plug ends are 1/2 of what they were when they were installed brand new. I'm wondering if they got sheared off in the cylinder????
 
Rodd said:
What should the compression be? My son just did the Driver side. The pressure is with 8 cranks. 1=240 and 3,5, & 7 are all with in 10lbs of 300 PSI. I know # 1 is lower than it should be. Additionally, all the glow plug ends are 1/2 of what they were when they were installed brand new. I'm wondering if they got sheared off in the cylinder????
Click to expand...
Refresh my memory, is this a stock compression motor ? What you posted is lower than a 18:1 motor with some ware would be....
 
My first place to check would be the heads & valve train.
Did you use HS roller rockers or stock ?
If HS did you use the stock pushrods, if so they are not the correct ball size on the rocker end, should be 5/16 ball ...
With the timing gear being off at first the valves need checking in case they touched the pistons.
New rings or ???
New pistons or ???
The motor is either bleeding of compression or not making enough for some reason, may a leak down test on each cylinder would narrow it down..
I'm leaning towards the valve train for issues... valves, springs, pushrods, lifters, all are suspect at this point, then rings & pistons if the heads check out good...
 
Chris has you headed right-
I absolutely start with a cylinder leak down test. Even if you don’t have a leak down tester, you can sometimes find the issue without one. If you have one it is better tomuse it but most folks don’t so:
All 8 glow plugs removed use the adapter and hose from your compression tester
Rig up plumbing from your shop air compressor to the hose.
If you can include a valve of some sorts thats good, otherwise you will have to use the air hose QD to plug and unplug each time.
Bring cylinder 1 to tdc compression stroke. Apply the air to the cylinder and simply listen for o where the air is escaping. Intake manifold means intake valve, exhaust manifold means exhaust valve, oil fill port means piston rings.
Knowing if it is heads vs block is critical for chasing the fix.
 
I reused rods and pistons. The block was re-sleeved and machined as well as balanced at a local machine shop. I ported the heads and labeled all the vales and springs to make sure they went back in the same place. I also re-lapped the valves just to be safe.

My son checked it with a camera through the injector hole and noticed a shiny spot on the piston so he started taking the head off. Just needs help lifting it off. He'll be by today and we'll get that done.

I'm thinking Chris is right, the valve probably touched when the timing was off.

One other thing concerns me. The glow plug electrodes on 1 and 2 are about 1/4 " shorter than when they went in brand new. The shorter one is from cylinder 1 the other is 3. They are both shorter than stock.
 

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Rodd said:
I reused rods and pistons. The block was re-sleeved and machined as well as balanced at a local machine shop. I ported the heads and labeled all the vales and springs to make sure they went back in the same place. I also re-lapped the valves just to be safe.

My son checked it with a camera through the injector hole and noticed a shiny spot on the piston so he started taking the head off. Just needs help lifting it off. He'll be by today and we'll get that done.

I'm thinking Chris is right, the valve probably touched when the timing was off.

One other thing concerns me. The glow plug electrodes on 1 and 2 are about 1/4 " shorter than when they went in brand new. The shorter one is from cylinder 1 the other is 3. They are both shorter than stock.
Click to expand...
I've seen that with the use of ether. I know that's not what went on here.
I'm assuming it's as Will stated
 
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