Last straw

[Rawze]

We got it all back together ...

The head is bad, like mentioned in previous post. Other than that, I helped him set the injector and valve cams back to their correct positions. He also got his CAC unit replaced under warranty "it did not cost him a dime", and we tested the new one before installing it.

When putting the valve train back together, during the overhead valve adjustment, I could tell the compression just was not there for several of the cylinders when turning the engine by hand. There was resistance, but no hissing, not much "spring-back" if any at all for most of the cylinders that is normally felt, like it had really worn out rings or something.

The engine pressure test had revealed that cylinder #1 was the strongest by far, and it also was just about the only cylinder during the overhead valve adjustment that had this spring-back feeling when turning engine by hand. It made me wonder heavily if the rings are aligned and offset improperly on the pistons, compounding the issues. - It would not surprise me considering the other work was not done right.

I put his original 500/1850 program that belongs in it back in the ecm.

Truck runs pretty well considering it is loosing compression on 4 cylinders.

-- I test drove it just to see how the truck felt, what it was like to drive it with lower than normal compression ...

It actually ran very smooth, like nothing was wrong whatsoever... HOWEVER ... I can say for sure that it was not making anywhere near its rated 1850 torque, it was obvious that the power was less than it should be. - A Dyno would reveal what it was actually making, but it seemed to me that it was was more like about 1550 -- maybe, if that. It drives like it has a set of really tall rears, like say 2.08's or something taller. That, or just like an engine that has a moderate intake or exhaust restriction.

Instant fuel mileage in the dash said all was well, matched whatever I was doing, showed high numbers when cruising like nothing was wrong, was showing no indication of lower than normal readings for the slightly lower power it was producing. He has however ran the holy crap out of his APU while he has been here. That would explain some of his low fuel mileage if he is doing this a lot.

Boost was a bit low (at 33-34~ish) due to the power/compression losses, but not low enough to cause a starvation of that much power or torque. It seemed a bit lazy, but it may just be the resulting symptoms of the engine not making good compression.

The truck rolls well in neutral, tranny and drive line feel fine, clutch is not slipping, brakes do not feel like they are dragging, etc.

-- With the head being bad on it, -- that may be all that is wrong at this point. Hopefully that is all it is, that problem absolutely needs to be fixed. After that, there are still more things that can be checked. Things like the diaphragms on the back side of the IFSM, and a few others. it also did not fair as well on the front 3 cylinders as it did the back 3 during cut-out tests. I told him that the metering/timing coils should be swapped front bank to back bank and see if this imbalance follows the coils or not... but Like was mentioned, the head is toast, and that needs correcting before much of anything else can be done towards a final definitive solution.

I just hope like hell he takes my advice and raises those liners while the head is off + looks for anything else that may have been half-arssed when replacing that head. - After that head is replaced, hopefully it is the bulk of the problem, but if not so, more tests and things can be done.

All someone can do is repair what they find along the way and keep going when looking for a problem such as this. The truck is in good shape otherwise, it looks nice, and it is definitely worth saving if possible.

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Things that can still be checked before pulling the head are...

* re-installing a missing seal on elbow pipe for the turbo cold side housing.
* Test drive with the air filters / intake removed to see if power/boost improves.
* Test drive with the exhaust disconnected to see if power/boost improves.
* Check the circuit/sensor and feed-pipe for the exhaust pressure sensor.
* Have VG ring and exhaust impeller on turbo inspected for any damage/wear with rear housing removed.
* IFSM diaphragms inspected/replaced.
* Metering/timing actuators swapped around to find why front bank is slightly weaker than rear bank.
* Injector part#'s verified for correctness.