I just had my "new" '03 HO engine re-rebuilt under warranty because the rings never seated properly the first time around. My truck has 126k mi since new (first rebuild was due to 2 broken rings).

Just got it back a couple weeks ago (I live 260mi from the shop) and for the first time, tried starting it hot today, and it WON'T.

It will spin over like crazy, but it won't fire. If I leave it for 15-20min it will restart and run perfectly for as long as you want, just like nothing's wrong, but if you shut it down, it won't restart.

When it DOES decide to start, it will fire just like normal (a couple of revolutions and running like a Swiss watch).

I have an Air Dog filter/pump system, and the lift pump is running fine, and opening the water separator drain on the engine fuel canister shows a good stream of diesel fuel, so I think the injection pump is getting fuel OK.

Any ideas?

As I said, the shop that R&R and rebuilt the engine is a 500+mi round trip, plus my warranty is now used up so I am kinda' on my own.

The engine "feels" like it has a bit less power than before the rebuild, and my wife following behind said it seems to be trailing some black smoke even when I am just cruising at 55mph on level ground, which it never did before that anyone noticed.

Thanks,
Bob

 

Any Codes set? Sounds like a timing problem.

 

NO MIL.

I haven't plugged a code reader in to see if there is a problem w/ the computer so it won't set a code.

Is there any component you're thinking of?

In the time the vehicle sits before it will re-start, it really hasn't had a chance to cool off (the water temp gauge is still at 195)

The timing would REALLY have to be WAY off, cuz it doesn't even pop til it's ready, and then it starts instantly like there was never a problem (until you shut it down again).

Bob

 

Sounds like the injector tubes may be loose or you have a bad injector.

 

Check the wiring up around the ac compressor. They're know to rub on one of the ac lines and cause a short. All kinds of wacky things will happen.

 

Thanks-

Given that before the engine was perfect before being R&R'd, and that the injectors were fully bench tested not long before the O/H, and the engine did not exhibit this tendency before, I am inclined to think something the shop did may have changed something (chaffed wiring as suggested or something related to to the recent work) if only because there are few coincidences in life. In the street, I tried manipulating wiring bundles, but I couldn't closely examine them. Tomorrow!

The one-bad injector theory would involve a leaking injector keeping the rail pressure from injecting fuel into the other cylinders I'd imagine? Would not a leaking injector cause the engine to idle, or pull at near-idle rpm with some engine shake? I've seen injector-miss before, though in my engine, you literally cannot feel the slightest vibration through the 3ft high manual gearshift lever. I would imagine checking the fuel rail pressure would be a good place to start to check for this?

RE: The connector tubes, I guess that since they were recently R&R'd there's a chance that they weren't torqued properly. Would one or more be that intermittent where one start may be absolutely fine, and the next an absolute no-go? Just trying to learn.

Thanks...

 

Latest Update-

I stopped at the shop where I left the truck yesterday and we found:

Using a Snap-On scanner, when cold the Set Rail Pressure (the psi commanded by the computer) and the actual rail pressure were the SAME with a cold engine.

As the engine warmed, the actual rail pressure started dropping, and at full operating temperature, was a full 2000psi LESS than Set Pressure! BUT, the engine ran perfectly smoothly, though is probably incapable of making rated power or torque, of course.

Shutting down the hot engine, then immediately trying to restart it, the Rail Pressure could not exceed about 800psi at cranking speed.

Letting the engine sit for 5 minutes allowed a cranking Rail Pressure of 1200psi, and a 10-15 minute sit allowed the cranking Rail Pressure to barely hit 1550psi, allowing the engine to start (w/ a slightly extended cranking time).

Obviously sitting 10-15min doesn't really allow the engine to cool off very much. In fact it may even heat-soak a bit during a short sit.

That means (to me) we have a mechanical bleed-down issue when hot, either through the injectors bypassing, the injector/s leaking into a cylinder, or at the connector tubes internally. I suppose it COULD be a CP3 pump issue, but again, all was well before the engine rebuild.

The tech says that the engine runs SO smoothly (smoothest he's ever experienced) he personally doubts we have an injector leaking into a cylinder (plus the injectors were just bench flow and pressure tested and found perfect just 300mi ago before the engine rebuild).

Any wagers what we should be especially looking for?

His intent now is to physically examine the injectors and connector tubes, then if everything looks perfect, to re-install and properly torque them to see if that was the problem.

I called the shop that did the rebuild, and they said they never encountered this before following a rebuild, and don't have a clue. I can only HOPE they did not swap my "like-new" injectors with a set of worn ones, of course during the O/H.

Comments, ideas?

 

If therre excessive black smoke driving that indicates an injector sticking whne warm. Possibly oyu could see the difference with an injector return flow test cold and warm.

Same with the cross over tubes, differences in return flow warm to cold.

A sticky FCA, a worn COV, a worn rail PR valve could also cause the issue.

I would check the PR valve, run the return flows for injectors and CP-3 both cold and warm, and check the cylinder contribution percentages cold and warm.

That MAY give you a idea what is going on.

Once a cross over tube that is scored a little and leaks warm it will drop the rail pressure on cranking to a no start level. Make sure the edge filters and tips are examined closely for any issues.

Bench testing the injectors only tells you they are in a broad range of spec cold. How they perform in the engine when up to operating temp can be a totally different scenario.

Good luck finding the glitch.

 

I think we have the problem pinpointed.

The crossover tubes are TOAST.

I haven't yet been to the shop to see them, but the tech said it looks like the guy in Houston (I live near Dallas) at the contract shop that stripped the engine before sending it to the rebuilder may have tried to get the injectors out w/o fully removing the tubes (that's how the tech reasoned it), saying the tubes were totally buggered and looked like they were used as nail-sets, all chewed up.

One he said had it's end peened over like someone flattened the end.

He said my injector seats (where the tubes contact them) have some very fine scratching where the damaged tubes were re-used when they put the long block back together at engine installation.

All 6 tubes are toast (not a fortune), but he's going to carefully examine the injectors to make sure they will seal w/ new tubes.

I called the rebuilder (over 250mi from home) and they said they normally replace all the tubes at overhaul, so were surprised that the shop they contracted with to R&R my engine reused (obviously) damaged components.

I can only imagine that the R&R shop assigned some new guy to do the stripping and building up the long block before re-installation of the engine.

A lot of the wiring is mis-routed in the engine compartment so the harness leads don't reach the factory clips and so forth, so I don't thing the shop had their top guy on the job. Obviously, I'll attend to this stuff after the engine is back running right.

Fortunately I have a set of Bosch rebuilt injectors on-hand still in their sealed sleeves I bought "outright" in case my injectors didn't pass muster on the first re-build. The shop in TN I sent them to told me my injectors were good-as-new (he has a flow bench that will test to 26,000psi), so to save my new ones. I'd like to keep saving them, but at least I have 'em if I need to use 'em.

It's amazing the incompetence out there!

Thanks!
Bob

 

Managed to save the injectors, so after all new cross tubes, engine runs (and starts) great.

This time we made it to the middle of New Mexico and blew a radiator hose off because the tech that re-installed the accessories on the long block failed to tighten the radiator clamps properly.

I caught it at 220F and used drinking water to limp into Deming w/ out 7000# trailer in tow where I got Mopar coolant ($43 a gallon??), distilled water, and were back on our way again wondering what "Easter Egg" the R&R shop tech left for us next.

Fortunately THIS engine is breaking in properly, and at the 1200mi point we're down only 1/3rd quart of oil (vs. the TWO quarts my last new engine used in the same distance).