6.2 Engine replacement not running

[befland]

And the saga begins. Not so recently my original 6.2 engine died at approx 367K miles. (crank broke after IP change...another long story) I replaced it with a GM Target Engine (long block) with (supposedly) 8K miles. All indications are that this is true. There are GM decals on the engine and judging by the looks of it I believe it had low miles. After swapping out all the peripherials from my engine and installing it in my truck it ran great. I believe the timing was slightly off still but it seemed to run good and I figured I would get it offically timed as soon as I put a few miles on it. I have the IHI Banks turbo (originally on a early Ford diesel) and the later model cooling mods (dual crossover, duramax fan, HO H2O pump, etc) with serpentine setup from a 93 6.5 installed. This engine ran about 200 miles before it shutdown one day while driving. I was passing a car on the interstate and floored the accelerator. When I got around the car I eased off the pedal and was cruising along for about 2-3 miles when it started skipping/running rough. The temp started to climb and I shut the ingnition off. I let it sit till morning and tried to start it. There were no unusual noises and everything sounded like it should start. It would try to hit but it sounded like it was out of time. Over the next several weeks/months I checked different scenarios that I thought may be the problem. I finally decided to change the IP. After installing the rebuilt IP and bleeding the lines it started instantly. I drove it about 1mile down the road and back. It ran fine. The next day I drove it about three miles down the road to get it inspected. While it was sitting in the garage bay it started skipping and knocked off. I have got it started 2 times since then (after LONG starting sessions) and it runs really rough. Another friend and myself have installed clear fuel lines, fuel pressure gauge, clear return line, tried spraying propane, etc. Nothing happens. We have 12lbs of fuel pressure. We can see clear fuel going to the cylinders and coming out of the return. We have fuel seeping at the injectors. The glow plugs are working. Any ideas?

[john8662]

Maybe spun injection pump drive gear on camshaft keyway?

The starting to get warm part is odd too, like a different issue.

I'd suggest a compression test to narrow out compression/cam issues going on.

Doesn't sound simple though...

[john8662]

On a very semi related matter.

You mentioned you already had cooling mods on this truck (Dual Stats, HO Pump) big fan and clutch.

Did this truck have cooling problems with the turbo setup/fueling with the stock fan/clutch combination?

My 82 C10 Shortbed that's hopped up sure does, thinking of stepping up the bigger fan/clutch. It's already HO (vbelt) water pump (Peninsular) and Dual stats. Cooling, not so well...

J

[befland]

A couple of other things that I did not include since the post was running long. I did perform a compression test but just on the passenger side...and cold. I got a little over 250 ft/lbs on ea cylinder. Jim B. suggested plugging the block heater in to let it warm up before checking but I didn't think about this when I checked. Also, I put a fuel pressure gauge in the fuel line from the filter to check pressure. It was a little over 12lbs. One of the first things I did was to bypass the tanks, lift pump and filter so I could eliminate them from the equation. I took the output from the filter and ran it into a jug. I took the input hose to the IP pump and attached a funnel to it and poured new fuel into the funnel. I let it gravity feed into the pump so I knew I had clean fuel coming in. Zilch.

Something that may affect timing but shouldn't affect starting (and it ran for 200 miles with this config)...when I was swapping over parts to this motor I installed later model valve covers (new) because I could never stop my old ones from leaking. Some of my fuel lines didn't fit exactly right over the valve covers so I used some of the lines from the 93 engine. I know the length on these are critical but I assumed they are the same length as the earlier models (for each injector). So if I used the same line for the same injector position would this create a problem?

One other thing I forgot to mention was after it quit running with the new rebuilt IP (4911)...and I never got it to start with this pump again...I replaced it with a pump that I had removed while running several years ago. So this motor has had 3 pumps on it since I installed it.

@John, I'm not sure how much the upgraded fan/clutch would help you. I would think that it would have to improve it. I have Kennedy's setup on mine with his calibrated clutch. This thing has heated up quickly since I installed this engine if I really stayed in it for any length of time. I attributed it to my timing being slightly off and running a little to rich. I also have a single 3" exhaust that is not mandrel bent. Everywhere there is a bend it is "necked" down to 2.5" or less. I had planned on welding up a 4" when I had driven it a while.

[john8662]

250 PSI on each cylinder is dead cylinder pressure, not going to start on that little of compression.

May have to verify the gauge you're testing since you're seeing the same results on the same bank. Temperature does matter some, a warm block will net slightly better compression results. You're still looking for a ballpark. If it's really 250PSI cold, it'll be 260 warm, still not good at all. How many strokes did you turn it over for. Is the schrader valve in the adapter working (it has to hold pressure).

To put it in perspective. An 18:1 engine will net 350 PSI at 6+ strokes. Stock engines are 21:1 and do 420 -450psi.

The injection lines won't matter. The lines are used on specific engines for specific cylinder head castings. Late model 6.2 heads (1990 and newer) will have 567 heads, which are the same as 6.5 heads because of the injector angle. The earlier heads have the injectors (external view) angling more downward. Mix in late heads, late valve covers, short body injectors, your stock 83 lines won't cut it.

I'd suggest taking the rebuilt 4911 to a pump shop and having it tested. But only after you've done compression/etc on the engine before you remove the pump and can no longer turn the engine over.

[befland]

Good info...I'll try it.

[CedarGrove]

Bill,
I have another compression test gauge if you want to verify those numbers. 250 certainly indicates a problem, but I do suspect it might be the gauge.

I'm looking for something to do tomorrow so just let me know. PM might be the best way to connect.

Lewis

[befland]

Thanks Lewis. I'll try to catch up with you.

One thing I forgot to mention was that I have part of the front of the motor off (H2O pump and plate) so I can see the pump gear and the gear below it. I don't have the AL cover removed so I can't see the crank gear or dual idler set. The marks are lined up on the two gears I can see.

[befland]

Oh...assuming the 250 is accurate when I check it....any ideas on what the problem may be? I would suspect this would mean engine removal time?

[DmaxMaverick]

If they are all at 250, something other than the combustion components is wrong. Gage, method or valve train. "Warming" the engine with the block heater is helpful, but it really needs to be near operating temp for a reliable test. It also needs full oil flow to pump up the lifters. If they are all at 250, I'd suspect the compression is good but the number is wrong, for whatever reason. It wouldn't be that uncommon to see one or two cylinders that low, but all 8, all at once, is beyond the odds. By your description, it sounds like something in the valve train may have let go, perhaps the crank key. I suggest verifying your timing before cranking on it any more. Bent valves and push rods are no fun at all.

[befland]

The reason I started taking the front covers off was to verify timing. I'm fairly certain it's right but I still plan on verifying.

Compression test...I saw somewhere to take all the GP's out to perform the test. Is this correct? When I tested it I poured oil in the GP holes, spun it over to get all the oil out, reinstalled the GP's and then took one out at a time to screw the test adapter in.

What is the correct procedure?

[DmaxMaverick]

No. Wrong procedure. Us NO oil. All glow plugs out. Fully charged/good batteries. Install gage adapter/gage. Crank for 6 "puffs" (gage needle movements). Read gage and record value. Move to next cylinder and repeat. If the engine isn't running, you obviously aren't going to get it up to operating temp. More warm is better than less warm, but do what you can to get it as warm as you can. Use the block heater, and perhaps a space heater under the engine (cover the engine compartment with a blanket to help keep in the heat). The cold to hot difference may only be 10-50 PSI, but that's the difference between marginal and totally shot. But, I don't think that's your problem.

If this engine was running "fine", then it quit, the compression test won't indicate anything telling, other than the compression. Something had to change almost instantly. If the crank key shears (or is missing), the valve train will be intact and lined up, but out of time with the crank. This can, and does, cause low compression as the timing departure increases. If it gets too far, you will have valve-piston contact, which isn't a good thing.

[CedarGrove]

The reason I started taking the front covers off was to verify timing. I'm fairly certain it's right but I still plan on verifying.

Compression test...I saw somewhere to take all the GP's out to perform the test. Is this correct? When I tested it I poured oil in the GP holes, spun it over to get all the oil out, reinstalled the GP's and then took one out at a time to screw the test adapter in.

What is the correct procedure?

I think you should take a very close look at the woodruff keys on the crank and cam sprockets. If it turns out to be your problem, O'Reillys in Mebane generally keeps two on the shelf. They come in an assortment pack so you get about 4 other keys that you don't need. Item 13125 @ about 4 bucks/pack.

Even if you don't need any help, I'd be interested in stopping by the shop and catching up on Saturday.

Lewis

[befland]

I'll try to catch up with you on Saturday Lewis. I'm working on this in the driveway since the shop is tied up.

[More Power]

The damper bolt must be torqued to 200 ft/lbs. I agree with the others, I'd eliminate a sheared crank/cam/pump key. Also with the valve covers off, you could spin the engine to watch the valve train cycle... Watch for equal rocker operation on all 16 positions. A bent pushrod, collapsed lifter, broken nylon rocker button... all could cause the loss of a cylinder.

Heating up... wrong orientation of the t-stats? Jim

[befland]

Took the timing cover off. No sheared keys. All gears look correctly positioned so tried another comp test. This time I took out all the GP's I could get to. It was reasonably warm today but I plugged in the block heater for about 2.5 hrs. I charged the batteries and got started. I took out all the GP's on the driver's side and the front one on the passenger side. Compression on the driver's side from front to back was 340, 180, 200, 240. The front cylinder on the passenger side was 340. Not sure if having the opposing plugs out had anything to do with the higher comp or not.
At any rate I guess my next step will be a leakdown to see if I can determing rings or valves are causing low comp. Any suggestions?

[DmaxMaverick]

If the key(s) are sheared, the timing marks would still "appear" correct. It must be checked with it at TDC, and it has to rotate with the crank. We'll assume that's what you did, so.......


Don't beat yourself up over the compression or leakdown test. You'll have to pull the valve covers anyway, then most likely the heads. The compression numbers you have now indicate the loss at 2 cylinders (3, 5). Most likely, they are sharing compression (head gasket between them), or the head has cracked. The compression at the rear cylinder isn't so far off, on a cold engine. The later builds have very loose rear cylinders, and will normally tighten up on a warm engine. If the rockers look good and the pushrods aren't bent, then it's a head/gasket problem. It isn't likely you'd lose enough compression due to cylinder wear (on all of them), under the conditions you described.

[john8662]

I think what Dmax is trying to say is, get out the cherry picker.

[befland]

HA!HA! I'm at the point where I think I could find out a lot faster if I just took it out. At this point it wouldn't take much to have it hanging. When you're height challenged and old... like me....it's kinda tough leaning down in the engine bay to work on heads and bottom end stuff.

[befland]

Looks like all keyways are in place. Guess it's time to take off the valve covers next.