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6.2L injector pump issues and questions

yunit

yunit

1/2 ton status
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1. What size thread are the two studs on the bottom of the pump? Previous owner stripped one and did not install the second one.

2. The timing marks are about a 1/4" apart from each other, I think the owner pulled the pump, had it rebuilt and just installed the pump. The pump mark is 1/4" to the left when looking at the front of the engine. How advanced do you think the pump is?

The truck smokes like crazy, smells like diesel, and idles like sheot.

Thanks homie's!
 
Can't help you on the stud threads. The pump lines should line up exactly with each other as a baseline. 1/32" misalignment is a lot. My pump is advanced less than 1/32" of an inch and my timing chain has well over 225,000 miles on it.


Hopefully Casey or Tyler will see this soon and help you a little more. I'm learning stuff about the 6.2 everyday...still pretty far from knowing diesel stuff like i do other stuff though. Timing can have a big affect on smoke though...and IIRC too retarded causes a lot of smoke. Does it seem pretty quiet for a diesel? clatter wise I mean.

The more the pump gets advanced the louder the clatter and eventually it'll sound louder than a 6BT.

Rene
 
The truck has almost no clatter at all. Hopefully I can get the nut off in one piece so I can verify the size. I guess I can also hit the local GM warehouse and see if they have them in stock.
 
Been thinking about it and i seem to recall the wrench size for those nuts was 15 mm. Might be an M10 thread.

No clatter and the marks over to the left that far...plus the smoke tells me it's timed very retarded. Rotate the pump so the marks line up dead even and it should run better and not chug smoke. You could go as far as 1/16" past the line the other direction pretty safely. Ideally when dead cold it should run kinda loud, and then after 5-10 minutes the idle speed should drop 100-200 rpm and it should quieten up some.

I'd definitely see if GM carries those studs. I might actually have some spares of those studs. I'm gonna root through my 6.2 parts box and see what i find.

Rene
 
OK Pete, no luck on spare studs. I thought i had a timing cover assembly but I guess not. I did find one of the injector pump nuts in the bottom of the box though. It does take a 15 mm wrench but the threads are 3/8" x 16 tpi. It's a flanged nut that i compared to one on my truck, then I double checked with some known imperial bolts in the house.

Hope that helps.

Rene
 
Did I mention those nuts are a total bastard to get to? Well...they are. :whistle:

I was wishing for little girl hands and a magic wrench when I re-installed my injection pump.

Rene
 
tRustyK5 said:
Been thinking about it and i seem to recall the wrench size for those nuts was 15 mm. Might be an M10 thread.

No clatter and the marks over to the left that far...plus the smoke tells me it's timed very retarded. Rotate the pump so the marks line up dead even and it should run better and not chug smoke. You could go as far as 1/16" past the line the other direction pretty safely. Ideally when dead cold it should run kinda loud, and then after 5-10 minutes the idle speed should drop 100-200 rpm and it should quieten up some.

I'd definitely see if GM carries those studs. I might actually have some spares of those studs. I'm gonna root through my 6.2 parts box and see what i find.

Rene
Click to expand...


Rene hit the nail on the head. With the IP rotated towards the passenger side of the engine and a 1/4" gap between the marks, that means the timing is severly retarded. This would cause the engine to smoke like a freight train, have very little diesel rattle, and not idle worth a darn. Lining up the marks, and even advancing it towards the driver's side a bit, should make it run a lot better.

If the lower two nuts aren't holding the pump in place, it could be that the pump has simply slipped out of time over a period of time. You need to get that problem resolved, then line up the marks, and I bet you'll be very pleased with the results. I'd run the engine with the marks lined up first, and then advance the timing a bit more later on to make sure everything is okay.

Casey
 
Ok, finally got the nut off. :mad:

Tried installing a 3/8" threaded nut on, but no go, the thread is actually 9.8mm. What I did was tighten the nut down until it locked up on the threads and just backed the stud out, then I used a 9.8mm bolt that I had from one of my old trucks. :cool1:

I advanced the pump about 1/32" past the mark and the truck started right up after not being started since yesterday. I went out for a few hours, came back, just tapped the ignition key and the truck started right up and runs like a champ. :D The truck has some old fuel in it, so I am going to pick up a few gallons of fresh diesel to add to the mix.

It's a shame this truck is so rotted out, would like to drive itthe way it is. I jumped into the passenger seat before and almost went through the floor. :(

Thanks for the input guys. :cool1:
 
I only let the truck run for about 10 minutes and I could see a little bit of smoke coming out, nothing like it was before.
 
I finally was able to let the truck fully warm up today, the temp guage hit 200 before the thermostat opened up. At idle the truck still smokes a little bit, the timing marks are almost dead on, advanced maybe a millimeter. When I rev the truck up it smokes pretty good, could this be happening from old fuel? The owner of the donor truck said the fuel was old. I might try advancing the timing about 1/16" and see if that reduces the amout of smoke coming out the pipes.
 
Advancing the pump timing should decrease smoke...just make tiny adjustmants though. A millimeter is a lot.

Rene
 
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