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TanM998
10-29-2004, 19:23
I am just curious here. I have a 1985 Humvee, with a 6.2 in it and my friend has a 1987 Humvee. Other then the year, the two trucks are identical. Now, when I bought the truck the engine was somewhat quiet (other then an exhaust leak) and kinda sounded like a gas engine when you took off. After trouble shooting a fuel problem, I had the injector pump rebuilt. I don't recall if it was right after that or what, but now when I go and accelerate, my engine sounds like a cummins. Its really noisy and very much a diesel. I just drove my friends 87, and his was quiet, no gurgling... is the only difference how the injector pump was rebuilt? I wouldn't say my truck is any faster or slower then his, but it is probably 10+ dB louder.

Any ideas are appreciated

Scott
'85 Tan M998 W/CTIS
NH2112
10-30-2004, 02:55
I'd have to say it sounds like your timing is advanced a little more than before, which would cause the diesel clatter to be louder.
catmandoo
10-30-2004, 05:57
yep what he said
TanM998
10-30-2004, 08:08
Is one detrimental to the other? When I put my injection pump back in the truck, I took the marks and lined them up... then I took it down to a local shop to get timed, and they said it was off 9 degrees. Even though it didn't seem to be running bad at all. Is this something to be worried about?

Scott
'85 Tan M998 W/CTIS
britannic
10-30-2004, 17:52
Did they say whether it was 9* BTDC or ATDC?


Originally posted by TanM998:
Is one detrimental to the other? When I put my injection pump back in the truck, I took the marks and lined them up... then I took it down to a local shop to get timed, and they said it was off 9 degrees. Even though it didn't seem to be running bad at all. Is this something to be worried about?

Scott
'85 Tan M998 W/CTIS
TanM998
10-31-2004, 06:37
No, they didn't... Since the pump was lined up on the default marks when I dropped it off, they moved the pump towards the drivers side, and currently is about 1/8" away from the set mark on the timing chain housing. I am not familiar with the details of timing a diesel, I just know its not a job to do at home, like the old Chevy 350. This was timed at a reputable diesel shop here in the detroit area, and the pump was rebuilt by a reputible shop down in Texas.

I am just trying to find out if the timing that I have is detrimental to engine life compaired to my friends timing where his truck is a lot queiter during operation.

Scott
'85 Tan M998 W/CTIS
NH2112
10-31-2004, 19:05
If your engine is noisier than your friend's that tells me yours is advanced relative to his. Without a meter there's no way to tell just how far it's advanced, though. Basically if it sounds like a Cummins it's too far advanced. Turning the pump toward the driver's side of the truck does advance timing, but you can't always go by the lines because 2 different pumps might not be lined up the same when both are set to TDC with a meter. From what I understand, the lines are stamped after the pump is installed and set to TDC, so each pump and engine is marked in a unique way.
TanM998
11-01-2004, 07:36
I just spoke with the diesel shop... and they told me that my truck should be more powerful with its current timing settings. They said that they could tune the enigne to sound just like a gas engine, but he said the power would diminish essecially at WOT. What do you guys think?

Scott
'85 Tan M998 W/CTIS
Peter J. Bierman
11-01-2004, 13:33
That sounds about right but too much advance is dangerous for the engine.
Check under the hood if there is a cummins or ford power stroke engine.....
If there is not, it should not sound like one :D

Peter