• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

97.5 H1 Hummer 6.5TD need help

Update: swapped out the ckp sensor for an AC Delco unit, they do look very different. The am general one had no visible metal pickups at the end but the AC Delco one does. Sadly it didn't change a damn thing, the truck runs so terrible now like it is hitting on maybe 5 cylinders if I'm lucky. I think the IP just totally took an internal shit and the first warning sign was the stepper motor adjustments not doing shit.
 

Attachments

  • IMG_20190106_183122.jpg
    IMG_20190106_183122.jpg
    61.9 KB · Views: 6
  • IMG_20190106_183131.jpg
    IMG_20190106_183131.jpg
    76 KB · Views: 6
If it turns out to be the IP I'm going to physically drive this over to Memphis and give diesel care the option of refunding me or me throwing it through their window.
 
Longer video?

I hear the diesel rattle so the timing is in range. That doesn't mean they are all hitting right. It sounds like timing is wandering.

I keep thinking about my 1992 project truck that ate the keyway and key on the lower sprocket. But it had no diesel rattle.

Does the radiator hose get hard as soon as you start the engine cold? Cracks, head gasket?

The no start with the OPS disconnected... If you buy another pump convert it to a DB2! Seriously I am not sure this clue and procedure was followed or explained well enough.
 
There is no way it is the head gasket this started with a P0216 code pump not following desired timing and got worse when I messed with the TDCO until we got to this point. Doesn't smell like burning coolant at all.

I'm trying to keep it stock I already bought a DS4 pump from Leroy.
 
Just throwing it out there - you are at the rig and we can't tell what the exhaust smells like... I feel your pain on junk IP's...

Keep us posted on how the new pump works out.
 
I just need the IP to run long enough to crack the block damnit! Or throw a rod or blow a HG something worth junking this D code thin block lol. The H1 radiator setup is particularly hard on these engines and mine has 170k just won't die, the block is so thin it sounds like a 50's tractor compared to new diesels.
 
Yeah so lesson learned there, if you're putting in something hard to put in only go New if at all possible. Like an alternator I could care less if it is reman.

As far as diesel care that happens tomorrow, I'll let you know what they say. If they won't take it I guess I'll just sell it as a core, the ancillary components on it are new and in good shape just the internal guts are no good.

I can see others making this mistake when a new one is $1700 and a warranty reman is only $700.
 
Soooooo I spoke to soon it would appear, here is the sequence of events.

  1. Replaced the IP with a new stanadyne unit from Leroy that was benchtested prior to being sent to me. Used the PMD that came with it just hooked it up to a new extension harness. All wiring hooked up good, no air bubbles in the fuel, already have a brand new AC delco CKP sensor in there from a week ago, which replaced another good CKP sensor.
  2. My friend points and laughs at how I can turn the engine over to get to the IP bolts by just turning the alternator pulley, says I have zero compression and that should not be possible. Makes sense but it works?
  3. Fired it up, took a little bit of cranking to bleed the air out but it ran pretty decent right off the bat with pump mounted vertical.
  4. It was fairly cold and late and raining so I left it alone last night instead of opening the garage door for the exhaust etc....
  5. Come out this morning fire it up let it idle up to 172F, the actual timing is following the desired timing fairly spot on no issues no codes.
  6. Go to do time set to set the base timing desired goes to 0.0 actual goes to 0.0 it will barely run. Cancel that, go to TDCO it was previously -2.46, after running the TDCO it shows 2.30 positive. Little bit of blueish smoke while it is idling.
  7. Tried turning pump towards passenger side to retard it, fire truck up runs worse but hitting on all 8 shows white smoke.
  8. If I do the TDCO or time set engine shuts off immediately with the pump retarded to probably where it needs to be (moved it 1-2mm).
  9. I put it back towards vertical/drivers side, it runs again, but now it shows positive 2.46 TDCO which is to be expected which is also way off.
  10. After trying one more TDCO it is back to barely running at all with tons of white smoke.
  11. So I unplugged the PCM and left it unplugged for 30 minutes.
  12. Plug it back in truck is back to idling just fine, slight blueish smoke but idles revs up fine, engine is around 160.
  13. As soon as the truck crosses 172 just idling it immediately starts blowing white smoke and barely running, desired timing stays 8-10 but actual is about 2.5
  14. I am ready to push this off a cliff.
  15. I am thinking either my PCM is bad, or I screwed it up doing too many TDCO procedures, or my engine is low on compression and only runs with the IP way advanced, or my timing chain/IP gear really did jump a tooth.
If I have to take the cooling stack apart to get to the timing chain I am most likely just going to take the entire engine out and throw it in the scrap pile with the rest of the thin block 6.5's that GM made. Suggestions?
 
Can you do a longer video? Do you have compression test tools? I am on this road of several pumps before compression test indicated bad pump bent all the valves during overspeed.

I second @ak diesel driver for testing the OPS.

Cut to chase... Do you have a spare ECM or buddy with an Electronic 6.5 to borrow an ecm from?

There is a reason some of us recommend DB2 and eliminate electronic... But that's a distraction.

End of the day it can take time to work out and find a specific issue. PIA, but, winning is worth it sometimes.
 
Which connector is the OPS? Top middle on the IP right 6 pin?

And no I dont have a diesel compression tester. But I can get one.

This is a brand new stanadyne pump benchtested prior to being sent to me from Leroy I seriously doubt the OPS is bad.

I am going to buy a spare PCM for the truck, they are only $250 new.
 
Last edited:
The OPS test is for wires and ECM at this point.

A compression tester would answer some questions and eliminate low compression as the cause or ...

I believe it's the top middle connection for OPS.
 
You must log in or register to reply here.
Back
Top