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1998 6.5 shuts off past 170° f

0.8" of slop (deflection) off the top of my head. The spec is just unreal, but, it's due to the shock load stretching the mediocre design.

A new chain goes on tight, but, stretches out a lot in under 30K miles.
 
Took the truck to the shop to have it timed again and was told that it still cuts off at 170°. Apparently this guy is the best around here for 6.5s and he still seems to I think that it is a mechanical issue somewhere. At this point I don't know if there's anything else to check.
 
WarWagon said:
Did you put a new timing chain in it?

For reference here is what they do when stretched out. (Ref from this expended 6.2 engine )



Click to expand...
no I didn't put a chain in it I figured the amount of slop it had was acceptable but now that I watch the video you posted above it makes me reconsider. I assume any slop is going to affect the injection pump and a little slop can come out to be a large issue with timing?
 
Going back it looks like someone has already changed the chain. We don't know how long ago or if a key is wearing and making a sprocket sloppy. You have looked at it, we haven't. It may be fine but you haven't given us much to go on. GM's slop spec is embarrassing. So what did you see?

I took another listen to it cranking and have to wonder how old are the injectors (miles)? It sounds when cranking just like some Commie China knock off nozzles I got that were sticking around 30K miles. If the injectors are all over the place in pop PSI or sticking it may throw off timing. This is a DB2 so it didn't care other than eating starter drives.

To be clear I hear yours fire then "stall" back to leaning on the starter. This bad injector video of mine sounds similar. It could also be air, but, you checked your lift pump PSI and for air in the return line, right?

 
WarWagon said:
Going back it looks like someone has already changed the chain. We don't know how long ago or if a key is wearing and making a sprocket sloppy. You have looked at it, we haven't. It may be fine but you haven't given us much to go on. GM's slop spec is embarrassing. So what did you see?

I took another listen to it cranking and have to wonder how old are the injectors (miles)? It sounds when cranking just like some Commie China knock off nozzles I got that were sticking around 30K miles. If the injectors are all over the place in pop PSI or sticking it may throw off timing. This is a DB2 so it didn't care other than eating starter drives.

To be clear I hear yours fire then "stall" back to leaning on the starter. This bad injector video of mine sounds similar. It could also be air, but, you checked your lift pump PSI and for air in the return line, right?

Click to expand...
I haven't checked the thread in a while. This truck has become one of those things that I dread working on. I've never pulled the cover on a 6.5 until now but comparing to other engines gas and diesel I wasn't concerned too much with the slop that it did have but if the timing cover comes off again it will be replaced regardless. The sprockets all looked fine along with the key Nothing was sheared or worn. I purchased the truck not running I am not sure of when the injectors were replaced. I did check pressure in line with the lift pump but it has been at least 6 months I believe I had somewhere around a 9 PSI maybe, my memory is fuzzy. No air in the return line. I ran the truck about 3 weeks ago with the coolant sensor unplugged. It now has been properly timed by a shop and it ran for about 4 hours (longest it has ever ran for me) and I would occasionally get in and rev the engine and watch the rpm drop. It seemed to drop a little lower than it should normally but it picked back up and continued running. After I shut the truck off it would not restart. Last week I drove the truck with the sensor unplugged as well and drove it around the block for a good 25 minutes. I'm driving the truck died and would not restart. I needed to get it back home so I sprayed the air filter with some brake cleaner and it fired right up and continued running until I shut it off at the house and it would not restart. It's confusing is it electrical or a mechanical problem. I was thinking about calling up quad Star or heath diesel And seeing what kind of tune they could put on one of my computers. let's add some fuel and raise the RPM to see if it won't stall.
 
A tune isn't the answer at this time to the problem causing the stall and no-start.

So you have it running past 170 degrees now?

I would have the injectors tested or rebuilt. Again by the sound of hit, miss, miss, hit during cranking.

Have you done a compression test?
 
WarWagon said:
A tune isn't the answer at this time to the problem causing the stall and no-start.

So you have it running past 170 degrees now?

I would have the injectors tested or rebuilt. Again by the sound of hit, miss, miss, hit during cranking.

Have you done a compression test?
Click to expand...
A tune is definitely not the answer but was wondering if there was a wrong way to take care of the problem. With the ECT sensor unplugged at the crossover pipe I did have the truck running for over 4 hours and I would only assume it surpassed 170 degrees but he gauge does not seem accurate compared to the PCM or a laser thermometer. With it unplugged obviously the PCM does not know what the temperature is. I tested compression on cylinder one while warm months ago since it was the only one that was very easily accessible. I should really go through and test all cylinders but I had I think 420+ PSI on that cylinder. Once the truck shuts off on its own with the coolant sensor unplugged the truck doesn't hit or miss while cranking, it's just a consistent cranking sound with no attempt to fire. If it shuts off with the sensor unplugged it seems to hit / miss while cranking obviously there is more fuel and timing with it unplugged.
 
Sell the DS4 on ebay and convert to a DB2... Esp. before spending another Ten Cents on the DS4 setup.

I would suggest looking at fuel pressure and a clear return line to make sure it has fuel during the no fire when cranking. It took me a couple years to find a soft hose that would kink shut behind the fuel filter on my 1995 DS4. It would have big bubbles of vapor lock in the return line. The biodiesel and tank lining plugging the sock did not help the situation. Get a fuel pressure gauge installed and understand "0" may be a vacuum due to a restriction unless your guage will read a vaccum.
 
WarWagon said:
Sell the DS4 on ebay and convert to a DB2... Esp. before spending another Ten Cents on the DS4 setup.

I would suggest looking at fuel pressure and a clear return line to make sure it has fuel during the no fire when cranking. It took me a couple years to find a soft hose that would kink shut behind the fuel filter on my 1995 DS4. It would have big bubbles of vapor lock in the return line. The biodiesel and tank lining plugging the sock did not help the situation. Get a fuel pressure gauge installed and understand "0" may be a vacuum due to a restriction unless your guage will read a vaccum.
Click to expand...
I 100% regret not doing the swap but I'll never get the $1250 back out of the pump. My clear return line shows no bubbles. I haven't pulled the tank to check the sock although the tank looks fairly new but im not going to assume that the previous idiot owners replaced the sending unit or sock or anything. I did T off on the line after the filter and before the IP and think I had consistent pressure. It was a fuel pump gauge that read vacuum as well.
 
So when it's not firing while cranking the return line is free of bubbles? And you have fuel pressure from the lift pump? This step is beyond critical thus why I ask to be 100% sure.

I watched the videos again and some observations:
1) You got a dead hole OR it's firing 1 of 8 cylinders while cranking. You get the "ZING!" sound where the starter isn't slowing down 8 times in a row.
2) Knock when running like timing is randomly off or injector acting up.
3) Cranking speed is fine - clearly no fuel.

I suggest you pull all 8 injectors have have them tested. Do a compression check while you are at it.

I don't take the "pain" of suggesting a DB2 swap lightly, but, you are the second person to attempt to find the bad trons on this DS4 setup. You have done the easy and expensive stuff. You are down to wires and scoping the PMD to see if it's trying to fire the pump. Assuming the new parts you got are good parts.

For the sake of argument lets say the injectors and compression are fine. Suspect a broken valve spring as a secondary problem, but, it should start. Even then I suspect from the way it misses 1 of 8 while cranking that the ECM can't find where the engine is at. Loss of optic sensor or crank sensor signal. Again need to scope it at the ECM to see if it's getting a signal from either sensor. A short knocking out 5V to sensors could cause this problem.

Any codes at all?
 
JMJNet said:
You may want to summarize what you did so far?
Click to expand...

Reman DS4 and new grey one with heat sink from Diesel Equipment who is an authorized stanadyne dealer.

Napa brand intake air temperature sensor

All other sensors and parts are AC delco brand which include:
Coolant temperature sensors
Crank sensor (tried 2 different sensors)
Oil pressure sensor switch
Lift pump
Fuel filter
Air filter
Oil change/ filter
Glow plugs but I have only replaced the plugs on the driver side cylinders

Used PCM from a reputable truck parts yard. This pcm came off a truck without an EGR or MAF. I have done the relearn to bypass the security light.

Used injection pump harness out of my parts truck.

The truck has been taken to pure diesel in kernersville. They checked over all electrical and I was told everything seemed correct. They recommended pulling the timing covers and checking timing as well as the gear and key on the cam. Everything seemed normal.bwhen I pulled the cover. I brought it back to them and they timed the injection pump. The truck starts very easily when cold now better than it did before I'm assuming due to the timing being correct.

There may be some I am forgetting I will update as I remember as this has been an ongoing repair since February.
 
WarWagon said:
So when it's not firing while cranking the return line is free of bubbles? And you have fuel pressure from the lift pump? This step is beyond critical thus why I ask to be 100% sure.

I watched the videos again and some observations:
1) You got a dead hole OR it's firing 1 of 8 cylinders while cranking. You get the "ZING!" sound where the starter isn't slowing down 8 times in a row.
2) Knock when running like timing is randomly off or injector acting up.
3) Cranking speed is fine - clearly no fuel.

I suggest you pull all 8 injectors have have them tested. Do a compression check while you are at it.

I don't take the "pain" of suggesting a DB2 swap lightly, but, you are the second person to attempt to find the bad trons on this DS4 setup. You have done the easy and expensive stuff. You are down to wires and scoping the PMD to see if it's trying to fire the pump. Assuming the new parts you got are good parts.

For the sake of argument lets say the injectors and compression are fine. Suspect a broken valve spring as a secondary problem, but, it should start. Even then I suspect from the way it misses 1 of 8 while cranking that the ECM can't find where the engine is at. Loss of optic sensor or crank sensor signal. Again need to scope it at the ECM to see if it's getting a signal from either sensor. A short knocking out 5V to sensors could cause this problem.

Any codes at all?
Click to expand...

The last time I checked there was no bubbles in the return line while cranking when it is not firing. now that I have the pump timed properly I can post an updated video and double check for bubbles now that the pump is properly timed. I believe I can get a full set of Bosch or ACDelco injectors from a local shop for around $350-$400. I need to replace glow plugs on the passenger side so I might as well pull the turbo and pull the injectors and replace glow plugs and compression test it on all cylinders. I suppose I could also pull injector lines and pull the valve covers too. Do you know of a good thread or any recommendations on how I should scope/probe the harness/ PMD/ ECM? Am I just searching for 5 volt reference voltages at these places? At this point you are correct I've done what seems to be the obvious, easiest, and expensive things I figure it is something simple but the shop I took it to seems to think it is a mechanical issue which I don't quite understand since it ran for over 4 hours. I would love a DB2 but at this point I am invested. This was going to be my tow rig for my Jeeps as I did not want to use my '99 Sierra with a 4.8. I purchased a '98 k3500 7.4 dually CCLB for a tow rig about a month and a half ago but I still would like the 6.5 to be up and going as right now it is just a yard ornament. It's also taunting me sitting in the yard because I have yet to figure out the problem. Again I do not hate 6.5's I just hate this one at this point.
 
It took me years to find the kinking shut fuel line including adding some exotic racing lift pumps. (Nevermind the clogged sock in the tank from the tank lining coming off.) I would recommend keeping the fuel pressure gauge on it so you can be sure it's not a fuel problem. It's acting up enough you can put it under the wiper on the windscreen if necessary. Intermittent electrical or interment fuel problem is my best guess assuming the engine is ok mechanically.

These are hard things to pin down thus the suggestion to make sure the engine is ok as possible. I would suggest you have the injectors tested to see what they are doing: for example because pop pressure can affect timing. High pop pressure takes more advance. Worn injectors pop at a lower pressure. Thus it's worth the price of admission to test them even if you are replacing them. Make sure they are genuine Bosch and not made in China as the China krap only lasts 30K miles.

You have looked at the timing set. I have seen others mention these engines will sometimes run with a busted crankshaft. I can't think of anything else that would throw off the timing.

A new video would help before you pull the valve covers. The busted spring on my last 6.2 was under the "cap" and not visible.

You will need a better turbo if you are going to use this as a tow rig. (IMO it's cheaper to pour fuel down the 454, but, they can be gutless.)
 
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