1998 Dodge Ram 2500 Turbo Diesel
Posted: Fri Nov 27, 2020 6:00 pm
So my latest FUN has been revolving around tinkering on my 12V Cummins Diesel. Had it a year or so haven't really driven it much as there wasn't much call with a lot of the races shut down.
I think it could probably use a new set of rings as it smokes a little, but honestly I don't see me doing that anytime soon. I'd need to drive it a bunch to make a real evaluation. In the meantime it has a few issues I am trying to eliminate - the latest is a HARD start it seems to have randomly.
Now keep in mind I know NOTHING about diesels so this is On The Job Training type deal. First thing I did was drill out one of the banjo bolts and installed a pressure gage so I knew what the lift pump was doing. In my haste I skipped the addition of a snubber and learned quick why that wasn't such a hot idea (the gage moved so fast it bent the needle!). I added a hilbilly snubber (the orifice was a tad bigger than I wanted, but it was the smallest drill I had), at least now I could see that the pressure was a bit low. That took me to evaluate the OFV. I "adjusted" the OFV pressure by stretching the tired spring a little and then shimming it to a 22lb. cracking pressure on my bench setup. That and I swapped out the ball bearing and lapped the seat. That resulted in being real close to factory fuel pressure from the LIFT pump.
Next I reset the idle to factory spec (it was a bit low) not sure that helped much, but couldn't hurt. Still I had intermittent hard starts. I noticed that I could use the manual primer button and it would hold pressure pretty good AFTER I tweaked the OFV. I also noticed that sometimes it'd get pressure with only a couple pushes on the primer and other times it took ALOT. That told me I was getting AIR in the fuel line somewhere. I deleted the fuel heater and swapped in a new O-ring into the fuel strainer (wasn't sure if that o-ring was bad but if not it was gonna be REAL soon so it had to go. Next I noticed that the supply hose from the strainer to the lift pump was ROCK hard and still had factory spring clamps - which also told me it had to go. In frustration I OVERPAID for that little hose (its a sharp 90 deg bend and while I didn't buy the one at the dealer (56 bucks - no thanks) I did find a cummins one on line for $32. Later I was digging around and found that the aftermarket sells a Molded Universal Fuel line for I forget 22bucks maybe but what is so cool about it is that it has a 45, 90, 135 and 180 degree bends molded in it. SO bascially you cut off what you need and STILL have some hose for future projects - they sell these in 5/16. 3/8" and 1/2" - Next time I need a molded bent fuel hose I'm gonna try these! I digress.
Truck started prefect for 3 or 4 days - I was CONVINCED I had it figured out. Oh I forgot somewhere along the line I machined a bulky 'gas cap' that I could pressurize the tank with to check for air leaks. I put 2psi in the tank but didn't find anything leaking. For those less familiar with diesels than I am - these things will "leak" air into the line, but NOT necessarily leak fuel out so finding the "leak" can be a challenge. Possibly more so for a non-diesel guy like me. Anywho it was working great so I claimed VICTORY!!!! did the Happy Dance and everything! And - you you saw this coming I know - boom another Hard Start!!! Dang it. This time the gage was reading CRAZY - bouncing from 40 to 10 psi - that says I have a SHIT TON of air coming in. More than ever before actually. I noticed there is a transition from steel to plastic back to steel on the fuel supply line - that was NOT checked with the air gage because I didn't realize you could slide the protective cover back. It also had a quick disconnect. Which I yanked and twisted for good measure - actually I may have just bumped it at first. Suddenly the hard start was gone again and my gage was smoothed out. Hmmmnnn I had to wonder if this quick disconnect had squirrely o-rings in it or it there could have been a crack under that protective sleeve. F-it! It's 30 years old - its got to go. So I made up a new line using a Dorman quick disconnect and some fuel hose with those crimp on clamps. After some fun trying to bleed all the air back out that I caused by replacing the line - it is finally starting easy again. Oh yeah some where in the mess I replaced a bad grid heater relay as well- way way way back in the beginning.
So it still needs some other work (like fixing the dipstick handle that some dipstick broke as he leaned on the motor to replace that fuel line (duh) and it has some other "typical" issues like popping out of 5th gear. Which there's a WHOLE other can of worms in that. I have a buddy that is an Engineer at Cummins so he's pointed me in a few good directions - so that's been pretty helpful. For those not familiar with the NV4500 5 speed - the splines on the shaft do NOT go the full length of the gear and apparently the pulsing and torque of the turbo diesel will hammer the lock nut loose that holds 5th gear in place. The good news is that that particular issue is exacerbated pulling heavy loads and lugging the motor - my trailer is super light and I really don't tow very far often so I think for now I can try one of the hilbilly repairs. The nice thing is that you can access the nut by pulling the tail housing off. Downside is with winter coming I don't think I'll start this before the snow flies as my truck sits outside all winter.
I probably ought to drop the fuel tank and verify the draw straw is in good order, but again it might be too close to snow flying to do that now. Oh well there's always this spring!!!!!
At least I got the door hinges rebuilt. Turns out the kit only gives you half the crap you really need and besides you have to pull the door to get all the pieces out - NOT anymore! I modified the shoulder bolts so now you can rebuild them next time leaving the door in place. Of course if I give it a squirt of oil every so often - it probably wont wear out again in my lifetime!!!
So in a nutshell THAT's my latest project. Time will tell.
For HOW long???? No idea - time will tell.
I think it could probably use a new set of rings as it smokes a little, but honestly I don't see me doing that anytime soon. I'd need to drive it a bunch to make a real evaluation. In the meantime it has a few issues I am trying to eliminate - the latest is a HARD start it seems to have randomly.
Now keep in mind I know NOTHING about diesels so this is On The Job Training type deal. First thing I did was drill out one of the banjo bolts and installed a pressure gage so I knew what the lift pump was doing. In my haste I skipped the addition of a snubber and learned quick why that wasn't such a hot idea (the gage moved so fast it bent the needle!). I added a hilbilly snubber (the orifice was a tad bigger than I wanted, but it was the smallest drill I had), at least now I could see that the pressure was a bit low. That took me to evaluate the OFV. I "adjusted" the OFV pressure by stretching the tired spring a little and then shimming it to a 22lb. cracking pressure on my bench setup. That and I swapped out the ball bearing and lapped the seat. That resulted in being real close to factory fuel pressure from the LIFT pump.
Next I reset the idle to factory spec (it was a bit low) not sure that helped much, but couldn't hurt. Still I had intermittent hard starts. I noticed that I could use the manual primer button and it would hold pressure pretty good AFTER I tweaked the OFV. I also noticed that sometimes it'd get pressure with only a couple pushes on the primer and other times it took ALOT. That told me I was getting AIR in the fuel line somewhere. I deleted the fuel heater and swapped in a new O-ring into the fuel strainer (wasn't sure if that o-ring was bad but if not it was gonna be REAL soon so it had to go. Next I noticed that the supply hose from the strainer to the lift pump was ROCK hard and still had factory spring clamps - which also told me it had to go. In frustration I OVERPAID for that little hose (its a sharp 90 deg bend and while I didn't buy the one at the dealer (56 bucks - no thanks) I did find a cummins one on line for $32. Later I was digging around and found that the aftermarket sells a Molded Universal Fuel line for I forget 22bucks maybe but what is so cool about it is that it has a 45, 90, 135 and 180 degree bends molded in it. SO bascially you cut off what you need and STILL have some hose for future projects - they sell these in 5/16. 3/8" and 1/2" - Next time I need a molded bent fuel hose I'm gonna try these! I digress.
Truck started prefect for 3 or 4 days - I was CONVINCED I had it figured out. Oh I forgot somewhere along the line I machined a bulky 'gas cap' that I could pressurize the tank with to check for air leaks. I put 2psi in the tank but didn't find anything leaking. For those less familiar with diesels than I am - these things will "leak" air into the line, but NOT necessarily leak fuel out so finding the "leak" can be a challenge. Possibly more so for a non-diesel guy like me. Anywho it was working great so I claimed VICTORY!!!! did the Happy Dance and everything! And - you you saw this coming I know - boom another Hard Start!!! Dang it. This time the gage was reading CRAZY - bouncing from 40 to 10 psi - that says I have a SHIT TON of air coming in. More than ever before actually. I noticed there is a transition from steel to plastic back to steel on the fuel supply line - that was NOT checked with the air gage because I didn't realize you could slide the protective cover back. It also had a quick disconnect. Which I yanked and twisted for good measure - actually I may have just bumped it at first. Suddenly the hard start was gone again and my gage was smoothed out. Hmmmnnn I had to wonder if this quick disconnect had squirrely o-rings in it or it there could have been a crack under that protective sleeve. F-it! It's 30 years old - its got to go. So I made up a new line using a Dorman quick disconnect and some fuel hose with those crimp on clamps. After some fun trying to bleed all the air back out that I caused by replacing the line - it is finally starting easy again. Oh yeah some where in the mess I replaced a bad grid heater relay as well- way way way back in the beginning.
So it still needs some other work (like fixing the dipstick handle that some dipstick broke as he leaned on the motor to replace that fuel line (duh) and it has some other "typical" issues like popping out of 5th gear. Which there's a WHOLE other can of worms in that. I have a buddy that is an Engineer at Cummins so he's pointed me in a few good directions - so that's been pretty helpful. For those not familiar with the NV4500 5 speed - the splines on the shaft do NOT go the full length of the gear and apparently the pulsing and torque of the turbo diesel will hammer the lock nut loose that holds 5th gear in place. The good news is that that particular issue is exacerbated pulling heavy loads and lugging the motor - my trailer is super light and I really don't tow very far often so I think for now I can try one of the hilbilly repairs. The nice thing is that you can access the nut by pulling the tail housing off. Downside is with winter coming I don't think I'll start this before the snow flies as my truck sits outside all winter.
I probably ought to drop the fuel tank and verify the draw straw is in good order, but again it might be too close to snow flying to do that now. Oh well there's always this spring!!!!!
At least I got the door hinges rebuilt. Turns out the kit only gives you half the crap you really need and besides you have to pull the door to get all the pieces out - NOT anymore! I modified the shoulder bolts so now you can rebuild them next time leaving the door in place. Of course if I give it a squirt of oil every so often - it probably wont wear out again in my lifetime!!!
So in a nutshell THAT's my latest project. Time will tell.
For HOW long???? No idea - time will tell.