1998 Dodge Ram 2500 Turbo Diesel

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Racin'Jacin
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1998 Dodge Ram 2500 Turbo Diesel

Post by Racin'Jacin »

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.
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Basement Paul
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Re: 1998 Dodge Ram 2500 Turbo Diesel

Post by Basement Paul »

I think I saw a glimpse of it on Facebook while your dog was running around the backyard, but wasn't sure if that was yours or not. Post a couple pictures here when you think about it. From what I could see, it looks like a solid truck. How many miles on it? Where did you find it?

-BP
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Racin'Jacin
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Re: 1998 Dodge Ram 2500 Turbo Diesel

Post by Racin'Jacin »

BP, Yep that was it. It was one of Stan's old trucks (he had a couple). As you might remember Stan was a man of many talents - one of which was he knew diesels like the back of his hand. He's probably chuckling right now over my follies. It's pretty solid, Stan went down south to get it. I've done a little welding on it - it could use a paint job - lots of little dings and dents. One day I'll paint it. It sat quite a while after Stan passed. I finally got it and its sat a bit here too - which is OK as it's given me some time to try and sort a few of the issues out. It needs some TLC as it is suffering from the typical Dodge Diesel issues. It makes for a real nice tow vehicle - pulls my little trailer like nothing. I tried to post some pics - but for some strange reason I can't login using my phone??? I tried changing my password a couple times, but it didn't help. I'll get some up eventually.
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Basement Paul
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Re: 1998 Dodge Ram 2500 Turbo Diesel

Post by Basement Paul »

Yeah they definitely prefer to be driven, that just sit. I didn't know Stan had that one. It's neat that you have that now. That truck won't even know your trailer is behind it. Good for the long hauls.

-BP
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Racin'Jacin
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Re: 1998 Dodge Ram 2500 Turbo Diesel

Post by Racin'Jacin »

Stan, Myself and Jill went to Byron, Illinois with that truck pulling my trailer - you couldn't tell not even a little.

I'm getting a little excited again - looks like I might have fixed my hard start problem....cautiously optimistic.
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Racin'Jacin
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Re: 1998 Dodge Ram 2500 Turbo Diesel

Post by Racin'Jacin »

So after another couple days of working perfect I had another Hard Start. This time I hadn't pre-checked the system pressure so I had to wait a day to see if it would repeat and sure enough it did it again - BUT ! THAT makes no sense - or should I say it says the problem NOW is not fuel pressure (or better stated not AIR). Which makes me think it must be the FSS (Fuel Shot off Solenoid) or the wiring to it. That solenoid has two coils a "HOLD" and a "PULL" - (hold working with key in the RUN position and pull working only in crank mode. So I tried briefly ot start it and when it didn't go I LEFT the key in the run position - then I checked the solenoid - it SHOULD be held in the OPEN position and it was NOT - I physically lifted it and it snapped into place - this tells me that the PULL relay is not working. SO I disconnected the PULL relay and jumpered the PULL - snap snap snap. OK the POWER wire is there so either the relay is goofy or the relay signal wire is. I found NO ISSUE and it started working perfectly again. So I must have had either a faulty relay (intermittent - although it bench tested perfectly) or an intermittent connection on the signal wire - which I believe is off the starter solenoid, but it was getting too damn cold to continue to work on it - so I am waiting for a warmer day. I ordered a couple spare FSS relays just to stick one in the glove box and have one in stock. Fired it up in the cold and it lit right off so I am pretty sure the fuel line air issue is resolved - so if I can get this FSS issue addressed I'll be golden. Fun fun fun
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Racin'Jacin
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Re: 1998 Dodge Ram 2500 Turbo Diesel

Post by Racin'Jacin »

So while there's a TON of articles written on this motor I think for me I was a little bit disappointed in them. I say that because there wasn't a ton of theory just a lot of try this or try that. After fiddling with this for a a while now what would have helped me a TON would to have had MORE theory on fuel pressure - or more specifically the output pressure from the Lift Pump and HOW it behaves. And here's why:

When I first installed the gage I could manually prime the system by depressing the plunger on the lift pump - what I would notice after getting pressure is that it would IMMEDIATELY loose pressure. That suggests a check valve somewhere isn't sealing up all that well. Also if you looked at how high the pressure goes up to - you can get an idea of how well the OFV is working (tired spring etc). Since I had LOW pressure and IMMEDIATELY lost pressure the OFV needed attention. Improvements there confirmed by improved bleed down time and increased pressure before releasing were steps in the right direction.

The next thing to realize is that when you depress that manual primer - HOW many pumps does it take to build pressure - if it takes 10 pumps well then your motor is gonna have to crank 10 revolutions to do the same - hint hint - that's NOT good. By going thru and finding "air" leaks you will notice it taking LESS pumps to build pressure. Ultimately you will see some pressure build up with a single depression.

Some articles did do a nice job describing the separate fuel system functions : Supply side being under vacuum, low pressure from Lift Pump to Injection Pump and lastly the RETURN (also pressure). Point being if you have a hard start as I did - why spend any time trouble shooting the return system? Matter of fact the ONLY part you're interested in at this point is the SUCTION SIDE - and you confirm that with the number of depressions on the Lift Pump before you build pressure. You don't HAVE to break into the system to look for air bubbles just yet. I saw many articles pointing you to replacing hoses on the return side for a hard start issue .... I just don't get it. Unless there's a return feeding the suction side somewhere (and injecting air) it doesn't make sense to me. The return goes all the way to the tank. So that's my "complaint" - if I had more time - I would draw up a fuel system showing the main lines and describing the theory a little better. For instance in my case once I knew the air was gone - I knew the new problem was with the FSS. YMMV
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MostMint
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Re: 1998 Dodge Ram 2500 Turbo Diesel

Post by MostMint »

Does the return line go into the sending unit on top of the tank? Do you know what the sending unit looks like inside the tank?

it's a long shot but maybe something in there being affected by air (like maybe the first liquid into the feed line is the return line?) I can't imagine why an engineer would design something like but maybe they had a reason?
[quote="Basement Paul"]Is that a mint rocketship on the hood?? :shock:
-BP[/quote]
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Racin'Jacin
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Re: 1998 Dodge Ram 2500 Turbo Diesel

Post by Racin'Jacin »

MostMint, That's exactly my "complaint" - with all the experts out there I'm very surprised someone doesn't outline the entire fuel system. I have found bits and pieces, but that's all. As for the return - I believe it runs back to the tank. If I experience any more air issues -I will drop the tank and ensure the pickup is sound. At the moment I think I have the air issue solved (famous last words). I think the only issue I have now is the FSS. We'll see!!!!
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MostMint
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Re: 1998 Dodge Ram 2500 Turbo Diesel

Post by MostMint »

Well someone has changed that fuel sending unit and there has to be YouTube videos where you could get a look at it and see if it has wacky design - should that be important down the road
[quote="Basement Paul"]Is that a mint rocketship on the hood?? :shock:
-BP[/quote]
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Racin'Jacin
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Re: 1998 Dodge Ram 2500 Turbo Diesel

Post by Racin'Jacin »

MostMint, Yep There's actually a couple good youtube vids on the sending unit. It IS goofy. I see that exploration in my future as I've seen the gas gage read goofy every once in a while - so I'll be in there for that for sure. I can check out the rest at that time....waiting for warm weather on that!
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GMJohnny
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Re: 1998 Dodge Ram 2500 Turbo Diesel

Post by GMJohnny »

Jacin, I'm wondering why an electric fuel pump isn't a solution to your issue. My diesel experience
is largely restricted to diesel machines ( skid steers, excavators, trenchers ) and I've worked on them
( at least enough to change fuel filters & get them started when run out of fuel ) since I was in my 20's.
The older machines didn't have electric fuel pumps, and they were horrible to start if they had an air
issue. New machines with electric pumps will self prime. The system can be dry, and in a minute or so,
from dry, the system will be primed and ready to go. I'd guess that an electric pump would allow you to
self prime then fire. Also, i haven't heard mention of pre-heating. Does the truck have a pre-heater and
does it work? I can tell you stories of having to use heat lamps on machines to keep the temps up around
the intake because the pre-heater was inadequate. Just some thoughts...

GM
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Racin'Jacin
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Re: 1998 Dodge Ram 2500 Turbo Diesel

Post by Racin'Jacin »

GMJohnny, Some guys do exactly that, but in the same breath some guys warn not to because the lift pump is super reliable. I don't know either to be more or less true as I am a newbie. This motor DOES have a Fuel Heater which after overwhelming suggestions I deleted (easily reinstalled should I ever change my mind - but removing it removed one more path for an air leak so off it went). Apparently it is located too far from the IP to do any good and instead is known to cause issues with you guessed it - air leaks. It also has a Block Heater which still works and is highly recommended to use when it's cold cold. Make no mistake I AM making progress - in spite of mediocre information. I basically started at the front of the suction side and inspected anything rubber - the slightest sign of any cracking and it got replaced. There's also a few steel lines that so far have looked fine. IIRC there's one more rubber line from the tank to the frame - I'd drop the tank to REALLY inspect that one, but for now it seems as it is NOT my immediate issue. I need to either rule out the FSS or keep digging. Last attempt it fired right up. The good thing is I do NOT drive it in the snow so it doesn't matter when I fix it. It's "sorta" nice though to trouble shoot it now because if you get it working right in the cold - it'll be golden in the warm weather!
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Racin'Jacin
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Re: 1998 Dodge Ram 2500 Turbo Diesel

Post by Racin'Jacin »

As it stands right now - I can go out and depress the manual primer and get 1/2 full pressure with a single depression. That's GOOD!!!! With that I KNOW it will fire right up so long as the Fuel Valve is open. This is part of my first "complaint" no where does anyone really explain that. Meaning the correlation between depressing that primer button and gage pressure. Maybe its so obvious that no one bothers to mention it, but had I read that FIRST off - it would have been very helpful.
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MostMint
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Re: 1998 Dodge Ram 2500 Turbo Diesel

Post by MostMint »

I've run into gaps like this. When I did power steering fluid change in Rachel's Charger - I saw a video that was basically wrong about what to do. This prompted me to do my own based on what I later found in factory service manuals and a bit of ingenuity to get it refilled. Like who puts the power steering pump behind the inner fender -> Dodge engineers!

Looks like you can help your Dodge diesel brethren by putting something comprehensive out there.
[quote="Basement Paul"]Is that a mint rocketship on the hood?? :shock:
-BP[/quote]
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