DennisT

I've only logged about 1800 miles on my, "new," '97 CTD 2500, 4WD, 5speed. So far, so good, except for needing a little tune up on steering, (128,000 mi. on truck).

Last week I noticed a few very small wet spots on the cement under roughly where the front diff. pinion/u-joint is. I peeked under and it seemed to be wet on the u-joint. Figured I had a pinion seal leaking. Since my back was bothering me then, I only crawled under truck this morning. Above the dif. and along the right, (passenger), side of where the pan mounts to the block I noticed a wire loom that was somewhat, "wet." It is diesel fuel. Then I smelled of the wet spot on the concrete and that is diesel. The wet spot on the wire loom is only where the loom sags slightly on it's course from front to starter and only is evident for about 3 inches of it's length. Most of the underside of my truck is very clean but the loom has a little old oil collected on it and that is where the fuel clings. I see no place the fuel is coming from.

Here's what I'm asking: are there any, "typical," leak-prone spots that occur with these truck in this area? I'm new to all this and am not sure where to look next. I'm going back out there to spend more time with it but right now it puzzles me. I have a 500 mile trip coming up next Saturday so I don't need a fuel leak/hazzard now.

As I recall the fuel preheater/pre-screen, etc., is on the left side of the engine, so that adds to my confusion. BTW, I've initially been getting about 18mpg on part freeway/part 2-lane country roads w/3.5 rear dif.

Any hints would really be appreciated. Thanks, Dennis

Box5

Im still unsure exactly where ur leak is, so it's on the passenger side below the oil pan where the wire going to the starter is wet? Check all ur injectors for a leak on the passenger side. A picture of where u found the wet spot of diesel would be really helpful.

DennisT

Thanks. I would expect my wire loom is wet only because it is below or behind where the actual leak is. My problem is that so far I can't see anything wet above it. If my leak is occuring when the truck is running on the road, (most likely perhaps), then there is the situation that anything producing fluid can be blown rearward because of the fan, forward motion, etc. (Like a water pump leak produces coolent drips other places than just under the water pump)

I'm not sure I can produce a photo. The wet place in the loom is about half way between where the loom begins near/under the right side battery and the starter. At a level adjacent to the right side pan bolts. And only wet for about 3 or 4 inches of the loom where it sags, (the fuel creeping to the lowest section of the loom). I doubt this is a major leak. The truck was totally dry underneath until the past few days, so this is new.

If there is a danger of major leaking beginning, I better cancel Saturday's trip. If this is very, very slight, I might be OK. I just don't know the track record of these trucks regarding minor fuel leaks.

I hope this helps; perhaps someone here will still recognize something for me. Thanks again, Dennis

chariotdriver

I replaced the fuel heater on both of my trucks. The original was prone to failure and Cummins has a new one out as of last year; it has bigger contacts and doesn't burn the terminals which causes a leak. Your leak description sounds like what I had. Since the heater is on the suction side it doesn't leak when the engine is running but if you have a fresh fill up or some tank expansion it will start leaking. You can put about 2 psi compressed air into your fuel tank using an air hose and a rag; if you have a leak it will show fairly fast.

The new part number is Fleetguard 3907766-S; don't buy it from Mopar unless you have money to throw away. If you subscribe to the TDR there is a 3 page article in issue 54.

Good luck, cd

DennisT

Thanks. That is beginning to make sense.

However, DUMB me; the wet loom is NOT on the passenger side, it's on the left side. So much for me laying upside down on the concrete and knowing what I'm doing. Sorry.

So this opens up lots of things. I had the KDP handled at the local Dodge dealer immediately after I got the truck. While there I just told them to change both fuel filters. They changed the normal filter, but forgot to change the heater/pre-filter. So I suppose the, "new," filter they installed might be dripping.

OTH, I like Chariot's comment best so far even though I'm not fond of beginning to replace parts. I made note of the Fleetguard number. I don't subscribe to TDR, but I guess I should. I suppose that issue 54 is only available to subscribers.

I just called my local Case/IH dealer and gave him that Fleetguard number. He does not stock it, but shows the price at $44.73. Sound right?

How hard is it to change the fuel heater?

That would be great if this is the answer, your part is a better unit, and it isn't leaking now when driving. I DO keep the tank full when I come home, and it is that way now. Maybe this is all adding up.

Dennis

patdaly

Could be fuel/return lines rusted or hose cracked. Just had to do mine from front to back about 2 months ago.

Unless you really like pain, don't have your local dealer put factory lines back on, they are really, REALLY pricey. I ended up running 5/16 and 3/8 diesel rated hose on each end and brake line where the old metal lines were. Easy enough to do and close to 500 bucks cheaper than just the parts from the dealer.

ccmckee

I would check the new fuel filter to see if it is snug, then the fuel heater where the electrical connection goes inside, then the lift pump primer button, then your fuel lines. I replaced all of my fuel lines with rubber ones from the tank to the motor.The fuel heater can be removed altogether with no side effects.

DennisT

Thanks guys. I'll do all that checking.

Any of those points likely to cause a catastrophic failure? On most of them I would doubt it unless a fuel line itself blows out.

I guess my only concern now is if the leak will remain slow or am I in danger of a road breakdown before I chase all those items down.

Great forum here, I appreciate it.

Dennis

patdaly

I drove mine for a few weeks while I waited for the fuel tank to go down, other than killing some asphalt where I part at work, no other obvious dangers, it got harder to start when the tank approached 1/4 full at which point I decided to fix it. ( hey, 34 gallons of diesel is heavy!)

We are coming into winter here, so in my case I would do it much sooner, but if you are still in a warm climate, I wouldn't think too much about driving it.

BTW, don't just torque the fuel filter nut too tight, spec is 22 Lb/Ft IIRC, and I have known people to crack the housing.

Another thing, you might be able to rule out specific areas by cleaning them with carb or brake cleaner and then driving a short distance and looking for the leak. From where you describe, I would focus on the rubber lines or where the steel lines turn upward drivers side front of the cab, thats where mine rusted through.

DennisT

Thanks. I'm in eastern Washington state, so in another month we'll be in temps from +5 to ??? We can run 10 days or so at 8 to 20 degrees night and or day. So I will probably chase this down over the next few days if I can.

One point I'll be interested in finding out about: the talk about rusting lines. This truck came from the Washington state west side, and although there is a lot of rain there there is no unusual salt conditions. Here on the east side it is very, very dry. If there is rust throughs on this 10 year old truck, I'll find that a bit interesting and disconcerting. OTH, many vehicles have odd rust sensitive areas. So far I can find vertually no rust on the truck.

Dennis

plow

also check and make sure the fuel filter drain valve is shut off completly and I have also seen people not get the o-ring on right when installing the filter and it will leak down the side of the canister.

patdaly

Probably not rust then, but certainly could be cracked rubber. That hose is further up towards the engine.

DennisT

Took truck in to friend/mechanic whose eyes and dexterity are better than mine. Took him about 5 minutes to see that the lift pump plunger area was leaking. He ordered a replacement pump which he installed today. Delphi pump $180; two hours to install and while he was under there he slipped in a new Fleetguard fuel heater screen and kit.

If the Cummins tech bulletin about Low Sulphur fuels causing this in 24 valve pumps is true, why couldn't the same fuel cause an O-ring leak such as I had in my 12-valve?

With 129K on the clock, probably wasn't a bad idea to change the pump anyway.

Thanks for all the help. I've saved most of it for future leak-hints.

Dennis