The Diesel Garage banner
1 - 16 of 16 Posts

·
Member
Joined
·
106 Posts
Discussion Starter · #1 ·
Hey my truck has leaked oil some since I bought it, maybe 1 quart per 1000 miles or so, but its gotten worse of late, now its going through a quart or two every 250miles or so. Its leaking enough that after a long drive the whole underside of the truck is covered in oil. Anyhow, seems I've put it off long enough, any ideas to stop the leaks? It seems to be leaking from the front of the engine somewhere, hard to know for sure since there's oil everywhere now. What are the common leak areas and where should I start?
 

·
formally dodge97ctd-sc member #12
Joined
·
2,001 Posts
the most common oil leak areas ive had with the 2 12valves ive had is the front main seal... my 97 i had, went threw like 4 of them while i had that truck. and this 98 i got started to leak more and more...so not sure if thats your problem but its a common problem with the ones ive had
 

·
Junior Member
Joined
·
3,533 Posts
What you want to do is wash it off I like to use "GUNK" citrus cleaner, not the foam, then preasure wash it. The front cover, dowel if it falls out it will crack the gear case in the middle below the fan mount. If the seal is bad, they made a new cover that stops the cover from vibrating, it does not leak as often, hoses, head, valve cover, and tappet cover also can leak. Wash it clean, inspect it and rewash, then run it up and look.
 

·
Senior Member
Joined
·
1,465 Posts
I bet money it's the vac pump....they ALWAYS leak after time...mine was. Now the tappet cover is leaking a bit.....
 

·
Member
Joined
·
106 Posts
Discussion Starter · #6 ·
I hosed it down and inspected it, it seems to be leaking behind the water pump (i assume that's the thing the fan is bolted to) and also the the front drivers side of the oil pan, above that is wet, like behind the timing cover and in front and above of the power steering/ hydra-boost pump.

I guess if i just replace the 3 gaskets mentioned, that would be a good start, it also seems to be leaking from the oil filler tube at the bottom.

Cheers!
 

·
Senior Member
Joined
·
1,465 Posts
Well the oil cooler is there behind the WP.....it might be loose. Front DS of the pan could be the oil pressure sender as it's common for leaks but most likely its the vac pump. If you haven't tabbed the KDP DO IT. The front cover has to come off to tab it so that takes care of the front cover and the front main seal in one shot along with the only REAL downfall to the 12 valve Cummins. There is an easy way to check the vac pump. You can look up from the bottom and in front of where the PS pump mounts to the vac pump there will be an opening and you'll see a silver aluminum piece. That is the seal retainer. If there is oil dripping from it then you need to reseal the vac pump.
 

Attachments

·
Diesel Outlaw
Joined
·
268 Posts
Trust me if that Dowel pin pushed out of the housing you would be loseing alot more oil then you are. I just did my valve covers and i still have to do my front cover and i think i'll finelly have the oil leaks fixed.
 

·
Member
Joined
·
106 Posts
Discussion Starter · #9 ·
Ok I redid all the seals in the vacuum / hydra boost pump, its was kinda leaking power steering fluid before, so killed two birds with one stone if ya will. So its leaking less, but still leaks. I had the local Cummins mechanic look at it and he told me that the front timing cover seemed to be fine but rather it was leaking from the 'timing stake' which is somewhere between the vacuum pump and the injector pump. Getting to it apparently involves removing either the vacuum pump or the injector pump, they quoted me $450 to to do it, I've never heard of this before, is this a real issue or is this guy just taking me for a ride? Right now I'm leaking about 1qt per 100 miles, or 10qts a month so its costing me about $25 a month just to keep it topped off. Not to mention my driveway looks like the Exxon Valdez lol
 

·
Senior Member
Joined
·
1,465 Posts
The timing pin is there......If you had the vac pump off once you can do it again and replace that timing pin gasket/seal as well. In fact the vac pump just needs slid back....leave the PS pump attached.
 

·
off to another home
Joined
·
15,472 Posts
the timing pin? reach in there and see if you can feel if its all oily. if so, id say clean it and cover it in RTV. you will be able to pull the rtv off later if you need to use it but it will stop the leak for now.

Garrett
 

·
Junior Member
Joined
·
3,533 Posts
The timing pin is there......If you had the vac pump off once you can do it again and replace that timing pin gasket/seal as well. In fact the vac pump just needs slid back....leave the PS pump attached.
You do not want to remove the timing pin, if it moves you have a process to time it again.
 
  • Like
Reactions: PhilipR

·
Junior Member
Joined
·
3,533 Posts
if you have the pumps off and have decent access then you need a gasket, and a new "O" ring. Pin the motor so is in the right position. Be sure the pin goes in and come out easily. Then take out the torx screws, and remove the assembly, push the pin out clean and inspect the housing for the reason of the leak. Clean it up and assemble.
 
  • Like
Reactions: PhilipR

·
Member
Joined
·
106 Posts
Discussion Starter · #14 ·
To be clear, the timing pin is mounted on the rear of the timing cover, facing towards the cab above the vacume/hyda boost pump right? Removing the injector pump seems a larger task than I want to do right now, Im going to try the RTV first. Thanks.
 

·
Registered
Joined
·
2 Posts
Well the oil cooler is there behind the WP.....it might be loose. Front DS of the pan could be the oil pressure sender as it's common for leaks but most likely its the vac pump. If you haven't tabbed the KDP DO IT. The front cover has to come off to tab it so that takes care of the front cover and the front main seal in one shot along with the only REAL downfall to the 12 valve Cummins. There is an easy way to check the vac pump. You can look up from the bottom and in front of where the PS pump mounts to the vac pump there will be an opening and you'll see a silver aluminum piece. That is the seal retainer. If there is oil dripping from it then you need to reseal the vac pump.
I am sorry but you guys that keep using things like DS and KDP and WP and PS
 
1 - 16 of 16 Posts
Top