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Speedjester · 07-12-2015, 11:02 AM

I am having a problem with a new oil leak... Yesterday I decided to degrease the oil pan..( thought slobber tube)... This morning I start her up and noticed a few steady drips coming from a few of the oil pan bolts...(I have the bolts with he noise isolators).. The bolts on my ol pan seem to have a rather thick rubber gasket sandwiched between the head of the bolt and the pan....most are ripped and half are missing...I believe that that is my issue.. Since the leaks are coming from the head of the bolts not he pan... Wondering if I can just change out the bolts individually or If I need to drop the entire pan...There are 32 bolts and rubber isolators (Cummins 3974808).. Anyone have any experience doing this? Also been looking on line and can't seem to find anyone selling them?..

Speedjester · 07-12-2015, 04:24 PM

Anyone ?? Could really use some info on this.l

palehorse89 · 07-12-2015, 04:34 PM

Hello, changing the bolts is not the answer, the gasket has failed if oil is leaking around the bolts. The seal is broken......... replace the gasket, before a failure has you on the side of the road, or worse.........engine failure due to lost oil........

Speedjester · 07-12-2015, 05:10 PM

Not sure if it makes a difference the oil is actually coming from the bolt holes....there is no leak from the gasket between the oil pan and block.. I have exactly 5 bolts leaking ... All missing the insulator(rubber washer).. When I clean them off I can actually see the oil come from the bolt hole..everything around and above the bolt holes are bone dry... Also not sure if it makes a difference I have a composite oil pan...

palehorse89 · 07-12-2015, 05:19 PM

My pan did not have the isolators that you describe, just a pan gasket, bolts with washers. Go to your local Cummins dealer and see if you can just buy 5 of them and give it a try. On the ISC if the inside of the gasket failed, oil will come out of the bolt holes. When you look at my oil pan, the OEM gasket went the whole way across the pan, with holes for the mounting bolts. I installed it with a thin film of Permatex Ultra copper.
What engine do you have?

Speedjester · 07-12-2015, 05:32 PM

Palehorse.. It looks like these rubber isolators are what actually push up on the pan to seal the gasket...the pan bolts have a sleeve that keep you from over tightening and crushing the rubber bushings.. Without the rubber bushings.. There is roughly a 1/2" gap between the pan and the bolt head without the rubber isolator (the bolt bottoms out on the sleeve before it snugs up against the pan.).. I'm hoping to get away with not having to drop the pan

Speedjester · 07-12-2015, 05:33 PM

Palehorse.. I have the ISL400

palehorse89 · 07-12-2015, 05:36 PM

The fella's at your local Cummins dealer will most likely be able to answer your questions. Sure seems funny, that there is 5 missing???? and leaking. The pan must have been off before.........and not properly installed. Good luck to ya!

Speedjester · 07-12-2015, 05:44 PM

Was hoping someone had dealt with the isolators before and could give me some info... Plan to give cummins a call tomorrow morning..

RichnSue · 03-19-2018, 01:09 PM

Hi, I'm researching why I have a small oil drip. Did you fix your leak by replacing the rubber isolator? Cost? Thanks,

Rich

what my rubber pad looks like https://photos.app.goo.gl/1dEx3rK6ZKcnMQ2J2 upper part of picture

Dav L · 03-22-2018, 06:12 AM

Drop the pan, clean the gasket surfaces, put a new gasket on (dry) with just a dab of silicone at block mating lines. If the oil pump intake is mounted to the pan, look to see if there is an "O" ring to replace. Install the clean pan with bolts loose, then tighten them up in three stages in a cross pattern. Snug them to spec torque. Fill your oil, enjoy trouble free.

Anything else is a hack.

Probably $60 in parts (less oil) and three hours of work. Make sure your RV is on jack stands before getting underneath.