8.3 mystery leak.

[Desertshark]

So I have a 931a2. Over the last week I have noticed that my motor has sprung a bad oil leak. The leak is in the front of the motor. At first I thought it looked like but was leaking front of oil pan. So made sure all bolts on pan where torqued to 18 ft/lbs. None where under that am out. Next retourqued the drain plug to required 60 ft/lbs. Took to car wash got front axle clean of all oil to see if fixed. Got to work today all is coated again with fresh oil. Anyone have some insight to what is going on here ? Livebin southwest night not too bad. Average low is 25 degrees. Truck has almost 15k on it now.

 

[simp5782]

Can you post a picture of the front of your motor so we can see maybe an oil trail? Pics can make it difficult on our end to pinpoint an exact location cause of blowback from air flow. You can get some UV dye from your local parts store and a black light. Add it to your oil and run the truck. It will make locating the source easier.

 

[Desertshark]

I'll try the if dye tomorrow then I get back home. I know some had a recall don't know if mine was part of that.

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[Scrounger]

Odds are it is either the front seal or the gasket for the front cover.

 

[BenRoberts]

From description sounds like a front crank seal

 

[Desertshark]

Dumb as it sounds which is the lesser of the 2 evils? I know any way I cut it the radiator and everything coming out. Plan on fishing cooling system since all out and maybe even water pump even though it's still good.

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[74M35A2]

Likely either side of the timing gear case. Front is easier to reseal than the rear. Make sure your timing pin is correct on the timing gear case rear side.

 

[Desertshark]

Thanks 74. I didn't even think about that..... either way I got some good reading ahead of me.

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[Scrounger]

The front seal is in the front cover, they are both replaced at the same time. I thought the front seal had gone bad on one of mine, found out the front cover was leaking on the lower left. I pulled my radiator since it had a leaking tank and I wanted to rod it anyway. It can be done without removing the radiator. It is your call on the water pump, however I tend to go by if it’s not broke don’t fix it. And since to R&R a water pump is only an hour job why. In fact, it takes longer to drain and refill the coolant. Total man hours to pull the hood, radiator, oil cooler and what not then reinstall everything was out five hours.

 

[Desertshark]

So would it be good to just replace both in one shot? Or just parts for both and just fix the bad? Agree with you on water pump after having a few hundred miles driving to think it all over.

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[74M35A2]

Could also be the air compressor mounting gasket.

 

[Scrounger]

The front cover has a gasket and the front seal is installed in the cover. I don’t have the part numbers in front of me and knowing Cummins the numbers have probably changed. However, they are a common stocked item at Cummins. The front seal comes as a kit with a steel sleeve for the crank and a plastic sleeve for installation. The metal sleeve it tapped onto the front of the crank, it is in case there is groove worn in the crank. Then the plastic sleeve is placed over the crank to ease the seal sliding over. It acts like a funnel. I fill the back of the seal where the metal spring is with grease. It makes the seal spring stay in better. Just remember to place the tachometer drive on the gear before you install the cover, ask me how I know.

 

[snowtrac nome]

The front covers on the b and c series are notorious fro coming loose. usually the bolts at the lower corners

 

[Desertshark]

The front cover has a gasket and the front seal is installed in the cover. I don’t have the part numbers in front of me and knowing Cummins the numbers have probably changed. However, they are a common stocked item at Cummins. The front seal comes as a kit with a steel sleeve for the crank and a plastic sleeve for installation. The metal sleeve it tapped onto the front of the crank, it is in case there is groove worn in the crank. Then the plastic sleeve is placed over the crank to ease the seal sliding over. It acts like a funnel. I fill the back of the seal where the metal spring is with grease. It makes the seal spring stay in better. Just remember to place the tachometer drive on the gear before you install the cover, ask me how I know.
View attachment 715292

Because you said ask how you lnowni now much know!!

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[Desertshark]

The front covers on the b and c series are notorious fro coming loose. usually the bolts at the lower corners

Didn't think about that . 30 min don't hurt to check if still torqued properly!

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[74M35A2]

The front cover has a gasket and the front seal is installed in the cover. I don’t have the part numbers in front of me and knowing Cummins the numbers have probably changed. However, they are a common stocked item at Cummins. The front seal comes as a kit with a steel sleeve for the crank and a plastic sleeve for installation. The metal sleeve it tapped onto the front of the crank, it is in case there is groove worn in the crank. Then the plastic sleeve is placed over the crank to ease the seal sliding over. It acts like a funnel. I fill the back of the seal where the metal spring is with grease. It makes the seal spring stay in better. Just remember to place the tachometer drive on the gear before you install the cover, ask me how I know.
View attachment 715292

Me too. I'm switching engines, and if I need to install any tach drive mechanism before the cover is buttoned up, would be appreciated. Have not disassembled old one to inspect. Thanks.

 

[74M35A2]

Cummins dealer may give you an oversized front crank seal with a Speedi-Sleeve. The original size front crank seal is also available by itself without the sleeve. Much easier to not install a new wear surface sleeve if you don’t have too, as it can take an installation tool to do so.

 

[Scrounger]

While there is a “special” tool for installing the sleeve, it isn’t necessary. Make sure the crank is clean and use a flat piece steel to tap the sleeve on. I was surprised the crank didn’t have a sleeve already. A lot of diesel engines have a sleeve installed from the factory to protect the crank. They get replaced when a new seal is required. Yes, it is one more step to install a sleeve, however I think it took about two minutes to install.

 

[74M35A2]

Find the leak first so you don’t waste your time.

 

[Scrounger]

As already posted find the leak first. It doesn’t take much oil to make a mess, especially when it is on the front of the engine with the fan blowing.
The best way to find a leak is to look at a clean engine. I use a suction gun drawing from a five-gallon container of mineral spirits. Just spray the cold engine front to back, top to bottom and it will clean the oil off. Just make sure to have something on the ground/ floor, cardboard works, to catch the run off. Then after it’s dry run the engine and see where it’s leaking.