Cummins 855 fuel leak

[charles walton]

My 230 Cummins has a fuel leak that appears to be coming from the crossover tube between the front and the middle head. Who can tell me what I need to do to fix it? Thanks in advance.

 

[Truck Shop]

First blow out or pressure wash it between the heads, If it has jakes remove them. Most of the time it will require one of the rocker boxes be removed, But if one crossover is leaking you may as
well do the other while you have the center rocker box out of the way. Then re-seal and run the over heads while your there. Should be a small cam but best check before you make a mistake
like someone else did.

 

[charles walton]

First blow out or pressure wash it between the heads, If it has jakes remove them. Most of the time it will require one of the rocker boxes be removed, But if one crossover is leaking you may as
well do the other while you have the center rocker box out of the way. Then re-seal and run the over heads while your there. Should be a small cam but best check before you make a mistake
like someone else did.

Thanks, I have been into one before but it was 10 years ago, I changed the injector o rings and I got it back together and it ran....b bu it took me a while.Maybe I can do this job a little quicker!

 

[kshansen]

Yes defiantly want it nice and clean down there before you loosen the screws that hold the jumpers in place. Need a set of eight of the right size orings.

I'm trying to recall but wasn't there a change to those jumpers. Seems the plate the screws go through were solid and then they changed to ones with the bottom plate split. Think it had something to do with a problem getting them to seal if two adjacent heads were a slight bit different in height due to on being milled during a rebuild.

Truck Shop, am I remembering right? Think it has been something like 20 years since I did more than change oil on an 855!

 

[Truck Shop]

Your right.

 

[Tenwheeler]

Had that problem with my 250 last year. The rear one was no problem other than trying to get the screws loose with an impact driver. The front one had a lifting bracket in the way. I cheated and took a bolt out of each rocker housing. Then R&R crossover o-rings.
Now a truck with with a L10 pump has a leaking throttle shaft.
Had a lot of o-ring problems when low sulphur fuel came out. Is this a repeat with Ultra Low Sulphur fuel?

 

[charles walton]

Had that problem with my 250 last year. The rear one was no problem other than trying to get the screws loose with an impact driver. The front one had a lifting bracket in the way. I cheated and took a bolt out of each rocker housing. Then R&R crossover o-rings.
Now a truck with with a L10 pump has a leaking throttle shaft.
Had a lot of o-ring problems when low sulphur fuel came out. Is this a repeat with Ultra Low Sulphur fuel?

I like to add a little hydraulic oil to the low sulphur fuel.

 

[Truck Shop]

Nige, didn't we have a short discussion about low sulfur diesel?

 

[Tenwheeler]

I inframed that engine in the early 90's with an aftermarket kit. Poor quality o-rings no doubt?

 

[charles walton]

I inframed that engine in the early 90's with an aftermarket kit. Poor quality o-rings no doubt?

Would you,or anyone else that happens to read this, happen to have a part number or size number for the o-rings ?

 

[Truck Shop]

I believe the Cummins part number is 152946 for o-rings. If my notes are correct.

 

[Nige]

Nige, didn't we have a short discussion about low sulfur diesel?

I wouldn't call it short........
You are referring, I assume, to fuel lubricity numbers..?

 

[Truck Shop]

I wouldn't call it short........
You are referring, I assume, to fuel lubricity numbers..?

That be the discussion.

 

[charles walton]

That be the discussion.

I am interested in the discussion you two had on that.

 

[Nige]

Fill your boots.........

https://www.heavyequipmentforums.com/threads/diesel-fuel-adding-lubricant.80494/#post-854491

FYI we burn between 15-20,000 gallons a day of ULSD.

 

[charles walton]

Thanks, I read it and it opens my eyes a bit! I WAS one of the "add some oil" guys but I am glad to hear that it is not helping as far as wear is concerned.

 

[Nige]

When I posted the link I was hoping that you weren't one of the "I've got my opinion, don't confuse me with the facts" people like most of those who apparently frequent the Diesel trucks forum........

 

[Truck Shop]

Arrr and who might that be?

 

[charles walton]

I believe the Cummins part number is 152946 for o-rings. If my notes are correct.

I went by the Cummins dealer near me a while back and picked up a couple of o rings that were supposed to be this number and they look to be way too big. Do you know what the dimentions and what material is best for this that I can pick up maybe at Napa?

 

[Tenwheeler]

Just take an old one with you and match it up. They are nothing special and I plucked mine out of a standard $25 o-ring kit in a box.
You know the poor quality o rings was a joke as they were over 25 years old. Some of the throttle shaft seals were different. Reducing the amount of sulphur after long time use seems to shrink the o-rings.