Sabre 120 Sump oil level increasing

[Sinbad1951]

My Ford Sabre 120 is a 2715E engine. It has run faultlessly for 20 years. After having no use for 12 months it is now increasing the sump oil level when running. There is no emulsification in the sump oil nor in the valve rocker cover so it can only be fuel oil mixing with the sump oil.
I have bypassed the fuel lift pump on the possibility that the fuel may be getting into the sump this way. It has made no difference and the oil level still increases. I have removed the rocker cover and tightened the connections on the injector return leak-off rail. I could see no fuel leaks on this rail or its connections.
As this is quite a common engine has anyone experienced similar with the 2715 Ford. What are the likely causes and locations of this fuel leak.
(I have of course changed the oil several times to avoid the engine running on fuel diluted engine oil)
I’m sure that there will be someone that has experienced the same fault on this engine so would appreciate some advice.
Thanks

 

[jim.howes]

Hi cant remember what the engine looks like, does it have the (almost) vertical injection pump at the free end?

 

[Divemaster1]

My Ford Sabre 120 is a 2715E engine.....
I have bypassed the fuel lift pump on the possibility that the fuel may be getting into the sump this way. It has made no difference and the oil level still increases. I have removed the rocker cover and tightened the connections on the injector return leak-off rail. I could see no fuel leaks on this rail or its connections......

Seem to recall that the fuel returns are a bit prone to leaks ... if over tightened the olives/connections may be a bit deformed... may not be prominent at low loads...

 

[Sinbad1951]

Jim the engine is a straight 6 with the injection pump (Simms) on the forward right hand side of the engine The Simms unit is mounted vertically.

 

[burgundyben]

I had a 2715E but never had this problem.

Can you take the boat for a run and lift the cover off to see whats happening?

 

[oldgit]

Dad had a similar problem...oil being diluted by diesel, turned out to be faulty fuel injector.

 

[jim.howes]

I had a faulty seal on the drive shaft of the injection pump once. I'm afraid i cant think of any way you could check this out without taking the pump to a diesel specialist. Jim

 

[Bilgediver]

I had a faulty seal on the drive shaft of the injection pump once. I'm afraid i cant think of any way you could check this out without taking the pump to a diesel specialist.

This is certainly a possibility as the pump appears to be flanged onto the engine.

 

[gordmac]

You have checked it isn't the lift pump. Some of the Simms pumps are lubricated by the engine I think, mine weren't. Do you have to top them up? If so probably not engine lubricated. The injectors are in the valve cover so any leakage from say the return lines will dilute the oil, not easy to find. Perhaps an injector dribbling into the combustion chamber?

 

[oldgit]

Perhaps an injector dribbling into the combustion chamber?

+1
Father had a complete engine rebuild carried out by a very respected outfit , one of the new/ refurbed injectors was eventually discovered to be weeping diesel into a cylinder and hence the sump.
It was diluting the lubricating oil with a resulting drop in oil pressure.
The rebuilt engine was actually removed and rebuild again before the problem was finally diagnosed.