Help! My engine oil reeks of fuel!😫

[Danny172]

Hi all,
As the title, I’ve noticed my engine oil is stinking of fuel. I’ve noticed this for a while and have tried to eliminate what it could be?
Thus far I’ve renewed spark plugs, breather system as far as the puck and the hose to the rocker cover.I’ve also had the injectors reconditioned and changed the c/o sensor to the cat as I thought the exhaust was smelling a bit rich.
I’ve used a smoke pro on the vacuum hoses and checked the notorious intake boot for splits, and I’ve swooped out the maf sensor.
The engine is showing no fault codes, although I only have use of a c180 reader.
I’ve just pulled the rocker cover off to try and see where my oil leak is coming from, and the stench was kind of overpowering ( wasn’t the cause of the leak in the end…coming from too lower portion of timing cover).
The car runs sweet as and pulls well I think, no smoke from exhaust, and save for a lumpy idle, runs great!
I did notice some oil in the breather hose when I pulled it off the rocker cover, but gather this is expected?
Any help would be appreciated, if I have to delve deeper I do have a mate with a super snap on reader.
Thanks in advance
Danny

 

[Danny172]

Sorry guys…forgot to add it’s a 98 1.9 m44 with 86000 miles, normally sits for a couple of weeks at a time before getting used, but gets used for a longish run.

 

[t-tony]

Oil filter housing is a very common leak on this engine. Are there any fuel leaks or is it just oil fumes?

Tony.

 

[Rudyrov]

Fuel-injected cars tend to have this when something in the fuel system is leaking such as injectors or engine-driven high-pressure pumps (this happened with Honda SUV's a few years ago, a massive recall). Since I don't think you have that sort of pump in the 1.9L engine I would guess that you have a leaking injector.

 

[Danny172]

Thanks for the replies! I did think immediately of the injectors, so removed them and had them overhauled. The oil leak is coming from the front o/s of the engine, seems to be a sandwich rubber seal between the top and bottom timing case covers

 

[Danny172]

Oil filter housing is a very common leak on this engine. Are there any fuel leaks or is it just oil fumes?

Tony.

Hi tony
It’s the engine oil, it’s smells strong of petrol. There’s no fuel leaks

 

[t-tony]

Might be worth taking the plugs out and looking at them. If 1 cylinder is getting excess fuel the plug may look different from the other 3.

Tony.

 

[Duncodin]

Fuel-injected cars tend to have this when something in the fuel system is leaking such as injectors or engine-driven high-pressure pumps (this happened with Honda SUV's a few years ago, a massive recall). Since I don't think you have that sort of pump in the 1.9L engine I would guess that you have a leaking injector.

Are you saying that while the car is parked - ie not not running - the injector drips fuel into the cylinder which seeps past the piston rings into the sump?

Is the fuel system under pressure even when the cars not running? It would 'syphon' thrugh the injector would it? The injector is higher than the fuel tank - is it?

Any fuel that made it into the sump would that eventually evaporate especially when the engine is warmed up. Or would it stay in the oil making it less viscous and possibly causing engine damage?

 

[Rudyrov]

Are you saying that while the car is parked - ie not not running - the injector drips fuel into the cylinder which seeps past the piston rings into the sump?

Is the fuel system under pressure even when the cars not running? It would 'syphon' thrugh the injector would it? The injector is higher than the fuel tank - is it?

Any fuel that made it into the sump would that eventually evaporate especially when the engine is warmed up. Or would it stay in the oil making it less viscous and possibly causing engine damage?

Q1. Yes, that's exactly what I am saying. After engine shutdown, the fuel rail will hold pressure for several hours, sometimes on new vehicles even longer than that. This means that there is pressure in the line at the injectors and all the way back to the high-pressure pump in most cars.
Q2. Fuel would leak out of the injector tip into the cylinder, go around the rings, then down to the sump.
Q3. Fuel would eventually evaporate if the engine sits for a while, this would go back into the intake as blowby in a sealed system.

Honda had this issue a while back, they have a high-pressure engine-driven pump driven by a shaft in the engine. Turns out the seals between the fuel and the lube section leaked and fuel drained into the oil.

 

[Mike Fishwick]

I have seen a few BMW motorcycles with similar injection systems showing a similar problem, caused by the diaphragm in the fuel pressure regulator becoming porous, and passing fuel into the vacuum hose, from which it finds its way into the sump. In some cases the oil level has noticably inceased.

 

[Danny172]

I have seen a few BMW motorcycles with similar injection systems showing a similar problem, caused by the diaphragm in the fuel pressure regulator becoming porous, and passing fuel into the vacuum hose, from which it finds its way into the sump. In some cases the oil level has noticably inceased.

Thanks for the reply, I did see you post this in response to another persons thread, on this advice, I replaced the fuel pressure regulator