[simon tompkins]

hi guys im getting quite a bit of fuel in my catch tank is this on over run and is it something i should get checked out



simon

 

[archaeic_bloke]

...fuel in catch tank = bad.

 

[hodgie]

That dont sound good,

 

[simon tompkins]

what do you guys reckon could cause it



simon

 

[hodgie]

I think the only way fuel can get into the top of the cylinder head and then onto the catchtank is through the valveguides.

 

[simon tompkins]

actually i maybe jumping the gun slightly its oil with a slight mix of fuel or could it be vapour,



simon

 

[hodgie]

Probably just vapour then,

 

[simon tompkins]

as said in the last post im getting vapour in my catch tank with quite a bit of oil,its a greddy tank which is quite small but after a few outings it can be 3 quarters full,is there something wrong surely this is not normal, The engine is running fine (well i think it is) its a fairly new build with forged internals,curently running just over 500bhp 482ft lb




simon

 

[simon tompkins]

has anybody got any ideas


thanks simon

 

[Mikster]

Could be due to blowby, i.e. worn engine.

 

[kismetcapitan]

definitely blowby. You're smelling petrol in your oil, right? Pull out your dipstick, see if it smells the same; I'll bet it does.

Blowby gets worse when you've tuned your engine and are running rich. When you've upped the boost, even more of the fuel/air mixture is getting past the rings and into the overall oil. And as noted above, worn rings also contributes.

If the engine's still making the same power as usual, I wouldn't lose sleep over it. If you're really getting paranoid, a quick compression and leakdown test will tell all.

My oil always smells like petrol, but I run fairly rich and I run a LOT of boost, so blowby is inevitable, even with a tight, newly rebuilt engine.

 

[simon tompkins]

thanks for that info,im currently running 1.3 low boost and 1.6 high boost i had a leakdown test the other day for a different reasson and it was 5% across the board which is supposed to be very good,my engine has only done4 about 7,000 miles if that and its been completely rebiult using forged parts balanced and even a new crank,it does pull like a train with 482 ft lb of torque and just over 500bhp is it a case that the ring have'nt sealed properly
is ther anything i can do to out this right or stop it from happening,

sorry if these questions sound silly but if you dont no, you dont no


thanks simon

 

[kismetcapitan]

5% adds up. Big power requires rich mapping and some of that fuel will blow past the rings and into the crankcase and oil. Unless...your dipstick does NOT smell of petrol but your catchtank does. Then it's something else.

With fuel collecting in the oil you will have to change it more often. I do mine every 3000km.

 

[simon tompkins]

ive been told that no engine on a leak test is 100%,i will check the dipstick tonight to see if it smells of fuel,but other than that if the car is running okay should i just stop being paranoid.



thanks simon

 

[ShaggyR32GTR]

As Kismetcapitan said just do regular oil changes, my oil smells of fuel but i supose its to be expected running big power and boost. I change my oil before and after every drag/track event.