Fuel in the oil sump

[gagvanman]

Today I noticed a smell of petrol around my 71 bay. Checked al the usual stuff, fuel pipes connections etc. all dry. I pulled the dipstick and it was covered in petrol. Drained the sump and after the oil a lot of petrol came out. I have never had this happen before.
My engine has an electric Huco fuel pump so it can't be that. I last took the bus out for a spin about a week ago and didn't notice anything unusual. The engine has twin ICT carbs, I have done the usual searches and have come to the conclusion that it could be a sticking needle valve\seat or perforated accelerator pump diaphragm (not so sure about that one).
Tomorrow I will take the carbs off the engine to investigate.
In the meantime would appreciate any other snippets of advice.

 

[sparkywig]

Either too much fuel pressure forcing fuel past the needle valves or stuck needle valve/s.

 

[ozziedog]

All the above ^^^ or possibly a damaged float. A needle valve will only work nicely if it’s been adjusted nicely, if it’s out of adjustment then it won’t do what it should. While you is fannying about in there, take the floats right out and shake them near your ear, if you can hear anything rattling about then your float may be damaged. Also hold your float up and turn it over and over and round and round to see if anything drips out, then do the opposite and submerge the float in water and see if you get any bubbles. Old style floats were brass, and new style floats are plastic but neither should leak at all. Easy way to test your needles is to blow through them and there’ll never be that much pressure on them.

Ozziedog,,,,,,,, carbs??? Who’d have em nowadays

 

[gas1man]

Some new floats are made from a porous plastic type substance. I had one that had a minute hole in it and suffered the same problem.
Good luck.

J & P

 

[67panel]

With the fuel tank as high as the carbs the fuel can syphon through a stuck needle valve when the bus is resting, ask me how I know! ITCs as well.

 

[mike202]

Do you have a fuel cut off solenoid.?
I am not sure if electric fuel pumps completely stop fuel from seeping past.
It may ease the pressure on the carb valves when the engine is switched off and left for periods.

 

[K@rlos]

Various reason why this may have happened.

Too much fuel pressure
Float heights wrong
Faulty float
Worn/faulty needle valve
Engine running rich
Fuel syphoning from tank
Fuel pump diagram damaged (only with standard fuel pump)

 

[K@rlos]

Do you have a fuel cut off solenoid.?
I am not sure if electric fuel pumps completely stop fuel from seeping past.
It may ease the pressure on the carb valves when the engine is switched off and left for periods.

In my experience it depends on the type of pump used. I’ve got a Holley ‘red’ rotary pump on my bus and I’ve never had a problem however when I’ve used facet cube pump on customers buses they have indeed let fuel through, over flowed the carb and filled a cylinder up over night. Not ideal… initially I started using a cut off solenoid but I found decent solenoids are hard to by so now I use carter rotary pumps which is a winner all round as they are quiet, don’t let fuel past and are self regulating to 3.5 psi which is perfect for IDF’s & DRLA’s so no need for a separate pressure regulator.

Never used a Huco pump so can’t really comment on weather they allow this to happen.

 

[mike202]

ICT carbs are a bit sensitive to fuel pressure if it’s more than around 3-4psi. I have a mech pump at the moment and as everything is running ok I don’t really want to change it. The push rod in it was adapted by Abel when I had the new engine. If I was going to put an electric fuel pump on it would be a Carter pump. It’s good to know they don’t allow fuel to seep through when they’re switched off.
I have a VW Aircooled works fuel cut off solenoid above the gear box and it’s been good so far. It’s a good safety feature and also reassuring that the fuel pipes in the engine aren’t under pressure from a full fuel tank when the engines off.

 

[pierrox]

I have a VW Aircooled works fuel cut off solenoid above the gear box

That's neat. Having a pair of those carburetors, that's been my fear for a while - mech pump and fuel pressure regulator. But that's a safe add-on you have here.

 

[gagvanman]

New 150 needle jets arrived today. Waiting for a break in the weather so I can remove the carbs and investigate.

 

[gagvanman]

Removed carbs and stripped down, fuel still in the bowls, needle valves not stuck but one of them did not have the retaining clip which connects to the float. Submersed floats in water - no bubbles. Replaced 175 needles with new 150's, the new ones have metal clips whereas the old ones had plastic clips. Checked out the accelerator pump diaphragms for E10 damage, both ok.
Replaced my external oil filter and filled engine with 2.5L of new oil. Ran engine with the electric fuel pump disabled to check oil pressure. Reconnected and ran engine, all seems ok. Will check oil again later to see if any fuel present.

 

[ozziedog]

Removed carbs and stripped down, fuel still in the bowls, needle valves not stuck but one of them did not have the retaining clip which connects to the float. Submersed floats in water - no bubbles. Replaced 175 needles with new 150's, the new ones have metal clips whereas the old ones had plastic clips. Checked out the accelerator pump diaphragms for E10 damage, both ok.
Replaced my external oil filter and filled engine with 2.5L of new oil. Ran engine with the electric fuel pump disabled to check oil pressure. Reconnected and ran engine, all seems ok. Will check oil again later to see if any fuel present.

Don’t forget to set your float levels and set them a bit tight. Those old needles did look to have a bit of wear on them, did you try and blow through them?

Ozziedog,,,,,,,, it’s nicer to prove the issue

 

[gagvanman]

Thanks ozziedog, I forgot to add that I did set the float height to 8mm measured with my new fangled digital calliper. Also did check to see if the needle valves had any crud in them, unfortunately not. Need to take it on a test drive now and hope it doesn't happen again. Looking into fitting a cut of valve as well.

 

[ozziedog]

I’ve seen various articles and recommendations on quite a few sites. Some aren’t distinguishing between setting the float height and float drop and there’s measurements bandied about all over the place. I eventually had mine off again and set them to 6.5 and that’s more than enough fuel as recommended by several peeps that have been setting these for years. One of them also advises to check that the float is hinging/ hanging level as some do not, so you’ll be busy accurately setting your measurements on one side but it’s meaningless if the damned thing ain’t level across. 6.5 might not be enough on some performance and drag motors, but anything under about two litres it should be fine. Next time you’re having a look, try blowing through the needle valves using some pipe and if you still have your needle and seats that you’ve replaced, try blowing through them and then you might play with recutting them in to their seat using toothpaste, a bit like lapping in cylinder head valves. If you can’t blow through em then fuel won’t dribble through em.

Ozziedog,,,,,,,,,,,and make sure your balls are springy

 

[gagvanman]

After the seasons festivities and crap weather, finally got round to checking oil level and taking the bus for a nice long drive to make sure engine got up to temp. Home again and rechecked oil. No sign of fuel, so fingers crossed that the issue has been resolved...
Thanks for all the advice.

 

[naskeet]

One can also experience petrol in the engine oil, if carburettor icing and/or inlet-manifold icing is occurring. This was something that I experienced with the Minnow Fish carburettor equipped, 1973 VW 1600 Type 2 during the winters of 1987/88 & 1990/91. At the time, I was using Mobil 1, SAE 5W/50, API SF, fully-synthetic oil, which is probably more tolerant of fuel dilution than ordinary mineral oil.