Volo Penta AD41b - Oil From the Dipstick tube

[Prose Echo]

I need some help. Volvo Penta AD41b occasionally during long runs vents oil from the top of the dip stick tube.

The engine does not have a crankcase breather filter, instead has a tube running from top of engine to the rear of the air filter housing. All is clear from blockage and the air filter is clean and clear of oil even when the oil is vented out of the top of the dip stick tube.

Oil level when cold is slightly above min but way short of the max line on the dip stick.

Any ideas of what the issue is please?

 

[Plum]

I need some help. Volvo Penta AD41b occasionally during long runs vents oil from the top of the dip stick tube.

The engine does not have a crankcase breather filter, instead has a tube running from top of engine to the rear of the air filter housing. All is clear from blockage and the air filter is clean and clear of oil even when the oil is vented out of the top of the dip stick tube.

Oil level when cold is slightly above min but way short of the max line on the dip stick.

Any ideas of what the issue is please?

On my 41p there is an o-ring at the top of the dipstick to seal the top of the tube. Is yours in place?

www.solocoastalsailing.co.uk

 

[BruceK]

Although you say there is no oil in the vent pipe is there any excessive blow by or even no blow by at all?

 

[Prose Echo]

On my 41p there is an o-ring at the top of the dipstick to seal the top of the tube. Is yours in place?

www.solocoastalsailing.co.uk

There wasn't one, purchased from Volvo Penta but it looks to be too big. I'm wonder if the tube and dipstick arent the correct.

 

[Prose Echo]

Although you say there is no oil in the vent pipe is there any excessive blow by or even no blow by at all?

Forgive me but, where would I look for this and what does it look like.?

 

[BruceK]

From the crank case breather. Over pressurization of the crank case will push oil out the dipstick but that is what the ventilation is for. Diesels are prone to higher crank pressures especially as they age but the fact that your air filter is clear and free of oil is at odds with what you are experiencing from your description above. I'd be looking for a blockage along the crank ventilation system and if there is none to worrying about rings or holed pistons.

 

[Plum]

There wasn't one, purchased from Volvo Penta but it looks to be too big. I'm wonder if the tube and dipstick arent the correct.

For mine, the O-ring VP part number part number is 960155 but I measured it as 4mm ID 9mm OD 2.5mm thickness. It is tricky getting it into its groove so may appear to be the wrong size, but it certainly stops the oil leak.

If you are not already aware, once the o-ring is sealing correctly, when you pull the dipstick to check the oil it sometimes shows no oil at all! Don't add any oil. Put the dipstick back, now you have broken the seal, and you will now get a correct reading. The o-ring was stopping the oil level in the tube and the sump from equalizing.

www.solocoastalsailing.co.uk

 

[Whopper]

I think it’s the o-ring as mentioned above. I replaced a cracked o-ring on a 41p dipstick. It was surprising how much oil can actually escape.

 

[QBhoy]

Out with suggestions above, excessive crankcase pressure can be a result of thinning oil, lack of proper compression, valve adjustment required, diesel from leaking injectors washing past and losing compression, but instead pressure building in crank case instead. Few things really. I’d start with any breathers and seeing how good the oil is.

 

[Prose Echo]

Thank you all for your input. I will be starting with cheapest fix and work my way down the list.

As the engine(s) have been neglected by the previous owner(s) I have put together a maintenance schedule so most of the above is already included on that list.

If I find the fix I will be sure to add the solution to the thread.

 

[QBhoy]

Thank you all for your input. I will be starting with cheapest fix and work my way down the list.

As the engine(s) have been neglected by the previous owner(s) I have put together a maintenance schedule so most of the above is already included on that list.

If I find the fix I will be sure to add the solution to the thread.

I suppose you could pull the injectors and do a diesel compression test on it.

 

[gordmac]

Take the filler cap off when running to check breathing.

 

[Prose Echo]

For mine, the O-ring VP part number part number is 960155 but I measured it as 4mm ID 9mm OD 2.5mm thickness. It is tricky getting it into its groove so may appear to be the wrong size, but it certainly stops the oil leak.

If you are not already aware, once the o-ring is sealing correctly, when you pull the dipstick to check the oil it sometimes shows no oil at all! Don't add any oil. Put the dipstick back, now you have broken the seal, and you will now get a correct reading. The o-ring was stopping the oil level in the tube and the sump from equalizing.

www.solocoastalsailing.co.uk

I purchased the o ring and have been on several runs now and no oil. Thank you for the tip on the oil level too.

I must mention that I have now added a 1ltr oil catcher system to each engine to help improve the quality of the air being pulled into the engine as the crankcase breather tube ran to the back of the air filter recirculating hot dirty back into the engine.

 

[Ron the boater]

I purchased the o ring and have been on several runs now and no oil. Thank you for the tip on the oil level too.

I must mention that I have now added a 1ltr oil catcher system to each engine to help improve the quality of the air being pulled into the engine as the crankcase breather tube ran to the back of the air filter recirculating hot dirty back into the engine.

I’m interested as to what catch can system you fitted as I’m having similar issues

 

[Prose Echo]

I’m interested as to what catch can system you fitted as I’m having similar issues

Ive fitted one these to each engine. The outlet is capped off and the pressure vents through the filter.

https://www.amazon.co.uk/dp/B07WGGK...abc_WNXJZBJFF940E3RK0ZGW?_encoding=UTF8&psc=1