Magic Volvo 120s saildrive oil drain o ring?

[MagicalArmchair]

The boat is out of the water and we’ll do our annual switch of saildrive oil this weekend.

The drain plug rubber o ring needs to be replaced each and every change. The part number for this guy is 3855081.

I have an o ring set of various sizes and thicknesses. Does anyone use their own o rings or is this a magic, special o ring made by Volvo out of pixie wings or something? I seem to remember it was slightly thicker than standard o rings?

 

[Daydream believer]

I had water in the oil which I found one cruise when in Le Havre. The useless volvo engineer in Cherbourg told me it was shaft oil seals. But a phone call to Volspec engineer in Tolesbury said it was the washer on the saildrive drain. They were right. The volvo dealer in Cherbourg could not source a seal, so I took a thick neoprene washer from the top end of the pump handle spindle of my Jabsco Heads & used that. It lasted several years & several oil changes. The suitable seal is just a typical rubber ring one will find in your box of rings
The Volvo one is a skiny little thing & I now have half a dozen.

 

[lustyd]

The useless volvo engineer in Cherbourg told me it was shaft oil seals. But a phone call to Volspec engineer in Tolesbury said it was the washer on the saildrive drain. They were right.

The trouble is, you can’t be sure until you launch and test which is a pretty expensive gamble unless there’s obvious damage.
Arguably though the washer ought to be cheap enough to replace every time you change the oil.

 

[Daydream believer]

The trouble is, you can’t be sure until you launch and test which is a pretty expensive gamble unless there’s obvious damage.
Arguably though the washer ought to be cheap enough to replace every time you change the oil.

Volspec advised me that I should change it every time

 

[MagicalArmchair]

I would always replace it every time, the question was more is the part by Volvo that is this rubber o ring any different to one from my o ring set? I will get my digital verniers out once the washer is out, but wanted to know if anyone else used a different washer to the Volvo part number of 3855081 - the postage itself will cost me lots more, and it might not arrived on time. Part cost = £2, postage = £20 for next day!

 

[scottie]

I would always replace it every time, the question was more is the part by Volvo that is this rubber o ring any different to one from my o ring set? I will get my digital verniers out once the washer is out, but wanted to know if anyone else used a different washer to the Volvo part number of 3855081 - the postage itself will cost me lots more, and it might not arrived on time. Part cost = £2, postage = £20 for next day!

Buy extra and always change

 

[johnalison]

The saildrive oil plays havoc with the 'rubber'. It is bad enough with Volvo rings, so I wouldn't want to chance it with a substitute. Some years ago I had to replace the top filler O ring and didn't have a replacement on board. The old ring had expanded and wouldn't fit back. I cut a section out and wrapped the lot with self-amalgamating tape so that I could motor to Lauterbach to buy a new one. This was quite entertaining because although they were Volvo agents and had a large charter business in the marina it took the engineer three quarters of an hour in the loft of a shed to find a cardboard box with the rings in.

 

[vyv_cox]

The O-ring material needs to be one that resists both oil and water. Some saildrive oils can be quite aggressive, in which case Viton would be best although nitrile should be OK. Neoprene is less resistant to oil than nitrile although it is sometimes used for oil seals. If your O-ring kit is for water applications such as water pumps it may well be that they are EPDM, which is very poor in any kind of oil.

 

[Ammonite]

With the exception of the 120SE I think all of the 120S's use regular 15w40 mineral oil so nitrile (nbr) should be fine for these. I suspect most of the problems stem from not using the right size o ring and/or not following the lubrication and tightening instructions in the workshop manual, which will cause the o ring to distort. On the 120SD, for example, the correct o ring appears to be the wrong size as its a loose fit on the plug but there's a slight recess on the bottom of the leg that it fits into.

 

[dod]

Uses engine oil. Have usd alternative rubber ring washers of size to fit. If sealed then no oil will leak out so try before fully filling. never had a problem. I don't change it every oil change. If you still get water in oil after that it will be the shaft seals. Fairly easy DIY job. Have a go.

 

[Daydream believer]

Uses engine oil. Have usd alternative rubber ring washers of size to fit. If sealed then no oil will leak out so try before fully filling. never had a problem. I don't change it every oil change. If you still get water in oil after that it will be the shaft seals. Fairly easy DIY job. Have a go.

Trouble is that you do not know until the boat is back in the water & one needs another lift out to sort. Shaft seal change is not that easy & does need a certain amount of care. It is not a job for a spanner monkey. For instance. Do you adjust the shims for wear on the gears at the same time, or ignore that issue?

 

[MagicalArmchair]

Thank you all, as I can’t confirm the rubber in my o ring set, I’ve ordered a pile of the official VP o rings so next time I’ll have them in stock.

It would probably be okay, however for sake of paying a little postage it’s not a “probably” worth entertaining.

Thanks again

 

[Momac]

I have bought the Volvo Penta O rings and did so last time I serviced the outdrives on my motorboat a year ago . I see they were 50p +VAT each but as part of a bigger order the cost was insignificant..

 

[Ammonite]

Trouble is that you do not know until the boat is back in the water & one needs another lift out to sort. Shaft seal change is not that easy & does need a certain amount of care. It is not a job for a spanner monkey. For instance. Do you adjust the shims for wear on the gears at the same time, or ignore that issue?

According to the workshop manual there's usually no need to change the shimming unless you are changing the bearings (or the housing). You just refit the existing which is what a typical marine engineer will do.

Having said that you do need to be mechanically minded enough to know if the bearings need changing. You're more likely to have to fit a couple of speedi sleeve to address the wear on the shaft.

As an aside the standard pressure test is via the drain plug but I can't (currently) think of any reason why it couldn't be done via the dipstick with an appropriate adapter. This would potentially be a lot more useful.

 

[Bilgediver]

I would always replace it every time, the question was more is the part by Volvo that is this rubber o ring any different to one from my o ring set? I will get my digital verniers out once the washer is out, but wanted to know if anyone else used a different washer to the Volvo part number of 3855081 - the postage itself will cost me lots more, and it might not arrived on time. Part cost = £2, postage = £20 for next day!

There is not a fixed standard sized 0 ring for each size. They come in a variety of both cord diameter and material depending on the application .

One source is Amazon and there I have found o rings suitable for all applications including drive belts on old 8mm. Projectors. Measure the ring you have removed and use those measurements to identify the replacement,

 

[dod]

Trouble is that you do not know until the boat is back in the water & one needs another lift out to sort. Shaft seal change is not that easy & does need a certain amount of care. It is not a job for a spanner monkey. For instance. Do you adjust the shims for wear on the gears at the same time, or ignore that issue?

Ha!Ha! Very technical advice. If washer seals, no oil leak before launch, all is well. Obvious you have not attempted changing the shaft seals or you would know the shims don't need changing. Why make it sound more difficult than it really is. And by the way, I object to being referred to as 'a spanner monkey'.

 

[Daydream believer]

Ha!Ha! Very technical advice. If washer seals, no oil leak before launch, all is well. Obvious you have not attempted changing the shaft seals or you would know the shims don't need changing. Why make it sound more difficult than it really is. And by the way, I object to being referred to as 'a spanner monkey'.

I did not call you a spanner monkey. i said it was not a job for one.
i have changed the seals 3 times now .
I would suggest that no leak prior to launch does NOT necessarily mean that the saildrive will be watertight.

 

[penberth3]

I did not call you a spanner monkey. i said it was not a job for one.
i have changed the seals 3 times now .
I would suggest that no leak prior to launch does NOT necessarily mean that the saildrive will be watertight.

Absolutely. Heat, pressure from either side, movement, vibration. The static state tells you nothing.

 

[Daydream believer]

Absolutely. Heat, pressure from either side, movement, vibration. The static state tells you nothing.

After a long run removing the oil filler cap allows a sudden inrush of air into the saildrive. That suggests negative pressure. This can only lead to water being drawn in to the chamber.

 

[Ammonite]

After a long run removing the oil filler cap allows a sudden inrush of air into the saildrive. That suggests negative pressure. This can only lead to water being drawn in to the chamber.

I've heard this said a number of times on here but cannot see how its possible, assuming you are referring to a VP 120/130s or similar.

The 120s, for example, is a sealed system, or it should be if the seals are working. When the oil and air heats up via the heat transfer from the engine and friction from the gears it expands causing the pressure to build which is then released when you unscrew the dipstick if the saildrive is still warm. However, when you replace the dipstick a vacuum will be created as the oil cools and the air and oil contract.

Exactly the same thing happens when you fill the saildrive with oil on a really cold day while on the hard and then unscrew the dipstick on a much warmer day...the pressure is released.

To create a vacuum the saildrive would need to be running cooler than the surrounding water or forcing air/oil out past the seals, which given the drive is designed to withstand a pressure of 11 psi shouldn't happen unless you've over filled it with oil.

It would also be impossible to create a vacuum of more than a few psi as there is a single seal on the input shaft, which is intended to keep oil in, which will fail, even if the seal is brand new. The correctly oriented lower oil seal would also have to fail before the incorrectly (for a vacuum) input shaft seal. This is why Volvo only specify a pressure test and not a vacuum test.

As an aside, I was also confused by your reference to spanner monkey which I've always taken to be slang for a mechanic, rather than a spanner, as in a spanner in the works, which is a derogatory term. I'm not saying you are wrong as these things change over time, but I suspect most on here would take it to mean mechanic.