PRM 150 selector oil leak

[John Lloyd]

Does anyone know what size the O-ring is? Chandlers charge silly prices for one when they're available on ebay in packs of 10 or even 50 for a similar price if you know the right size.

[Tony Brooks]

3 minutes ago, John Lloyd said:

Does anyone know what size the O-ring is? Chandlers charge silly prices for one when they're available on ebay in packs of 10 or even 50 for a similar price if you know the right size.

 

And you know what they are made from. I doubt an ordinary rubber one would last long in that situation.

[Tracy D'arth]

9 minutes ago, John Lloyd said:

Does anyone know what size the O-ring is? Chandlers charge silly prices for one when they're available on ebay in packs of 10 or even 50 for a similar price if you know the right size.

This seal around the selector shaft is not a normal round section "O" ring but is square in section.

Using an ordinary "O" ring it will always leak.

Buying the correct seal from Newage/PRM will be better.

[bizzard]

Check out Viton and Buna seals, square section as well in all sizes, high temp and impervious to oil. I used them on model steam loco as piston rings.

[Tracy D'arth]

8 minutes ago, Tracy D'arth said:

This seal around the selector shaft is not a normal round section "O" ring but is square in section.

Using an ordinary "O" ring it will always leak.

Buying the correct seal from Newage/PRM will be better.

 The part number for the selector shaft seal ring is 04301525

[Jess--]

Much as I hate paying for original manufacturer parts I went with the original part on the selector shaft seal when ours failed.

the main reason for this was that the original had lasted at least 28 years before failing so I replaced with the oem part expecting it to last a decent amount of time.

 

couple of bits of advice...
1. don't lose the ball bearing
2. if you are struggling to get the old seal out start the engine for a couple of seconds with the box in gear and nothing fixed to the selector shaft, use a cloth over the shaft as oil will pop the seal out

[Eeyore]

21 hours ago, Jess-- said:

Much as I hate paying for original manufacturer parts I went with the original part on the selector shaft seal when ours failed.

the main reason for this was that the original had lasted at least 28 years before failing so I replaced with the oem part expecting it to last a decent amount of time.

 

couple of bits of advice...
1. don't lose the ball bearing
2. if you are struggling to get the old seal out start the engine for a couple of seconds with the box in gear and nothing fixed to the selector shaft, use a cloth over the shaft as oil will pop the seal out

Very good advice. NEVER try to remove the seal with any kind of metal tool; you will score the alloy housing, and it will leak despite fitting a new seal.

The PRM 150 seal used to be a round section O ring (probably still is), the larger boxes use a square section seal.

Edited April 27, 2022 by Eeyore

[blackrose]

I found this video if it's of any use to anyone.

 

 

Although it seems to be a common place for them to leak I've never had to change the selector shaft seal on my PRM 150. Can it be done with the gearbox in-situ?

[Tony Brooks]

40 minutes ago, blackrose said:

Can it be done with the gearbox in-situ?

 

Yes, but don't lose the detent ball & spring, don't use steel tools to hook the seal out so you don't scratch the shaft. the way to use oil pressure was give someway back up the post.

 

I do wonder if the leaks may be caused by a maladjusted gear cable overthrowing the lever so it pivots on the stop and pushes the shaft to one side. A bit like the throttle spindle leaks on DPA injector pumps. I have not closely inspected a 150 lever stop so don't know if that is possible.

Edited April 30, 2022 by Tony Brooks

[Tracy D'arth]

On 27/04/2022 at 12:13, Eeyore said:

Very good advice. NEVER try to remove the seal with any kind of metal tool; you will score the alloy housing, and it will leak despite fitting a new seal.

The PRM 150 seal used to be a round section O ring (probably still is), the larger boxes use a square section seal.

The manual shows a square section ring on the PRM150 as well

[Steve56]

Just be aware that relatively recently PRM have modified the selector valve and seal. As has been mentioned on this post the original seal was an o-ring which could be removed after taking off the selector lever. The modified version has a square section seal. But also to change this seal it is necessary to remove the oil pump, and remove the selector valve. 

[Jess--]

 

12 hours ago, Tracy D'arth said:

The manual shows a square section ring on the PRM150 as well

I was fairly sure that the seal on ours was square section but didn't comment because I changed ours over 4 years ago, don't have the boat to check any more, and can't be 100% sure of my memory.

 

When ours failed it only leaked in neutral, we found it just after being put back in the water from blacking, we started the engine and talked for about 10 mins, then pushed off from the wharf and put it in gear to find nothing happened (I felt like a total idiot floating in the middle of the canal with no drive). I refilled the gearbox with oil and found that when in gear (only tested forwards) it didn't leak, so headed back to our mooring shutting off the engine rather than dropping into neutral.

[Steve56]

1 hour ago, Jess-- said:

 

I was fairly sure that the seal on ours was square section but didn't comment because I changed ours over 4 years ago, don't have the boat to check any more, and can't be 100% sure of my memory.

 

When ours failed it only leaked in neutral, we found it just after being put back in the water from blacking, we started the engine and talked for about 10 mins, then pushed off from the wharf and put it in gear to find nothing happened (I felt like a total idiot floating in the middle of the canal with no drive). I refilled the gearbox with oil and found that when in gear (only tested forwards) it didn't leak, so headed back to our mooring shutting off the engine rather than dropping into neutral.

Not quite sure when PRM did the modification but it could be 4-5 years ago.

[blackrose]

I've just ordered one from ASAP to keep as a spare. PRM 04301526 Selector Shaft O Ring (PRM Delta & 150).

 

£8 including postage & vat. I know it's a lot for an o-ring but trying to save a few quid by getting an equivalent o-ring from ebay which may be incorrect hardly seems worth it.

[blackrose]

I've just received my selector shaft o-ring and it's NOT square section. It's definitely round. But my gearbox is from c. 2004/5 or perhaps earlier, so have I got the correct o-ring?

 

 

Edited May 6, 2022 by blackrose

[Psychalist]

Yes and you'll be glad you paid the extra as the material is noticeably denser than a general purpose one.

[blackrose]

Ok thanks. That's good to know.