Just wish I hadn’t touched the bow thruster anode!

[shortjohnsilver]

Inspected the bow thruster today - VP QL800, probably twenty years old and still operating fine and noticed some movement of the right plastic prop on its shaft. Got that off and I’ll need to replace it. Not a major problem.
Checked the anode and that needed changing., it has a securing bolt that appears to bolt into the gear housing oil plug, through the anode. Straightforward. However, the bolt turned very easily and the anode fell away from the housing and I extracted it. It was shot.
Then I noticed oil dripping from where I had just extracted the anode! Gear box oil. The oil plug in which the bolt to secure the anode bolts into has fallen apart corroded whatever and now the bow thruster gear box is happily draining down and into a container I’ve placed in the tunnel.
So, I thought okay purchase a new oil plug gasket and anode kit and replace. Obviously I need to get out the remnants of the old oil plug before inserting the new one.
But the oil plug VP Part number 41100276 and gasket 41100275 are no longer manufactured. In fact the QL 800 BP is obsolete,

Just wished I’d left well alone and not touched that bloody anode!

So anyone know of anywhere I might be able to get hold of parts for this bow thruster, particularly the part numbers above?

Or anyone who’s in the process of ditching changing their old QL BP bow thruster and wouldn’t mind me scavenging the parts needed

As mentioned the bow thruster works like a dream and for the sake of a tiny gasket and this unusual oil plug thats tapped for the anode bolt, I can see problems!

Never ending, this boat lark. Touch something and other things break!

 

[Daydream believer]

Photo of the old part that is left? If we can see the thread etc it might be a simple process to just turn up a new one.
A chap on the boat next to mine in the marina lost a filler plug & had to pay £14-00 for a new one. So simple I would have made him one for nothing if he had told me .

 

[ChromeDome]

Isn't the first number the anode?
00732 - Tecnoseal Zinc Volvo Penta QL 41100276 Bow Thruster Anode

I believe the second number is replaced by 41100834 whic is plenty available

 

[penfold]

Even if the part identified by CD isn't right it sounds like a very easy part to fabricate, a setscrew with a tapped blind hole in the head for your anode.

 

[shortjohnsilver]

Yep, you’re right, that is the anode and I have a spare one aboard. The second is the gasket and the oil plug itself should be 41100274.

The remainder of the oil plug anode tapped thread is in the gear housing. The more I think about it I wonder if the thread of the oil plug is opposite to that of the anode bolt.

 

[shortjohnsilver]

Pendold, that sounds good. ? Just got to get the remaining section of the oil plug out!

 

[penfold]

How much clearance do you have between the gearbox and the tunnel?

 

[dankilb]

Welcome to (vintage-ish) marine engineering! Even if parts are available, it often makes most economic or practical sense to source and/or fabricate your own alternatives.

You’re in luck here that alternatives will be possible. I’ve only got a pillar drill, but could probably knock up the plug. A pistol drill would probably even work! But if a lathe-equipped mate/forumite can help, that would be optimal.

 

[Daydream believer]

It would be helpful if the OP said where he is based if wanting a part made

 

[shortjohnsilver]

Gents this is all good and has given me a couple of options. I’m currently in the yard at Chatham and it now looks as if I’ll be staying ashore for another couple of months. Standing rigging. Osmosis issue on the skeg etc and that’s before I get to anti fouling, polishing and sorting the nav lights.
When I’m next at the boat, I’ll drain off the remaining gearbox oil and see if the remnants of the oil plug screw are out, or whether I have to get them out.
There’s not a lot of clearance in the tunnel - the minimum required to extract the shaft I assume and if necessary, I’m going to have to dismantle the drive motor to allow release of the drive shaft down and pull the whole gear box and propellor shaft out. Preferably I don’t want to go that route, seeing all is nice and waterproof and the bow thruster working.
I’ll see how I get on and update.
You’re right in that I’m going to have to fabricate something myself, as per Penfold’s image, as there’s no trace out there of a like for like replacement. Certainly not VP. When I say myself I really mean somebody who understands such things Marine engineering like.
I’ll get there.

 

[penfold]

CD's article does appear to be just that.

 

[DinghyMan]

VOLVO PENTA PLUG KIT #41100834 | eBay
&
AA3 Genuine Volvo Penta Marine 41100834 Oil Plug Kit OEM New Factory Boat Parts | eBay

 

[shortjohnsilver]

Thanks Dinghyman & Penfold.

Dinghyman, I note your website detail and I wonder, whether you could maybe fabricate one of these oil plug screw/bolts?

I have the anode bolt and a slither of the oil plug, embedded around the anode bolt end. I’m hopeful of somehow removing the remainder of the oil plug from the gearbox casing and should then be able to identify diameter and thread.

Where are you based?

 

[DinghyMan]

We are based in sunny Brighouse, West Yorkshire

If you can remove the remains from the gearbox casing and send me them I can make you a new plug - or if anyone can get the dimensions, I've done a good bit of googling but havent managed to find the actual size anywhere

 

[Raindance]

Hello - reigniting an old thread as I have a the same problem with my QL bow thruster. The gasket/anode screw snapped when attached a new anode. @shortjohnsilver how did you get on eventually? Did it involve removing the whole unit or you could remove the broken piece in the tunnel? I hope the latter but assume the former!

 

[Plum]

Hello - reigniting an old thread as I have a the same problem with my QL bow thruster. The gasket/anode screw snapped when attached a new anode. @shortjohnsilver how did you get on eventually? Did it involve removing the whole unit or you could remove the broken piece in the tunnel? I hope the latter but assume the former!

Can't answer you question but this link should take you to the QL parts list and if you scroll down to the BP800 it shows the part numbers of all the parts:-
QL_PARTS_LIST.pdf

 

[shortjohnsilver]

Yes, eventually, but sourcing a replacement oil plug bolt in this country proved to be impossible and importing from the USA - the only source I could find via internet would have been excessively expensive and would have taken weeks to arrive and too late around my relaunch date and storage costs.
As you know the unit has been obsolete for ten or more years.
I got hold of a brass bolt, shortened it, grounde the bolt head accordingly so that it would accommodate the anode and drilled a hole in the head and machined it so it would accept the anode bolt itself. Bit of a palava but it all worked and the bow thruster lived to fight another day.
The sheared off section of the bolt/plug remained imbedded within the gear housing and impossible to get to withi the thruster in situ in the tunnel. I removed the prop on the starboard side and was able to remove the gear housing flange plate from the port side. Allan key bolts secure the flange to gear housing but these were tight and of course you’re working in a confined aperature. Then from the starboard side got a very long metal rod and carefully tapped the flange off of the gear housing. Took a while.
Then you have access to the gear box and the anode oil plug part bolt end is clearly seen protruding into the gear box. Amazingly a pair of nose pliers were sufficient to get hold of the part bolt end and I was able to turn it and screw it fully through the casing and remove the sheared end of the bolt.
Replaced the flange plate and I was then able to screw in my adapted brass bolt fashioned accordingly, fit the anode and bolt that securely into the head of the oil plug. Refilled the gear box of the thruster warmed gear box oil - this took a while to work down as it this was February and still bloomin cold. Replaced the prop and hoped for the best.
Relaunched and all is good without any problems and the thruster happy and working.

 

[Raindance]

Hats off to you for the ingenuity…must add nose pliers to my tool bag! The access point is a real challenge, especially with the part partially corroded. I did weigh up removing the flange but wasn’t sure it would improve the angle I had.
I went a different route in the end and removed the gearbox altogether via the bolts on the inside housing. Was a little easier than expected…surprisingly…and has made it possible to remove the broken oil plug/anode bolt thread. I found someone locally to fabricate a new piece with the gearbox and anode bolt in hand to get the right fit (i hope). The downside was some minor damage to the fibreglass tunnel detaching the gearbox, which would suggest a more patient removal like yours makes better sense if possible. Nothing major and epoxied earlier but something i would have liked to avoid. The plan is to put back together over the weekend or next week, so fingers crossed. Thanks for the detailed summary…great insight.

 

[rotrax]

Our 'Sidethruster' anodes are held on by the prop retaining bolts, M6 cap screws. Once these were off it proved almost impossible to get the anodes off-they were stuck fast.

A tip from these pages fixed it-I used a 'multy tool' cutter, started cutting through the anode but the vibration loosened them quite quickly.

Before fitting the new ones I ran an M8 thread though the 7mm central fixing hole.

Now, after taking the M6 cap screws out, screwing in an M8 bolt will push them off.

A method often used in motorcycle magneto/dynamo systems for extracting parts.