Pump Seal Change

[Ocean30]

So.....I'm not telling you to do this, however, I had to have a tinkle. So I kept the pump and purchased a kit. Given that I'm not doing much more than changing the shaft seals I considered it a challenge. Took me 30 minutes to replace them. It may be turnout to be a worthless repair. One thing I can say is that the seals were tough and split. 

I will give it a try to see if it works next week. If it does it's a bonus. I have enclosed some instructions that proved invaluable. 

P.s the current pump just isn't operating as it should. 

BMC CAV 1.8 pump.pdf Shaft seal replacement 1.8 BMC CAV.pdf BMC CAV Governor Housing.pdf

[Ocean30]

 

Edited April 4, 2022 by Ocean30

[Tony Brooks]

Reported to request pinning at top of BMC forum

[Ocean30]

My plan has recently unravelled slightly. 
Having switched out the pump shown on this thread for the reconditioned one from Calcutt I was plagued with poor starting, rough idle, loss of power and stalling. Try as I might I could not get her running well. I believe the problem to the governor housing and throttle shaft. If the throttle lever was just slightly pushed up it would rev higher and down would almost cut out. Not forward and aft. possibly the two o rings in the throttle assembly leaking air? Although no leaks. 
 

so I swapped out the pump to the old one that I’d done and bled her. She started on the key and run as smooth as you like…….then I saw the oil pressure had dropped off a little having fun the boat for 5 hours.  Checked sump oil and notice a slight increase again. Most depressing. To note this had not been an issue with the refurb pump re oil increase. 
 

So I’m going to have to send the refurb back and whip off the old pump and investigate. Ordered some Delphi seals so will replace the ones I put in and check for any defects. 
could be the pump shaft retaining circlip causing too much movement? 
 

On a positive, although don’t want to be doing in that often, I can now remove the pump in 40 minutes. Fingers crossed I can repair before half term so we can have some nights on her. 
 

Bloody boats. 😉

[john.k]

I have done this seal swap many times on the hydraulic DPA on 354 Perks .....its best if you have a device to ease the new seals over the bosses on the drive shaft............even though the plastic is very tough ,its possible to nick or cut the sharp sealing edge with steel tools.....I also oil the seals and shaft before assembly....................in any case,the definitive test for seal leak is to apply air pressure to the pump while its submerged in test oil(or diesel,kero,petrol etc)

[Ocean30]

Thanks John

 

checked seals and seemed good. Unlike the circlip to the back of the pump. After many visits to mechanical parts I sourced a couple of good clips. Re-fitted and stuck pump back on. fitted new seals and smeared with oil. 
 

Now I’m tolerant, but I can only tolerate so much… Now pissing diesel out of the back of the pump. I know the culprit. A rubber o ring that slots between the body and outer shell. Thought it would be fine but no. Maybe I nipped it up? 
 

pump off. I have another one coming by Friday. I’ll fit the re furb and fingers crossed. I’ll see to the old one and service as much of it as I can. 
 

spent hours sorting this. Although pump removal time is now 30 minutes. At least I have a some records to aim for 😤😢😂

[john.k]

The O ring between body and hydraulic head is a common place for a leak,and I think its a victim of no sulfur fuel.........oddly enough this is the only place these pumps leak from o ring shrinkage,whereas the Bosch VF pumps would pour fuel from everywhere and had to be repaired immediately.......That was a big ripoff too,the oil companies  offered to fix the pumps free ,there was always a $400 extra charge "to replace worn parts not included in the O ring replacement program."

[Ocean30]

Blimey that’s a lot! The bio fuels are hard on the rubbers. I remember making some and when my pump went on my Escort it spilled diesel on the wishbones. Turned it to jelly. I used to be able to make 100 litres at a time for around 15p a litre. They were happy times. Given it up now. 

[Ocean30]

Feeling flummoxed. 
 

So new pump has been working beautifully. Did over 50 miles without issue. Went out yesterday and noted a slight drop of oil pressure to 30 psi on tick over. Checked the sump oil and guess what. It’s gone up a little. I’m a bit stumped now as to why this is happening time and time again. The fuel pump was changed for a new one. I noted it happened when I pushed the boat a bit harder. Not over working her though. Maybe I just have to periodically change the oil after 30 hours of cruising? If anyone else can enlighten me as to why this should be happening I would be most grateful! I’m going to take some oil out tonight and top it up with some fresh stuff. Then see what happens. 
 

depressing indeed 😳

[Tony Brooks]

I have lost track of what has been done and when etc, but have you tried bypassing the lift pump by using an electric one, just in case it has started leaking fuel into the sump.

[Tracy D'arth]

There are only 2 ways to get fuel in the oil, the injection pump and/or the lift pump.

 

Which is it ?

 

Experience would suggest that the lift pump is most often responsible.

[Ocean30]

I know Tony but I stuck I new one on so was ruling out it could’ve failed so soon? Replace it again? I suppose I could. Any experience of the lift pumps failing so soon? I certainly don’t want to be changing the pump for the 50th time😂. I was wondering if another interaction could cause the shaft seals to leak? 

[Tony Brooks]

56 minutes ago, Ocean30 said:

I know Tony but I stuck I new one on so was ruling out it could’ve failed so soon? Replace it again? I suppose I could. Any experience of the lift pumps failing so soon? I certainly don’t want to be changing the pump for the 50th time😂. I was wondering if another interaction could cause the shaft seals to leak? 

 

The lift pump failing so soon is not that likely but if the diaphragm was not pulled down during the assembly before the body screws were tightened then yes, the diaphragm could split quickly, the trouble is one never knows how diligent the assembling was,  especially from such as Ebay type sellers.

 

If it turns out to be the injector pump shaft seal then either the shaft was scored by the original seal or the wrong sized or material seal was fitted. It seems far too soon for it to be a biofuel reaction and I can't think of any other reactions that could cause it.

[Ocean30]

Me neither it is very strange. I shall endeavour to seek an answer. 

[Ocean30]

I have a hypothesis. Could the Pump timing cog be worn causing excessive movement in the pump shaft when under load. Having seen the assembly stripped dow this seems a possible cause. Maybe I’m clutching at straws. Thoughts? 

[Tracy D'arth]

1 hour ago, Ocean30 said:

I have a hypothesis. Could the Pump timing cog be worn causing excessive movement in the pump shaft when under load. Having seen the assembly stripped dow this seems a possible cause. Maybe I’m clutching at straws. Thoughts? 

I have never experienced that.

 

There is the torsion spring in the gear drive which is to prevent backlash in the drive.

 

Is the timing chain quiet? or does it thrash on the overrun?

[Ocean30]

No it doesn’t sound bad. I removed the lift pump a couple of days ago and replaced. Upon inspection of the old lift pump, which was new this year, I discovered one of the housing  retaining screws had nearly totally undone itself. On the priming pump lever.

 

I did do some serious priming when I refitted the new pump. Maybe worked it lose. I then checked the rest of the screws to find they were all quite slack. I wonder if this was allowing some diesel in?

 

Chap from Calcutt boats suggested that if the tank is higher than the lift pump then the fuel can slowly drain in without you knowing much about it, even if the boat isn’t running. I’ve refilled with fresh oil tonight and taken her out for 30 minutes and oil level was unchanged. Gave her a bit of a work out.  Oil pressure at 46 psi.
 

 So, I’m hoping and preying I fell foul of a poorly torqued fuel lift pump. Ive ensured the screws on the new pump are tight prior to fitting.
 

I do hope I can finally close the chapter on this bloody saga! Please say a little prayer for me……😂🤦🏻🤯 

 

Thanks for being patient. I hope what I’ve learnt can help others out. 

[Tracy D'arth]

I have recently heard of a 1.5D BMC engine that was feeding lube oil into the fuel tank. At a rate of approx. 3 pints in an hour.

The engine started and ran OK.  The only possible way this could happen was if the lift pump was taking oil from the camshaft lubrication through the diaphragm and into the fuel to be returned via the return lines, past the injector pump, then directly to the fuel tank.

Never experienced this before, but every day we learn.

[Ocean30]

Now that is different! Such old engines though! I’m going to replace the timing chain and check for wear when she comes out for an overhaul at the end of the summer. I think the exhaust gasket is also blowing as she sounds a bit raspy and oil can be seen to be leaking. Tender loving care…..Or a new engine. Not quite sure yet. Keeps me occupied although so does working full time and raising a family 😂

[john.k]

Funny you should mention pump screw loosening....back in the 70s,one model of Ford car was notorious for fires caused by all the pump screws coming loose .....slight pressure on the steel fuel lines would result in a torrent of petrol squirting out of the pump diaphragm joint......and POOF!

[Ocean30]

Glad I’m diesel 😳

[Ocean30]

So…….I know I’ve been on this for sometime but I think this could be the issue? 
when I removed the pump initially there was no torsion bar key. Thus I didn’t assume to refit one. Could this be the reason why I’m getting fuel in the sump? Exceed play in the shaft? Tony, thoughts. 

[Tracy D'arth]

I would doubt the connection between the torque bar being absent and the seals leaking.

 

It would make the timing erratic but not much else.

[Ocean30]

I was thinking that if the guide dog, part 45 was turning then the fuel could be leaking at this point any actually the seals? 

[Tony Brooks]

1 hour ago, Tracy D'arth said:

I would doubt the connection between the torque bar being absent and the seals leaking.

 

It would make the timing erratic but not much else.

 

And only by any play in the shaft splines. i think the torsion bar is more likely to ba an anti-chatter device. Calcutt are reported to have said they are not strictly necessary.

 

53 minutes ago, Ocean30 said:

I was thinking that if the guide dog, part 45 was turning then the fuel could be leaking at this point any actually the seals? 

 

But O ring 46 should stop that, I assume that was changed at the same time as the main shaft seal.