When Ignorance ISN'T Bliss

KeelsonGraham · September 16, 2023, 12:57:27 PM

Because I have ongoing engine overheating problems, any post on here about the cooling system attracts my attention. So, when Ron recently posted a thread about rebuilding the Sherwood pump I asked him what prompted him to do it. 'Water dripping from the pump' was his reply. And with these few words, down the rabbit hole I went.

No sign of water weeping from my pump so initially I was happy - except I couldn't see any weep holes. In fact, before Ron's post I wasn't even aware that there was such a thing as weep holes and that you should check for water drips. A while later after reading loads of stuff I realised that my pump sure does have weep holes and, on closer inspection, there they were - completely gunked up with rusty crud so you couldn't see them.

So, now I know that water weeps are a BAD thing I thought I better take off the impeller housing check that all looked OK. It did. As expected I couldn't turn the pump shaft because it is, of course, keyed to the camshaft. But I did notice that it could turn through about 15 degrees. This niggled me a bit. I was about to close up everything when I thought again. Surely as much as 15 degrees of play shouldn't be expected with this design. So off came the pump (which as far as I know has never seized up - even momentarily) and this is what I found.

I reckon that it hasn't got too long before the entire end of the camshaft shears off. What puzzles me is how this can happen with a pump that hasn't seized. Resonance of some kind within the pump due to excessive wear of th ceramic plates? I'm just guessing but it could be anything considering that its OEM (17 years old).

Also, from the damage, it looks as if the pump drive has never fully engaged in the slot. I can't understand how this could be.

Now I'm busy researching camshaft costs and replacement. Folks on the C36 forum seem to think it can be done without taking the engine out. Hmm.

KWKloeber · September 16, 2023, 07:22:37 PM

@Keel

If you put your engine model in your forum signature it will help us to help you.

What appears to have happened is the pump was installed with the shaft tang misaligned (not seated in the female fork) and when tightening it down, it damaged the fork. What does the end of the pump shaft look like? I guess that it's harder than the fork on the camshaft.

It seems to me that the tang on the shaft **should** sit deeper in the fork, past the divots in it, that the tang will fully engage. With a digital caliper, measure the distance from the pump land (with no gasket) down into the gear cover to the end of and the inside of the fork. And measure from the face of the pump to the end of the tang on the pump shaft.

The end of the male tang should protrude 0.25" beyond the end of the shaft and should protrude 0.562" beyond the mounting face of the pump. Do the math to see (without a gasket) how far the tang seats down into the fork.
Too heavy a gasket (or using two) will screw up how the pump shaft mates into the female fork on the camshaft.

If it's an "ok" fit into the fork w/o a gasket you might try using RTV to install the pump instead of the Westerbeke gasket.

I know of one "B" engine that the camshaft R&R'd with the engine in place -- the tricky thing but doable is to hold the valve lifters in place when the camshaft is pulled out.

KeelsonGraham · September 16, 2023, 11:50:09 PM

Hi KW,

Yes, I agree the tang should have engaged more deeply into the slot. It's a puzzle why it doesn't because the gasket appears to be the stock item. Longitudinal play in the pump shaft or camshaft must have something to do with it. Though what might have caused that is a mystery.

The end of the pump shaft has some very slight score marks and damage, on its side walls, consistent with repeated forceful engagements with the camshaft. No damage to the top of the pump shaft key, so the damage to the camshaft wasn't caused by forcing the pump into the slot when misaligned.

I'm going to replace the camshaft hopefully in situ. There's a great post on the C36 forum detailing how it's done. It also details the part numbers for the original Kubota camshaft which, surprise surprise, is a third of the cost of the so-called Universal/Westerbeke one.

https://www.catalina36.org/forum/technical-discussion/dreaded-cam-shaft-failure

Obviously I need a new pump so my choices are an Oberdorfer at half the cost of a Westerbeke one or a JMP at a third of the cost of the Westerbeke one.

I'm starting to get mightily pissed off at the rampant price gouging done by Westerbeke. A thoroughly unscrupulous company.

The take-home point from this sad saga is that a Sherwood pump doesn't have to seize before it causes irreparable damage to the camshaft. Here's my suggestion for critical maintenance.

Whenever you remove the impeller housing, check for play in the pump shaft. If you can rotate it even slightly, then pull the pump off and investigate.

Jim Hardesty · September 17, 2023, 06:03:46 AM

QuoteWhat appears to have happened is the pump was installed with the shaft tang misaligned (not seated in the female fork) and when tightening it down, it damaged the fork. What does the end of the pump shaft look like? I guess that it's harder than the fork on the camshaft.

I think Ken's thoughts are correct. Hard to imagine someone doing that with the small mounting bolts. But Keel comment is

QuoteThe end of the pump shaft has some very slight score marks and damage, on its side walls, consistent with repeated forceful engagements with the camshaft. No damage to the top of the pump shaft key, so the damage to the camshaft wasn't caused by forcing the pump into the slot when misaligned.

So I think someone assembled it misaligned then replaced the pump shaft or the entire pump.

Either way it's good to see that the camshaft tangs didn't crack off. The engine mod to add the bushing over the tangs worked.
Jim

KeelsonGraham · September 17, 2023, 10:11:17 AM

Sorry guys, but I have to disagree with you both there. There is no way that forcing a misaligned tang down onto the slot could have caused this. The end of the tang is still pristine with the original machining marks.

The indentations must have been caused by the cutting action of the edges of the tang (like the action of a router bit).

The reason why is because the tang hasn't seated down fully into the slot. If it had, then the torque forces would have been taken up by the full two faces of the tang and thus would have been spread over a much greater surface area.

What I need to explore now is what caused this less than full engagement.

I've bought a new JMP pump ($360) and some engineer's marking blue to find out what's going on. If I can achieve a full engagement, then I might risk running it without replacing the cam shaft.

KWKloeber · September 17, 2023, 11:03:42 AM

I agree now that we see the pump shaft.

It may be an illusion due to chamfers on the ring and fork, but it appears that the reinforcing ring sits proud of the camshaft fork. Maybe slightly less than the depth of the divots?
If so then the shaft is bottoming out on the ring before the tang reaches its full depth in the fork.

I have no clue how much end free play there is on the Sw pump shaft - Is there enough that the pump will bolt up if the shaft end is hitting the ring?

The Tang won't seat into the full depth of the fork - it's a smidge shorter so that there's some allowance between them — so a shaft not completely seating gets critical on the tang. IIWMB I'd take those measurements to verify. Dye will tell you what you already know. With the exact distances you'll know what the options are - one might be to take a little surface off the pump land and install permanent studs (I have stainless ones I can send, see photo) instead of using bolts.

KeelsonGraham · September 17, 2023, 12:55:59 PM

Hi Ken,

Yes, I've also been looking at that reinforcing ring quite closely. It does appear to be sitting proud of the camshaft slot.

One of the first things I'll check when I get back to the boat next weekend.

I'll also take those measurements!

KWKloeber · September 18, 2023, 12:02:58 AM

It's telling that the fork on Silhouette (pic) snapped w/ the reinforcing ring installed. Westerbeke engineering.

That says to me that if the Sherwood pump corrodes (greater torque on the camshaft) the fork may survive but totally seize the shaft and Bingo, you need a new camshaft (or a 12v livewell pump on the thru hull as a friend used for many years after his camshaft snapped.)

Does your pump shaft spin freely or is there corrosion that may have torqued the fork, so to speak.

Ron Hill · September 18, 2023, 03:03:55 PM

Keel : The corrosion that filled the weep holes has slowly cause the effort to allow the shaft to turn to GREATLY increased. So your water side leaking continues inside and no water drips are coming out of weep holes - like should happen. Don't understand why the shaft tang does not seat all the way into the fork!!

A few thoughts

KeelsonGraham · September 19, 2023, 09:00:02 AM

Hi Guys,

The pump doesn't spin silky smooth but it does spin relatively freely. Maybe it went through an intermediate phase of being very stiff until it wore itself down to nothing.

Either way it's toast. My new JMP pump arrives on Saturday. Given its very low price, I'm very interested to see its build quality and how it performs.

Still debating whether to risk running it with the damaged camshaft end provided that I can get the new pump to seat properly. Maybe with epoxy to fill the holes. Any thoughts?

Got a quote for a new camshaft from the Kubota main dealers - $536. This is a whole lot cheaper than buying one from Westerbeke.

Jim Hardesty · September 19, 2023, 09:22:50 AM

QuoteMaybe with epoxy to fill the holes. Any thoughts?

The only thing that I can think of is JBweld.
Jim

Stu Jackson · September 19, 2023, 09:46:22 AM

My experience is that DEVCON is far superior to JBWeld. I wrote it up in a repair of my raw water pump studs in a tech note in 2017 or 18

KWKloeber · September 19, 2023, 10:34:22 AM

Reserved until we see the numbers from the caliper!

>>> This is a whole lot cheaper than buying one from Westerbeke.<<<
Yeah, but it's not "Marine version"!!

KeelsonGraham · October 30, 2023, 10:20:09 AM

Looking forward to installing my new JMP pump. At less than $250 it's a bargain. It seems pretty solid so hopefully it'll give me good service.

KeelsonGraham · October 30, 2023, 10:47:25 AM

But first, I've got a good bit of work to do including: cleaning the land, investigating the emulsified oil, repairing the camshaft slot and replacing the cooling hose with its almost rusted-though hose clip.

Then remove the HX and descale, replace aging hoses and replace the leaking exhaust hose. Should keep me busy during the winter🙄

It really pisses me off that the PO let it get to this state. I went across Biscay twice with this heap of junk last year. 50 hours of motoring and it could have failed at any point.

The trouble with finding a problem like this is the loss of trust in the boat. Now I'm wondering what other vital maintenance has not been done. Really, the only option is to go through the whole boat and replace every lifed item that I can't personally account for.