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I've seen folks who rebuild those pumps, but for $70-ish new Kb, why?  It would be a good test though to let us know how long it lasts.

At $70 it's a no-brainer to go with genuine Kubota. Please let me know who has it for that price (maybe you?), because I haven't found it anywhere near that price. Thanks!

I have answers for your other questions - will explain when I'm back at my computer with a real keyboard.

Hi all, I hope you had a great holiday weekend! Here's a brief update on my prior post.

I was able to remove the water pump pulley without first de-tensioning the belt. I just removed the screws and slid it off the pump. Obviously this did ultimately loosen the belt. Putting it on again will just be a reverse of this process, and as long as the pump is the proper design the belt should have exactly the same tension without the need to adjust the alternator positioning at all.

In cases where the belt tension does not need adjustment, it would seem that this could be a very easy way to accomplish an exact replacement-in-kind with a new belt, if(!) tension adjustment is not needed. I can imagine that as a belt wears and falls deeper into the groove, pulleys need to be tightened, so a new belt might need the pulleys to be loosened a bit. But if you do periodic replacement of belts as a precaution before they become severely worn, you might be able to avoid some headaches by just pulling off the water pump pulley and putting on the new one without adjustment.

Once I removed the pulley I could get a very clear look at the source of the leak. It's definitely losing a drop of coolant every minute or so out the weep hole. I assume that this means the pump's bearings are at end-of-life. Is there any value in rebuilding the current pump, or is it best to just buy a new one?

I'll be calling the Westerbeke dealer to price out a "genuine" replacement, for comparison against the ~$50-70 Indian knockoffs and the $140-170 genuine Kubota part.

I'd still appreciate comments or links to some very basic instructions about how to remove old coolant and replace with new. I'm aware of the need to burp air out of the high points, and actually purchased a radiator pressure tester that could be helpful with this. (I've borrowed one from AutoZone the last few years to do an annual pressure check, but they changed to a different brand that doesn't fit the motor, so I found the compatible one on Amazon:

https://www.amazon.com/gp/product/B0067UE6IY

Quick update on my status:

Due to two weeks of business travel I haven't done anything except monitor seepage upon my return. There are definitely a few drops per day of coolant coming out somewhere. One small piece of paper towel that I left was saturated (but not dripping) when I returned. The others were completely dry, so I have a general idea where the leak is coming from, but still can't see the exact source. I've decided that I need to remove the water pump pulley to try to get a better look. The pulley's shape appears to be a cup that covers much of the pump bearings, and I have a feeling that the leakage may be going into the cup first before oozing out onto the gear cover. This may also create corrosion problems inside the cup that I should inspect.

I have a few extremely basic questions which I can't find answered on the wiki:

• First, I need clarity on how best to de-tension and remove the belt. It looks like the primary source of tension is the alternator, and if I loosen its attachment to the bracket I will get enough slack to remove the belt from the pulleys. (Obviously the belt itself is held captive by the raw water hoses.) It this correct?


• Planning ahead, when I go to reassemble everything, are there tricks to tensioning the belt again? Is there somewhere I should stick a tool to get leverage in re-attaching the alternator to the bracket with sufficient leverage to establish tensions? (Sorry if this is too rudimentary, but I don't like to assume anything.)


• I've noticed a small amount of corrosion in some of the pulley grooves, perhaps from last year's raw water bearing leakage getting some moisture on them. Should I take this opportunity to get a rotary brush to knock off the rust and perhaps re-paint the pulleys? Or is this just not worth worrying about? If I paint them, is there a suggestion for what matches the Universal light green metallic? Or do I have to go to Westerbeke for that?


• Finally, if I'm going to open up the coolant system for the pump replacement, I should replace the coolant which is at least 3 years old (maybe more). Is there a recommendation for how to go about replacing this? Do I try to drain the whole system, or just push through the old coolant with new stuff? Please note that my hot water heater is in the MkII location down next to the batteries in front of the galley sink and refrigerator. That means I have a low point in the loop that is extremely hard to reach. Adjusting those fittings is almost impossible.

I have not yet purchased a pump. I am still fiddling with hose connections, and placing dry paper at various places to trace the exact origin of my leak before I conclude that it's the pump. I think it's likely the pump, but not ready to pull the trigger yet. My measurements and related questions were intended to ensure I get the correct one when I am ready. Still debating between genuine Wb, genuine Kb, or Indian knockoff.

Thanks for your help.

Obviously I measured the wrong part of my pump. I did not realize that half of the impeller housing was built into the outside front engine casting.

FWIW, the two top screws are spaced 2-5/8" apart. Does that narrow it down a bit?

70mm impeller would exceed the diameter I measured for the pump housing. Did I measure the wrong thing?

I can try to get a picture when I return to the boat in a few days.

You mentioned different sized gear covers. What, exactly, is a gear cover?

Is it possible that Wb spec'ed a larger impeller than Kb because of all the extra hose to/from the hot water heater? Maybe the late model Kb is still too small?

FWIW, my pump is original (has factory paint) and the pump housing (behind the pulley) is approximately 2" dia, which strikes me as pretty small. I don't plan to tear it down to measure the impeller.

Breakin— how often do you change your transmission oil? Must have been keeping that one quart for a long time to warrant 3 changes?

End of every season, at the same time I change the motor oil.

One other thing: Although my electric suction pump prevented me from measuring how much fluid I sucked out, I got EXACTLY 3 oil changes (to the last drop in the bottle) out of my quart of Dex III. So I was right at the 0.33 qt spec for fluid capacity of the HBW100. My little Teflon pump tube must have been getting to the very bottom of the oil sump.

Rather than start a new thread, I'll wake this one up since it's already linked in the Wiki.

My situation is a little different from OP's: M35B motor (Kubota V1305 block). I have a very slow leak of coolant from the "weep hole" at the bottom in my freshwater pump. I suspect the bearings are leaking. I'm starting to shop around for replacements in anticipation of replacing it this off-season.

Diesel Parts Direct lists genuine Kubota #16251-73034 ($168). There are a bunch of knock-offs on ebay and Amazon, including the ubiquitous Kumar Bros stuff, for around $50. All try to make it appear like a Kubota pump, but it's obviously a "pump for Kubota". Some call it #16241-73034, or other totally different part numbers.

In addition to concerns over the bearings, I also noted that breakdown pictures on the listings show an impeller that looks like a cheap stamped sheet metal impeller that looks sort of like a cowles blade. The Universal parts list (p. 43 #34, p/n 200825) shows what looks like a spiral-fin casting that would seem to be better quality.

Do any of you have experience with replacing this pump? Is there a recommended dealer with genuine Kubota part for less than $168? Do the cheap knock-offs last? Any idea how outrageous is the cost of the genuine Westerbeke part?

I'll have additional questions as I move forward about various things like how to remove and re-tension the v-belt, since I've never removed it before (on any motor). So I'm totally new at all this.

Also, I'll be asking for recommendations of other things to replace while I have it all apart. I can imagine that coolant hoses may be softening up a bit after 17 years exposure to ethylene glycol.

This is a very old thread, but its potentially incorrect information caused me a lot of confusion, so I'll post a correction to avoid others wasting time on this issue.

Not all M35B motors have the Hurth HBW 150 transmission. My boat (#1535) -- and after researching other threads, it appears that most MkII boats -- have a HBW100 transmission. Transmission fluid capacity is 0.33 quart = 10.5 oz. That's a little over half what's reported in this thread, and accounts for most (but not all) of the discrepancy.

Hull #1660 is the only one I've seen that reports a HBW 150 - all the others I've seen report a HBW 100 or ZF 10M (same thing). Maybe there are others who can report their actual transmission model so we can get a broader understanding. But bottom line, don't assume your M35B has any particular model of transmission. Remember, "If you read it on the internet, it must be true" (not)

Also, my drain plug is not in the low point of the sump, so there's a good chance that sucking out the oil with a tube will get more than the drain plug, if the hose is properly positioned. I am not able to accurately measure the amount that comes out because my pump sucks into a 3 gallon pail. But when I hunt around with my tube I do get to lower points that pull additional amounts out.

Also, my manual recommends filling the transmission completely with oil only if storing for over 1 year. I have not done that because I'm afraid I'll forget to empty properly before launch.

As previously reported, my boat has the same behavior as John and Roc. I wonder if Catalina changed components/design between #1535 and #1570.

Wait.  Wb switch?  Does your engine have a Universal panel or a Seaward panel?
The Seaward panel doesn't have a Wb switch in it.

My boat has the panel at the binnacle under the wheel, typical of MkII boats of my vintage. I don't recall whether it's made by Universal or Seaward - I'll have to check next time I'm there.

I definitely want a switch that comes with a rubber cap (or accommodates one purchased separately). With the key switch at the helm, that seems prudent.

I guess my main question is whether it is normal for the low pressure alarm to not be active until after you have turned past the detente. Does that mean replacement is needed, or would the replacement just do the same thing?

Does your fuel pump run in the first position? Or when you return to that position?

I am 95% certain that the fuel pump only runs when the key is turned and held in the solenoid position. It does not run when initially turning the key to first position, or when returning to first position after heating the glow plugs. However, the buzzer does continue when returning to first position, so I guess it's possible the pump continues to run but I can't hear it.

By the way, once the buzzer comes on, it is not anemic at all (hence the "can't hear it" comment about the little ticking pump).

It sounds like I should just replace the key switch, and that should fix the problem. (I know you don't like the wiring scheme, but changing that is above my pay grade.) I'll try shooting some contact cleaner in there first just to try. Is there a good substitute part, or should I just order the genuine Westerbeke key switch?

I had a leak in a similar place that was eliminated by re-sealing the LP storage locker above. Add that to your list if things to check.