Impossible to Fix Westerbeke? 7.6BTD mocks all repair efforts!

[MicHughV]

you guys are funny....I've been in this boating game for around 40 years now...it's fair to say, I've seen my share of engine related problems......always relatively easy to figure out when you are there in person, but following this thread on this forum was like reading a dectective novel...Tspringer went thru' a variety of gyrations trying to solve this problem himself, input from y'all led to him trying this, that and the other without much success.....this kinda narrowed it down to the impeller for me......and seeing as I have had similar impeller issues....
Tspringer, went one further, he reversed the plate cover and took the paint off and cleaned it, brilliant move....!!!!
I typically slather the impeller and everything else with grease, when I take one of these apart...it doesn't stay on long, but allows the rubber to seat itself.
When you first put the impeller back in, there is no water in there to lubricate the blade/wall friction. The grease allows the blades to rotate without breaking until there is water inside.

Anyway, nice to see the forum spring to life to provide assistance. Kudo's to all y'all.

[jakkum]

All the soutions that I could come up with, have been metioned, but now I would like to know the end of the story.
If covid had not been here and there I eve might have opted for a holiday on a beneteau 473, a working holiday
Oooh, there are three more pagrs to read...

[iseadreamer]

I'm with Uncle Bob. Is raw water pump impeller turning with the shaft? Has impeller key slipped? Sounds like pump impeller is turning well.

[Tspringer]

NOT FIXED.

Same issue returned today when I ran the generator. Spits too little water, overheats slowly but surely.

So Im at a loss on what to do so I guess that means it's time to start throwing parts at it.

Complete new raw water pump comes first. Then electric boost pump setup. I do not think the factory installation of the generator is adequate at all. So it seems a re-engineering is required.

Terry

[Uncle Bob]

Originally Posted by Tspringer

NOT FIXED.

Same issue returned today when I ran the generator. Spits too little water, overheats slowly but surely.

So Im at a loss on what to do so I guess that means it's time to start throwing parts at it.

Complete new raw water pump comes first. Then electric boost pump setup. I do not think the factory installation of the generator is adequate at all. So it seems a re-engineering is required.

Terry

Sorry to hear this update, did you ever do the waterpump check where I suggested that you disconnect the pump output and see just how much water it actually pumps when the engine is running? Only needs to run for a very short time but will tell you if the problem is after the pump or before it.
My money would still be on the pump or suction side, it only takes a very small air leak to produce the results you have.

[Tspringer]

Originally Posted by Uncle Bob

Sorry to hear this update, did you ever do the waterpump check where I suggested that you disconnect the pump output and see just how much water it actually pumps when the engine is running? Only needs to run for a very short time but will tell you if the problem is after the pump or before it.
My money would still be on the pump or suction side, it only takes a very small air leak to produce the results you have.

I did do this and it does pump more water when I first flipped the impeller cover but looking at the water coming out of a hose into a bucket and looking at the water coming out the exhaust is much the same thing. I have no reading as such from this from before so I have nothing to really compare it to and no means of really measuring output other than the eyeball. I do agree that the issue has to have something to do with the pump.

at this point I am going to start trying to source a complete pump rebuild kit or an entirely new pump but being in the Bahamas right now I would wager anything they'll not have one in country.

I also think at minimum the strainer needs to be a different type that can be mounted below the water line safely and then I may see about adding a boost pump in line to boost water to the raw water pump or to circumvent it completely. I think that the entire cooling system is extremely marginal and is only effective if everything is an absolute perfect working condition there is no margin for any error.

[Uncle Bob]

Originally Posted by Tspringer

I did do this and it does pump more water when I first flipped the impeller cover but looking at the water coming out of a hose into a bucket and looking at the water coming out the exhaust is much the same thing. I have no reading as such from this from before so I have nothing to really compare it to and no means of really measuring output other than the eyeball. I do agree that the issue has to have something to do with the pump.

at this point I am going to start trying to source a complete pump rebuild kit or an entirely new pump but being in the Bahamas right now I would wager anything they'll not have one in country.

I also think at minimum the strainer needs to be a different type that can be mounted below the water line safely and then I may see about adding a boost pump in line to boost water to the raw water pump or to circumvent it completely. I think that the entire cooling system is extremely marginal and is only effective if everything is an absolute perfect working condition there is no margin for any error.

One last suggestion from me , have a really close look at the strainer and its connections, the slightest air leak will severely impair pump performance. The fact that pump output equals water out the exhaust says that there is not a restriction after the pump so no need for further boat yoga.
Also, if you have another impeller, even a used one, install it in the pump, you never know.....

[chrisr]

i've been fighting with a overheating problem on one of our 4JH yanmars

we ddi the tests mentioned by others to check water flow at various points through the engine. decided the water pump needs to be replaced

believe all w/ps operate on the same principal, with a raised cam at one point inside the case. this causes the impeller blades to bend and creates the suction needed.
over time the impeller wears this cam down slightly and the pump loses efficiency. still pumps water...just not enough to cool correctly

here is a sample pic



on many pumps the cam is replaceable...and may be on yours. unfortunately mine is not, so a new pump is required.

hope this helps

cheers,

[rslifkin]

On the strainer topic, smear a little grease on any gaskets, cap seals, etc. you can get to on the strainer. If one is just barely leaking, that might be enough to keep it from sucking air in.

[OldGreyB]

Tspringer, so sorry to read of the ongoing issues with your cooling system. This one is certainly testing the CF community.! I was happy to read your post # 37, not so happy to read the update post #49.

If you go down the electric driven pump conversion, it is has been well covered by others before you. Lessons to take on board are to ensure the chosen pump flow rate is correct, (6.0 -7.0 US gpm according to the Page 60 of the Westerbeke 7.6 BTD service manual) and it is powered directly from the generator power output terminals so it starts / stops automatically when the engine starts / stops, to ensure you do not flood the engine. March magnetic pumps have a good reputation for this application within the yachting community.

Links you may find of interest:

https://www.marchpump.com/pump/mdxt-...ic-drive-pump/

https://www.westerbeke.com/technical...cal_manual.pdf

https://www.cruisersforum.com/forums...an-170287.html

https://www.cruisersforum.com/forums...mp-164651.html

https://www.youtube.com/watch?v=v3rs8YVTIUE

From the 8 minute mark

https://www.youtube.com/watch?v=BibAbvMeGU8

[Rob_P]

You don't know if there's a blockage that you dislodged with the coat hanger, which came back after you ran the genset, or if your pump is bad. Nothing you've done has eliminated either possibility.

Pull any belt cover (if there is one) and disconnect the belt to the coolant pump. Beg borrow or steal a small electric motor with a pulley on it that will accept your pump's drive belt and hook it up to the pump pulley only. Don't mess with the pump cover, or impeller, anything, just attach the electric motor. You can have the electric motor mounted to a board and have it clamped someplace to tension the belt.

Disconnect the water hose as far downstream as you can like you did before and put into a bucket again.

Drive the pump with the electric motor (genset off) to see if you get water out the hose.

No/low water flow you have a pump problem. Good water flow, you have a blockage somewhere after the bucket end of the hose. You can restrict the hose by taping something over half the opening to see if the flow pressure increases (like putting your thumb over a garden hose). If it doesn't then it's the pump not pumping under load.

I'm thinking a loose bit of something is moving and blocking the exhaust elbow under the water pressure from the pump.

If you have to pull the exhaust elbow, a small hole that you can stick a long extension through to get to the clamp is a much smaller repair than cutting half the lazarette out.

If that's too much work, then $15 is my bid for the boat just to keep you from sinking it.

[callistov42]

Tspringer: I had 7.6 BDT's for years. It was the only thing that would put out that many watts in that amount of space. I had 5 of the damn things over 30 years and fought overheating problems with everyone of them. Then I got rid of my 120v watermaker and could live with a little less power and bought a 5.6kw Northern Lights. My life changed completely. It starts every time. It runs perfectly, it DOESNT OVERHEAT! Do your self a favor, get rid of the Westerbeke and buy a Northern Lights. You will be DELIGHTED!

[Lodesman]

Have you verified that the exhaust exit is clear - no bird's nest, mud-daubers or what have you?

[jimbunyard]

Originally Posted by Tspringer

NOT FIXED.

Same issue returned today when I ran the generator. Spits too little water, overheats slowly but surely.

So Im at a loss on what to do so I guess that means it's time to start throwing parts at it.

Complete new raw water pump comes first. Then electric boost pump setup. I do not think the factory installation of the generator is adequate at all. So it seems a re-engineering is required.

Terry

Do you actually want to fix it, or do you just want to "throw parts at it" and hope for the best?

A new pump is about 600.00, a complete overhaul kit is about 175.00. I looked pretty hard for an alternative, but Westerbeke appears to have you over a barrel, though I did find some things that indicated an actual phone call or two might improve matters. The pump is a Johnson F4B9-10-36006.

But --- until you know what the actual problem is you might as well just buy a new generator, as suggested above.

Some simple methodical troubleshooting should narrow the culprit down in a few hours or less.

As has been suggested repeatedly, you must make an accurate evaluation of the water pump output at some key locations, at a minimium directly at the outlet of the rw pump, and at either the outlet of the heat exchanger or the inlet to the exhaust elbow.

Until you have these baseline observations you are wasting your's as well as everyone else here's time

There is no need to have any special equipment to make these measurements, I find it hard to believe that even somewhere as remote as the Bahamas (haha) doesn't have a piece of garden hose and some duct tape... As for measurement of the output, if you don't have a measured bucket, give us the the measurements and we'll be glad to figure it out for you. Or if you have a measuring cup (or any small container you know the volume of) you could just use that after you've collected whatever has been pumped into your large container in a minute. If you don't have a watch or timer count to 60 at a moderate speed. Or 30 and multiply by 2.


If, as you say in your first post "- with the hose off and the valve open water floods in as it should" and there are no suction leaks between the valve and the rw pump, and there are no inordinately long runs or high head (say above 3 ft) a rw pump in good condition should easily provide 2 gals a minute. If it does, there is no need to 'improve' the water supply to the rw pump situation.

Have you made double sure that the strainer is assembled correctly and that the gaskets and any sealing surfaces are good?


That the generator worked at least adequately before shows that it is capable of working so again, and that it must be at least as adequately designed and engineered.

[jimbunyard]

Forgot to add;

If you don't have a waterlift muffler, the discharge from the exhaust at the through-hull should be a fairly uniform, unpulsed stream. The pulsing is a function of the operation of the water lift.

The possibilty of a clogged exhaust elbow is not ruled out; the reason being that the holes where the cooling water exit the cooling jacket of the el are typically small and are placed in a postion that can be hotter than the areas surrounding them. This can promote a buildup of scale and/or rust over time. Add in the fact that cast iron is relatively 'porous', and age and especially intermittent use can result in rust forming at the areas most exposed to heat, as edges tend to be, which gradually chokes off the seawater exits in the off season.

And finally, I notice that the mounting flange on the rw pump is axially symetric.

http://www.depcopump.com/datasheets/...0-36006-01.pdf

Has someone inverted the pump and so inadvertently switched the inlet and outlet? Most flexible impeller water pumps will pump in either direction, but the flow will be signifigantly reduced if not spun in the direction designed.