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HiDHo 10-12-2019 10:15 AM

Volvo TMD31A Raw Water Pump
I noticed a drip of water coming out the tell tale hole on my raw water pump. I know that means the pump side shaft seal needs replacing. The pump looks original so fixing it may mean replacing the shaft also, pretty much a total rebuild or worse case replacing IF a new pump is available.
Question... has anyone converted to a mag drive electric pump ? If so can you give me the pump model/size used. Never having to replace impellers would be a plus. :)

healhustler 10-12-2019 11:41 PM

Bill: Here’s the complete pump on Ebay.

healhustler 10-12-2019 11:54 PM

Bill: To match up the flow capacity of your pump with a mag drive electric, you’d need to know the flow of your pump at cruising RPM. SPX Flow is Johnson’s parent, maybe you can ask them if you have a part number. They may even build a suitable mag unit for it.

HiDHo 10-13-2019 08:33 AM

Thanks Larry, I’ll give them a call.
I got the idea from a boater that did a mag drive pump conversion on his generator, it’s been working fine for over ten years. Other than the pump hookup he had a cover plate made for removal of the engine driven pump. A constant speed engine may work better at this conversion but exploring this type conversion for a propulsion engine MIGHT be beneficial.

kchace 10-13-2019 09:23 AM

Since an exact replacement Johnson is available and your existing pump has lasted 32 years, why not go with that and be done with it? No guessing, no conversion.


HiDHo 10-13-2019 03:08 PM

I thought maybe someone on the forum had eliminated the engine driven pump. One less maintenance item is appealing also since there’s no of telling when the impeller vanes break off, not a good thing on a single engine boat.
Your right, Johnson Pump availability very good, I may install a new one and rebuild the old pump as a spare.

kchace 10-13-2019 05:33 PM

I agree, I've even considered it myself. But the mag Drive pumps do fail too and keeping a spare of those would also be expensive.


JeremiahM 10-14-2019 06:32 PM

I would buy the new pump and a rebuild kit for the old one. Rebuild the old pump and carry as spare. My 2 cents.


HiDHo 10-15-2019 11:02 PM

Thanks, I ordered the repair kit $90+, it includes 2 ball bearings and shaft seals, impeller, cover plate screws, gaskets and o ring. No shaft or axil as Volvo refers to it.
Best price on a new pump $325. Most suppliers refer to the Johnson pump F7B9 # 10-24277-3 as obsolete or no longer stocked. I will make a decision on buying a new pump after I rebuild the original.
My pump research did discover the engine driven pump specs are 26 GPM @ 1750 rpm and it has a 10 ft head and most be mounted below the waterline so maybe an electric pump is still a possibility.
Also for TMD31A Manatee owners if the turbo goes bad it can be deleted using a filler tube and the cylinders are sleeved so the engine can be rebuilt.

HiDHo 10-20-2019 03:58 PM

Just finished rebuilding the Johnson pump aided by a you tube video. I entered the video address but it didn’t compute.

Watching episode 5, water pump repair. shows a Volvo mechanic disassemble the pump on a TAMD 41A and rebuild it saved me some trial and errors. During removal from the engine I discovered a badly worn shaft cross piece so the test of the pump will be delayed until the new cross piece arrives from Sweden. $10 shipping on a $16 part not to bad for a Volvo part considering the distance shipped. Hopefully it will last 32 years like the old part. :)

Voyager3 11-12-2019 05:04 AM

How is your pump working? Mine just started leaking and rapidly got worse. I bought one off ebay, looks like the one shown above. Haven't put it on yet but it looks a lot less work then my old one.

HiDHo 11-18-2019 02:53 PM

I installed the pump just prior to winterizing. I silicon grease lubed up the suction and discharged o ring pipe sockets and the install. was text book. I test ran the engine for 15 minutes no leaks either at the pipe sockets, mating o ringed flange with the engine and the new shaft seals are working, no tell tale leaking.
I may order a spare pump like you did, I saw prices from $500’s to 300’s hoping for a bargain price if possible.

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