Installing a new raw water pump 6LYA Yanmar

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Iggy

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Joined
Mar 1, 2020
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1,168
Location
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Vessel Make
Pacific Trawler 40
I am going to replace my raw water pump. Part of the problem is that the bottom of the pump is level with the floor. Also a aluminum plate for the engine mounts runs about 3" away. The two things, make changing the impeller very challenging. Oh, also the heat exchanger hangs about an 1"over it Only a person with this engine would understand.

Having never changed out this pump before. It maybe easier to remove the heat exchanger. Here is my questions, any short cuts, advice and am I getting ahead of myself about the heat exchanger. I always think its better to ask first, rather than diving into it.

The parts book shows two bolts, the the pump has 4 bolt holes. Plus no gasket between the pump and the engine. I think there is 4 bolts (I am home now), the gasket I am not sure.

Thanks in advance.
 
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Iggy I have two 6LYA-STE Yanmars on my Lindell 36. The impeller change is pretty easy. Whats the specific part of the change that is an issue? Do you use a threaded impeller 09-821bt and the impeller puller - 3001.4386 09-47163-01? When I put the new one in, I lube it up with divers silicone grease, zip tie it and that facilitates the install. I also lube up the O-ring groove on the cover with silicone to keep the cover O-ring in place when I am fumbling with the cover bolts.
I haven’t had to actually remove a pump so not much help on that one though.
Hope that helps
Eric
 
I know it should be easy. But I am fighting with very little room. It generally takes me about 1 to 2 hours to do. I end up lying on my side with or on my knees. In ether position, I only have one hand free.

The puller I have. The housing in such a tuff spot, I used a longer bolt on the "nut" to drive the impeller out more. Its like working in a hole, and you can only see the side of the pump. I can't even see any part of the impeller shaft.

But that not my real problem. The pump need to be replaced. So I was looking for some insight for the best way to approach this. Just bought the pump and the fun begins.
 
I feel your pain. I have twin 6CTa Cummins. The water pump is low on the port side. The port engine sits 4” from the port fuel tank. I was changing out the water pumps because Cummins uses crap Sherwood pumps. Formula nicely provided a small hatch in front of the port engine to get to the water pumps. But the hatch was way too small so I cut the opening up as much as I could and installed a larger hatch. My mechanic who is a lot smaller than me was able to change the pump in about 15 minutes. He said the larger hatch made all the difference. Maybe you could access your pump in a similar way?
 
That pump is just hard to get it. Even coming in from the front of the engine. There is about 8 to 10" of room in front than a bulkhead wall. You would think 4 bolts would be easy. But the one inner lower bolt on the engine side is going to be the hardest. That's why I was thinking that the heat exchanger may need to come off. But I shall see which way will work out the best in getting this done.
 
I have changed mine a couple times. The threaded nut / bolt type extractor is essential and the longer bolt is also needed unless the vanes are nearly completely gone. This requires the threaded "BT" impeller mentioned in another reply. When I had a yard replace my impeller once they needed to borrow my puller as none of theirs would work / fit. If impeller is not the threaded version be cautious removing the impeller so as not to damage the housing prying... I'd find another way to remove and NOT pry against housing.

I did not have to remove a cooler or the pump body, just removed zip ties and moved some wiring out of the way for better visibility.
There is no gasket just an O Ring. Grease does help keep it in place. The cover bolt pattern is not symmetrical so note or mark cover & housing before removal to make reassembly easier.

The cover is reversible if worn on impeller side, clean / polish & reverse.
I have exchanged messages with another member that has removed the pump body and he indicated it was doable but not easy. There are 4 bolts and 3 are accessible but the 4th is much more hidden / difficult.
I have posted a Yanmar Service / Parts Manual and Johnson Pump Manual in the TF Resource section that might be of use to get good mental picture of what you are attempting to do working blind.
 
Will I am glad am not the only one that used a longer bolt. That 4th bolt is going to be fun. Thats why I was asking for the best way.

If from the top, heat exchanger must come off. From the front, a long extension and very hard to see . From the bottom, very hard to move a ratchet and see.

The first time changing the impeller I found out about the cover. I marked the cover now.
 
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Iggy said:
I am going to replace my raw water pump. Part of the problem is that the bottom of the pump is level with the floor. Also a aluminum plate for the engine mounts runs about 3" away. The two things, make changing the impeller very challenging. Oh, also the heat exchanger hangs about an 1"over it Only a person with this engine would understand.

Having never changed out this pump before. It maybe easier to remove the heat exchanger. Here is my questions, any short cuts, advice and am I getting ahead of myself about the heat exchanger. I always think its better to ask first, rather than diving into it.

The parts book shows two bolts, the the pump has 4 bolt holes. Plus no gasket between the pump and the engine. I think there is 4 bolts (I am home now), the gasket I am not sure.

Thanks in advance.
Click to expand...
I have a pair of 6ly2a-stp engines. The port side is very difficult to work with. Every time i change the impeller on the port side, I have to remove the pump. Mine has 2 bolts and 2 studs. Removing the pump is difficult like yours, my big problem is wrangling the big raw water hose. It's difficult but doable. Nothing else needs to be removed, just 2 bolts and 2 nuts. Oh, almost forgot, it's a kind of puzzle to get it out once loose, hose must be removed. Silverton 42c here.
 
I have taken off that pump every 2-3 years and use a 12mm ratcheting box wrench. The hardest bolt is that lower inside one but the ratchet feature makes it fairly easy. I know some use screwdrivers and pliers but I use the Jabsco impeller puller to avoid damaging the pump body. Put a reference mark on cover and pump before removing screws makes it easier to lineup.
 
Just an update in replacing my pump. The boats in the water and I have the new pump. I eye balled the job again and and found that taking off the ALT gave a lot more room. More so to take the hose to the heat exchanger off.

My real point is, others mentioned that the lower, inner bolt was hard to get it. Also to use a ratcheting wrench. I found that using a long 3/8s drive extension, about 15". Going at it found behind the pump. The nut come right off and I had room to swing the ratchet. Far easier than using a wrench from under the pump.

I hope this helps someone!
 
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