Seawater pump on a Yamar 6LYA-STP

[Cartouche]

I am trying to change the Impeller and having a Heck of a time figuring out how to take the water pump off, I think I have attached a picture any help would be great, I see a Square plate with 4 12mm Bolts facing forward, but that is not right, Many thanks

 

[GreySky]

I have two 6LY2A-STPs, so it should be fairly similar. First question is are you sure the pump needs to come off to change the impeller? Neither of mine need to come off. There's a plate on the back (facing stern) that comes off giving very easy access to the impeller.

If you don't have that, then those 4 bolts going forward probably are the ones holding it on. I have the parts diagrams for the 6LY2A and that's how it shows it attaches. See image attached:

 

[DavidM]

The impeller on the 6LY is very difficult to change in place. The cover plate is fairly easy to remove, but prying the impeller out takes some tools and finesse, which I have found can't be done in place.


But removing the pump isn't easy. First remove the inlet hose and loosen the outlet hose clamps. The outlet hose will come off as you remove and twist the pump out.


The pump is held in place by 4 cap screws that bolt forward into the engine. They aren't easy to get to. The lower starboard one is a bitch. I think I used a 3/8 breakover bar and a 10 or 12 mm socket with no extension to get that one loose.


Once it is loose it is also tough to get your hand in to turn it. If my fingers were a half inch shorter I probably couldn't do it. I reached under the pump with my left hand and grabbed the screw blind with my fingers. The other three screws are relatively easy.



Once I got the pump off I removed the cover, put some Dawn detergent inside to lube it a little and used a couple of small screw drivers to pry it out. You have to be careful not to bugger up the housing when you do that. Once I got it out a half inch I grabbed the vane with a channel lock wrench and pulled it the rest of the way out.



Replacing the new impeller is easy. Don't worry about which way the vanes go. The first rotation will set them right. Lube up with Dawn and maybe put a hose clamp on to compress the vanes until you get them in the housing.


Reinstalling is the opposite of removing. Be careful not to drop the screws in the bilge.



Good luck!


David

 

[GreySky]

I've been using an aftermarket impeller that has threads cut in to the last 3/4" of the impeller. Those threads allow you to use a small threaded puller that requires very little clearance. See attached pic. I don't know if that would work in the 6LYA, but in my 6LY2A it couldn't be easier. They're available on eBay.

 

[DavidM]

Yes, if your impeller has the threads, that bolt puller makes getting the impeller out easy and you should be able to do it in place. But it was not used as an OEM part. But after you get yours out, replace the impeller with one with the threads.



David

 

[helm]

The impeller puller is Johnson pump 09-47163-01. It helps to replace the center bolt with a longer bolt, it will pull the impeller out further, makes it much easier to remove. When you put the new impeller in it really helps to compress it with zip ties and remove them as you insert it. I use plenty of pure silicone grease on mine, the hardest thing is keeping the O ring in place when you put the cover on, lots of silicone grease on that will usually keep it in place while you fumble with the cover. The puller makes it an easy job.
Hope it works for you
Eric

 

[Bacchus]

The OEM pump is a Johnson # F75B-9 (Mainship custom design)
The Impeller is a Johnson # 09-821BT - the "T" is the newer threaded version
The impeller puller is a # 09-47163-01 as helm reported

If anyone is interested the Johnson catalog & 6LYA-STP applicable excerpts is available on my Bacchus website - Maint & Parts section

Also - A piston ring compressor makes impeller replacement/ insertion easier
for about $10 - Sears, Harbor Freight, or auto store - its a worthwhile add to the parts / tool bin. The beauty is in addition to being adjustable size it holds any set diameter until it's released making it EZ to compress the impeller and then push it on through... as in many situations - lube helps

 

[Cartouche]

I have the impeller and have the tools that was not the question removing the pump is my problem looks like it is going to be a pain. To give me a point of reference is one of the bolts visible in the picture attached, many thanks, on my original post

 

[Seevee]

I have the impeller and have the tools that was not the question removing the pump is my problem looks like it is going to be a pain. To give me a point of reference is one of the bolts visible in the picture attached, many thanks, on my original post

You picture doesn't show a clear view of the pump. Take a shot with top up, pointing to starboard. If I get in the bilge in the next few days, I'll take a pix.

It's a pain and can be tricky, that's why I suggested having someone who has done it with you first time. Not that you can't figure it out.

As a general rule, unless fairly simple, I like instruction the first time doing things from an expert. (and that's a requirement on aircraft mechanics).

 

[Cartouche]

Will do, my problem is there is know one Local that I can call on, many thanks for your help. I am down at the boat later today and will take a picture as you suggested.

 

[LongJohn]

The impeller puller can be replaced by a simple metric thread bolt; my recollection is 26mm but I can't verify that right now. But it's a lot cheaper at Fastenal. The ring squeezer makes the job easier. I do not have to remove my pump on my 6YLA to replace the impeller. It was convenient to remove the pump outlet hose and the heat exchanger zincs to vacuum impeller pieces from the tube bundle face without disassembly of the heat exchanger.

 

[Cartouche]

Many thanks Seevee, here she is on the bench at home, your help was great many thanks, as you can see I had to change the intake hose anyway, as the wire was starting to show through

 

[Cartouche]

Larry I have the O Ring for the End cover do you change the ORing at the shat end if yes do you have a Yanmar part # Cheers

 

[Seevee]

Larry I have the O Ring for the End cover do you change the ORing at the shat end if yes do you have a Yanmar part # Cheers

No, I don't change the shaft end O ring.... isn't it a bit hard to access? If it's find, I'll leave it. PN 119578-42640, according to the parts manual.

 

[Cartouche]

Many thanks Feel good this job is behind me, as you know it is good to have the maintenance issues on my schedule rather than wondering when things were done by PO

 

[Pmcsurf1]

I know it's an old thread but...
We're on the loop and I'm wondering how many hours of regular running before changing impeller?
I know some change it once a year but many of those boats are in storage for months. We're run our boat most every day while on the loop.
Paul

 

[DavidM]

You could change it on some schedule, maybe yearly with your extensive use. But changing the impeller on that engine is a PITA, so here is a quick way to see if it and your cooling system is performing ok:

Warm the engine up and take it out at cruising speed. Then after the temp stabilizes run it at wot and watch the temperature gauge for five minutes or so. It should not go up more than about ten degrees and stabilize at 200-210.

This test does more than check impeller condition, it checks the complete cooling system. If the impeller is at the end of its life and isn't putting out enough flow then the engine temperature will rise too far, but other causes like a fouled main heat exchanger or injection elbow will do the same thing.

Also while you are running at wot, check to make sure that your engine reaches rated rpms or a bit more. If not maybe you have prop or bottom fouling that needs to be taken care of.

David

 

[Bacchus]

Paul
My experience with that engine...
Had one fail at about 5 yrs very little seasonal use by PO
Replacement ran 5 seasons w/o issue replaced as PM prior to a long trip
IMO the yearly change is conservative but cheap insurance. I figure 3-5 very doable w winter lay up.
Get the threaded puller and impeller and changing is not that challenging. I did need to pick up longer metric bolts to get the impeller out as the stock bolt was too short.
I also picked up a piston ring compressor the correct size to easily compress the impeller tabs to ease inserting it... works well.

 

[Cigatoo]

The OEM Yanmar impeller is well constructed and tough. I think Yanmar recommends 600 hours. Once you have a known Yanmar impeller in there and you are not sucking up sand and silt I wouldn’t be too concerned about frequent changes.

 

[helm]

The Yanmar operation manual says change it at every 1000 hours. I change my every year, actually easy on my 6LYA-STE engines. You can download all the manuals for your engine at https://www.marinedieselbasics.com/diesel-engine-manuals/yanmar-diesel-engine-manuals/.
You can get the impeller puller on amazon Johnson Pump 3001.4386 09-47163-01 Impeller Puller for 09-821BT. I put a longer bolt in mine, lets you extract the impeller further and easier to get it out. I lube mine up with silicone grease as well as the pump body or you can use the little package of glycerine they send with the impeller.
Enjoy your Loop!

 

[porman]

I just changed both of mine at 3 years and 500 hours. They looked like new. Yanmars recommendation is 4 years or 1000 hours, according to my manual.