Impeller replacement problem

[deborahmaas]

We have a caliber 40 lrc with a yanmar 4jh2 e 50 hp engine. The impeller is very hard to get to as it is behind the alternator, so while we had that off we decided to check the impeller. It was fine, but got torn up taking it out. The impel loper originally sat recesses about an eighth of an inch within the pump but now will go in no more than an eighth inch protruding. We decided to remove the pump to install the impeller but have come to find out it lies behind the motor mount bracket, so to get the pump off you have to raise the whole motor. Any suggestions before we surrender and call out the mechanic?

[Mark1948]

Not sure of your language use, sounds like the impeller shaft was pulled out on removal. Try replacing the shaft first for proper seating. The install impeller. Use a hose clamp to "squash" it down to size and a little water to lubricate and simply slide it into position. At least this worked on my Universal 18.

[deborahmaas]

The raw water pump is behind the alternator. The alternator is out right now allowing us to access the raw water pump and check the impeller. The shaft the impeller slides on to is attached inside the pump which we cannot remove because two of the four bolts holding it on are inaccessible behind a motor mount bracket. We used a tie wrap and lots of lube to put the impeller and it slides in easily for the first part and seems to get hung up with about a quarter inch or so to go in. We tried putting on the cover plate to mash it in the rest of the way and no go. Is it possible the back plate is coming out?

[christyleigh]

This is interesting to me because my Yanmar 75hp Turbo is probably set up the same way except that I have no side access to the engine at all. I can just barely Touch the impellor while laying on top of the engine. That's why I haven't changed it yet.

I'm wondering if the shaft is driven by a slotted drive that is now not lining up with the shaft that may have been pulled out a little and turned. My Wild Guess would be to try turning the shaft to see if it slips back in a bit ???? Can you see if the shaft has moved out any ? Is there a lip on the shaft back near the back plate ? Have you checked to be sure the impellors are actually identical. Just making wild guesses because one of these days I'll be doing it with my blind finger tips ONLY Please keep us informed.

[deborahmaas]

We checked part numbers and also physically compared the new impeller with the old and they appear identical. The old impeller was difficult to get out and we tore several vanes removing it, so perhaps we did somehow move the shaft out. It looks like the shaft is somewhat out of line (we can only see it with a mirror) to me, but one diesel mechanic told me that it was supposed to be that way to bend the vanes. He also told me corrosion behind the wear plate could be causing it to back out in which case the pump is bad and will need to be replaced. Will let you know how it all shakes out.

[tdw]

I know by reputation that Yanmars can be difficult when it comes to impellor replacement. I'm not going to be much help in fitting your new impellor (though my guess is that its catching on something) but for future reference .....

Welcome to Speedseal

This works.

[MitchM]

1) install the speed seal, it is so easy to remove the pump cover.no more tryng to align the #$%^ little pump cover bolts on t he asymmetric pump cover. 2) buy a joabsco impeller pulle tool which is a clawlike device that grabs the impeller then pulls it out as you thread the center screw (i use the small on my yan 3JH4E 3) call a big yanmar dealer like mack boring in union nj their east coast distributor- yanmar offers a new style 'threaded impeller' that makes getting them in and out a breeze. dealers like to sell their stock of the old style impellers 1st so you have to ask for the new style.4) i hope the impeller vanes broke off as you took the impeller out, and all broken vanes are accounted for and not traveling down to get stuck in your heat exchanger ?

[SabrinaKS]

Our '98 Caliber 40LRC with a Yanmar 4jh3E has a small access panel on the nav station side of the engine compartment. It's about 8"square and held in by four screws. It appears to be factory installed and provides easy access to our water pump which is in the same location as you describe. I found this panel after I spent 4 hours changing the impeller by feel. Check to see if you have this panel. Also, try rotating the impeller once you have it in, you might find that it will seat to the proper position. Tom

[Zanshin]

deborahmaas - if you look at my blog page describing my ordeal on an 4JH3TE engine set up the same way at December 2009 Trip Blog and Diary 2009-11-28 then look at the last picture to see the circlip holding in the shaft - perhaps that slipped out during your impeller removal. I find that a small digital camera belongs in my toolkit on the boat as it lets me take pictures of hard-to-see places; I've also got a dentist's mirror but that isn't quite as good.

[jrd22]

I pulled the seal out of the back of the pump when replacing the impeller on our Volvo which prevented the new impeller from going all the way in. Not familiar with Yanmar so I'm not sure if this could be the problem. I had to buy the rebuild kit and replace seals, bearings and shaft on ours.
Like Tom says above, try rotating it and pushing it in at the same time.