REPLACING IMPELLER ON 1GM YANMAR FOR 25D

[jamescbethea]

Replacing impeller on 1GM Yanmar for my 25D. Recognize the need to replace the impeller and would like to install the "speedseal" kit, but having a devil
of a time getting access to the cover. Feel like the main crankshaft pulley has to be removed first and it won't budge. Any ideas on how to break it loose? or an alternative approach. Jim

[Joe Myerson]

It does help if you remove the pulley. I installed a Speedseal years ago (I've got version 1), and I do remember that it was a PITA. I think I ended up removing the belt and finding a block of wood that held the alternator out of the way.

Good luck!

--Joe

[RC James]

It's been years ago since I put in the Speedseal, but do remember (pre-Speedseal) having to replace a failed impeller while attempting to cross a restricted navigational area (Navy Helicopter towing a sonobuoy and an approaching freighter) as the Temp Alarm did it's thing.

A correctly sized offset box wrench, a friend who could steer in 3mph winds, and adrenalin saw us through the ordeal.

Ordered the Speedseal the next week. It needed a bit of a 'snugging' w/pliers to eliminate a weep, but all in all.....good money for a great product.

I still keep at least 3 impellers in the plastic tub over the engine, just in case. Had one spin on its shaft when new, necessitating instant replacement, although under much more relaxed circumstances.
RC

P.S. While you're in the engine compartment, you might want to check all the engine water hoses for scale buildup. Mine were fouled, which added to my TEMPERATURE alarm problem, but a small dental tool judiciously moved about cleared up the problem. Then went home and ran some de-scaling solution thru the engine as a possible preventative. I believe it was LSR , the lime-scale-rust removal product available at most hardware stores.

[tjr818]

I don't know about the 1GM, but on a YSM8 they just won't work. There is not enough clearance between the cover and the engine block. It seems as though the pump is mounted backwards, facing the engine block instead of award the front. Our surveyor said not to bother with the Speedseal, because to change the impeller you have to remove the pump anyway. I wish it was usable for the YSM8

[Sea Hunt Video]

Tim:

Have you called Speed Seal to confirm that their part will not fit your Yanmar My recollection is when I talked with them (or I read it somewhere ) that one of their versions of the speed seal (they now have 2 different versions I think) will fits almost all engines.

If you have not called them try:

1-800-675-1105

I found them very helpful and patient.

[tjr818]

Thanks Roberto,
I could not recall all of the particulars when talking to Doug at Speedseal, but he said that he could not find a kit for the pump on the YSM8. Even if a Speedseal kit would fit, I would still have to remove the pump to access the impeller. The fit is just too tight. Besides, it almost assures that I will replace the belts at the same time since I have to take them off anyway to remove the pump.

[jamescbethea]

Thanks for the insights ... agree may have to replace water pump. My biggest concern is getting the darn crankshaft pulley off right now!

[steveg]

Hi James,

Admittedly, the pulley makes accessing the screws to remove the water pump cover more difficult, one in particular. If you are not worried about it being frozen in place you can clamp a pair of vice grips on it to get it loosened and hopefully back it out by hand from that point. Penetrating oil will help if it is stuck. Alternatively you can remove the whole water pump by removing three bolts so it is easier to access the cover screws. Once you have the right size wrench you can get at the bolts by feel to put the wrench on them. It should be easier than removing the pulley.

Once you have replaced the cover with the speed seal and have the thumb screws securing the cover it is not too bad removing the cover by feel as the screw behind the pulley does not need to be fully removed. This is due to the speed seal cover having two slots and one hole.

It was my experience that the supplied thumb screws were just a touch too long, even after requesting the shortest available. I compensated for slightly too long screws by putting one or two washers on the thumb screws. Also used some gasket sealer to keep them stuck to the head of the screws so they stayed in position. This was very helpful with the one behind the pulley which was not fully removed while replacing the impeller with the new cover.

Good luck.

[jamescbethea]

Steve,

Thanks for your input. Sounds like removing the water pump might be the better solution if I can't get the pulley off.

Jim

[Joe Myerson]

Jim,
Why don't you call Doug at SpeedSeal for advice. He's very helpful. If you have to take out water pump, so be it.

--Joe

[jamescbethea]

Joe,

Good plan. Thanks for the contact at SpeedSeal. Will call Doug.

Jim

[Bob Ohler]

I built a special screwdriver just for changing the impeller on the 1GM. I took a short, 1/4" box wrench and welded in a #2 Phillips bit into the end. I now had a very short, close-clearance screwdriver that did the job perfectly. I replaced the soft screws with tougher ones and I dipped them in grease before I re-installed them. This made removal much easier next year. The impeller should be replaced every spring. Using this maintenance schedule has never failed me.

I would carry a spare impeller regardless, even if it is the one you just removed.

[jamescbethea]

Great idea ..... if I can get the screws loosened and not have to remove the pulley, that would be the way to go.

[Bob Ohler]

James,

If I remember, one or two of them are pretty easy with a #2 Phillips screwdriver. Use a quality screwdriver, not some made in China version.

The one on the lower left as you face it is the bear! Be careful and use small Vise Grips but ONLY if the head of the screws are stripped out. Replace the screws with new ones and carry extra screws in a labeled container or baggy of some sort.

Good luck!

[Bob Lascelles]

Once you get the screws were out, I found a quick fix was to replace the screws with stainless cap screws. I believe the screws are metric M4 x 8 threads. The socket head of the cap screws let you use an Allen wrench. You can shorten the wrench as needed to get behind the pulley and the socket holds the wrench securely in position for tightening/loosening. I think I got mine at McMaster Carr. Just a thought...

All the best,

Bob