Jabsco impellor installation

[Bob Bradley]

I just picked up a pair of impellors for the Jabsco's on my 6v92 engines. This will be the first time I'm replacing them. At $137 each from Atlantic DD, I was disappointed >: to see that there was no gasket included with the impellor. Neither did Atlantic ask or suggest that I might need them. I guess I can make do with Permatex.

Are there any tricks to installing these, like pre-compressing the vanes with wire wraps? Should they be lubricated with anything prior to installation?

Also, there is a small black rubber plug, about the size of a quarter in the box with the impellor. Can anyone confirm my suspicions that this will fit over the end of the drive shaft.

Finally, does anyone have any more economical sources for these?

[Genesis]

Get 'em anywhere else.

Saunders engine has them (Panama City) at a much nicer price, heck, Boat/US has them around here!

You got raped on the price. The gasket is NOT normally included. The plug goes in the end of the impeller over the shaft once you install it.

You need a puller to get the old ones out. Jabsco makes a nice one that isn't too expensive.

Reinstallation is made MUCH easier with a couple of long cable ties to pre-compress the vanes. Cut them off as the tie is about to go into the body. Lubricate the impeller with KY Jelly prior to installation to protect it during the first (otherwise dry) start.

[Bob Bradley]

:smokin But, I wanted to be sure I got the correct parts, as this is the first time I'm changing them. I'll check the Jabsco site for the puller, unless you have a good source for that as well.

[Genesis]

... I think I got mine from West - they're easy to find. Jabsco makes two sizes - "small" and "large". You want the large one - the small will not fit around the body of the impeller.

[mikep996]

Well, somebody has to keep the economy going!

I get a lot of parts - impellors, filters, etc from:

www.go2marine.com/g2m (http://www.go2marine.com/g2m)

The prices seem reasonably good and they are quick to ship. I paid 68 bucks as I recall for each 8V71 impellor (and I thought THAT was exorbitant).

Never tried wire ties/KY jelly to install them - I've always been a hose clamp/vaseline kind of guy. :lol

[Bob Bradley]

I just did a lookup on Boatfix.com. $68.33 for the same impellor that Atlantic charged $137. Now I really feel dirty. Oh well, it's about an hour and a half round trip to Atlantic DD, so I guess I'll keep them. I ordered the large puller while I was there. About $50.

[Bob Bradley]

If you have to use KY, maybe you haven't snugged down those wire ties just right;)

[mikep996]

Those Atlantic DD guys have to make the Mercedes and Porsche payments, just like everyone else.

[CapetaniosG]

It is not recommended to lubricate the impeller. All you need to do is to prime the pump with a water hose thru the zinc holder opening before you start the engine.

George
1975 53MY

[Genesis]

Its water soluble, and disappears on the first startup.

It can only help picking up prime.

And it makes inserting the new impeller MUCH easier.

There is a very real risk on insertion of damaging a blade on the cam plate as it slides in. The KY makes this a non-issue - dry installation in these large impellers requires a LOT of force (like your FOOT on the back of the impeller) and can cause premature failure down the road.

Use the KY.

What's a fairly bad idea is to use any sort of petroleum product (including Vasoline) as those can attack rubber and (once again) cause premature failure.

[Genesis]

Its water soluble, and disappears on the first startup.

It can only help picking up prime.

And it makes inserting the new impeller MUCH easier.

There is a very real risk on insertion of damaging a blade on the cam plate as it slides in. The KY makes this a non-issue - dry installation in these large impellers requires a LOT of force (like your FOOT on the back of the impeller) and can cause premature failure down the road.

Use the KY.

What's a fairly bad idea is to use any sort of petroleum product (including Vasoline) as those can attack rubber and (once again) cause premature failure.

[Nick]

When should the cam, cover and wear plate be replaced. I assume if the pump hasn't seeen sand and crap, that if the parts are not scored there is no need to replace them.

Nick

[Dick]

Genesis:

What about dish soap? Also, you mentioned that the gasket is not normally included. Is there in fact a gasket in there? Seems like the last time I replaced, I couldn't see a gasket. It hasn't leaked! If so, I guess we should buy separately?

Dick

[mikep996]

I actually thought you were kidding... :o

The DD service manual in the raw water cooling section calls for Water Pump Lubricant, a petroleum based grease made for that purpose. That being said, I don't know anyone who actually buys Water Pump Lubricant. Most mechanics - good and bad, use whatever grease they have around.

Raw water pump Impellors for normal temperature water (above 40) are neoprene or nitrile which are not affected by any grease you might consider putting in there. Vehicle wheel bearing seals are neoprene or nitrile and they are, of course, covered in grease and last for years with the only attention being total abuse. I'd suggest that any grease you have around the boat will work just fine in that water pump. Heck, KY might work too! ;)

[Genesis]

The newer style is a thin rubberish gasket. The older style is paper. The newer one sometimes comes off whole. The older one nearly always comes off in pieces.

The cover has to fit fairly closely in order to not bypass water, so the gasket is actually important (e.g. making one out of cork is a bad idea)

The cam is replaceable, but unless its damaged I don't know why you'd change it. Look at the fold over of the vanes of the pump when the cover is off. They should be basically compressed very close to or touching the hub where the cam is.

In the "clear" part of the bore of the pump the vanes must have a cant to them (that is, there must not be a gap anywhere between vanes and pump body.

If the vanes are not compressed nearly to or actually on the hub at the cam, replace the cam. Ditto if the cam is scored significantly. You can remove it easily and dress it with crocus cloth if there are light scratches on it.

If the vanes of a NEW impeller have no cant all the way around the pump bore or if the bore has significant scoring, the bore is damaged or worn out. There is no fix for this other than replacement or reconditioning of the pump itself. Minor scratches in the bore can (and should be) can be buffed out if they are present as imperfections will wear the vane ends very rapidly.

I like KY for impeller lube primarily due to its immense slipperiness - it makes inserting the impeller very easy - and it immediately disperses on startup without residue.

While it is true that most impellers are nitrile, the problem with petroleum is not limited to the pump - grease on heat exchanger vanes will reduce heat transfer and also attracts debris.

[Nonchalant1]

Here's how to feel less dirty. If we're bidding on stupid prices, Detroit Diesel charges $254.57 for an impeller for 8V71TIs, but for your extra $150 you get the paper gasket!

Also. the head service tech at DD says to "slather the impeller in vaseline" and no need to prime it when started.

My own tip is to make sure you know which way your impeller turns before compressing the vanes. Mine turn different directions port vs. starboard, even though it's the identical raw water pump. I watched the impeller shaft turn while I had somebody hold the shutdown button and crank the engine half a second.

Doug Shuman
1978 53MY

[nick]

Thanks!

Nick

[Bob Bradley]

Karl,
In the absence of a new gasket, is there any reason why I should not use Permatex? On other applications, I've applied a liberal amount of formagasket, then inserted the screws just a little more than finger tight, then let it set up for a couple hours before final tightening. Do you see any problems with this?
Bob

[Banshee36]

KY Jelly for inserting the impeller wow , I just use Dish soap, works great, plus you can see nice bubbles come out the exhaust pipe if everthing is working right. My buddy has the 8-92's in his rig! His impeelers were a bitch to get out and in. A freind suggestedthat get the impeller started then bump the motor over , the impeller goes right in, no fuss no muss.
JW

[Genesis]

I've done the Permatex thing before and haven't had trouble with it.... I wouldn't call it a recommendation... but I've done it.

[Nonchalant1]

Second tip - If you do take the cam out, when you put it back in you need to put pipe thread compound liberally on the screw threads of the screw that holds it in. DD recommends regular PTFE paste compound with teflon. Some people say put it in the screw hole too, but be careful not to put in so much that it could get squeezed out into the pump chamber.

Doug

[Captcoop]

I'll give you the poor mans method to install. Remove the old impeller with 2 flat screw drivers. Buy or borrow a piston ring compressor put it around the new impeller. Turn all the vanes the correct direction leaving maybe 1/8" past the end of the tool. Then cover the impeller with Dawn or your favorite dish washing liquid and tap the impeller in place. Good Luck

[garyd]

My mechanic showed me a trick that works great.

a large flat blade screwdriver place it just a little ways into the pump touching the side of the pump and the flat section on the rubber on the shaft of the impeller. Use the screwdrive as a lever and work it out from side to side.

I've used this with greatr success and no damage.

save ya the price of a puller.

[NANPO 41]

While it is true that you can pry the impeller out with a pair of screwdrivers (done that in an emergency) what happens is that you put force on the impeller shaft. This can damage the seal (ceramic) at the front end of the pump. Likewise if you tap the new impeller onto the shaft with a hammer. Buy the puller. Murphy's law and all that.
Fred

[mikep996]

Pulling large impellors can sometimes be very difficult.

So buy the puller.

This is one of those situations where, although you can certainly get the darned things out eventually using a variety of methods, the puller makes it very easy and very quick.

I think you should buy the puller.

After using the puller once, you will say, "Why the heck didn't I get one of these X years ago."

Did I mention... buy the puller.

[Genesis]

... you can't possibly get the screwdrivers in there to perform the extraction via this method.

The puller fits without drama.

[mikep996]

I like the piston ring compressor idea! As I mentioned, I always used hose clamps but the ring compressor should work MUCH BETTER and easier! Never thought of it and I have a bunch of 'em around.

Thanks!

[Traveler 45C]

I use zip ties for compression.

Greg

[garyd]

it just plain works no problem at all!

[Bob Bradley]

I ordered the puller on Wednesday from boatfix.com, and it arrived yesterday. I probably should have gone down to do the job today, but I had an invitation to ski Sugarbush one last time for the season, and I couldn't pass it up.

I particularly like the ring compressor idea. I'll bring the cable wraps as a backup, but it sounds like a great approach.

I'll probably use the dish soap approach. My wife is a pharmacist, and I didn't have the guts to call her up and ask her to bring home some KY ("Honest, honey, it's for the boat... really"). I mean, why ask for trouble?