Impeller question

[YukonRon]

I replaced the raw water pump impeller yesterday for my first time. When I opened the package for the new impeller there is a little white rubber disc with it. I checked my second spare and it has one too. I didn't see anything like it come out of the pump, and had a towel underneath to catch anything dropped so I don't think I lost it. Previous owner had impeller replacements done by the dealer.
Does anyone know what the disc is for, and should I have installed it, and how? It fits neatly into the hole in the end of the impeller, but doesn't seem to have a purpose. Is it left over from the BMW automotive days? I have the Yanmar 4BY2-180.
I was on a roll and carried on assembling. If I do need to install the disc I will call it a practice run and do it again.
I figured under 3 hours start to finish,solo, isn't bad for a first run but I'm sure it won't take that long next time. It helps a lot that I can (barely) squeeze my arms, head and shoulders into the step access hatch and reach the pump with both hands 😱 I'm just glad to be practising this in the driveway!

 

[Pilotnavigator]

If it fits the end of the impeller it would be a friction disk to run against the cover. Keeps the impeller from scoring the cover plate.

 

[tugnnaweigh]

Guessing that it's a little spacer to keep the impeller just out of contact with the cover plate? Aftermarket kits you buy on eBay don't come with these, shows the value of buying manufacturer kits.

 

[Katmat]

Don't think that impeller was used on the BMW's.

 

[YukonRon]

Thanks John. I did consider that, but:
firstly, it could only go in the rear of the impeller since the shaft passes through the front end. So is there any benefit to having it in one end only?
Secondly, the depth of the hole in the impeller is much deeper than the thickness of the disc, so the disc just pushes way in until it hits the brass spline insert. At this depth it will not contact the back plate. Even if the shaft, when it goes back in place, is just the right length to hold the disc out against the back cover plate, there is nothing stopping the impeller from moving in or out over the disc.
If the disc was made thicker so that it pushed in tight to the spline insert, and was then still flush or barely sticking out past the impeller face, then I could see it serving a purpose.

 

[YukonRon]

Don't think that impeller was used on the BMW's.

Duh, good point! Raw water cooling on a car, what was I thinking 😳

 

[knotflying]

I have the same engine on my R-27 and never saw that.

 

[BB marine]

It is a spline plug. It is to help protect the splines from corrosion helping to maintain the spline grease from wash out. Many impeller kits do not come with them. I personally do not see a foul in not using one. The impeller fits tight in the housing and unless the impeller cover/wear plate is worn badly it is sealing the splines by impeller to wear plate contact. I change my impeller once a year and still have evidence of grease on the shaft (no spline plug). If it came with the kit use it won't hurt. If it doesn't come with the kit ok just applied small amount of grease to the splines install impeller without it!

 

[TexasEye]

It is a spline plug. It is to help protect the splines from corrosion helping to maintain the spline grease from wash out. Many impeller kits do not come with them. I personally do not see a foul in not using one. The impeller fits tight in the housing and unless the impeller cover/wear plate is worn badly it is sealing the splines by impeller to wear plate contact. I change my impeller once a year and still have evidence of grease on the shaft (no spline plug). If it came with the kit use it won't hurt. If it doesn't come with the kit ok just applied small amount of grease to the splines install impeller without it!

Brian,

Have you ever used a tie wrap to fold the impeller blades over for installation? Second, any tricks in keeping the O ring in while putting the plate on...Fat Boy impeller replacer!!! Oh, I got my head stuck in the engine compartment, my center of gravity isn't where it was when I was a gymnast...

I have used Fuel Lube (EZ Turn) to hold O rings in, works well, but hate introducing sticky stuff to the system

 

[ALICE J]

As an aside I had a dealer replace my impeller who was a gorilla. When I tried to replace the impellor it took a 1/2 inch air impact wrench to loosen the bolts. So becareful and make sure YOU can loosen the bolts holding the water pump.

 

[YukonRon]

Thanks all.
It sounds like it's probably not worth pulling it apart again to put the disc in, but I will use it next time.
I did use a zip tie to bend the impeller vanes for installation. It was a bit tricky getting all the vanes to bend the same way as I tightened the strap, but once done it did make installation easier.
I applied Dawn dish soap to the vanes to help it slide in, and to lubricate the vanes until the pump primes, as per this article written by Steve Zimmerman in Passagemaker:
https://www.passagemaker.com/technical/ ... ater-pumps
No gorillas allowed to monkey wrench on my boat! I hate it when tire shops do that to your wheel nuts too 😱 I didn't try to get a torque wrench into that tiny space, but tightened it "good and tight to hold without stripping but not too tight to be able to loosen it again" measure, as determined by gut feel and 45 years of wrenching experience 🙂

 

[BB marine]

I use "cold Vaseline" place a tube of Vaseline in the freezer to thicken it then apply it to the o-ring to hold it in place. Many say never use Vaseline on o-rings it will distort or swell the o-ring. It May, I have never had an issue using it. EZ turn is used for aviation fuel lines that should be ok to use too.

I have never used zip tie straps but if it works for you good method. When I install the impeller in the housing (Volvo D3 ) I slide the impeller on the spline shaft, bearing housing and pulley. Lubricate the wear plate and inside the impeller housing with glycerin lubricant. I apply a slight pressure pushing the impeller in the housing and turning the pump pulley at the same time in the direction of rotation. The vanes will start to conform to the concentric of the pump housing while turning the pulley and the impeller slides right in. Once the impeller is in the housing slide the pulley and bearing assembly out inspect impeller install, install o-ring, apply grease to the spline shaft and reinstall pulley bearing housing align bolt holes, install and tighten fasteners. It sounds easy. I know it isn't in the tight quarters of an engine compartment. PIA

 

[TexasEye]

Thx, no it isn't easy...