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Bellows Longevity

J

jeffnick

Regular Contributor
I see where it's recommended to store the boat with the drive down in a straight ahead orientation. One should also remove the drive yearly at winterization? I'm wondering if this means bellows can be reused for several years, if not why does it matter how we store the drive in season?
 
rubber gets a memory, storing it for winter layup with the drive up puts that memory with half of the bellows expanded completly and the other half compressed, which can lead to tearing. with normal wear ive seen bellows in the utah/northern arizona area go 8 to 10 yrs, there is a 6 to 8 month boating season. I believe that its suggested replacement is 5 yrs. I check mine every time i go out with a quick look and feel as if it leaks you will know when you launch and check your bilge on startup. its a maintenace item and wear item, recomendation is for longest life.
 
Yep!
Drive Shaft bellows are heat formed in an orientation (or position) that most ressembles a drive position of Fully Down, steering straight ahead.
When we keep this orientation, we extend the life of the bellows.
Limited UV exposure helps as well.

The OEM bellows are a better quality, and tend to fair Father Time a tad bit better than the Sierra, for example.

I do not remove my drives for the winter. I see no value in this what-so-ever... unless you have theft concerns!
When a drive is fully down, any residual water is drained.

If you want to pull something, pull your impeller out of the pump body, and store it for the layup duration.
Impellers do not normally go bad from normal usage..... they go bad from sitting at rest within the pump body while three/four vanes are folded over against the cam.
This is when the "Set" occurs to the rubber...., similar to bellows when a drive is stored fully UP and/or turned one way or the other.
Do this, and you will gain impeller longevity.

.
 
RicardoMarine said:
If you want to pull something, pull your impeller out of the pump body, and store it for the layup duration.
Impellers do not normally go bad from normal usage..... they go bad from sitting at rest within the pump body while three/four vanes are folded over against the cam.
This is when the "Set" occurs to the rubber...., similar to bellows when a drive is stored fully UP and/or turned one way or the other.
Do this, and you will gain impeller longevity.
Click to expand...

Rick, I find that when I pull the pump cover off to remove my impeller for the winter, the paper gasket often is damaged and cannot be re-used. In those cases, I end up having to use the gasket from a new impeller, so I'm always a gasket short vs. the number of spare impellers I have. Is there a secret to being able to re-use the paper gasket?
 
I hear ya!
My secret is to glue the gasket to the cover using a very thin layer of RTV.
I don't like RTV for anything wet, but it seems to work OK.

See if Volvo can supply you with extra gaskets..... or, next time that you have the pump removed, make up several gaskets.
You should be able to buy some thin material for this.
 
several of the autoparts stores here in FL sell a 3ft roll of gasket material for like $7.00 if you can find the same in your area just lay the cover from the pump on it,trace around it with a sharpie, then carefully cut it out with a razor.you can get 30 gaskets easy with the one roll.
 
Thanks. These gaskets are made of very thin material and at their widest part, about 3/16" wide, so cutting them out will be a challenge but I'll give that a shot.
 
Thanks Joe! I never thought to check to see if they were available separately from the impeller. DOH!
 
FYI, not that you need this........, but the cover plays a role in the compression force against the thrust surfaces of the impeller.... ya know, the ends that ride against the deepest bore and against the cover!

Side step:
The later V/P V-8 crankshaft pump (the one that is integral with the serpentine style front shiv), uses an impeller that looks identical to the std 1027 impeller (that is common among the Johnson style crankshaft pumps).
Appartently there is .010/.020" differennce in the width of these two impellers..... otherwise, they look the same!
If the 1027 is installed in this pump, it bleeds back pressure to the suction side while at low RPM, and apparently can cause over-heating at low RPM.

Point being... yes, this is a very thin gasket, and we don't want to install a heavy gasket here that may change the thrust clearance dimension.
So always use the thin gasket here.

Long as we're on topic:
The lower volume FB5-9 Johnson crank pump is similar to Jabsco's lower volume crank pump.
Johnson uses 4 cover screws.... Jabsco uses 6.
Each uses the same 1027 impeller (and an array of other p/n's for an equivilant impeller).

Both Johnson and Jabsco offer a higher volume crank pump.
These pumps look the same as their lower volume...... but the impeller is wider... pump body is deeper!
Each uses a different impeller, but they look identical unless you were to measure them.

Johnson impeller is 1.900" wide.
Jabsco impeller is 1.990" wide.
Same diameter.... same blade count, etc. and it's tough to tell the difference by appearance only.

If you were to install the Johnson impeller in the Jabsco pump, you will have a problem.
It will breach suction!
(Jabsco impeller will not fit into the Johnson pump..... so no issues that way)
Parts guys often get this wrong by not asking the customer for a pump ID and/or model number.
The customer walks out the door with the wrong impeller.

So..... use caution! :D

.
 
Thanks Rick. Now that I know I can order OEM gaskets for my pump, I will do that instead of trying to make my own. On a related note, MPE wants $12 shipping for 10 gaskets! Unbelievable considering you could stick them in an envelope and send them via the USPS for 44 cents.
 
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