250 water pump

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chris
Posts: 142
Joined: Sat Mar 02, 2013 7:52 am

250 water pump

Post by chris »

Hello Tom, all,

I do have two question for the experts and hope you can help me there. I have fully reconditioned my 250 Gte engine and now have it running on a small self build test rig - see photo.

It is running fine but after some time water started to come out of the seep hole of the water pump. I overhauled this with a kit from GTO and they said they use this without problems. I did therefor not use the old spring as recommended in other threats.

Now that I have to do it again I was wondering if you have experience with the update kits available using the latter seals from 365. I know there are conversions from Bell Classics and Roeloefs. Any experience or recommendations?

The second question is about removing the pump: do you slacken the cam chain tensioner before dismounting the pump? I would guess so but would like to know what the experts do? I am not sure how much strain the chain puts on the shaft when the water pump is dismounted. It is clear to me the dismounting has to be done carefully to make sure the shaft with bearing at the end stays in the chain housing.

Any hints welcomed. Thanks a lot.
Christopher
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tyang
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Re: 250 water pump

Post by tyang »

Hi Chris,

Unfortunately, if you use the 365 water pump seals, the whole water pump housing has to be removed to machine the housing to fit. This will require removing the shaft that locates the timing chain. Removing this will require dropping the chain and retiming everything. I would confirm this with the other kits available.

Changing out the water pump seal with a stock 250 seal does not require removing the whole housing, and can be done by pulling the front housing off, removing the impeller, carefully pry the old seal out while keeping the shaft seated in the timing case. If the water pump shaft comes out, it will come out of alignment with the rear bearing holding the chain sprocket. if this happens, everything has to be retimed. Since your engine is out of the car, it will be a lot easier to do this seal change, but put the engine on TDC just in case!

Check the flatness of the sacrificial plate on the back of the impeller. I've found some soft spots in this steel piece that didn't mate up with the carbon face of the wp seal. Also put some kind of lubrication between these mating surfaces like petroleum jelly or even anitfreeze so these parts don't fuse together on start up. I've seen the steel plate corrode from sitting for long periods of storage before initial start up.

Good luck!

Tom
'63 330 America #5053
chris
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Joined: Sat Mar 02, 2013 7:52 am

Re: 250 water pump

Post by chris »

Tom, Thanks a lot!

I will need to think of what to do now.

Thanks
Christopher
DWR46
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Re: 250 water pump

Post by DWR46 »

Tom: We have done quite a few of the Daytona style conversions and we NEVER release the chain tension. As long as when you remove the center seal holder, you make sure the shaft is pushed back into the chaincase, the shaft will stay in place secured by the rear bearing.
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tyang
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Re: 250 water pump

Post by tyang »

DWR46 wrote: Mon Nov 16, 2020 12:12 pm Tom: We have done quite a few of the Daytona style conversions and we NEVER release the chain tension. As long as when you remove the center seal holder, you make sure the shaft is pushed back into the chaincase, the shaft will stay in place secured by the rear bearing.
When I made the modification to the Daytona seal, we found the diameter of the ceramic disc was larger than the one in the wp housing, so the back plate had to be removed. We did this before assembling the engine so we didn't have to worry about the shaft staying in place. The front bearing is held in place with a c clip in the wp housing, so it can get tricky to keep the shaft in place if it hangs up on the front bearing.

Tom
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Menlodon
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Re: 250 water pump

Post by Menlodon »

I just did the water pump seal on my 250.
I worked in the chemical industry and worked with several US seal manufacturers.
They agreed on one thing - never lubricate a shaft seal face.

I gave up on Ferrari type seals a long time ago and have sucessfully used John Crane seals and modified the pump to suit. I have had the Ferrari seals just fail wher the carbon attaches to the rubber. I did this mod to other Ferraris too.
Also, the rotating ring has to be extremely flat To do that coreectly takes special equiopment I had mine relapped by the local John Crane distributor.
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tyang
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Re: 250 water pump

Post by tyang »

Menlodon wrote: Tue Nov 17, 2020 1:42 pm I just did the water pump seal on my 250.
I worked in the chemical industry and worked with several US seal manufacturers.
They agreed on one thing - never lubricate a shaft seal face.

I gave up on Ferrari type seals a long time ago and have sucessfully used John Crane seals and modified the pump to suit. I have had the Ferrari seals just fail wher the carbon attaches to the rubber. I did this mod to other Ferraris too.
Also, the rotating ring has to be extremely flat To do that coreectly takes special equiopment I had mine relapped by the local John Crane distributor.
Thanks for your thoughts. With the modified seals, we leave everything clean. We tried lubrication as a last resort after installing a original type carbon seal and face plate only to have it leak after somehow sticking to each other and pitting the steel plate. Perhaps moisture got between the surfaces before start up, so we tried this to keep the surfaces from rusting. Not sure if this worked, but luckily we didn't have a leak.

Tom
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chris
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Joined: Sat Mar 02, 2013 7:52 am

Re: 250 water pump

Post by chris »

Hello Tom,

have the water pump dismounted an shaft still in as adviced by Dyke and will have Daytona style seal conversion.
Build a simple tool to fix the shaft. See pic. Worked fine.

Christopher
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