Need help water pump… Two steps forward one step back

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michaelbalk330
Posts: 130
Joined: Fri Feb 06, 2015 8:28 am

Need help water pump… Two steps forward one step back

Post by michaelbalk330 »

1) I am having trouble getting Water pump seal to seal. I have late 330, similar to 365GT seal. this is my second attempt and I have a few questions:
a) is it possible it takes a little run in time for the seal and impella to marry and stop dripping out the weep?/.. the reason i ask is as I was filling the radiator the weep hole dripped, but after driving a few miles, the dripping seems to be decreasing. I am pretty sure i did a great job installing this and used some of Tom's tricks which he told me about
b) Is the spacer supposed to protrude thru the center of the carbon seal--- obviously I assume not as then the carbon wouldnt seal with the impella back but just making sure
c) are there any other tricks I need to know about?

2) on a positive note, did all the fluids , new Oil pan gasket, and replaced the MC with a new Bonaldi from europe ( strong dollar!) and she stops like a new car and no leaks.
Michael
1967 330GT #9693
1960 190SL
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1973 450SL
1988 Mercedes 300CE 5 spd
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michaelbalk330
Posts: 130
Joined: Fri Feb 06, 2015 8:28 am

Re: Need help water pump… Two steps forward one step back

Post by michaelbalk330 »

pics
Attachments
_DSF5123.jpeg
_DSF5124.jpeg
_DSF5122.jpeg
Michael
1967 330GT #9693
1960 190SL
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1973 450SL
1988 Mercedes 300CE 5 spd
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tyang
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Location: New York
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Re: Need help water pump… Two steps forward one step back

Post by tyang »

Hi Michael,

WIth a new impeller, it may have to "bed in," but shouldn't leak too much. It may get better as it runs. I hope...

Tom
'63 330 America #5053
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michaelbalk330
Posts: 130
Joined: Fri Feb 06, 2015 8:28 am

Re: Need help water pump… Two steps forward one step back

Post by michaelbalk330 »

thanks Tom
I decided to pull the housing off again-- down to 65 min start to finishe ( from 3 hours the first time!).
The carbon washer cracked- look at about 5 pm on the pic.
I got a new seal from Geoff-- much better than the one I had-- thicker spring, thicker carbon washer.
I will post pics later of the 2 seals. today I am putting it together after using RTV and letting it set 24 hours... hopefully good news..
and i figured out why it cracked.. its all about math- spacer length, if you set the seal to correct depth etc.. I have an old FAF manual that gives all sorts of tolerances etc, and i think this time I will be ok.. we will see!
Attachments
water pump seal cracked carbon.jpeg
Michael
1967 330GT #9693
1960 190SL
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1973 450SL
1988 Mercedes 300CE 5 spd
User avatar
michaelbalk330
Posts: 130
Joined: Fri Feb 06, 2015 8:28 am

Re: Need help water pump… Two steps forward one step back

Post by michaelbalk330 »

For the seal to work the following must occur.
1.the perimeter of the base of the rubber seal must seat well in the engine case, and may benefit from RTV around the perimeter, as long as you are careful not to block the weep hole
2. The surface of the back part of the impeller must be clean, polished smooth and have no imperfections or scores
3. The carbon washer of the seal must be clean and free of any significant imperfections
4. The spring tension on the back of the seal must be sufficient so that the face of the carbon seal and the face of the polished Impeller surface are in perfect contact, parallel. The thin layer of coolant between the 2 surfaces acts as a surfactant/lubricant and will complete the seal.
5. The tolerances are listed in the attachments from the factory manuals.

These are my tips and tricks:
1. I cleaned the engine case very well so that the surface was dry and free of any oil or contaminants
2. I placed a roughly 2 mm solid rod up through the weep hole for 2 purposes:
a. It prevents the hole from getting blocked with any RTV
b. By pushing the rod up to the protruding impeller attachment shaft, you prevent the seal from being pushed in to far. Once seal is placed correctly I removed the rod
3. The spacer that goes around the shaft needs to be short enough to allow the carbon washer to compress as the Impeller is installed. The magic here is the impeller is pushing on the carbon and spring is resisting that push.. it needs that tension to work. If the spacer is too long, it prevents the spring from doing its job and the back of the carbon washer will hit the shaft and no longer compress. This will break the carbon washer if forced. I did purchase a new shaft spacer… However it was far too long for my application and I had to cut off over 5 mm to make it work correctly.
5. There are 2 different seals available. The OEM is what was present in my car likely from 1987 engine rebuild by Bob Wallace. The newer version, shaped as a "top hat "is shown side-by-side with the OEM style. My observations are that the OEM style has a thicker more substantial carbon washer and is less likely to crack. The spring inside is also of larger diameter (this is better). However the OD at the base is a little bit shy of the Top-Hat version and as you can see the shape of the base is not completely perpendicular. That said, with RTV I actually like the OEM style better.
6. You can see one of the Top-Hat styles developed a crack in the carbon but I am quite sure this is because the spacer was too long and overall I think you could get away with both seal types as long as you are careful with measurements, installation, tolerances etc.

Please see the attached pics and ask questions !
Attachments
330oem.jpg
330comparo.jpg
330 comparisonside.jpg
d330diagram.jpg
330FAF1.jpg
330faf2.jpg
Michael
1967 330GT #9693
1960 190SL
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1973 450SL
1988 Mercedes 300CE 5 spd
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