3.5 waterpump leaking water...help

[werminghausen]

I had my waterpump out because I had broken off one of the 3 top screws holding the housing for the temp sensor after I had a leaking coolant rubber form the steel line across the block to the waterpum. The 3 bolts holding the top housing were entirely corroded, so I had to remove the pump and operate the remaining bolt threads out...very delicate...
I succeeded in the end with a machine shop helping me and I reinstalled the pump with the result that the pump was leaking coolant after reinstall ...grrrrrr.
What on earth is going on? Are these pumps prone to leak? Pump is leaking only under coolant pressure... when engine is hot and not when cold.
Water is dripping from the underside of the shaft from a hole in the housing. Must be a seal
What is the cure? ...I know: replacing the pump....
Best, Martin

[WANT '71 280SEL]

It's coming out the weep hole. "I hate to say I told ya' so..." ha ha ha. I'm literally in the middle of doing mine. It's a pretty straight forward job, just time consuming. On the bright side, it opens up the whole front of the engine so you can spend 4 hours detailing it! I wouldn't say it's any more prone to leaking than any other water pump. Here in the States I paid $80 for a new one w/ a lifetime warranty. The rebuilt one was $70. I know you're in Oman so I'm not sure how it would work out for you.

Best Regards,

David

[Graham]

Originally Posted by werminghausen

What is the cure? ...I know: replacing the pump....
Best, Martin

I have same problem on my car. I only get a small drip with no noticeable loss of coolant, so job keeps getting put on back burner.

But I did look at alternatives (prices are rough and from memory, but in right ballpark)

- New pump from dealer ($500)
- rebuilt pump from dealer ($400)
- aftermarket pumps ($60-$150) Cheap ones not recommended. Laso recommended. Graf also likely OK. Not Bosch.
- rebuild existing pump myself (seal from dealer about $60 - method in shop manual))
- have Cardon rebuild existing pump (low cost - about $40 but with shipping back and forth not much less than new pump?)

Cardon stock rebuilt pumps, but for some reason, they say they are only good for 73 and later. Some vendors of new pumps say this too. I know of no difference between 72 and 73, but when I asked I received to good answer. For 72 cardon say to send existing pump for rebuilding.

[werminghausen]

Originally Posted by Graham

I have same problem on my car. I only get a small drip with no noticeable loss of coolant, so job keeps getting put on back burner.

But I did look at alternatives (prices are rough and from memory, but in right ballpark)

- New pump from dealer ($500)
- rebuilt pump from dealer ($400)
- aftermarket pumps ($60-$150) Cheap ones not recommended. Laso recommended. Graf also likely OK. Not Bosch.
- rebuild existing pump myself (seal from dealer about $60 - method in shop manual))
- have Cardon rebuild existing pump (low cost - about $40 but with shipping back and forth not much less than new pump?)

Cardon stock rebuilt pumps, but for some reason, they say they are only good for 73 and later. Some vendors of new pumps say this too. I know of no difference between 72 and 73, but when I asked I received to good answer. For 72 cardon say to send existing pump for rebuilding.

Hi Graham,
I am really loosing water it is not just a few drops. I need roughly 1 liter per 50 miles.
Do you have the specs of the shaft seals...which I guess are replaceable? Is the set of seals a normed part I could chase down here in Oman? Or is it a custom part from the pump manufacturer? I don't know where to get it.
The impeller can be pulled which might work somehow with a standard puller ( I have a few pullers).
The bearing seems to be a 'compact bearing' instead of 2 standard ball bearings. So I won't touch this one as they seem to be just fine.
Can anyone send me the seals in an envelope... this thing can't be $60!....then I'd attack the job here in Oman.

[werminghausen]

Originally Posted by WANT '71 280SEL

It's coming out the weep hole. "I hate to say I told ya' so..." ha ha ha. I'm literally in the middle of doing mine. It's a pretty straight forward job, just time consuming. On the bright side, it opens up the whole front of the engine so you can spend 4 hours detailing it! I wouldn't say it's any more prone to leaking than any other water pump. Here in the States I paid $80 for a new one w/ a lifetime warranty. The rebuilt one was $70. I know you're in Oman so I'm not sure how it would work out for you.

Best Regards,

David

David
I was just removing the pump for one reason: the replacement of the broken bolt sticking in the aluminum housing...enough pain to remove all the pump for pulling one broken bolt..... having now a seal failure after reinstall is a disaster.
But second time the removal will a piece of cake.... I just need the seal or a new pump....

[WANT '71 280SEL]

Martin,
Did you pull the radiator when you did all this work? It looks like I need to go back into mine as I had a buddy replace my WP and it's leaking almost as bad as the old one. I don't know if he omitted a bolt or what. It's not coming from the weep hole and the hoses are tight.

Thanks,

David

[Graham]

Originally Posted by werminghausen

Hi Graham,
I am really loosing water it is not just a few drops. I need roughly 1 liter per 50 miles.
Do you have the specs of the shaft seals...which I guess are replaceable? Is the set of seals a normed part I could chase down here in Oman? Or is it a custom part from the pump manufacturer? I don't know where to get it.
The impeller can be pulled which might work somehow with a standard puller ( I have a few pullers).
The bearing seems to be a 'compact bearing' instead of 2 standard ball bearings. So I won't touch this one as they seem to be just fine.
Can anyone send me the seals in an envelope... this thing can't be $60!....then I'd attack the job here in Oman.

I have not tried to find a standard seal. I used EPC to find the number and checked prices from dealer. Here is a picture with part numbers - you can check them with dealer or maybe on-line suppliers. If anyone finds a low cost seal, I am interested too!

In checking a few places, it seems that seal may be hard to find. I did find this one and price is as I stated.

[werminghausen]

This is great information Graham. Thanks so much. I have seen the seals in the shop manual in section. I still don't get how the seals are working technically. The 2 parts seem to be pressed against each other?

Well the prices for the seals are insane. This is in the region a new pump!
Replacing the seals under these conditions doesn't seem to make sense.

This must be a custom seal. Otherwise the prices would be way lower.

[werminghausen]

Weird thing is that I have not lost a drop of coolant today and I was driving like 80 miles. I am confused.

Does the seal be able to repair itself ...if there was a small damage by a metal part which got stuck there for instance?

[Mike D]

Post #6.

http://www.peachparts.com/shopforum/vintage-mercedes/337351-300sel-4-5-water-pump-replacement.html

[werminghausen]

Originally Posted by Mike D

Post #6.

http://www.peachparts.com/shopforum/vintage-mercedes/337351-300sel-4-5-water-pump-replacement.html

You are right so with your warning. Thanks. I'd hate to have the pump puke and kill the engine. I'd love to replace it but I don't have a new pump. I am hoping that someone can bring me the pump from Europe...cost point 63 Euro. If I have it shipped it will cost much more.
Martin

[Graham]

Originally Posted by werminghausen

Weird thing is that I have not lost a drop of coolant today and I was driving like 80 miles. I am confused.

Does the seal be able to repair itself ...if there was a small damage by a metal part which got stuck there for instance?

Martin,
It is most likely a mechanical seal. In other words, it has an integral spring that pushes the seal against a face. This pic shows a typical seal (but on MB, the bearing is integral unlike the one in pic)




It is possible that dirt would affect such a seal. It is also possible that if the bearings have slight wear, that the seal self aligns as it gets up to speed. On my car, it seems to leak when started up cold, but not much while driving. then it leaks again when parked. But I no doubt have a much smaller leak.

Cardon charge less than $40 to rebuild the pump, so I suspect that there is a standard commercial seal available. To find one, I think you would need to take a sample to a company selling mechanical pump seals.

[werminghausen]

Originally Posted by Graham

Martin,
It is most likely a mechanical seal. In other words, it has an integral spring that pushes the seal against a face. This pic shows a typical seal (but on MB, the bearing is integral unlike the one in pic)




It is possible that dirt would affect such a seal. It is also possible that if the bearings have slight wear, that the seal self aligns as it gets up to speed. On my car, it seems to leak when started up cold, but not much while driving. then it leaks again when parked. But I no doubt have a much smaller leak.

Cardon charge less than $40 to rebuild the pump, so I suspect that there is a standard commercial seal available. To find one, I think you would need to take a sample to a company selling mechanical pump seals.

Thanks Graham, I found the set of seals on US ebay for $ 30 (plus 23 shipping) :
Mercedes Benz W107 W116 M116 M117 Engine Water Pump Gasket Kit 350 450 | eBay
I can at least see the pictures and can imagine how the seals work. Does the plastic edge of the big seal (with the spring) press against the metal ring (w/o-ring) ? Does this rubbing connection not get hot?...may be it is water cooled?
Martin
$ 53 is too expensive. Martin

[Graham]

Originally Posted by werminghausen

Thanks Graham, I found the set of seals on US ebay for $ 30 (plus 23 shipping) :
Mercedes Benz W107 W116 M116 M117 Engine Water Pump Gasket Kit 350 450 | eBay
I can at least see the pictures and can imagine how the seals work. Does the plastic edge of the big seal (with the spring) press against the metal ring (w/o-ring) ? Does this rubbing connection not get hot?...may be it is water cooled?
Martin
$ 53 is too expensive. Martin

Yes - The part with spring has a stationary face, often ceramic, that mates with a rotating hard metal face that is fixed to the shaft. Known as single mechanical seal - very common on industrial pumps (and it seems car water pumps!)

I will first try NAPA and see if they can have my existing pump rebuilt by Cardon (In Canada Cardon said I should go to NAPA). If that doesn't work out, I will probably buy the Laso pump or failing that, a Graf. Mercedes pumps are just too expensive. If I get a new pump, I may then try and find a generic seal that fits the old pump and keep it as a spare.

[werminghausen]

Bugatti
I found a water pump on German ebay for 63 Euros (found also someone bringing me the pump for free!). Now the manufacturer is Bugatti.
Does someone know this manufacturer? Is this decent quality?

On the internet I found the Italian company Bugatti..manufacturing since 1973 (http://www.bugattiautoricambi.it/catalog/searchByCodes.jsp) look for #PA0139

Martin