6.9 Water Pump replacement

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FYI you should always remove the distributor with the engine on TDC & sufficiently marked to allow easy installation

 

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I have a NOS seal but without a press with suitable equipment & specific knowledge about how it comes apart, I don’t wish to risk damaging the fragile impeller or housing. It should be finished mid week, so we’ll see the quality of their work.

 

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Note when rebuilding the pump that the distance bw the housing & the impeller (a) cannot exceed 1.2mm

 

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Tightening torque & capacity

 

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Note the different pumps that were available

 

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Just in case you decide to attempt balancer removal…

 

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I decided to check the water pump after the inlet manifold disaster where I thought there could be nothing left of the impeller. I did find coolant deposits blocking the weep holes in the pump so it was beginning to leak anyway. The housings are relatively good with minimal corrosion, but it’ll certainly need a good clean.

 

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A curious feature of the engine block is the large round hole behind the water pump distribution (secondary) housing. The hole leads directly into the crankcase but is sealed from outside by the gasket. In addition, the bolt holes are also open & lead to the timing chain cavity & sump. Care must be taken when cleaning the area that nothing drops in & when flushing the block with water it would be unwise not to pay attention. Anyone take a guess to the purpose of the large hole??

 

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Note if the secondary housing fails or corrodes through, it will fill the sump with coolant which is hardly a great design!

 

[Patrick_R]

More excellent work Mark.

 

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Thanks Patrick! Below is the pump after reco & finished in just 2 days!! They even supplied a free gasket which it seems they made in house… I’m getting the impression they can fix anything cooling system related & probably many other things too!

I am concerned about the level of corrosion in some areas. I could have it repaired, but the cost may be significant. Certainly a new pump & housing would be better, but I’ve heard they’re NLA now & were $2.5k when you could order one anyway. I wonder if you can still get the secondary distribution housing??

 

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The work was undertaken by ‘Auto Cooling Pty Ltd’ F7, 216 Blackshaws Rd, Altona North, Victoria, 3025 Ph 93627799 email autocooling@bigpond.com

They also do radiators & intercoolers & I can now recommend them highly.

 

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Worthy of note is it appears they replaced the impeller so it may be impossible to remove without destruction. Obviously they have a source for new impellers with the correct dimensions.

 

[Styria]

Mark, what an excellent write-up and so well illustrated. Any budding home mechanic should now be able to perform this task with a certain amount of confidence. I would just add, if I may utilize your post, that it is not entirely necessary to remove the crankshaft damper. It's easy enough to remove with the right puller, but re-installation can be very tricky and, if not done correctly, can result in damage to crankshaft and balance surfaces. Remedial action would be just about impossible. It can also be possible to extract the water pump itself -, but the impeller is an interference fit and sometimes the pump cannot be eased past the Aluminium housing itself.

BTW, I have on hand two rebuilt pumps on an exchange basis, subject to satisfactory core units in exchange. From your illustrations, I would be very guarded in accepting a pump on exchange. A lot of neglect is evident. Again, thanks for a great write up. Oh hell, I meant to also mention that I have a genuine Mercedes Benz replacement bearing on hand- it's going at a good price. Regards Styria