Water pump housing leak - PeachParts Mercedes-Benz Forum

eatont9999 · #1 03-02-2014, 02:09 PM

All,

I did some cooling system work yesterday and thought I had everything buttoned up. I am getting a pretty heavy leak at the water pump housing to the engine block that I just noticed today. I replaced the coolant hoses, thermostat, bypass hose and tstat housing gasket. I didn't touch the water pump or water pump housing and the system did not leak a drop before the maintenance was performed. I was not planning to do anything with the WP since it seemed fine, so I don't have any of the gaskets required for it or the pump housing. I am fairly sure that the leak is coming from the WP housing to the block because I don't feel any wetness under the WP. The leak is so bad that without pressure in the system and the engine off, it is dripping 1-2 drops per second. Remember, I did not touch anything to do with the WP housing aside from clean the hose connectors.

I am mid-way through flushing the system. Last night I left a mix of 3/4 gallon of vinegar and the rest water in the system to help remove any residual rust. The mix came out clear this morning. After that, I noticed the leak. I have straight water in the system right now. Yesterday it was 80F out and this morning it was 30F out and sleeting. I checked to see if anything had froze in the cooling system but everything was liquid.

I obviously can't drive the car until the problem is fixed. I have never pulled a WP or housing but the threads I have read seem to indicate it is a PITA to do mostly because of the fastener locations. I will need to remove the belts, fan shroud and bypass housing but what other tricks can I use to get the housing, pump, fan assembly off the engine and into the house where it is not 30F? One of the housing bolts looks like a real PITA to get at. Do I have to remove the WP first? If so, I will just replace it now.

eatont9999 · #2 03-02-2014, 02:28 PM

Wait, I might have a gasket for the WP housing. I think I may have gotten the orientation reversed in my mind. It seems that there may be a small gasket going to the engine block. If so, I have one as well as the WP to the housing gasket. I was thinking that there were two large, flat faces of the WP housing.

Can anyone confirm this is correct? All I have to go off is online pictures. Also, I still need advice on the most prudent way to remove these things.

funola · #3 03-02-2014, 03:32 PM

What probably happened was the vinegar dissolved whatever was plugging up the leak. If the water pump is good, I'd get some GM cooling system stop leak tabs and it will probably stop the leak. After reading so many horror stories of cooling system flush with acid on old cooling systems, I've come to the conclusion it is not a good idea. Lets hope the heater core is not next.

eatont9999 · #4 03-02-2014, 03:42 PM

Quote:

Originally Posted by funola

What probably happened was the vinegar dissolved whatever was plugging up the leak. If the water pump is good, I'd get some GM cooling system stop leak tabs and it will probably stop the leak. After reading so many horror stories of cooling system flush with acid on old cooling systems, I've come to the conclusion it is not a good idea. Lets hope the heater core is not next.

Yeah, let's hope. You might have a very good theory going about the leak. Vinegar is a lot less acidic than the citric acid flushes but since I observed a small amount of rust, I decided that it might be good to get it out. The vinegar was also diluted to about 1/2 strength. It may very well have dissolved particulate plugging a leak and I hope that is all that happened.

I have a water pump and several gaskets on order already. Hopefully they will come in soon. I'm against using stop leak products, so I will drive my other 300SD even though it is mid-way through paint preparation.

funola · #5 03-02-2014, 03:51 PM

Another option is do nothing and just drive it and keep watch of coolant level. I am sure the system is not 100% free of debris even after the flush so the debris will slowly find it's way to the leak and slowly plug up the leak.

cooljjay · #6 03-03-2014, 01:04 AM

This is why I never want to do a flush with anything but water on my cars....to many horror stores...

eatont9999 · #7 03-04-2014, 09:01 AM

Does everyone agree that the order of operations should go like the following?

Unbolt fan clutch
Remove fan and shroud
Loosen alternator and pull the belts off the WP pulley
Somehow unbolt the WP from the WP housing
Remove thermostat housing
Hopefully have access to the bottom passenger side WP housing bolt - remove WP housing
Clean, inspect WP housing and block for cavitation or cracking
Clean surfaces and apply new gasket
Bolt everything back up in the reverse order.

Do I have a good understanding of what needs to be done? The parts should be here today or tomorrow. I will take a day off work to get this done. I might head to the junk yard, after I get the car operational, and pull a thermostat housing and WP housing just to have on hand.

eatont9999 · #8 03-04-2014, 09:03 AM

^Water pump will be replaced in the steps above.^

crazy4diesel · #9 03-04-2014, 01:29 PM

Seems like a good plan, I hope you don't find the level of corrosion I found with mine...was like something ate the aluminum.

eatont9999 · #10 03-13-2014, 08:55 AM

Update:

The job went well with no issues aside from breaking the alternator bolt. It is helpful to remove the water pump from the housing to help access the lower housing bolt. You will need to spin the harmonic balancer until the cut out portion is aligned with the lower housing bolt. I was able to sneak a 13mm open end wrench in there to get the bolt out. It should not be too tight but beware not to round the bolt. Taking the fan off was not bad since I had a thin, long handle Snap-On 10mm box end wrench that just fit right.

Always remember, no one at the factory used RTV to seal anything in the cooling system, so neither should you.

eatont9999 · #11 03-13-2014, 09:00 AM

After repairing the car, I went to PNP and picked up a radiator and shroud, fan and clutch, WP and housing and a thermostat housing for $150. Now I have spare parts for both cars if something ever cracks or corrodes.