Water pump WILL NOT SEAL. Need Help, I'm at a loss here...

[appatula]

The C36 has been sitting for over a month after coolant decided to start pouring out from what I thought was the seal between the water pump and M104 Block. I bought the MB O-ring and have installed the O-ring dry, twice. Each time I carefully tightened the pump bolts criss-crossing evenly until torqued. Third time I coated the O-ring with high temp permatex coolant sealant which also failed. Fourth through the Sixth (YES SIXTH R&R of pump) I gobbed on tons of sealant and after about 10-15 seconds after startup the water starts pouring. From my observations the water is leaking somewhere from the pump bolt closest to the front of the car on the bottom. I can just manage to peek in and see the drips comming from here. It then drips down the side of the engine block and continues to the opposite side of the oil pan and onto the ground. I have tried cleaning both the surfaces with steel-wool and solvent, then graduating to 600grit wet sanding after the third failure. No cracks are seen whatsoever on the pump housing or the engine block? Believe me I've gone over this six times, looking for a reason each time . What am I missing here? I'm completley at a loss here, both mating surfaces have been checked with a straight edge, cleaned many times, etc. There HAS to be something I am missing, any help or suggestions would be greatly appreciated guys! I miss the Benz and I really don't want to go into a shop. I also have been thinking about a new pump but NOTHING seems wrong with the one I have, I just can't win over this leak? Thanks guys, hoping someone can save me here. it's been 20+ hours of painful labor and I've gotten nowhere.

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[ECTurboGSX]

Can you get it up in the air while its running to locate the leak? Water pumps are a notorious wear item on MB's and it could be leaking from the shaft seal. I had an O-Ring leak on another car and it took about 15 minutes for the car to get up to temp in the air before it started leaking, so don't give up on it if the leak doesn't appear right away. You could also add a dye to the coolant and use a black light to try to trace to the source.

[appatula]

Eric, thanks for the reply. I can get the jackstands out after work and see if that helps any. I should add that the water appears to dribble right on top of a mount that blocks my view from underneath.
I have no clue what this mount is but it has a few things bolted onto it, is fastened directly to the block, and is located under the pump. I recall it supporting the AC compressor and serpentine belt tensioner. Does coolant run through this support block part?!?

I decided to bite the bullet and buy a re-manufactured pump via NAPA. At this point I'm willing to take the chance, it'll either fix this or rule it out as the culprit. The thing I'm worried about is if they will they take the pump back if it turns out not to be the problem?
I'm going to try to be useful to the forum and take some shots of my water pump R&R method. On the bright side I'm getting darn quick at this!

20-25 Minutes to pull it off. (with no plastics or vicious clutch/fan in my way.)

[AMG140.6]

The pump housing flange is most likely warped ?

[appatula]

I agree, that's the only other logical cause that has crossed my mind!

Hopefully this weekend the new pump will fix the issue, keep you posted.

[appatula]

Okay just a heads up to anyone going through the issue of a "non-sealable" water pump. The housing is warped, buy a new one! Just make sure you know your engine number as the M104's had various pumps with additional ports etc. On NAPA they specify "From motor #" or "To motor #". Easiest way to find the Engine number is either to look on the block near to the front of the exhaust manifolds or submit your VIN here : http://www.auto-parts.spb.ru/cat/cats/m.mycat?cat=mb&client=dr2000 Click the Datacard link in the upper right hand corner and find your Engine number .


Now I STILL need help, any master MB mechanics still around??? I'm back to my original problem, overheating, pressure buildup in the coolant system, and crap floating in the coolant resivoir. All signs point to headgasket, no? The thing that is really bumming me out is the cold and hot compression tests I did seem normal. All cylinders are between 135-150psi. Motor has 180k on it and I REALLY dont want to pull the head unless I can get a definitive answer as to whether this will fix this nightmare.

I pushed water through the radiator manually with the hose, no obstructions. Same story through the water pump inlet, water rushed out of the port in front of the block.

I'm thinking somehow when the engine gets warm, the headgasket isd allowing pressure to bypass into the coolant system. So much so that the water pump cannot circulate water, the pressures cancel eachother out and eventually the coolant being stagnant overheats causing the overflow to gush?

I'm working on theory here other than compression tests, and pushing water through the head and radiator to rule out any obstructions.

[ECTurboGSX]

Could it be as simple as a bad radiator cap not allowing the excess pressure to bleed off and run into the overflow tank or a thermostat not opening?

What kind of crap are you seeing in the coolant? I had a warped head on my old Eclipse that did not reveal itself on a compression test. Took the head off to inspect and set it on a table and it rocked a little. I'll have to ponder on your symptoms a bit.

[appatula]

Ahhh good to know I have some brothers with me here on this.......


I have NO thermostat in as of now, is that an issue? Figured it ruled out the thermostat.....thats how desperate I am!

The crud floating looks kinda like lighter colored grease, feels like it to. When the water was dumping out today I could see the tell-tale rainbow effect as it streamed down the driveway with the sun reflecting on it. My radiator cap is however completly shot, the seal has indeed succumbed to age and crumbled.


I'm purchasing a UVIEW 560000 Combustion leak tester to see if any combusion gasses are present or coming up through the head and into the coolant system, good instinct?

Thanks again for sticking with me on this!

[DRBC43AMG]

Looks like a head gasket to me and you could have oil seeping in the cooling system making the crud floating around. By the way, what color is it? Light brown, beige? If so, that is defo oil in the cooling

[ECTurboGSX]

Running without a thermostat would just make the car slow to warm up. Have you done a leak down test? If you pressurize the cylinder and see bubbling at your radiator cap, then you have your answer. You may also want to run your front wheels up on ramps just to ensure that the radiator cap is the highest point in the system. May already be the highest point on a C36, more of a general recommendation and it helps get air out of the system. Good luck.

[appatula]

Originally Posted by DRBC43AMG

Looks like a head gasket to me and you could have oil seeping in the cooling system making the crud floating around. By the way, what color is it? Light brown, beige? If so, that is defo oil in the cooling

Looks just like lighter colored grease just a bit lighter, frothier. I'm colored blind but I'd say Beige, not a lot floating but blobs are in there. I also get the rainbow refraction from the coolant when the water is drained =(

[appatula]

Originally Posted by ECTurboGSX

Running without a thermostat would just make the car slow to warm up. Have you done a leak down test? If you pressurize the cylinder and see bubbling at your radiator cap, then you have your answer. You may also want to run your front wheels up on ramps just to ensure that the radiator cap is the highest point in the system. May already be the highest point on a C36, more of a general recommendation and it helps get air out of the system. Good luck.

It's absolutley worth a try! I'll keep you guys posted.....another thread may be in store!

[DRBC43AMG]

Originally Posted by appatula

Looks just like lighter colored grease just a bit lighter, frothier. I'm colored blind but I'd say Beige, not a lot floating but blobs are in there. I also get the rainbow refraction from the coolant when the water is drained =(

Sorry to say, but that defo points to oil in the cooling. One talks of "mayonnaise" in the water

[appatula]

Originally Posted by DRBC43AMG

Sorry to say, but that defo points to oil in the cooling. One talks of "mayonnaise" in the water

Yep, the crud on my finger felt just like mayo; looked like it as well, just a bit darker in color. If this combustion leak test confirms the headgasket needs to be replaced I guess I'm in for my first head gasket job. Going to start going over reputable local automotive machining shops. From what I've read, AMG didn't leave much to be skimmed. What's a good price for a pressure test and resurfacing on these heads?

[DRBC43AMG]

A bit of skimming and you will obtain a slighly higher compression ratio = small increase in power
I imagine AMG left some material on the head to be skmmed to deal with gasket blowing so that should be no problem

[ECTurboGSX]

I just got my WIS dvd's from Marcus, so I'll have to check this weekend if it gives any kind of spec. Are you going to remove all of the valves and what not? If you take a bare head, maybe $150 to $200?

[503C43 ////AMG]

Originally Posted by ECTurboGSX

I just got my WIS dvd's from Marcus, so I'll have to check this weekend if it gives any kind of spec. Are you going to remove all of the valves and what not? If you take a bare head, maybe $150 to $200?

Unless you have an older version of the WIS than I do it doesn't have the C36 listed

P.S. definitely sounds like a head gasket

[appatula]

Well, UVIEW combustion leak test kit turned up flat out negative! Bought a new vicious fan clutch and radiator cap. Going to flush the water out and fill her up with Prestone sometime next week and see what happends. This gunk is starting to look like a mistake the previous owner made, mixing incompatible coolant colors . It's a possibility, again I'll keep you guys posted.

[desired_speeds]

stick an air hose into the spark plug of each cylinder one at a time and fill the water up all the way. pressurize up to 150psi. then watch to see if any bubbles come up.

Theres this other kit that napa auto parts sells that a hydrocarbon test. you hook it up and the color changes if there is hydrocarbons in your cooling system.