Answer
 

Clean and dry both metal surfaces.
Use one of these products on both sides of the paper gasket, and install following product directions on curing time.

Permatex 22071 Water Pump & Thermostat RTV Silicone Gasket
http://www.permatex.com/products/Automotive/automotive_gasketing/gasket_makers/Permatex_Water_Pump_Thermostat_RTV_Silicone_Gasket.htm

Permatex 80057 300 Form A Gasket
http://www.permatex.com/products/Automotive/automotive_gasketing/gasket_sealants/Permatex_Super_300_Form-A-Gasket_Sealant.htm

Note: Never pressure test the cooling system above 12 PSI.

Thanks, I've got some of the first one. I think I'll get a plastic syringe to apply it because when I tried to use it before it just smeared all over. Hopefully the combination of the re-surfaced face and the RTV will be the charm.
I couldn't find the number to pressure test but I've been going up to 9 PSI; I thought it was a 1 bar system so I didn't want to get too close to that.

OK, tonight I took it all back apart, and carefully dried everything. I removed the stubby hose and trimmed it a little bit, because I think it was overlapping the wrong part of the housing hose and not getting clamped on tightly. I also sanded some crud off the side of the water pump tube, which I thought maybe could have created a leak from that hose. I was really careful to line up those clamps and tighten them propely, which is a fun challenge with the York monster in the way. I took the dried off gasket and put a thin line of the 22071 Permatex on each side ... which for some reason is very difficult to do, it just smears everywhere.:confused: But, I very carefully stuck it on and stuck the housing onto the block, and torqued down the bolts at my best guess torque level. Now I just wait for it to cure. I kind of feel like I just handed in an exam I'm not very confident about and I just have to sit around waiting a day or two for the grade.:P

Auuuuuuugh, now it's leaking out of the water pump.:( It doesn't seem to be coming out of the thermostat junction or bypass hose anymore (victory?), but it's dripping steadily out of the bottom of the water pump and dripping off the front of the oil pan. Please tell me I don't have to take the now-sealed thermostat housing back off to fix this new leak ... I'm afraid to even look at the procedure.:P

Answer
 

NO.

The only accessory drive belt that does not need to be loose is the power steering belt.

The cooling fan needs to come off.

There are five bolts holding the water pump to the pump housing.

Water pump
MB# 110 200 17 20

Water Pump Gasket, Pump to Housing
MB# 616 201 00 80

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Whew ... for some reason I thought the pump was bigger than that. The belts, fan and pulley are already off so this should not be too bad (knock on wood) ... I should probably be glad it started leaking now and not after I put everything back together!
Does the housing itself ever leak? It kind of looks like that's where it's coming from, but it would make a lot more sense to just be the gasket or pump.

Answer
 

Gasket, Water Pump Housing To Block
MB# 616 203 01 80

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Thanks! I hope it's just the front part leaking and not the housing gasket. Will hav to clean it off to see. If nothing else this has been a roundabout way of getting the engine really clean.

So ... when I went to order a water pump they said there was a rebuild kit that would be cheaper, so I ordered that (it was about $30) ... but now that I'm reading through previous forum threads it doesn't look like a rebuild is a good idea. Is that the case? I don't mind taking extra time, but no point in going to all this work if it's just going to fail in short order. I'm sure they will let me change the order to the full pump. Anybody rebuild them or just not worth it?

Gack
 

If you have a machine shop in your garage, a rebuild kit is OK.

I rebuild water pumps on prewar cars all the time, because they are easy.

The MB pump is a pita, requiring at least a two ton press + a few specialty tools, illogical unless there is no option.


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I have a press but probably not the other tools or the skills. I will order the new pump!:o

... it's coming from behind the water pump housing, sort of in two directions, must be that rear gasket. So, not as simple as the water pump.:( Now I have to figure out at least how to get the AC compressor detached, which is a whole seperate project to me because I don't know anything about AC systems. I guess at least I am learning from this. I am getting a little concerned as to why every coolant gasket is failing at once on this car. From what I searched the tstat housing gasket and the pump housing gaskets aren't really common items to be replaced, but both mine went one after the other? Guess I'll just fix it and see what happens.

FYI
 

You have e-mail. :D

..

:eek::D ... thank you!!! That will be a big help.

Now what I'm trying to decide ... the job of changing the housing gasket does not require removing the pump from the housing. Since the pump itself does not seem to be leaking, should I just leave it? Or should I just change it on principle, seeing as I don't really want to have to revisit this job anytime soon. This is when I really wish I had records for this car ... for all I know, the pump was changed 10k miles ago, or maybe it has 366k miles on it.:rolleyes:

Answer
 

It is easier to remove the water pump + wise to replace the gasket as precautionary maintenance.


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