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Rubber or Flat? - Water Pump Gasket

14K views 42 replies 11 participants last post by  plinker17722 
#1 · (Edited)
I'm in the midst of replacing water pump. It didn't go well, head of one of the long bolts broke, rusted out, pump must have been leaking. With help of PB Blaster, somehow able to remove the water pump out.

I have a few questions as I'm having some difficulty, please help.

1) GRAF water pump(said to be OEM) came with two gaskets, one flat one rubber, which one should I use? Original gasket just removed was rubber with some trace of sealant, should I use sealant with rubber gasket? What I read in DIY section on this forum shows to use FLAT one, different year but still confused.
Here's the DIY link mentioned above;
http://www.benzworld.org/forums/w163-m-class/1597370-diy-coolant-water-pump.html

2) Once I removed water pump and gasket, I noticed what looks like a groove / slot as shown in photo #1 below, is this normal, no need to worry about?

3) I'm soaking the broken piece with PB Blaster overnight and then try to turn with vice grip, what's my best option if this doesn't work?

Any and all help is always be appreciated.
 

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#3 ·
You definitely need the rubber gasket with that one. Try get a 6 or 8mm flat punch and give the area around the bolt some light but firm taps. It will spread the alloy slightly to help free up the rusted bolt. Do not deform the alloy.



Give it about 5or 6 light taps in each position. Repeat if necessary
 
#4 ·
You don't have to use sealant , but you can use a bit to keep the gasket/rubber in place.
Don't worry about groove. Just clean everything gently with gasket remover spray or something. Don't use abrasive stuff. Your another option is to carefully use a blow torch. Don't damage hoses & electrical wires with the torch.......
 
#6 ·
When I did the WP on the 2000 ML320 I got the Graf pump also. The engine as put together with the gasket that went in the groove so that is the one I used. Been holding tight for over a year. Once the pump is tightened into place it pushes hard enough on the groove gasket to make a strong seal.
 
#7 ·
broken piece is out finally

Thanks noodles, for confirmation to go with rubber gasket.

Soaked overnight with PB blaster and liquid wrench(yes, I used both), with periodic re-spray, broken piece is finally out. Initially I got freaked out when the rusted bolt gave away without much force at all. A few other bolts are showing some degree of rust, it was pretty obvious the water pump was on its way out. Preventative maintenance is the way to go.

Matt, I gave light but firm taps around the bolt housing area a few times with large punch as in your instruction, I think it helped out a lot. Thanks for the great tip. Now, off to store to buy some replacement bolts, gasket remover and anti-seize.

You guys are great! :thumbsup:


Photo below - one or two more turns to go.
 

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#11 · (Edited)
Matt, there are 3 of the same length bolt, right?
These are #4c in the pic below. I took one of the 4c to a fastener shop in town, the lady measured it as 42mm. You got me concerned.

Now, looking at the picture, I counted there 6 different length of bolts, not 6, I'm worried now. I thought bolts marked as #4d(one), 4e(one) and 4g(two) are all the same length. I'mgoing to undo all #4d, 4e and 4g out and make sure they're the right length.

Do you have the length of these? Thanks.
 

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#14 ·
Here's the measurement I just did.

#4d (only 1) - 80mm
#4e (only 1) - 90mm
#4g (2 of the same) - 110mm
I had placed all the bolts removed onto corresponding hole on cardbord box I made (those shown on many DIY) as soon as I remove each bolt, but now I'm worried that I may have mixed a few, especially #4d, 4e and 4g.
Someone please confirm above size, I'm waiting so I can wrap up the work.



#4c (three of same size) - Replacement bolt filed down to 42mm(with double washer) is on LEFT
Original bolt is almost 43mm long on RIGHT
 

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#15 ·
Oh, one more . . . this isn't going well at all.

Temp senor housing got busted completely while trying to turn it to its original position. Naturally, I tried to plug in to bare poles, broke those as well, new sensor is needed.

I'm going to MB dealer in Portland(80 miles away) tomorrow, but doesn't know how to replace it. Looks like air pump need to be removed so the clip holding the sensor in place can be lifted out, then just pull the sensor out, is this correct way? If not, please help. Thanks!
 
#17 · (Edited)
Thanks Matt.

Can anyone confirm these bolts are the correct length?

Here's the measurement I just did.

#4d (only 1) - 80mm
#4e (only 1) - 90mm
#4g (2 of the same) - 110mm
I had placed all the bolts removed onto corresponding hole on cardbord box I made (those shown on many DIY) as soon as I remove each bolt, but now I'm worried that I may have mixed a few, especially #4d, 4e and 4g.
Someone please confirm above size, I'm waiting so I can wrap up the work.

Thanks!
 

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#19 ·
Sparky, Matt gave you a good advice in post 13.
Also buy bolts which are fully threaded. Not like the one in the picture you posted.
After trying post 13 advice if you are still unsure, use a washer to reduce the size of the bolt.
 
#21 ·
Art, what I got was the best replacement from 3 specialty fastener places. I don't like it but I'm prying for the best. I'll follow Matt's advice and will check how long the bolts in question are.

The cardboard thing is a waste of time. Use the new pump as a template.

What everyone should do is, after removing each bolt, place in the corresponding hole in the new pump. Then when finished with all the bolts, transpose those bolts back to the old water pump.

Here are the confirmations.
Thanks for the confirmation and how I should have done. I'm scratching my now, but it's a bit too late. Those numbers are exactly what I measured. If I had placed correct bolts into corresponding slots, I should be OK, I hope.

I have new hoses, temp sensor and thermostat, hope everything ahead of me is going to be OK. Thanks all for your help.

Steve
 
#23 · (Edited)
Jim posted part numbers for all the bolts, but doesn't show which bolt goes to which hole. The first two bolts are 80mm 90mm long, respectively. But which one is for #4d or #4e wasn't shown. Right now, I had placed 80mm long bolt in hole #4d, 90mm to #4e, they are the ones I need to confirm. I'm 99% certain they're placed right, but the 1% . . . the reason I'll pull them out then see if I can measure the depth or not. All others are 100% certain. In Jim's list, #4d & 4e, they're both for "to timing case and to cylinder crankcase"

No, replacement bolt is not fully threaded, what's pictured is the closest one I could find. This is an industrial port town, the stores I went have millions of bolts, nuts and every fasteners imaginable available, but not what I was looking for, I'm truly shocked.
 

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#27 ·
Mine came with a rubber o ring that sits in a groove .And i used hylomar blue also as a fail safe .But if you do use a sealer as well , you have one strike at it ,, so push it on the bolts and dont remove it after . If you do it dislodges the o ring .I know i did lift it off to see if it was in the right place ,and o ring came out of its groove .So i had to start all over a again. Good luck by the way with the pump .
 
#28 ·
Thanks for your advice, but I'm not going to remove the water pump. We're talking about just a single 42mm bolt out of 14 bolts. I don't think the O ring would know.


Art and Jim,

Thanks again for your concerns on 'partially threaded bolt. I tried to get exactly what came out, but thinking holes in water pump are not threaded, instead they're pass through holes, no gripping there, right?

Here's what I read in the article Jim suggested to read. But I'm worried enough, will look for a fully threaded bolt, I'll get one from somewhere sometime, my ML will sit in the garage over the weekend. I'll heed to your concern, will get a fully threaded bolt from somewhere sometime. After all, you folks know better and more from your experience. I'll be needing your help for long time to come. :bowdown:


Someone please tell me which hole this M8, 80 mm long bolt should go in, 4d or 4e?


* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 

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#30 ·
Water Pump - different bolt sizes and lengths

Thanks Matt, I'm waiting! :thumbsup:

There are 15 bolts that are critical to water pump mount including the idler pulley mount(internal torx, I'm not worried about this one). 4 different shank sizes, 7 different lengths. I think I have them all mapped out correctly, but I'm waiting for confirmation. Here's the list.

#4b (7 pieces) - M6 23mm
#4c (3 pieces) - M6 43mm(I measured these to be 42mm)
#4d (1 piece) - M8 80mm
#4e (1 piece) - M8 90mm
#4g (2 pieces) - M8 110mm
#4h (1 piece) -internal torx - didn't measure this one
#4i (1 piece) - didn't measure this as well, mounted on alternator


Just stopped at local Napa Auto Parts to pick up a torque wrench capable of 5-80 lbs , what'd ya know, they had this 42 mm fully threaded bolt! I only checked big specialty stores not the small local one, my bad, shame on me!:banghead::banghead::banghead:
 

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