430 I Rebuilt my water pump

Pretty summed up title. I noticed that one of the weep holes had some crusties, also noticed fresh coolant on the bottom cover once removed. It was very obviously leaking for quite some time even prior to purchase and I'm a little frustrated that the PPI didn't catch it otherwise I would have asked to have it addressed prior to purchase, c'est la vie. I also noticed that the upper o-rings of the oil pump side appeared to show some leakage. With the pump removed it was pretty clear they were in not great shape. I feel like it should go without saying, but everything was replaced with new o-rings prior to install.

Pictured is the coolant on the cover the first time I pulled the cover off about a week ago to do some fluids. I cleaned everything and figured I'll keep an eye on it but get a kit coming anyway. The next one is the cover today upon starting the work, so it was certainly getting worse.

As for the job, with anything on this car there are some difficult things. The two items I struggled with:

(1) one of the four bolts holding the motor mount bracket to the engine was really difficult to get something on. The service manual even has a welded together wrench to access this one bolt (B5.02, page 149). I ended up grinding down one of my cheaper Cornwell 17 mm sockets, used a wobble head extension, and a specialty wrench from snap-on in my collection to get it off and on.

(2) one of the two snap rings to remove the water pump impeller shaft from the housing is buried fairly deep (as in about an inch down) but in a very limited circular area, and technically requires some deep reaching but also really narrow snap ring pliers. I was able to essentially disassemble a pair of my snap ring pliers (they're reversible so it's a button to release the two halves) and use half of the plier and a straight pick to get the snap ring out.

For the most part it's pretty straight forward to replace the seals and all. Once inside the water pump it was clear that both of the mechanical seals were bad, the one obviously allowing coolant out of the weep hole, and the other, while still holding fluid okay, showed more crusty than the obvious bad one.

I used the rebuild kit from AW Italian, everything worked and fit perfectly with no issues. I also bought a new thermostat to get that on there too as a "while I'm there" thing. I also replaced the 3 large o-rings between each oil pump section as yet another "it's already apart so I might as well." Prior to starting the work I drained all the oil and upon removing the coolant hoses obviously drained the coolant. Once everything was reinstalled with a new oil filter, I refilled the oil and I have a coolant flush machine from a company called BG at my shop that I hooked in to the expansion tank hoses and flushed/bled the cooling system with new coolant (I literally never read a conclusive comment on what coolant to use but given there was already blue in my system, I landed on BMW blue coolant). Ran the car for 30 minutes with the covers off and not a drop of fluid to be found from anything. My 20 minute drive home the coolant temp was extremely steady, oil pressure was good, and had really warm heat from the vents.

Lemme know if you have any specific questions!
- Shane

 

Lol I get it. I've been hoarding exhaust parts to do it all at once along with a trev tune (I REEEAAALLLY want your old Kline exhaust but I need to get thru taxes, my a.s.s. always owes! can I give you a down payment to hold it for me!?) But regular maintenance can't take a backburner, can't have a nice sounding car if the water pump seizes!

They sure can! Having done one now I'm confident it can be done in 3-4 hours start to finish. So it's really not horrendous. It definitely beats spending $2300+ on a new unit to simply replace when it's just the seals that go bad.

There is, however he doesn't really go in to a huge amount of detail of the actual rebuild. It's more of a "here's the water pump, we're rebuilding it, and also here's the oil pump side." It is however where I got the details for the large o-rings that go in between the oil pump sections so it wasn't completely useless.

 

That is the correct rebuild kit, the difference between the two is the one you linked is more complete essentially. In my haste I purchased the other kit which is JUST for the water pump and doesn't include the o-rings for the mounting back to the engine block and the large o-rings for resealing the oil pump sections so I ended up having to order all of them separately. Long story short, purchase the kit you have linked. As a word of caution, I wouldn't continue putting it off for too long. The whole unit runs off one shaft and if for some reason the coolant corrosion causes resistance in the bearings due to infiltration, it could technically lock up the oil pump as well.

There is a guy on here who also sells a kit (it wasn't the person you linked however). I did reach out to him but in the immediate moment and concern for getting a kit and not knowing how quickly he would respond, I ended up going through AW Italian. Not trying to bash him at all but his email after I had mentioned I went with this kit he sent back a "good luck with the Chinese seals" response which was slightly off-putting for character. The bearings in the kit were labeled with an Italy stamp and granted the seals were not labeled with much indication, they all fit absolutely perfectly. Sure, for all I know it could start leaking again, perhaps then I either purchase his kit or simply purchase a whole new unit. But for $400 shipped (he sells his for I think $380 or something?) I'm genuinely not concerned about it especially after driving it and seeing perfect temperatures, no obvious leaks, and no noises from anything water pump/oil pump related.

 

No problem, you are remembering perfectly fine Rob. I have no doubts that the other kit that is sold by the member on here is good. It was really my quick decision combined with not knowing how much longer I had on the current leakage that I went with the AW kit.