E-Water Pump

[Jorgensen54]

2008 135i/n54

I'm unfamiliar with electric water pumps, but do they fail in a similar way to mechanically operated/belt driven pumps? i.e. weep hole leaking coolant

This past Monday, my car gave me a low coolant light upon shut down after an hour commute to work. As I exited the car, I noticed the faint smell of coolant so I inspected and sure enough my expansion tank is bone dry and there's a puddle on the ground. I haven't had much opportunity to look at the car, but today I finally got under it to remove the belly pan. I then topped it off with distilled water and ran the pump purge procedure. I let the car sit doing this for about an hour while I resumed work then went to check on it. No overflow, no leak, nothing. I thought this would be a good opportunity to really pressurize it with heat and took it for a very short drive; just long enough to allow my thermostat to open. Upon return, parked the car, looked underneath and saw my coolant once again pouring out... luckily heavy in the water aspect of the ratio. I looked around the expansion tank, all is well. Followed several hoses and everything appeared dry. Underneath was another story. Coming directly from the flange of the waterpump(seemingly) is my leak. Is this the norm for others that have failed?

I haven't compression tested the cylinders or performed a leakdown test yet, but is the likelihood of this being the head gasket pretty rare? I've read that these motors are quite robust and my only modifications are axleback, cp/bov, and MHD Stg 1. I'll admit that I've abused the burble setting on the MHD and caused my oil level to dip twice in this particular oil change interval as well as neglected a leaky OFHG. I'm not the most aggressive driver - I'll throttle hard every so often but it's rare for my car to exceed 4k RPM.

This all has come about very quickly and I'm wondering what DIY the forum's would suggest in correcting this issue.

I'm not one to throw parts at a car, but I consider these necessity/preventative maintenance - I have already ordered a new water pump, thermostat, OFHG and OCG and hope to have the parts in early next week.

Also, aside from risking contamination of the motor-what downside is there to removing these parts now and cleaning up the mess several days prior to installing new parts?

[juld0zer]

It can fail in many ways but usually they fail electrically more than physically. I've seen them leak through the plug connector also.

So, if you can see the leak then you have no choice but replace it. Just make sure there is no other leak from components above the pump like the thermostat housing, expansion tank seam and connections beneath. Dont delay your OFHG repair. Do it at the same time as you'll open up the coolant system for it too. You might be losing oil via the OFH. Is there any trace of oil/milkshake in the expansion tank?

[Dackelone]

The e-water pumps often fail with little to no warning. After 60K miles... they should be replaced on a 135i. The 128i's seem to last a lot longer.

Replace the water pump, the thermostat and the U-shaped hose. that connects them.

Also inspect your valve cover for any cracks. They often crack and throw oil all over the place. Your OFH leak could just be a cracked valve cover. ?

Dackel

[Jorgensen54]

Thanks guys for the response. I'll definitely be replacing all of the components at once(forgot all about the U-shaped hose so I'll order that today)

My expansion tank and valve cover look fine from visual inspection. No evidence of leaking. I can see under the OFH that it's got quite a bit of oil residue running down the front of the motor. So much to the point that I leave oil spots where I park.

I do have a small amount of evidence of oil/coolant mixture under my oil fill cap, which has me a bit alarmed. The car starts, runs, drives absolutely fine though. I still don't drive it for the time being. I'm waiting for my parts to arrive before I drain the fluids as I don't want it sitting empty for long, so I guess official diagnosis is still up in the air.

For any of those wondering, I'm at ~86k miles. I'll update this as needed and with whatever resolution comes of it.

[Jorgensen54]

Did this stuff over the weekend. Oil cooler gasket was in far worse shape than the Oil Filter Housing Gasket.
Plastic water neck below the oil filter housing was also degraded to the point of no return. Replaced with a billet aluminum piece - http://www.ebay.com/itm/BMW-335i-115...72.m2749.l2649
Primary coolant leak was the mounting point of the thermostat housing to the waterpump. Mine was completely cracked in two.

Needless to say, I have the same gripes in regards to the quick-release hose couplings.

Now I have no boost so I guess I'll look at my CP fittings and vacuum lines in the area.

[BimmerE82]

I just replaced my electric water pump again 6 months out of parts warranty!! I had it replaced by the dealership 2.5 years ago because it failed. This time around I was getting low coolant warnings and was having to top off my coolant everyday for a week until I could get it into the shop. My Indy BMW mechanic told me my water pump was cracked! He attempted to get BMW to do a "good will" replacement but they said No because the part was 6 months out of warranty!! Unbelievable! So I was on the hook for a brand new water pump again!! I also had the Oil filter housing gasket and the oil cooler gasket replaced while it was in the shop.

[Jorgensen54]

Originally Posted by BimmerE82

I just replaced my electric water pump again 6 months out of parts warranty!! I had it replaced by the dealership 2.5 years ago because it failed. This time around I was getting low coolant warnings and was having to top off my coolant everyday for a week until I could get it into the shop. My Indy BMW mechanic told me my water pump was cracked! He attempted to get BMW to do a "good will" replacement but they said No because the part was 6 months out of warranty!! Unbelievable! So I was on the hook for a brand new water pump again!! I also had the Oil filter housing gasket and the oil cooler gasket replaced while it was in the shop.

Such a drag. Hopefully this one lasts you. I order all of my maintenance items via FCPEuro - so they come with lifetime warranty.

I'm still glad I went through the trouble of replacing all of these items because it was a good DIY on my first BMW and familiarizing myself with my car is one of the fun parts of ownership IMO.

[brytom]

Originally Posted by Jorgensen54

I do have a small amount of evidence of oil/coolant mixture under my oil fill cap, which has me a bit alarmed.

That's normal when a car gets a lot of short trip driving. Condensation and oil will build up to a chocolate milkshake goo on the bottom of the oil fill cap. I see it quite often.