Water pump

Searched for water pump; no results.

Need a new pump with cast-iron impeller. Have a good housing; don't need another. Thought the pump part # was 037 121 005C, but AutohausAZ shows that part has a stamped sheet-metal impeller.

Anyone know of a good part # for a Mk3 water pump w cast-iron impeller?


Thanks!

The part number is good, 037121005C but impeller design will be up to the manufacturer. Some use stamped steel, some use cast but I'm not sure anyone does cast iron anymore. I have seen some with cast aluminum impeller and some with a synthetic impeller in the shape of the cast product.

Geba used to be the pump of choice a while back and based on the pics at ECStuning it looks like it still might use a cast impeller, but I would want to verify that with ECS before I purchased one if that's your preference.

Seems the last one I installed on the wagon was Geba but also I think I have a GMB in a box somewhere too, but I don't think that one has cast impeller.

Good luck

Steve

Thanks, Steve!

With that part #(005C) ECS offers both cast and stamped impellers. A GEBA with cast and a Graf with stamped.

What's the performance record of the stamped impellers? Do they stay on?

I’ve had no issues with stamped steel impellers. I had a plastic cast Bosch pump, and the impeller started freewheeling.

-Todd

I’ve had two stamped impellers (Graf) fail early and a dozen more that we’re fine. I’ve also seen the cast ones fail, so nothing is immune. I refuse to install one with a non-metallic impeller. The Geba does have the cast impeller and the Hepu stamped. I just installed one of each not long ago.

every stamped impeller i have ever used, i always have put a small tack weld on it, never had any issues.

Mongler98 said:

every stamped impeller i have ever used, i always have put a small tack weld on it, never had any issues.

Click to expand...

That's a good idea! Are the impellers stainless?

clyde said:

That's a good idea! Are the impellers stainless?

Click to expand...

not that ive noticed, if it is, its defiantly not 304. it welds like any other steel sheet metal thats been galvanized. i have never noticed a burn off of the galvanized metal though or rusting on the welds as the pumps i do it to all live in a healthy antifreeze mix of whatever the car it goes into needs.
If i had to guess, its a cheep stainless plating thats on it. If i remember to, i will leave one that i take off and let it sit outside for a bit and see if it rusts.

I can say that the tack weld i do is very small, i basically just put 2 pencil eraser sized spot welds on it and file it flush and let the penetration of the weld do the work.

clyde said:

That's a good idea! Are the impellers stainless?

Click to expand...

Not really since it'll throw off the impeller being balanced.

Abacus said:

Not really since it'll throw off the impeller being balanced.

Click to expand...

Of course you're right, Abacus, the rotating mass will change the balance of the rotating parts.

It's a crapshoot, though, whether the direction of change would be negative or positive. The rotating mass is probably not very close to being balanced to begin with…

The two tiny spots of weld are so close to the center of rotation and the mass of those welds is insignificant compared to mass of the hub and the pulley. Would the tiny change even be noticeable without using very sensitive scientific instruments?

Give it a try and let us know how it goes.

I've never noticed any balancing holes or grind marks on a water pump impeller.

TOP KEK

these pumps spin (depending on the car) at about 1/4 the speed of the crank RPM. Balance this small make NO difference as long as that difference is within say (15 grams) i have no clue as to how much but you get the point.
the cast ones might be balanced enough from casting marks ect but never have i ever seen any marks to indicate that the pump was balanced at all.
Granted i have not done a water pump on every make and model car out there so i can only speak on what i have worked on. I can also say that the only reason i did the welding thing was when it was clearly a slip fit, i have seen pumps come in with the impeller being metal but where it connects to the shaft there is a seam where it slips over as in, NOT a press fit but rater a glue fit. I have seen this on mostly Chevy and GM sh!t boxes.
Maybe it the balancing issue is why so many fail?
All i know is that i have never had a failure of a impeller coming off on these and i cant report any higher than normal failure rate.

I bought my water pump kit from ECS and it came with a GEBA pump. For what it’s worth, I say don’t sweat the pump - sweat the gasket that seals it to the pump housing. The rubber/metal gasket is what you want. Throw out the flimsy paper one that comes with the pump.

I replaced the pump on my '98 for the first time with the last timing belt. Well over 300k.

Really hurt to toss the perfectly good original plastic (I think) pump for a crappy looking cast. Looked like it had 2/3 the flow path of the original.

A tip
put a dab of gasket maker on the backside of EVERY bolt hole that goes though the housing so no water will get into the threads.

When i put in bolts on parts like this, i put them in 3/4 the way in, then add some gasket maker to the threaded area of the bolt then tighten them down and put some on the back side to seal the other end of the few holes that expose the bolts.

Guys,

I may never drive as much as you folks, but I change my water pump every time I do my timing belt, and I've never had any issues with a pump failing.

That said, I pulled a 1ZMotor out of a 96 sedan at a local pick and pull junkyard for about 500 bucks that the belt was still on and engine turning over. In doing the teardown,The pump seal was bad, but somebody had tried to Band-Aid it along with that leak-seal stuff. The impeller was still attached.

I know for newer models it's a rather safe choice to replace the WP at belt change. On the ALH where the pump is driven by the timing belt I guess it's kind of standard practice, however, on the AHU / 1Z where the WP is independent from the timing belt I prefer to do these things at separate times.

When I first launched the B3V tdi car back in May 2016 I sent it out the door with a new Gates water pump, but it wasn't even 2 weeks before it went back in the door for a replacement due to shaft seal leakage. It was replaced with a VW factory water pump brand I can't recall off-hand.

So in this case I did replace but it was short lived and I had to go back in and do it again. One reason I keep it if it's working and not showing any signs of failure. At least on the AHU / 1Z / AFN engines if it fails it doesn't take out the TB.

Steve