Apparently, the 4B11T has a rubber impeller on the water pump. This is reminiscent of the BMW plastic water pump impellers in the late 90's which were responsible for the failure of many motors.

Has anyone had any experience with a rubber impeller on a water pump?

well actually yeah i think my buddy had a poblem with his 329i ill get details tommorow.

o wait not the question huh

:bump:

so i looked around and the problem with the rubber one is pretty much the same with the plastic ones. they get old, cracked, brittle, and break off to clog ports making water flow less efficient or even not at all. wich leads to blown heads and or warped cylinder walls.
i guess check at every oil change and replace if theres any wear i dont think they'd be too expensive.

It's hard to check a water pump without pulling it off.

I guess after some time i'll upgrade to a metal one. Wonder why the hell they chose rubber?

From my understanding, plastic ones are more prone to cracking and breaking, and that rubber is much less likely to deform under heat and stress. Most decent quality rubber compounds today use a certain amount of silicone, which increases longevity and the tendency to dry out. It is my understanding that mitsu has made it a point to actually use this as a selling point of the new car. To me, this shows that it must have some benefits over the typical plastic design or they wouldn't have even made mention of it. We'll see, I suppose.

I have some experience. My family had a ski boat back in the day. Every season that rubber impeller would rot out and we would have to replace it. I know that there are many differences between the two, but the general concept and construction materials are similar.
You would think that this part would be on the list of parts not to cut costs on.

So in other words, when I do my first head swap, do a water pump with a metal impeller along with it.

sounds about right.

I have some experience. My family had a ski boat back in the day. Every season that rubber impeller would rot out and we would have to replace it. I know that there are many differences between the two, but the general concept and construction materials are similar.
You would think that this part would be on the list of parts not to cut costs on.


im new to the forum, but I highly doubt their intention was to cut costs. im sure the rubber compound they use is much more "advanced" compared to your ski boat "back in day" im assuming implies years ago? I'm sure they made some effort to test it. and it probably has some kind of life expectancy anyways. of course im sure it will need replaced just like any waterpump. hopefully prior to failure.

True, but it's definitely worth keeping our eyes on until we know more.

I really wonder about this water impeller thing. Where is the water pump anyways? I want to make sure that I keep an eye on it.

i would much rather replaced it right away instead of waiting for something to happen to it.

i don't think it will be an issue on stock dd car. Now if you start racing and modifying, that is a different story.

thanks for bringing this issue to the forefront, i will keep an eye on this when i get mine.

I really wonder about this water impeller thing. Where is the water pump anyways? I want to make sure that I keep an eye on it.

It's underneath the timing belt cover close to the crank. It won't be easy to "keep an eye on" per say, but if you're timing the motor and such, it may be worth pulling the pump off to look at.

Thanks dino, I'll try to have it checked whenever the timing chain (no belt on the 4b11, but I know that's what you meant) is inspected at each recommended interval.