e30 expansion tanks - what gives

[havand]

So, I am in the process of changing my cooling system and bought a Mahle-behr late model expansion tank from ECS. I can't figure out how to get it to fit. So, I go online and look at pictures of engine bays. Seems like it mounts fine for them.

Mine has a tube coming out the bottom and no level sensor port. Since I am changing from the M42 to a full size, I didn't have one in hand to compare when I bought it.

In short, the OEM vs Mahle-behr are different. Same P/N. The BMW part seems to not have this extra tube on the bottom. What am I missing? Help me understand my stupid. Please. Thank you.

OEM:

https://www.ecstuning.com/b-genuine-bmw-parts/coolant-expansion-tank/17111712641/

Mahle-Behr:

https://www.ecstuning.com/b-mahle_behr-parts/surge-tank-bmw-e30/17111712641~mbr/

[TobyB]

dat don't look right.

t

[jgilber0]

In short, the OEM vs Mahle-behr are different. Same P/N. The BMW part seems to not have this extra tube on the bottom. What am I missing? Help me understand my stupid. Please. Thank you.

OEM:

https://www.ecstuning.com/b-genuine-bmw-parts/coolant-expansion-tank/17111712641/

Mahle-Behr:

https://www.ecstuning.com/b-mahle_behr-parts/surge-tank-bmw-e30/17111712641~mbr/

It’s not you. I bought the Mahle-Behr part too and had to send it back.

My 1992 325ic tank has a level sender port on it and a single bottom tube that projects out of the tank at 90°. The Mahle-Behr unit I got had no sender port and a bottom tube that came out at a 45° angle.

But P/N was the same. Clearly a numbering issue on the Mahle-Behr part.

ECS was very nice about it. They paid return shipping and gave me a full refund. The OEM BMW replacement part fit perfectly.

I suspect that Mahle-Behr has one P/N covering multiple BMW P/Ns. Go check out RealOEM and I think you’ll find that there are a few different configurations of the tank depending on year, equipment package, and engine.

[havand]

Thanks for the feedback. I took a minute and looked at realoem. It looks like that part number is used on every m20 that isn't the old style tank. I dunno. $100 for the OEM is rough though.i don't really see another option.

[jgilber0]

Thanks for the feedback. I took a minute and looked at realoem. It looks like that part number is used on every m20 that isn't the old style tank. I dunno. $100 for the OEM is rough though.i don't really see another option.

Interesting. It may be that the Mahle part isn’t intended for E30s at all, and is just offered for users to adapt.

The issue is that it’s under pressure, so modifications to it could lead to leaks or other problems.

I’d swing for the OEM part, although I do feel your pain regarding the cost.

[havand]

I'll have to take a look at that bottom nipple. That's really my issue. I don't have a level sensor hooked up now, but trying to seal that nipple probably isn't the best idea.

[ghrays]

I have one of these Behr units I bought a couple of months ago for an upcoming coolant/radiator/hoses replacement projectand I just took it out of the box and see it doesn't match the original so I am going to return it to RMEuropean.

[jgilber0]

I'll have to take a look at that bottom nipple. That's really my issue. I don't have a level sensor hooked up now, but trying to seal that nipple probably isn't the best idea.

Had an idea. If you can fit it on the car with the nipple intact, maybe you can attach a short length of hose to the nipple and block off the other end with some sort of plug and clamp arrangement.

[havand]

I thought about that too. The trick is trying to fit it in. That nipple sticks up like 3/4-1"? So it holds it up kinda high. It doesn't really fit the contour of the fender. Might be able to cut some of it off, thread in a screw with some silicone.

[ELVA164]

Guys, that's supposed to stay open. That's an overflow. Your car has one already.

[jgilber0]

Guys, that's supposed to stay open. That's an overflow. Your car has one already.

I thought the overflow came off of the threaded flange at the top of the tank.

The nipple we're talking about comes off of the bottom, which means it would be underwater (undercoolant?) the whole time.

[havand]

I tried to fit it in again. I don't see how the hood will close with it sitting up on that nipple. I'm debating cutting it off and using some rubber washers or rtv and some stainless steel hardware to sandwich the tank and seal it.

[havand]

Nevermind. That wouldn't work. Don't have access to that area inside to out hardware inside. Think it's just time to source the OEM parts.

[jgilber0]

Nevermind. That wouldn't work. Don't have access to that area inside to out hardware inside. Think it's just time to source the OEM parts.

My solution too. Sucked to pay that much but it was the right thing to do.

[ELVA164]

Oh, I didn't see that clear one down there. Yeah, that's weird.