Top Fill radiator conversion

[ZettaE30]

I have a question on whether I could convert an early model E30 to use a top fill radiator and effectively delete the coolant reservoir. I currently own an early model 325 which has the 2 ports on the water pump and I was wondering if its possible to use the late model water pump with 1 port and get a top fill radiator to delete the coolant reservoir completely.

[flyboyx]

welcome with your first post and all but....why? no one makes a drop in radiator of this sort. the cost of getting a custom one would by far offset any cost savings you might be thinking you could benefit from.

besides, bmw made it the way it is for a reason. i would suggest not fucking with it. you are better of just leaving it the way it is.

[DrJosh]

Doesn't the m42 come with a radiator that has the coolant resevior attached? It's kinda similar.

[adam.nonis]

I have a question on whether I could convert an early model E30 to use a top fill radiator and effectively delete the coolant reservoir. I currently own an early model 325 which has the 2 ports on the water pump and I was wondering if its possible to use the late model water pump with 1 port and get a top fill radiator to delete the coolant reservoir completely.

Whenever I want to do something like this I usually just head to Pick n Pull and just walk the yard looking at other cars and measuring. I too would be interested in deleting the reservoir. I think the problem you’ll run into is that even with a radiator fill option, most cars still run an expansion tank. I’ll be watching to see what you might come up with.

[ForcedFirebird]

The fill cap needs to be the highest point in the system, or you will always have air. Even if you did get it to fill completely, the pressure cap would be submerged and bleed coolant (instead if air) when the cap pressure limit is reached. Each heat cycle will lower the coolant level until only air comes from the cap relief. So, you will probably still need an expansion tank that's fed from the pressure cap relief hose so that when the coolant condenses, it will draw the coolant from the reserve expansion. This is how you see a lot of domestic vehicles. The expansion is a reserve and not pressurized with a top fill.

[adam.nonis]

Depending on how bad you want to delete the tank, some fabrication could get you there with the OE radiator. Honda guys (don’t kill me please) do stuff like this:



In order to put a “stealth” radiator down low and tucked away. Another option could be to add the filler inline on the highest radiator hose (clearance allowing) like this:



Or

[ZettaE30]

Thanks for the replies, I don't normally post because there is usually a post about anything but I can't seem to find anything about the option that i am going for. There might be a reason for that lol.
However, the reason I am thinking about trying this out is that my radiator is leaking and i cant seem to find an upgrade option without having to change the coolant hoses over to the late model cooling system. And i feel that it would be more expensive to do that than to delete the coolant reservoir completely. It would free up space in the engine bay making it look a lot cleaner.
I understand if i will get a lot of hate for going this route but why not try. I will be running a coolant overflow off to the side as well.

[DrJosh]

https://www.r3vlimited.com/board/showthread.php?t=163373

[flyboyx]

^that will more or less work, but....first, there is no fan shroud, and second the rad is of smaller capacity. both of those will reduce your capacity increasing the likelihood of overheat.