oil cooler or not? (m30B35)

[Yoozt]

We are building a m30b35 engine into a E12.
The first donor engine doesn't have a oil cooler on the oilfilter house. This one came from a E28, but originally came from a E34. So maybe they switch it to not cooling, to make things easier.
The second donor engine is from a E24. This one has the oil cooler connections, so we would need to score a radiator + hoses to hook it up.

My question: is it worth the effort to build in the cooler, or just leave the cooler out?
(we will not be racing with the car, but off course we like to have fun and put the peddle to the metal sometimes)

[Peter E12 525]

yes Yootz,

You will need an oilcooler when building a 3.5 into an E12. Otherwise is getting to hot. Why it's not on an E28 3.5 I don't know.

It's not that difficult to build on an E12. If you like you can check my brothers project M535i Replica (www.classicbmwparts.nl) . There's also an oil cooler mounted.

Maybe he has an oilcooler on stock I don't know.

Grtz Peter

[Peter E12 525]

We have one 635csi e24 with oilcooler and hoses on stock.

[Yoozt]

yes Yootz,

You will need an oilcooler when building a 3.5 into an E12. Otherwise is getting to hot. Why it's not on an E28 3.5 I don't know.

It's not that difficult to build on an E12. If you like you can check my brothers project M535i Replica (http://www.classicbmwparts.nl) . There's also an oil cooler mounted.

Maybe he has an oilcooler on stock I don't know.

Grtz Peter

Hello Peter, The engine from the E28 came from a E34, I think the B35s weren't delivered in a E28, just the B34s. So I think the owner of the E28 made things easy by leaving out the cooler.
But we will have to build in the radiator, so do you have a link to the M535i replica topic where I can see how you fitted the radiator?
thanks

[323baur]

Honestly, i dont think you dont need a oilcooler if you use this thing occassionally on full power.
There are several e21s with a m30, without an oilcooler, only with serious pedal to the metal it will be an avantage.

You can always add it later.

[bmw e12 e21]

Honestly, i dont think you dont need a oilcooler if you use this thing occassionally on full power.
There are several e21s with a m30, without an oilcooler, only with serious pedal to the metal it will be an avantage.

You can always add it later.

+2
You don't need an oilcooler.

[Yoozt]

okay, thanks, it will save us the extra work (and costs) to fix the radiator of the oil cooler to the car.

[Peter E12 525]

It wil run hot. But we sell also replacement engine's

The E12 M535i Always came with an oil cooler. I don't think they put that in for show..

We don't have a link. just come to the shop and look and take as many pictures you want.

[bmw e12 e21]

Yes, the M535i came originaly with a oilcooler, but is it necessary? NO.
There are so many 635csi(like Peter_p, and he has a heavy foot) without oilcooler without problems. I know e9 models with e34 3.5 engines without problems.
So why will it run hot in an e12 awithout oilcooler and not in an e24 / e28 / e32 / e34?
Can you please explain that to me please? I am curious.

[Peter E12 525]

I don't know for the e28, e32, e34

But the E24 and E23 al have aluminium radiators and not the old style like the E12. Maybe that's the issue?
Maybe a thermostaatm that opens earlier?

But all the E24's 635i's we dismantled had the oilcooler fitted. So that's why we fitted it on the E12. better safe then sorry i guess

The modern engine oils could also be a reason the don't run hot i guess? they are better then 30 years ago.

I also have seen on early style mustangs with old skool 2 row radiators running hot and after replacing it with an aluminium example the problems where solved.

So I can't argue with cold hard facts. And maybe it will go without any problems. But if you have the connections on the engine like topic starter (most expensive part) then I would fit it. The hoses and radiator are not that expensive.

This is the link to the topic viewtopic.php?f=74&t=24629 but we are busy with customer cars at the moment so it's not finished. I will make some pictures of the E24 oilcooler mounted on the E12 m535i replica.

[Yoozt]

thanks all. I've also asked on the E28forum and there someone is driving a 535 E28 with no cooler and no problems.
We are fitting a aluminium radiator of a E34 535, so maybe this will help cooling the engine.

that said, Peter, what does a oil-radiator + hoses cost?

[Jeroen]

The only way to know for sure is to install a oil temp meter en monitor. In most cases it will be fine I guess.

[bmw e12 e21]

The e9 3.0cs i know runs a e34 3.5L with triple webers and original 3.0CS radiator without oilcooler without problems.
So i don't think the alu cooler makes a big the difference.
I think an oilcooler can be usefull for racingcars wich rev high all the time.
But like Jeroen says, an oiltemperature reading gives 100% certaincy.

[Yoozt]

The e9 3.0cs i know runs a e34 3.5L with triple webers and original 3.0CS radiator without oilcooler without problems.
So i don't think the alu cooler makes a big the difference.
I think an oilcooler can be usefull for racingcars wich rev high all the time.
But like Jeroen says, an oiltemperature reading gives 100% certaincy.

I think, for now, we go with no oil cooler. I will keep the oil filter housing with the connection to the hoses as an extra/reserve, you never know.

Do you think that the original radiator of the 528 (E12 1975) will cool enough for the M30B35? It's heavier than the aluminium one of course, but it fits, the aluminum one needs to be fitted.

[Jeroen]

It is always hard to compare used and new radiators, sometimes old ones are damaged, clogged up internally and with a bit of luck someone has applied a few layers of spray paint to make it look better. Then it's no miracle a new one performs better, but in basis the old type should be just fine, even on a B35. If it's a used example I'd flush it clean though.

Old ones vs new, well in both cases they should suffice as well, especially in our moderate climate and for road use. If the original solution doesn't work there's always a workaround but my approach would be to look for the cause.