Coolant header tank conversion

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AardHawk
E30 Zone Newbie
E30 Zone Newbie
Posts: 52
Joined: Sat Jan 15, 2005 11:00 pm

Post Fri Apr 14, 2023 11:59 am

Not an E30, but an E28. M20 engine so nothing different there!

Some years ago, I did a basic e to i conversion. M20B27 2.7 block with 731 head and Motronic 1.3.

Before;
Image

After;
Image

When I did the conversion I also converted the coolant radiator to an E36 318i with the attached header tank and also used the steel cross flow pipe from the later E30. All was good, and everything worked okay for a few years until I laid the car up for five years or so. When I bought the car back to life last year, the first thing I noticed was a lot steam from the exhaust. It didnt bother me as it was a cold day etc. A few days later I checked the coolant and the header tank was empty. Oh dear! The temperature gauge was working fine and sat at 10:30 which is where you want it in an E28. I topped it up to halfway up the header and took her for a run. A bit of steam when cold and nothing when I got back. Checked the header when it had cooled and it was empty again. Did the a few more times. Definitely no leaks, so looks like a minor, at the moment, head gasket problem, so sometime in the near future I will nip the head off and check it out etc.

The one thing that bugs me is that I cant see the header coolant level athe header has gone all cloudy, so I would like to go back to the original header tank, that you can see in the first pic. I,ve got an E28 528i M30 radiator sitting idle that I would like to fit. It has the upper and lower coolant pipes in the same location as the radiator that is currently fitted. See pic 2. I am also using the later coolant pump that doesnt have the inlet for the header tank.

As I am taking the head off, I will fit a new cambelt, so will need to disturb the pump.

So this is the question, can I just replace the current pump (new style pump) with the old style pump and hook up the old header tank? Is it that simple, or am I missing something obvious?

Thanks for your time guys.
DanThe
E30 Zone Team Member
E30 Zone Team Member
Posts: 28647
Joined: Sat Sep 10, 2005 11:00 pm
Location: Staffs

Post Sat Apr 15, 2023 8:17 pm

The hose that is connected to the bottom of the E36 expansion tank is rerouted to the new expansion tank, no need to change pump