Expansion Tank?

[withinward]

I bought an '85 318i with a rebuilt motor. It runs great but I've noticed that I have weak heat into the cabin. It barely gets warm. Checked the radiator fluid level and was low. Added new fluid. That's when I noticed there was no expansion tank, just an overflow hose coming out of the top of the radiator draining to ground.

The motor is an M10B18. Realoem.com doesn't list an expansion tank for this car. Is there one?

My worry is that as the system heats up, I'm just dumping water and coolant out of that drain line.

[Hey_You]

No overflow tank for the m10. You can get a universal tank, or swap to a m42 radiator

[withinward]

No overflow tank for the m10. You can get a universal tank, or swap to a m42 radiator

lol. I guess that might explain why I've been having so much trouble finding one then.

how is fluid level supposed to be maintained in the radiator then? As the system heats up, won't I just be spilling water out on to the ground? from that overflow?

As far as the weak cabin heat, I guess I'm looking at a clogged heater core or stuck valve. Any suggestions?

[jeffnhiscars]

The coolant level in my M10 318i settles about 3\4-1" below the top of the tank. I'd fill it a bit closer to the top when its cold and when it reaches OT and expands any excess will push itself out the radiator cap.

[Smelser]

A lot of cars and trucks do this.

My mack truck has no expansion, and the coolant is happy just below the rad cap. when it heats and expands it is full.
most local race cars use that as well, no expansion and just dump to the ground.
most street cars never had an expansion tank, but as time goes by and enviro stuff is key, dumping glycol on the ground wasnt deemed nice. so expansion tanks became the in thing.

bottom line, its not needed you can easily fab a nice one in.

[jeffnhiscars]

The environmental benefit of the expansion take is obvious but there was actually some science behind it. By eliminating any airspace in the cooling system itself, it was found that the boiling point was higher and that the system dissipated heat a little more efficiently.

What's even more interesting is that when the expansion tank become standard on just about every new car the machinist who invented it started going after the auto manufacturers. After years (if not decades) of litigation they started to fall in line one by one. $15 million from Ford, $10 million from Toyota etc etc....PLUS ROYALTIES on every new car sold !!

I think he quit his day job

[thebutterson]

^ That's a pretty cool story.

[FLG]

Not sure on the m10 but I had my coolant hoses going to the heater core reversed and the heat sucked.

Sent from my Galaxy Nexus using Tapatalk 2

[withinward]

Very cool stories and good info all around.

Sent from my SCH-I535 using Tapatalk 2

[jeffnhiscars]

Then there was the guy who invented the ratchet while working for Sears (aka Craftsman). Decades went by until he decided to challenge who REALLY owned the intellectual property rights to it. He got about $35 million when the dust settled.

[TobyB]

one more nice feature with the expansion tank is that, with no air in the cooling system,
there's also no oxygen (eventually) and so corrosion's reduced too.

I use one on both race cars. Ya gotta run a catch tank anyway, why not have it do something useful?

t

[jeffnhiscars]

Then there was this small software company in Mass with the name "Lexis". In the weeks before Toyota introduced the brand to the world, these guys sued for trade mark infringement.

In a rather novel decision the judge said that, while there is little likelihood of anyone confusing products from the 2 companies, a trademark is a trademark, so he ordered Toyota to pay them $6mm plus a license fee on every LexUs they sold.