Build Thread?
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That should link to recirculating style tanks on summit, pick your shape/size/fittings. Most look like they would mount to the firewall nicely. Try to mount it as high as possible but it is not necessary to be higher than the rest of the cooling system. The small line from the top of the radiator constantly flows a small amount of coolant (and air if there is any) to the expansion tank and fluid is drawn from the bottom of the expansion tank leaving the air in the expansion tank.
Most important thing to look for is the connection point for the radiator small line is low on the tank or has a tube going to the bottom like the OE tank for an m20. This is so if the tank is not at the highest point in the system when you shut the car off that air doesn't go back through the line into the radiator. It wouldn't wreck anything but it would give you a false level reading when checking the level. Then when the car is started it will bleed itself every time and the level will drop.
Those bottom fittings are quite small compared to what the hose size for the expansion tank that BMW uses!
This still feels different though, as it doesn't look like this would be a way to fill the cooling system, or would it? I am clearly confused here. -
I have a very similar overflow to use from Chasebays: http://www.chasebays.com/chase-bays-coolant-overflow/
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I have a very similar overflow to use from Chasebays: http://www.chasebays.com/chase-bays-coolant-overflow/
That won't work with a regular BMW radiator. It is an overflow not an expansion tank.
Those bottom fittings are quite small compared to what the hose size for the expansion tank that BMW uses!
This still feels different though, as it doesn't look like this would be a way to fill the cooling system, or would it? I am clearly confused here.There needs to be one connection for a 5/8" hose (about 16mm) for the hose that is on the suction side of the water pump. And one small hose 1/4" to the radiator. The tank will have another connection for an overflow tube by the cap that runs onto the ground.
Most of the aftermarket ones have NPT ports. For the larger hose a 3/8NPT is a common size to use with a 5/8 barbed hose fitting.
This one has plenty of ports. https://www.summitracing.com/parts/mor-63769
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@jc43089 Thanks for your persistence, I think I'm finally understanding the smaller details about how the system works.
The link for the one you just posted is pretty darn large, but I feel like I have a better idea of what I'm in need of now.
I guess the missing link for me was not thinking about the fact that the expansion tank connection is on on the suction side of the pump and that the small line on the radiator was always seeing flow.
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That won't work with a regular BMW radiator. It is an overflow not an expansion tank.
Hence why I am not using an OEM radiator and have a fill cap inline to dump into this when it over pressurizes=)
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Hence why I am not using an OEM radiator and have a fill cap inline to dump into this when it over pressurizes=)
Right I assumed you knew that but it might have confused somebody.
There are so many different expansion tanks and overflow tanks and some for sale don't even specify very well what they are designed for.
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@jc43089 Thanks for your persistence, I think I'm finally understanding the smaller details about how the system works.
The link for the one you just posted is pretty darn large, but I feel like I have a better idea of what I'm in need of now.
I guess the missing link for me was not thinking about the fact that the expansion tank connection is on on the suction side of the pump and that the small line on the radiator was always seeing flow.
No problem. Yes there is always a small amount of flow going through the small line from the top of the radiator. In the OE (e30) expansion tanks there is a metal tube from where the bleed line enters to down near the bottom of the tank to act as a trap preventing air from going back into the small line. If you drain and fill the system and start the engine to push any air out you will see bubbles coming from the bottom of the tube up through the coolant in the tank until the air is purged from the system. The cooling system works the same way on an m20 and an m50, the plumbing is very similar other than the switch from auto bleeding to the bleed screw style.
The e36 and later systems do not always have flow though the small line, they block the end of that tube with the bleed screw. I am not a fan of that and prefer the auto bleeding of the e30 style expansion tanks.
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https://www.summitracing.com/parts/mor-63766/overview/
this may do the trick. I'll have to measure things and see where I could put it.
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Following this for expansion tank relocation options.
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Installed the front stainless brake lines last weekend. Looking forward to new brakes!
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Got some silicon radiator hoses in the mail, along with a delrin steering coupler.
Haven't touched the car much lately because I'm not supposed to be in dusty environments (eye surgery stuff)
I did order the new head gasket and spacer today. That always hurts the wallet.I have seriously spent about $1300 in head gaskets. Believe it or not I'm sick of buying them. This should be the final one though.
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I miss driving this thing! @suspenceful does damn good photography work too btw.
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This car looks so good.
I also need to contract Jake to do photos.
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That photo is so old

I owe you better photos than that.
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Most annoying e30 job I have done to date. But it is done.
Upper U joint replaced and guibo changed out for a delrin counterpart.Cleaned up the block, and found that it is also a can holder!
Dropped the head of to get decked and tanked, may not have needed it but peace of mind is well worth it!
I also tried on some seats, and am trying to figure out if they were too low or if they were okay. Picture for reference. Yes, it's grainy, the shop was quite dim.
I think they were a bit too low, as I had to use the door sill to get out and the wiper arm was a bit in the way lol.
Hoping to get the head back on this weekend!
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Going to make the E30 picnic?