I've only been around the block once or twice but I have never seen a rad inlet so low down. That's super strange. Especially considering that, I'm putting myself in the camp of an air pocket somewhere although that doesn't explain why you could drive it around and have temp be OK but you've got a more-than-average number of places where air could hide with how big the system is.
I'd definitely jack the thing up in multiple positions to see if you can work more air out. If you go the route of attaching a hose to that upper port for bleeding, I'd also jack the front of the car way the berkeley up in the air while doing that to extend the effect.
Did your local buddy recently help drop a K into a Crown Vic? He's popped up a few times over the years on a few youtube channels.
Poor performance at idle but okay being driven at higher rpm sounds like a coolant flow issue to me, the stock water pump just isn't pushing the coolant hard enough for your setup at idle. BMW has been using brushless, fully enclosed water pumps that can be controlled by a simple PWM signal from your ECU. Yes, they only last 100,000 miles or so but that sort of life span is more than enough for a car like this.
This site has a bunch of info on them, the CWA200 is used in the BMW N52 and the CWA400 which flows more and is supposed to be more reliable is used in the newer N20 turbo 4 cylinder that replaced the N52 NA 6. There is mention that possibly the newest version of the CWA400 is not PWM controlable anymore so you'd need to dig into that but I'd say the 200 would be more than enough for your application. Pierburg is the OEM and you can buy them through Rockauto. I don't know how hard it would be to just get rid of/bypass the stock water pump.
This all presumes there is no air in the system somewhere so chase that first.
I don't think it's the pump. There are others running a k series in this chassis without this issue. I had this issue with my FRS and it is probably either trapped air or a flow issue near the thermostat. These are notoriously difficult to bleed properly.
In reply to adam525i :
:) thats the guy, Ben Sipson at Bayside Fabrication. I use the term "buddy" pretty loosely. I bought an e36 roll bar that he fabricated a few years ago and I've bounced a few k24 swap questions off of him. I'm going to continue investigating trapped air and/or thermostat before I go down the road of adding a pump.
Do you have a bleeder valve at the top of the radiator? X1-9s have one that is accessed through the frunk. The amount of foam you get before it is bled completely amounts to almost 1/3 of total capacity. Messy too, you can't get a hose on it.
TurnerX19 said:
Do you have a bleeder valve at the top of the radiator? X1-9s have one that is accessed through the frunk. The amount of foam you get before it is bled completely amounts to almost 1/3 of total capacity. Messy too, you can't get a hose on it.
It does not have a valve per se (although I'm considering adding one). But I can loosen the clamp and pull the cap off enough to bleed air. I've done that 4 or 5 times and only gotten any air the first time.
