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.
I've now read quite a few examples of the thermostat that comes with the k-tuned/generic coolant swivel neck being problematic. This cooling system holds a ton of water and I didn't design a good method for draining it. Maybe if I have to do this thermostat, I'll add a convenient drain. Grrr.
In reply to Lof8 - Andy :
You might consider just putting the stock thermostat back on and splicing in a hose that bends where you need it to. I'm fairly certain the one I have will work but until I mock it up in the bay it hasn't been confirmed.
I also keep meaning to ask you but what tire sizes are you running currently?
In reply to captainawesome :
225/45/16 fronts
245/45/16 rear
latest finding. I can move the temp needle down by adding some revs. I'm still leaning toward an issue with the thermostat. Might remove it completely for a try or might swap it out with a different one, not sure yet. Jacked up the LF of the car to elevate the nipple on the radiator. Nothing but coolant came out.
Is there anywhere you could try bleeding on the motor end?
In reply to adam525i :
The fill location and the expansion tank are both at the motor end, on opposite sides of the water pump/thermostat. I've bled from both locations.
Lof8 - Andy said:
the clutch is disengaging way at the floor of the throw. I'm going to bleed the system again and possibly some adjustments at the pedal linkage.
Just was reading through the KEP adapter instructions and thought this might have something to do with your clutch issue if you haven't already sorted it. Mine didn't come with any shims but maybe yours did?
KEP said:
Due to the very small amount of travel on the Audi slave to bearing ratio, we have provided 2 shims to use behind the pivot for the release bearing arm. If you need more travel to release the pressure plate, install a shim. When the clutch wears and you need more free play, remove the shim. You may not need any shims, but they are provided so you can get more clutch use.
In reply to captainawesome :
👍 I was able to adjust some slop/free play out of the pedal to master cylinder linkage and I'm liking the feel now.
Huh, usually temps coming down with revs tells me there is steam around the sensor.
Well I pulled out the thermostat and did the ol' boil-it-on-the-stove test. It's a 180 degree thermostat and the water was boiling before I got it to initially pop open. After that, it was consistently opening at 180. However, I have the fans set to come on at 185. I'd like a little more gap between those two functions, so I've ordered a 170 thermostat. I've been extra cautious during my previous testing and been shutting the car down around 200 degrees, after the fans kick on and the temp does not recover.
this likely wasn't enough heat to open the thermostat. I'm hopeful and relatively confident that this is my issue. I'll boil the 170 thermostat before I install it and hopefully I'll be moving forward again soon.
It doesn't really give me any explanation as to why I was able to bring the temp down a bit with rpm's though.
In reply to Lof8 - Andy :
OK totally crazy idea incoming. I assume the sensor is the normal place - I don't recall where that is on a K engine. Any chance that because of the long path the coolant has to take it's measuring the temp coming in which has already been cooled (or hasn't gotten hot)...but because when you're idling it's not cycling through that long path very quickly so the sensor thinks it's cooler than it is because it hasn't yet seen the hot stuff coming back around and then all of a sudden it's heat soaking, temp sensor catches up to kick on the fans and it's too late and because it's not under a lot of pressure it boils at closer to 210 and creates an air pocket and now we're in trouble?
Agreed. No. That's a bit too crazy.
Interesting that the t-stat was slow to open. Maybe it was just partially stuck and with revs/higher flow, you were able to push fluid through to let the system work.
In reply to AxeHealey :
I appreciate you tossing in ideas! the temp sensor is right on the back of the head, where, theoretically, it's the hottest point. The cooling system has a little bypass hose that dumps the same water that passes the sensor, onto the thermostat. So the thermostat should be seeing exactly the same temps that the sensor sees.
partially stuck thermostat does seem a likely possibility after watching it function on the stove.
The sensor will be off the back of the head so it should be reading higher temps than what's in the rad. The problem can also be that the fans are kicking on too early before the thermostat opens. I think part of that comes from there being a single 5/8" line connected to the back of the thermostat which doesn't pull enough heat to activate the thermostat. It just percolates in the head.
Well, the 170 thermostat was no improvement. Acted exactly the same. So I got pissed off and gutted out the 180 stat. Sure enough, it's happy now. Takes 6 or 8 minutes to get up to the 185 fan trigger then oscillates happily between 180 and 190. I don't know what the deal is but I'm running a gutted thermostat until I find a reason not to.
So weird. I would say as long as it's not staying too cool to the point your Haltech tune is effected carry onwards.
Reading through it all I think Captain has the answer. The problem only surfaces when the cooling system has the long runs in this application. If the radiator was close to the engine the coolant would be circulating with more thrust, making the little pipe enough.
edit: This solution with the fans the only regulator will have a minimum running temperature. Drive north until you find descending coolant temperature under low load. Pull into a rest area and let it idle 5 minutes and watch when you get to about 35* air temp. Long ride today cause it is 40* here in PA....
In reply to TurnerX19 :
It could be an easy fix to test. Add a second coolant line from the coolant neck to another port on the thermostat, preferably closest to the thermostat.
I don't know how the swivel neck thermostats are set up but the stock one has an actual shield from allowing heated coolant to get to the thermostat from where the Tractuff part Lof8 has feeding it. If the new line is added to the front where it pours heated coolant directly on the thermostat it's probably more likely to open properly but also flows enough coolant to evacuate the head properly. This is the exact issue I had with my K swap on the FRS. The fans kick on because the head is hot but the thermostat won't open so it just sits in the head and the fans will never kick off since nothing is flowing.
Basically you have only one 5/8 hose feeding the thermostat, and that needs to double.
Just finished a 2nd garage tuning session with my Haltech guy. It is a rowdy little car and a ton of fun!!
He fully configured my dash and calibrated a few things. We put some miles on the car with him riding shotgun and watching AFR's and he says things are looking good.
the throttle hangs a little bit when I let off sometimes. He thinks the throttle plate might be sticking a bit inside the tb. So my homework is to investigate that and fix it. Then we're ready for the dyno.
it feels like a 55 year old car with more than twice the hp it had before 😂. NVH is not insignificant, but it's bearable. (It was certainly not a luxury car with the original drivetrain either). I was mostly getting on it pretty hard so he could look at the tune. I'll take another run with it tomorrow at a more subdued pace to feel it at a cruise.
im very excited to finally reach this part of the build!!
Just put about 25 street miles on it. What a freakin hooligan machine!! 😁😁
