Here's a new wrinkle. The car sat for four days while I fixed other things and today when I started it to back up and put a white plastic sheet underneath to check for leaks, it made a strange whirring sound that I thought might be the suspension compressor running (but I had never heard anything like it before) and the check engine light came on and P023B was set. The red temp warning light also came on above the dash temp gauge and stayed on although the dash gauge still read cold. I let It idle for just a minute or so while I put the plastic sheet down and I then pulled forward and turned off the check engine light with the UG; when I did the idle sped up a bit. I shut it off and on restart the the check engine stayed off but the red temp warning light stayed on. I later checked the coolant tank and the level was below the max step where I had filled it four days ago, but was not quite down to the min step.

OBDII diagnostics. Trouble code definition for code P023B says P023B is "Turbocharger (TC) intercooler coolant pump - circuit low. The IC pump does still run with the ignition on, so I wonder if the ECM is now suddenly trying to provide a ground for the pump relay coil that it was not before and now is not sensing a voltage or current because I grounded the relay coil at the relay to get the pump to run.

Perhaps I'll disconnect the ground I added and see if the pump still runs, but first I'll hook up the I930 and see what else it has to report. Strange things are happening.

 

Phil

Did you figure things out?

 

I've been having an ongoing battle with the County Assessor that is time sensitive and not yet checked the jag specific codes or tried disconnecting the IC relay coil ground to see if the temp warning light goes away or if ECM will now ground it and run the pump. Dealing with incompetent bureaucrats just sucks the energy out of me.

I will definitely report back when I have any further news, good or bad.

 

I had an intermittent overheat problem previously and couldn't find the cause of the problem. It turned out to be that the cooling fan was not running properly. It would run, but it was actually very much slower than it was supposed to, but because it was still running, no one could tell that it was not running properly. Once I changed the fan, the overheating stopped.

 

Did it overheat at normal driving speeds, or was it at idle or low speed? The last time mine overheated while I was driving, it was at 55 MPH and we had just left some friends house where we had been visiting and the car had been parked for more than an hour.

Here's an update on what I have done since last post:

8/18/2016 133,321 2:00pm
I disconnected the IC pump relay coil external ground I had added and turned on the ignition and the IC pump did not run and the red light over the temp gauge did not come on. I connected my i930 and turned on the ignition. The CE light flashed and then went steady on, and the oil and brake warning lights were on along with “Bonnet open” and “light switch is off” in the message center. I read the jag codes with the i930 and got:

Powertrain: P0116; engine coolant temp – circuit range/performance
(It was 1 of 2 but I neglected to read the #2)

Instrument pack: U2199; invalid coolant temp data, B2139; data Mismatch

There were others but not temp or cooling related; I cleared the DTCs

I turned the ignition off, reconnected the external ground on the IC pump relay coil, and turned the ignition on; the IC pump ran (but not the Aux pump), the red warning light over the temp gauge stayed off, I saw no coolant under the car, and the coolant level was just above the min step.

I started the engine and the cooling fans came on immediately (must be the unusual sound I had heard the last time), the idle was 1100 RPM, temp on the Ultragauge was 104 F, the temp warning light was off, and the dash gauge was at cold.

I turned off the ignition and then restarted the engine and this time the cooling fans did not run and initial idle was 1000 RPM and then down to 650 RPM as it ran awhile. I read the DTCs with the engine running and Powertrain now had P023B; (Charge Air Cooler Coolant Pump Control Circuit Low) and the Instrument Pack had no DTCs. I let it idle for half an hour and it was a tick over 600 RPM, UG temp was 197 F to 199 F, cooling fans stayed off, dash gauge stayed at its center hash, and the red temp warning light stayed off.


While it ran, I set the i930 to graph the coolant temp and at first it was a steady 92C but then had momentary spikes as high as 161C and as low as -40C with steady periods of 93C between them. I had seen spikes in the graphing of other functions on the i930 so I don’t know if they are actually temp sensor spikes or if something is going on between the i930 and the OBDII outputs.


I guess my next step is still to drain the coolant and pull the top radiator hose and the Auxiliary pump to see what its problem is, but I might try another pressure test at 16 PSI for longer this time to see if I can detect any coolant leak under that pressure.

Sorry about the crappy i930 pics - my camera just doesn't want to focus on its screen and these are the best of the bunch.


EDIT:
This morning, after yesterday's half an hour of idling, I checked the coolant level cold and it was 1/8” below the min step so coolant is going somewhere and it did look like there was some orange on the white plastic sheet under the car, (although there was also water from yesterday’s rain). Looks like there is a leak somewhere which would explain how it runs normally for 100 miles until the coolant gets low and then overheats.

 

Mine overheated even while driving, but we don't have 55mph limits. Ours is much lower at 50-70km/h on many roads, and 90 km/h on the highway.

 

Wow! 90 km/h = 56 MPH on a highway and 50-70 km/h = 31 to 43 Mph on other roads. (sorry, I can't think in km/h) My land Rover Discovery doesn't even shift into overdrive until 53-54 MPH and that is a real pain on some rural roads with a 50 MPH limit and even on those with a 55 MPH limit because it goes in and out of overdrive a lot if I try to maintain exactly 55 MPH. I have to drive a little over 55 to keep it in OD with the usual speed variations of hills and curves.

It must be really hard to keep an X350 down to those speeds.

 

Agreed Phil. Kitty gotta run!!!!

 

Yeah.... the traffic jams help to keep the speeds down.... That's why the hifi system must work.....

 

Update: I did another pressure test starting at 10:00am yesterday and overnight. I first pumped it up to 14.5 PSI (1 bar) for three hours with no drop in pressure and then increased it to 20 PSI. I heard some gurgling while I was pumping (I think I had heard it the first time too) and thought it was air going under the bleed screw into the reservoir. Looking underneath there was now a little orange liquid on the white plastic sheet I had slipped under it to check for leaks. There appeared to be orange liquid on the front oil pan bolts and there was a drip clinging under the top radiator hose at the radiator (although that might have been from the little bit of coolant that came out when I disconnected the small hose at the tank to install the T). I could not see a specific leak from the top, but it is hard to see among that jumble of hoses. I wiped the liquid from the pan bolts and from under the large radiator hose and put a clean catch pan underneath where the orange was. At 4:00pm it was still at 20 PSI, but at 10:00am the next day it was down to 16 PSI and there was a half ounce of coolant in the catch pan. I didn’t see any drips under the top radiator hose or on the pan bolts this time.


So...there is a leak but I can't tell where. I still plan to drain it and remove the Auxiliary pump to see what its problem is and see if I can identify a bad hose or traces of a leak in the process. That will be a new thread if I find something, so thanks to all for the suggestions and info so far.

 

https://www.amazon.com/ACDelco-10-50.../dp/B008I2VKNI
They make a tracing additive/dye for coolant. It would be much easier to see it with a UV light. I know that they make the additive for a/c systems. When used it is like a CSI crime scene. The dye shows everything. Just make sure it is for dex-cool antifreeze. Some work with a blacklight, and are used sort of in the dark which is great in dark, limited spaces in the engine area. It will also show trails.
After all the attempts to make this car run right, it seems that you have it down to a leak/leaks.
I was thinking for a while that it may be like the XJ-40 older water pumps that come apart and lodge small parts of the impellers in the cooling system. But that does not account for the lose of coolant, and the coolant on the pan.
Find your leak, fix it and call it a day. Easier said than done.
I miss the days of 2 radiator hoses, and 2 heater hoses. (sometimes 1 heater hose in the summer)
Mark

 

Thanks, Mark,

Great suggestion. I called O'Reillys and they have dye but it says not for Dex-Cool so I ordered the AC Delco from eBay for $14 and a 21 LED inspection flashlight (torch to you Brits) for $6 (chosen from the thousands there for promised arrival by Sep 1st) Now I just have to decide whether to wait to look for the leak first or go ahead and pull the Aux pump and look later. I am leaning toward the pump first and leak detection after.