Yes, I replaced almost all of the coolant hoses when I replaced the head gasket. In particular the “snake hose” in your picture and the hose to the water rail under the intake manifold. The car ran fine for about 2 weeks after the rebuild before this happened, so it wasn’t an immediately result.
I have my electric cooling fan (which is operating properly) jumped to the A/C relay, so it runs all the time the car is running.
I’m still trying to figure out the connection between the serious overheating and the Check Engine Light “Oxygen sensor, system indicates full rich”.
Scratching my head and I’m thinking either the radiator is clogged up (but why would that trip the CEL) or one of the CATs are blocked.
Honestly not sure where to go next to troubleshoot this.
Hi grooveman. Are you losing any coolant ? Is there a possibility you have an air lock somewhere in the cooling system ? When you refilled the coolant following the recent head gasket job did you put the heater control to full hot ? Is the seal on the cap for the coolant header in perfect condition ?
Are any of your brake calipers dragging ?
Sometimes the quality of replacement hoses is very poor and the smaller bored ones can collapse internally when hot.
How is the car running in general ( besides the higher temps ) a weak mixture can cause the engine to run a lot hotter than normal, pull a couple of spark plugs out to see if they look too white.
If your oxygen sensor is failing this will effect the mixture, especially if it’s informing the ems that the mixture is too rich when it actually isn’t.
Groove, I’m also wondering the same thing as you about the CEL and the running hot. Have you priced a coolant temp sensor? If your current sensor is faulty, it could play havoc on your fuel trims and may have the ability to affect the running temp some.
I replaced my coolent temp senser from oreillys pretty cheap, also rember years ago, and I mean years, putting a tstat in a pot of water on the stove with a thermometer to see what temp it opened if at all, mom wasn’t too happy but I found I needed a new one.
If the temperature is slowly creeping up it is possible the radiator is clogged especially if it is running the original radiator. I had to replace my radiator as one of the plastic pipes broke off and I got an all metal radiator. I agree with Casso possible air lock or expansion cap, plus have you checked the overflow? sometimes the overflow bottle tube can get obstructed which may cause the car to run hotter.
Hi Grooveman, It 's quite possible the O2 sensor got fouled up or contaminated during the brief period before you noticed the oil was contaminated with coolant. Whatever it turns out to be I hope it’s only something minor and easily fixable.
This is exactly the kind of stuff that makes these cars very challenging. They have all the emissions components of a modern car (O2 sensors, MAP, MAF, etc) but don’t have an OBD port where you can hook up a scan tool in order to actually figure out what data the sensors are sending. I would love to know how the dealer techs figured this stuff out in a reasonable amount of time back in the day.
So yesterday I made a trip over to see my good friends at British Auto Specialist. After three of us stood around discussing the problem Jeff the owner came out with a professional thermal gun. He told me to take it home (I drove my wife’s car over) and find out if the car is actually overheating or if it’s just a false reading. Well if the thermal gun can be trusted the car isn’t overheating.
I took readings at both the thermostat housing and the upper radiator hose when the thermostat opened (which I could determine by the drop in temperature on the gauge). The temp gauge read 90C and the thermal gun read around 85C. When the car temperature gauge eventually jumped up 3 or 4 bars I again took readings at the housing and upper hose … and … there was very little difference, maybe a degree or two, around 87C. Just to be sure I boiled a pot of water and read it with the thermal gun … 212F, so the gun is very accurate.
I still can’t understand why the gauge would be giving me accurate readings while warming up and then
go crazy on me. I recently replaced the sending unit with a new one.
So just to be on the safe side I ordered a new radiator. And to combat the check engine light I’ve got a new catalytic converter and O2 sensor on the way also. Even though I HATE troubleshooting by parts replacement I figured that since both the radiator and cat have never been replaced it’s money well spent.
As someone who monitored warranty costs for Jaguar for my 32 year career, I can say that dealers often did struggle to diagnose issues with engine management and other complex electronic features. There was often too much “straight time” used in these situations. But having said that, they did have the advantage that the cars were relatively new, and if they had a good parts inventory in stock, parts could be substituted as a diagnostic process, but hopefully NOT left on the car if resolution was not achieved. And hopefully most of the technicians, and surely the shop foreman, were recently trained at our training facilities on all the latest products. When issues became initially unsolvable, a company field service engineer would be dispatched to assist with a new set of eyes and verify that the basics had in fact been checked. It was often found that this was not the case and dealer techs, with preconceived ideas of the issue, ran down the wrong path wasting much time and effort.
I don’t know what all years this equipment, or the portable version (Portable Diagnostic Unit, or PDU) covered but I believe it was most if not all XJ40s.
I checked the ad on EBay and sadly it’s a nonfunctioning/parts only unit … shucks. And it only weighs
about 400 lbs. While I believe I could probably purchase a nice used hand-held unit for a modern Jaguar for about $73.99, I seriously doubt it would have the heft of this baby
It’s usually only the CD drive that is the problem on these (so I’ve heard) …you have to get a very old CD drive to replace it though, newer ones won’t communicate with the old OS …
Now that’s cool! I’ve never seen that machine before. If the diagnostic port is indeed in the boot, I’m guessing it would hook to one of the unused plugs back there. If I ever came across a working unit that was local to me, I would actually consider buying one. After all, beggars can’t be choosers.
My car is one of the earlier ones, so there is no battery tray. If I recall, there are two or three unused round connectors though. They look just like the connectors found throughout the rest of the car, but I guess they would be a possibility. You’ve certainly got me curious!
I was hopeing my CE light was being caused by my O2 sensor. I just installed a new Bosch one and I’m still getting the light. I also received a new front CAT today so maybe that will solve my problem. Although since the O2 sensor sits just in front of the CAT not sure if the Cat could be actual causing the light ??
And my new radiator just showed up so tomorrow will be a busy day.
Hi Groove, just wondering if you have back probed the o2 sensor to see what it is actually reporting back to the ECU?once its in closed loop (?) it should be fluctuating around the 0.5v range IIRC
Since I replaced my old O2 sensor with a new Bosch sensor and I’m getting the CEL at about the same amount of time after start I kind of ruled out that as a problem.
But just for fun I’ll try reading out the voltage anyway.
