The engine doesn't feel right.And, on the way home, the engine started to over heat. I stopped and let it cool.
I found what may be the cause. I don't see the radiator fans coming on at all.
Also, I think the thermostat is sticking.
The temp gauge would go into the red and then suddenly drop to the middle.
It was not blowing radiator fluid anywhere, the upper passenger side hose was bulging.
And, the check engine light came on.
Looks like more parts.
Now I have to figure out why the radiator fans aren't spinning.
-C

 

One other thing, the fail safe mode came on.
Can anyone tell me what this actually does to the motor's function or how it restricts it?
-C

 

Fail safe is just that, it hopefully prevents it from failing unsafely and gives you the opportunity to move your car to a safe place. For Fords its called Limp Mode.
Whenever any motor overheats, you can create an imbalance in the cylinders to the point of cracking a sleeve, boiling your oil to break down, warping a head...on and on very bad stuff.
I would most definitely replace the thermostat, but before doing that, test your fluid, it may need replacement more than likely. When you pull the thermostat, you can easily test it by either using a heat gun on it or dropping it in some boiling water to see if it works.
I would be suspicious of a failing water pump also. You'll have the system drained, so now it the opportune time to replace it.

 

Thanks Highhorse-
I'll replace the thermostat and look at sourcing a waterpump also.
The reason I asked about failsafe is that I was doing about 55mph and it didn't seem to be restricting anything.
-Thank you-
-C

 

It depends on the fault, but you said the engine didn't feel right. Well, there is your fail safe (even though it may not had shown on your dash immediately), something went into a default to attempt to prevent damage. It may just not had received a hard code to trigger the signal.
A good example was my old Expedition. When a coil pack was failing, I knew it, I could feel the lack of engine performance and a slight intermittent miss. Sometimes it would send a hard code right away, sometimes it would carry on for a couple weeks. For that vehicle I needed the hard code to read it to know what coil pack to replace.

 

So....
Here's what I know.
I put the code reader on the and Torque listed two codes.
P0507 & P1000

507 is one of the following:
A vacuum leak
Leaking air intake after the throttle body EGR valve leaking vacuum
A faulty positive crankcase ventilation (PCV) valve
Damaged/failed/dirty throttle body
Failed EVAP system Failed IAC (idle air controller) or faulty IAC circuit

P1000 is system readiness test not complete.
Still trying too figure out what that one means.
It's possible that the P1000 is just there because I haven't driven it long enough for the ECM to run through all it tests since I disconnected the battery while I was working on repairs.

P0507 concerns me.
Visual inspection is how I'll test for vacuum leaks. I know no other way.
The other items on the list, I'm not to sure how to test.
I did get a new thermostat. I'll put that in and I'll get a new temp sensor and replace that also. I need to check the fan relay too. I am going to dive into why the radiator fans are not coming on also.
Two more things to solve and 14 more trips to the autoparts store.
-C

 

P0507 meaning is sometimes dependent on the year/model. I assume you have a XJ8, but what year? You can include this information in your signature, click on USER CP in the upper left of the forum page.

P1000 means the emission system internal tests are incomplete. When they are P1111 will be displayed.

 

The following pertains to the fan operation for the 1998 / X308 :

The ECT sensor is a thermistor vs. the old school variable Temp. sensitive resistor so it responds to Temp in the opposite direction of experience , as the resistance goes up outside of the sensor it believes it is seeing colder Temps. as it signals the ECU .

Check for a secure and clean connection in the pic below .

Fuses :# 67 on print = #12 - 30 amp Engine Compartment Fuse Box

..........# 63E...........= #14 - 10 amp Engine Management Fuse Box

..........# 68.............= #14 - 30 amp Engine Compartment Fuse Box

To see the fans run just remove connector and short with a paper clip , low current so no concern .

Or you can remove the sensor and heat with a heat gun to see them run .

The IAT sensor will read the same resistance value before you run the engine and warm up the coolant .

See the thread below :

https://www.jaguarforums.com/forum/x...-sensor-70566/

 

It's a 1998-
Sorry, I put that info in my profile, I don't understand why it's not showing up in my sig.

 

Thank you-
I will check the those fuses.

 

I've been out of town for a few days.
Looks like the 30A fuse in the large fuse box in the engine bay is blown.
I've replaced it and I'll test it this evening.
I still have the vacuum leak.
I suspect it is the line that goes to the base of the throttle body on the passenger side. It was damaged the repaired badly.
-C

 

Replaced the thermostat and housing ( Metal ) and found loads of vacuum leaks.
The brake booster vacuum line was broke and fixed badly. There is a vacuum nipple on the exact opposite side of the throttle body as the brake booster line that someone used RTV to close off and left the line that connects to it, just laying in the engine bay.
When I get back to it, I'll see if I've solved the vacuum and cooling problems.
-C

 

All the old codes but the P1000 are gone.
However, now I'm getting a P0328 code.
That's a the Bank one knock sensor.
Is there a way to determine whether this sensor bad or not?
-C

 

Yes on the P0328 . I will link you to a on car test later as I made a post for someone else earlier

See post # 7 :

https://www.jaguarforums.com/forum/x...000rpm-193820/

 

Ok- I've looked over various email threads concerning the knock sensors.
Am I reading these correctly?
You can substitute the original barrel type sensors with the later version, AJ85676 for the stock LNE1692AA?
Is this correct?
-Cash
1998 XJ8L

 

AutoZone SU7012 connector lead is longer than the SU7015 but it is about 1/3 the price.

I have heard that the connector will fit and the sensor will work properly, just coil up the extra wire and tuck it somewhere.
For $29.99 I am going to buy one and try it on one of my X308s.

bob

 

It looks like I'll need to put studs in where my XJ8 has just a threaded hole.
Mine has the barrel type knock sensor. The newer 'ring' type goes onto an engine with the studs.
does anyone have an idea what size these old barrel type sensors thread into?
-C
---
1998 XJ8L