Hi All. After about 3 hours on the road at 75 I got an amber engine fault followed by the temp gauge shooting all the way up.

I pulled over and saw no leaks and nothing felt excessively hot. Top hose from radiator feels full and wasn't too hot to touch.

Put it on my one code reader and the only code is P0118. Temp gauge on dash command read 246. Let it cool down a little. Started it again. Temp guage shot up again a 3 blocks later so stopped again.

Defroster on hi blows no heat. Revving it briefly to 3k rpm didn't bring heat either.

I don't have my tools with me and I'm in a small farm town 70 miles from Des Moines IA at a funeral.

Anyone have thoughts on diagnosis?

 

You should really update your signature with the year/model of your car for better help. Sorry to hear about the circumstances of your trip.

For the code, the '03 book comes up with these causes:

Engine overheat condition
ECT Sensor to ECM wiring: short circuit to ground
ECT Sensor failure

So, check the sensor and its wiring. It should be towards the front of the car, near the thermostat and radiator hoses. On my '03, it is on the "thermostat tower", just off of a plastic pipe. There is a connector to it, and it just clicks in. If you have a meter, check the resistance of the sensor. Apparently, low resistance is high temperature.

If you have no heat at all, and it overheats quickly (assuming the sensor is right), then it sounds like the water pump has given up. At 75, you should have had PLENTY of air flow to cool the car off, assuming water is flowing. Thinking out loud, a stuck thermostat should give you plenty of cabin heat. Another thought is the main belt. If it is off, then the water pump does not spin.

At operating temp, you should have a temperature difference between the supply and the return hoses to the radiator. If they are the same, then there is no water flow. Test this with the A/C on to make sure the fans are running.

Just my thoughts, trying to help. Best of luck.

 

Many thanks. It's a 97 w/ 86k, sorry that used to be in my signature but I'm on my iPhone so I can't see my footer.

The belt is good. Will go wiggle the sensor wires when I get back to the car. . So far fearing that it's the main water pump.

How hard is the the water pump to do in someone's driveway? Not looking forward to a 70 mile tow to a jag mechanic if that turns out to be it.

 

The water pump is easy. Break the pulley bolts loose before removing the belt. There are five 8mm hex head caps for the pump.

You probably won't have a torque wrench but just in case it's 8nM + 90 deg. for the pump and 10 nM for the pulley.

 

Take a look at Gus' page NB it's for a '99 but close enough:
JagRepair.com - Jaguar Repair Information Resource

Aargh: sorry - that won't be much help on a mobile.
Mike

 

Many thanks.

I let it cool down during the funeral. Started it up and no errors at first. Initial temp 118.

Pronounced difference in temp between the 2 hoses. So I think that means I have water flow

Was steady at 234 degreees but then when I revved it it hit 246 again and the light came on. The hose coming out of the engine to the radiator was quite warm tho I'm not sure it was also 250 degrees.

Thoughts 9n what's wrong? Driveable? Tow it somewhere?

 

Others more knowledgeable will chip in here, but I'd be very wary of driving it - particularly as it may be a 'Nikasil survivor' - unless you are comfortable that it definitely isn't overheating.

Mike

 

Seems like your temp sensor is fine and can be trusted. From memory, my car (a later '03) runs at more like 190 deg F, way below what you are seeing.

I am still thinking the water pump is the problem. Sounds like the pulley is being spun by the belt, but the impeller is no longer going along with the plan, so no flow. Did you make any changes to the cooling system recently? Add coolant, possibly incompatible (green vs. Orange)? Is this water pump original?

One last thing to check just to be sure: check the fuse to the auxiliary heater pump. If it is blown, there is an off chance the water flow is blocked by that secondary pump. I think this is unlikely, and far fetched, but might be worth checking as you re on the road.

 

Call my Indy Jag mechanic back home and he thinks the thermostat is stuck shut.

I took it it out and it did seem stuck. Gonna try running it without a thermostat to get it home

 

One would think that with a thermostat stuck closed, you would have plenty of heat in the car. The heater core would actually become the radiator and allow you to get home, possibly. As you have no heat in the car, it seems inconsistent with that hypothesis.

Supposedly, running the car without a thermostat leads to overheating as well. Something to do with confused water flows when the thermostat is missing.

As you said, you need to test this before you commit to getting on the road. Best of luck, I hope I am wrong.

 

Definitely do not drive with the thermostat out. Coolant distribution will be affected. The pump is still a likely suspect.

 

Yep. That didn't work. Making arrangements to store the car at an in-law's driveway down here. Will borrow my brother's trailer and come back for it in a week or so.

 

Water pump replacement on one of these is a very easy task. Few tools required. I'd save the tow
and do it in the driveway.

 

Be careful with those plastic parts and little fasteners.

 

You may want to replace the temp. sensor first since that would be easier and cheaper and is a possible fault.
You'd probably be better off replacing when doing the water pump and thermostat anyway.

 

It's a better move to replace the crossover pipe which is subject to failure. A new pipe will include the sender.

 

Update- Okay it's been about 2 weeks and I towed to car back to my home state today using a borrowed trailer. I will acknowledge that it took me longer than I'd hoped to figure out where to hook the trailer tie-downs to the car but I go it eventually.

I have a new thermostat and a new water pump (& extra gaskets for each because I didn't realize they would automatically come with gaskets).

I have an aluminum thermostat housing coming from SNG. I'm planning to put those in this week or next and hopefully they will resolve the overheating issue.

While I am at it, are there other things I should probably replace (without making this an epic job)?

The car is a 97 XK8 with 86k in great shape. None of the hoses or plastic bits show any signs of visible distress.

I'm thinking maybe upper and lower radiator hoses since they love fine but seem just a wee smidgeon more pliable than might be perfect and probably new Jaguar spring clamps for them... Thoughts? Bypass hose?

I also know I'll need a bent or crowfoot 8mm wrench for the thermostat housing rear bolts, is there anything else I'll need that I'm probably forgetting?

Also the coolant, The current coolant is orange, am I corrected in assuming that Zerex Dexcool will be fine or do I need to hunt down something more Jaguar specific?

Thanks!

 

You can just break the old housing apart to access the rear screws and use socket heads and a ball drive for replacement. Stuff a rag down in to keep little chips from being lost.

 

The hose between the tower and the crossover pipe, they tend to expand. The two gaskets on the ends of the crossover pipe.
Before you start, put some rugs behind the tower and keep water from going under the intake. Your knock sensors are under there and don't like water running under them, it will give you a code when you get through.
Those clips on the tower are the knock sensor ones and they are a little bit of a pain, be careful.
Now getting the air out, leave the top of the tower off, slowly pour coolant down there and pump the top hose at the same time. Don't get too close to the top of the tower yet. Once you are getting no bubbles, fill to the expansion tower outlet and connect you tank to the tower. Now put the top on the tower and almost seal it. Fill the tank and as soon as the fluid comes out, tighten it down, you have gotten as much air out of the system that you can.
Have fun.

Wayne