past month or so the radiator fans have been operating at stop lights and when I shut the engine down. Went to the dealer today for an inspection and he showed me where the water pump is leaking. Not so much that I have seen any antifreeze on the floor but there was orange drips around the pump.

My question is, they topped off the fluid but the fans were still running as I drove home and when I shut the engine down. The temp gage is normal--engine is not overheating. I will have the pump replaced but are there any other sensors that could be causing the fans to engage?

Gary

 

The temp gauge is an idiot gauge. It always reads mid range until just before the engine smokes so you could be running a little hot due to low coolant.

The sensor is located in the outlet pipe above the thermostat housing.

Over heating can cause other problems. Best not put off the job. I would change the thermostat and flush the coolant while in there. And since the thermostat housing is a common leak problem also you might consider changing the plastic one to the aluminum one now available.

 

Thanks for the tips--guess I will bite he bullet and have jaguar fix it. I have replaced many water pumps in my time but I am always cautious about getting into this car.

BTW on my engine the T-Stat housing is aluminum already--maybe the plastic housings are only on the XK8 engines.

I added some coolant this morning but it was not very low--

Gary

 

I am glad to see this thread... ( I think ) ... because, by some strange coincidence, my fan(s) have also started running the last couple of days while I am driving. Coolant level is fine and no sign of leakage. I have 20,000 miles ( 34,000 km's) on a 2001 XKR. The fans go on and stay on till I turn engine off, then they immediately come back on for about a minute or two. The one time I pulled over and opened the hood with the engine running. The engine was not at all hot, as I had only gone two or three miles, and I got no errors or warnings. This was not highway driving. So I drove off, sounding like a jet...

Next nice day, I will go on the highway and see if it does the same thing.

Also, while poking around this evening, it appears my T-stat housing is aluminum. Is this normal on a 2001 XKR (Canadian car)? I thought they were plastic?

Cheers.

 

I think the "R" engines must have he aluminum T-Stat housings. Your description of the problem is exactly what I am experiencing. Even if the pump is leaking slightly, if there is enough coolant in the reservour why would the fans engage??

Gary

 

Guys you all are panicking over nothing.......The fan motor automatically kicks on at a set temp.

Your car has been doing this since day 1. You have just only realized it is all.

Having said this...It never hurts to check ALL fluids once a month.

 

Update... went for a drive today... with the heater on, the fans did not come on... neither while I was driving NOR when I shut the engine off. It was 60 degrees out. If I turned the heater off, the fans came on while I was driving AND when I shut the engine off. I know the fans are running more often now than they used to.

Since I am taking it in for an oil change on Thursday, I will mention it to the mechanic (independent shop,Jag trained specialist) and see what he says. I will report back.

 

I had the same problem. Remember there are two speeds to the fans. It is normal to run the low speed fans, but the high speed should not kick in until water temps reach about 190 degrees F. The fans turn on after engine shut off, but only for 15 seconds and only at low speed.

Here are some possible causes for you to examine (besides the obvious of a leaking cooling system):

1. T-Stat not opening completely, or intermittently
2. Fan Relay faulty and sending wrong signals to activate fans
3. AC line [condenser] sensor faulty and triggering fans to activate
4. Collapsing radiator hose (intermittent) which choked off water circulation

My problem was solved when I noticed the lower hose had been installed backwards. As such it was rubbing on the fan shroud and had worn a section of the outer sheath, which undoubted was weakened at that point. It's structural integrity was compromised enough to allow a collapse at that point. It collapsed sporadically, triggering the high speed fans, but I would not know about it when I popped the hood to inspect for problems. This was a very tricky problem and it's unlikely to cause your situation.

Here is the thread. Read it and then you, or your mechanic, will have a better idea of what to look for. https://www.jaguarforums.com/forum/s...ad.php?t=10791

 

Fan Relay...

Where would I find the fan relay on a 2001 XKR?

Thanks...

 

On my 97, they are behind the front facia, under the driverside headlight. You need to pull the black plastic spoiler shield/pan off to gain access. There are two. One each for low and high speed fans. gordo

 

Thanks Gordo... I will check them out...

The problem is that the fans don't come on till the engine warms up... if the relay(s) were faulty, would they not come on right away?

What would be the symptoms of the T-Stat not opening completely?? ... would it be enough to keep the engine from overheating but neccessitate the need for the fans to run to keep the engine form getting TOO hot? As soon as the needle reaches the halfway point, the fans kick in (on high) and STAY on... even though the engine does not seem to be that hot... I can even hold my hand on the engine and it is only warm... certainly not so hot that the fans really need to be running but I am not a mechanic so I am not sure...

Thanks...

 

Your low speed relay may be faulty. As the engine begins to overheat, then the high speed relay is signaled and that fan comes on.

If the T-stat is not opening it is a quick engine overheating because all cooling is limited to water in engine block.

You need to get a lazer thermometer to read the precise engine water temps. Our gauge is NOT linear. It is almost a go/no-go gauge. Like a warning light.

My symptoms were similar, but the cause was a collapsing radiator hose due to an abraded area on the exterior surface. Check out my earlier thread on this very same topic. The link is here: https://www.jaguarforums.com/forum/s...ad.php?t=10791

 

Yes Gordo... I had read that thread and had seen the post about T-stats not opening completely or intermittently... And so I was thinking that if it IS opening but not all the way, then maybe the coolant temp. is too high and is triggering the fans...

I will report back.

Thanks

 

You can pull it out and check it. But IMO, it is either working correctly or fully closed. I have never heard of one opening partially. I you have a multimeter, you can get resistance readings off the water temp sensor right on top of the black plastic pipe. Either way, you need to accurately ascertain the water temp. The OEM gauge is not helpful in this situation.

 

Ok... so it WAS the thermostat.... had new style waterpump put on at the same time... now it doesn't sound like I have a shop-vac running under the hood non-stop

 

problem with my 1998 XK8 is that the radiator fans continue to run for 3-5 minutes after i shut off the engine. this happens ONLY when i drive with a/c on.

am i looking at the same issues with the water pump, thermostat housing & relay sensor? does anyone have a technical explanation for why this is happening?

thanks...

 

Welcome to the forum. Sounds like you just bought the car.

The fan is designed to run after shut off to blow off the high end of the heat but 3 to 5 minutes is a little long. In the Summer, with AC running, my fan will run, probably, about 90 seconds max.

The cool down fan run is controlled by the temperature sensor in the plastic manifold at the top front of the engine. That advises the ECM which operates the fan relay.

 

If I don't have the a/c on, the fan shuts off almost immediately when I shut off the engine. But with the a/c on, the fan will continue to run for 3-5min after engine shutoff.

Does it sound like a fan relay problem or thermostat?

I have owned the car for 2 years and it's not a big problem, just annoying. Temp gauge always stays normal.

 

it sounds like a similar problem the xj8-xjr owners (up to 2003) have with a relay for that second fan, which is vital when running the a/c. It was a relay, but I wasn't paying too much attention to which one or where it was. If you try an advanced search, it wasn't more than 6 mos ago I saw it. the xj & xk are built very similar in regards to transmission/engine, mechanical and electrical components/systems.

 

Usually the issue is the thermostat is stuck open....on most cars we see at the shop the thermostat will stick and the ecu will keep the fans on because it will detect the slite overheating issue...but your ect sensor wont show this reading inside the car until it gets very hot.I have seen this several times on many xk and xj series...To test the ect sensor crank the car and unplug it,the coolant gauge should show hot within 5 to 10 seconds