Driving a 2001 XK8 Convert. 78K miles. In the past two months I have repaired the heater hose to water valve assembly as the car was leaking coolant and then the heater hose junction fitting as it started overheating. The temp gauge didn't register, but the Low Coolant light came on. I opened the filler valve and the coolant started gushing out. This was after the heater hose to water valve assy was replaced to stop a pesky leak.
After the first valve assy was fixed, I started to hear the radiator fan spinning over the engine noise while driving. Then the fan started to stay on after I shut the car off. That's when I started getting the low fluid warning and noticed the over heating. Back to the shop to repair the heater hose junction fitting was replaced.
I notified my mechanic the fan never ran after stopping since I've had the car (8 years) and now I can hear the pitch of the fan as it spins.
Yesterday I had the car on the highway and noticed the temp gauge was registering to the 3/4 mark toward HOT.
Any ideas on whats going on? Could the bearings in the fan assy be going? Looking to avoid another $1,000 + bill.
Thanks

 

Hi Johnny,

It is normal and appropriate for the fans to stay on after you shut ignition off if coolant temps are high. They do shut off after a bit right?

It made me wonder if your thermostat is bad. Coolant, or not enough coolant, is not getting to the radiator?

Noisy fan? I'm not sure what to say about this one.

Let's see if others agree. Johnny changing the thermostat is a very easy quick job.as I recall the part costs a bit over $30.

John

 

Any chance this is actually progress of sorts, that the fan should have been running after shutoff all this time but wasn't because something wasn't correctly registering the coolant temperature?

That thought is separate from the other issues of overheating and coolant loss, of course.

I was always under the impression that the fan will normally run for tens of seconds after shutoff, and my '97 always has. Maybe for those 8 years whatever is supposed to trigger post-shutdown fan wasn't getting enough coolant to register that they should stay on?

 

Good point Volkris, maybe a bad temp sensor?

 

Agree with the above. It seems you could have multiple problems and you’re right to be watchful as over heating is an engine killer for these Aluminium Aj-V8 engines.

You mention a history of overheating so have fixed hoses etc. Coolant temp sensor replacement is a way to go. Quick cheap fix. When was the last time coolant was flushed and changed?

checking the reservoir float sensor is a quick and easy task. Take unit out and check continuity at the contacts turning the unit both upside and downside

Fans running on after engine shuts off is a good thing if engine bay is hot. Here in Bahrain it’s a hot desert climate and after a long drive, when I shut the car down I even open the bonnet to help the fans cool everything down. Fans should turn off though after a short time.

Rattling fans is a sign of age and some garages can just grease/repair/replace the fan spindle bearing. Thus avoiding cost of replacing whole unit.

Good luck and let us know how things pan out.

 

Not long after I bought my car in 2005 the fans would run after I shut the car off. I had a warranty and the dealer changed the thermostat. Problem solved.

 

Mine usually doesn't keep its fans on unless I was driving at noon on summer months. Otherwise, the fans shut off at the same time I shut off the engine. The one time the fans started staying on longer than normal, I replaced the thermostat and the problem was solved. Cost me about $15 for a stant thermostat.

 

Hi there, coolant was drained and changed last month.
I understand the fan remaining on for a bit after shut down if engine is hot. Its mostly the sound of the fan while driving. I never heard that before, so perhaps its spinning faster if that possible, to help cool down the engine.

 

that seems to be the quickest/cheapest route to try first. Will give it a try.

 

Your present problem may be due to air in the system, but I would change the thermostat. Also a good time to replace the plastic thermostat tower with aluminum and get a new outlet pipe (crossover) which includes a temp. switch and the short connecting hose. These are all basic preventive maintenance items.

 

You have two fans, they come on at different temperature's and each fan has it's own fuse,
if one is not running this will make the other run for a lot longer after shut off,

I would check they are both working at the right time's/temperature's.

This is for the xkr but xk8 maybe the same.