I have an intermittent overheating problem. 06 XKR. I have it at a repair shop who wants $1200 to replace the fans before they diagnose further and I am not sure they are doing it right.

Overheating has happened twice. Both first thing in the morning starting the engine from cold. 7 minute neighborhood drive, 3 minute highway drive followed by sitting in traffic for 5 minutes followed by a couple minutes of ~40MPH driving and then the car overheats. Steam coming out of the expansion tank etc, it's definitely overheating. AC happened to be on in both cases (I usually have it off with top down). I live in Texas so the temperature outside was probably 80 degrees F but I regularly drive over 100F with no problems.

Shop says that one of the fans is running slower than the other and that's why they want to replace the whole fan assembly. But they are both running.

Problem seems more sticky thermostat-y to me than fan-related?

Replace thermostat first and see if it still happens? Or dump $1200 on new fan assembly?

Any tricks to take care of an aging fan?

Thanks,

Marcgr

 

Can you tell us more? How did they discount:
The temp sensor? The thermostat? The coolant pump?

does your fan come on when you switch on ac?

I'd fist suspect the thermostat. Really easy to replace on 1998 cars , we'll need someone with a 4.2 to endorse that for you .
John

John

 

Thanks John. Basically they're saying that they can see that there's something up with the fan, so they want to fix the fan before diagnosing further. I'm like, fix the $20 thing before you fix the $1200 thing...

 

The 4.2 fans are variable speed, not simple two speed like the 4.0. I would suspect the thermostat first, but I also changed the housing which is subject to failure. The shop seems a little to ready to throw parts at the car, expensive parts first. If the fans are running it shouldn't overheat while you are moving.

You should monitor the temp. while driving using a cheap OBD tool like the ELM327 connected to your smartphone. The Jag temp. gauge is useless.

 

 

I have never seen a melted water pump impeller. How often have you observed this phenomenon?

 

If the car overheats at 40mph, then it doesn't sound like the fans - as RJ237 mentioned. That would indicate a circulation problem, or thermostat.
It does appear that the shop is throwing parts at the problem. They could be right, but it's an expensive gamble.

 

Buy infrared thermometer (about $20 from HarborFreight or ebay) and check thermostat, heads, radiator top and bottom, hoses.
Sometimes thermostats (including new ones) don't open all the way.
I always check thermostats in boiling water, sometimes it is possible to find specs opening distance. about 1/2" is good, 1/4" is probably bad.
there were 2 problems I could only diagnose with infrared thermometer:
Corvette: bad new thermostat
Jeep partially clogged radiator.
Your fans don't need replacement, your mechanic does.

 

Marc, Suggesting you spend the $30 + 30minutes (at the most) and just replace the thermostat. Given the endorsement above that's how I'd go.

let us know your plan or how it works.

John

 

Just remove old one and check it in boiling water.