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sprinkles08
sprinkles08, ASE Certified Technician
Category: Jaguar
Satisfied Customers: 22534
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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94 jaguar xjs v12 6.0, changed radiator, heavy flow core

Customer Question

94 jaguar xjs v12 6.0, changed radiator, heavy flow core installed(rebuilt), water pump, thermostats, coolant (original jaguar) installed water wetter, changed the whole system to electric high performance fans bought from jag-lovers, car is still overheating on the highway or longer trips. Im strapped for solutions. I noticed the spoiler lip(under front bumper is missing). I read that it doesnt allow extra air flow to radiator if missing. Could it really be just that after replaving the whole damn cooling system? Cylinder head gasket test result, normal, not damaged. PLEASE HELP! thank you
Submitted: 10 months ago.
Category: Jaguar
Customer: replied 10 months ago.
I found the fiberglass lip. Going to install now and test again. I feel it will still overheat, please contact me
Expert:  Clayso replied 10 months ago.

Hi There,
This is Clay, I'm a certified master automobile technician with 30 years of automotive repair and diagnostic experience.

Hope I'm not to late to help with this overheating problem. The lip under the spoiler does provide air flow through the radiator at highway speeds, but from your description I don't think it's the only problem. A couple of things to make sure of is the cooling fans (when on) are pulling from the radiator and blowing towards the engine. Make sure the jiggle pins on the thermostats are up when installing the thermostats into the housing. The link below is a description of the cooling system for this vehicle.

Cooling System Description and Operation

Also make sure the coolant mixture is 50/50 water and antifreeze. A high ratio of antifreeze compared to water will not cool properly. Coolant capacity is 21 quarts. Let me know if the coolant is boiling over or if the gauge is the only indication that the engine is overheating.

I hope this information is helpful. If you have any questions let me know. You can reply back to me through this thread at any time.

Customer: replied 10 months ago.
The lip on, same result. The coolant is not boiling. Thermostats and coolant is done properly. We are also a repair shop. Just this car is stumping us as its a special vehicle with constant overheating issues. Need a mechanic fully familiar with this particular vehicle. Any other suggestions? Only the gauge, continuously shows after longer driving and is giving proper reading. Because the fans act according to the gauge.
Expert:  Clayso replied 10 months ago.

That was really all I had was the basics. unless there is a flow problem through the block and heads. I'll opted out. There's another Jag expert on site that may help.
Thanks

Expert:  sprinkles08 replied 10 months ago.

Hello and welcome to JustAnswer!

Do you still need help?

Customer: replied 10 months ago.
Expert:  sprinkles08 replied 10 months ago.

It looks like you installed some sort of 'rebuilt' radiator?

Customer: replied 10 months ago.
we took out the original, sent it to cool heat, and they recored and put heavy flow core in there, and made it like new again(supposedly) it looked like new when it arrived back to us
Customer: replied 10 months ago.
After 20 min of driving, we took the pic of temp gauge
Expert:  sprinkles08 replied 10 months ago.

I haven't seen good results from companies claiming to repair radiators.

How did you determine the gauge reading is accurate?

Customer: replied 10 months ago.
The fans react turning on accordingly to the thermo switch when the temp reads between 190-195 degrees. They attempt to cool down the vehicle by that range, which seems appropriate from diagnostic info available
Expert:  sprinkles08 replied 10 months ago.

How did you determine the gauge reading is accurate?

Customer: replied 10 months ago.
I'm so ready to try and buy the high performance radiator, new, from Byers jaguar, which I already purchased their upgraded electric fan kit. My issue is I paid the damn rebuild guys 750 for this and the Byers jag radiator is 850. So I would be out near another 1000 if it didn't solve our issue. I don't even know how to tell that to the customer. Pretty crappy situation. We've already put so much money, parts, and labor into this
Customer: replied 10 months ago.
I sent this earlier, The fans react turning on accordingly to the thermo switch when the temp reads between 190-195 degrees. They attempt to cool down the vehicle by that range, which seems appropriate from diagnostic info available
Expert:  sprinkles08 replied 10 months ago.

I did see that earlier but I'm trying to determine how you determined the gauge is actually showing a correct engine temperature. A scan tool needs to be used to monitor temperature to see if there is actually an issue with temperature or indication, and coolant temperature also needs to be looked at after a cold soak to see if it showing the same as ambient.

Customer: replied 10 months ago.
it's showing that properly. Once the temp goes down, the gauge shows accordingly the temp on the gauge needle drops. We just don't have a jaguar scan tool for this old mpdel
Customer: replied 10 months ago.
My head tech said yes from what u stated has been accordingly so. And when the temp gets hot, the fans constantly run
Expert:  sprinkles08 replied 10 months ago.

Can you clarify your last post?

Customer: replied 10 months ago.
When its cool the gauge shows temperature well below half, and fans dont run. When car gets hot, fans constantly run, and gauge goes higher
Expert:  sprinkles08 replied 10 months ago.

But you have not done the proper testing to determine actual engine temperature or determine that the gauge indication is correct?

Customer: replied 10 months ago.
We are only using the fan to dictate this. Any way to figure this out without the scan tool? Infra red thermometer is not very accurate either. Head tech says the engine actually gets hot at time of overheating and runs cooler at not. Mechanic intuitive, he's pretty dang good. Works on AUDI BMW and many high end cars successfully. This car is just stumping us Asa specialty vehicle. Cylinder head test result with liquid block test passed
Expert:  sprinkles08 replied 10 months ago.

A scan tool would be needed to know if the gauge was correct, coolant sensor signal is correct and whether the engine is actually running hot.

The liquid block test isn't an accurate test. On numerous occasions I've proven this by inserting the vial directly into the tailpipe of a running vehicle and the liquid stayed blue. Is the cooling system staying full or is it pushing coolant out?

Customer: replied 10 months ago.
Coolant remains level, no back flow, no boiling
Expert:  sprinkles08 replied 10 months ago.

A combustion leak shouldn't be a concern then.

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