I only had a short time this morning, and did not access thermostat.

I ran the engine stationary just outside my garage

As the engine warmed up, I had the Gendan connected to see the temp info provided by the car.

First thing I noticed is that the top input hose did seem to pressurise, quite difficult to squeeze.

So I assume this means there is pressure from the water pump, which is functioning?

Secondly, with the infrared thermometer I saw that as the engine temperature increased, so did the hose temp, but when the engine temp suggested 100 degrees C (212 F) the hose temp never went above 76 C (170F)

Also (and I'm not sure how relevant this is), when the thermometer was pointed at several places on the face of the radiator, it showed only 26 degrees C (80 F) - virtually ambient temperature (hose temp showed 76 degrees C)

Does this suggest no flow through radiator, or is this just a misunderstanding on my part?

Due to time constraint I turned the engine off at 100 degrees C.

The car temp gauge was showing 50%

The fans had not yet started to operate.

 

The pressure rise is from coolant expansion as it warms, not flow.

This more likely indicates a stuck thermostat, inhibiting flow.

 

Ok so firstly the the pressure you feel on the top hose is not from the water pump ! It's from the engine and coolant expanding due tho heat and causing pressure within the cooling system . Regulated by the pressure cap .

You were at the critical point were the thermostat should be opening and at that point the the coolant will then cuculate through the radiator

However if the coolant was in fact only 70odd as indercated by the laser ,and you can not get the two gauges to agree . then the car is still not up to temp for the thermostat to open , and the only problem here is a faulty senser . These are cheap on eBay .

The radiator should not always match the temp of the hot top hose but you should see the temp of the radiator rise quickly when the thermostat opens .

 

Do your self a favor and test and/or replace the thermostat and replace your temp sensor . Both easy cheap jobs .

 

Thanks for advice above

I took the car round the block - it was slightly warm from this morning.

I attach 2 pics of which the second is the more important.

I stopped at the temp shown by the Gendan/sensor at 110°C (230°F) so as not to cause any damage. The car gauge only showed 50%!

The fans were blowing, but the Input hose temp was 86°C (187°F)!

- and the radiator was still showing ambient temp at 26°C (79°F)

So I assume that there may be a sensor issue, since the thermostat has not opened (at 110°C with fans running) - and/or the thermostat is stuck?

Either way, as you guys say, the percentage golf shot is to change both sensor and thermostat!
D

 

Start by replacing the thermostat - very very urgently. I cannot stress enough that your engine will not tolerate overheat and is liable to need replacing - more than the car is worth.

 

+1 don't destroy the car for a 20 euro part.
If you can't do the work yourself the place Mikey linked to earlier will come to you IIRC.
I'd give the dealer a body swerve if I were you they should have figured this out when you were there.

 

Thanks Norri (and Mikey) - I have emailed them, with link to this thread, and will call them tomorrow morning
D

 

Not meaning to muddy the waters, but 230F is considered as still within the normal band, albeit at the very top with no margin:


https://www.jaguarforums.com/forum/x.../#&gid=1&pid=9


I only mention this so you aren't perplexed why the needle was still centered.

Of course, you should not see 230F under virtually any circumstances. It's something you'd only rarely see, such as barreling up a steep grade on a very hot day while riding the brakes and pulling a heavy trailer with a drag chute...

One quick question: Did you ever replenish the coolant drained by that mischievous dealer? I've seen no mention of that. Low coolant, and the resulting air bubbles, can interfere with an accurate diagnosis of the cooling system. Moot point, of course, as I agree with the consensus to replace the thermostat and temperature sender and go from there. I'm busy going down my rabbit hole that a minor problem changed drastically for the worse after some coolant was drained.

Will you be doing the work yourself? If so, I'd suggest taking a little extra time to compare the new and old thermostats. Suspend them side by side in a large pot on the stove, heat the water, and record the temperature when they open. If nothing else, it's really nice to have confirmation when a part has failed, and also that the new one is good. In my recent experience, I had an existing thermostat that had clearly failed, but the first replacement was opening way too late. It was better than the original one, but not by much. A bad part from stock like that is rare, but it happens.

 

Thanks Sandy for observations and links.

At 230°F, 110°C I could not risk the sensor shown temp getting any higher.
Very interesting link re inaccurate Jag gauges.!

I had no dashboard warnings re low coolant or high temperature
There were no faults shown via my Gendan Engine checker!

*I never replenished the coolant, since the coolant level, whilst just below minimum on the indicator, showed coolant in the fill area, and the tank was full. (and I had no orage jag liquid)
No air bubbles!

see the pics
I regret I can't do the work myself (getting older!) even though I have changed engines, gearboxes and turbos in my younger days.

So (having lost all trust in Jag dealer - who said he could not take the car when I was there, "because he had no space") - I have taken Mikey's (above) advice and will be talking today to his suggested local independent garage, which is actually nearer than the Jag dealer, and will get thermostat and sensor changed.

Yes, things seemed worse (gauge got up to 80+%) on way home from dealer! - and I am hoping that whatever he did, it was not to let the engine get too hot, causing damage which I will only find out about at normal running speeds.

 

Let us know how you get on, fingers crossed!

 

The "independent" guy did not turn out to be useful unfortunately. I phoned him, and it seems he is a one-man enterprise (not that this is a bad thing), but when the landline number jumped to a mobile, and I had to leave a couple of messages, then my enthusiasm began to waver.

I suspect he originally had staff, but not now.

Eventually I could call him, but he said he was busy until Wednesday, then he was going on a car rally. I asked if he knew the S-Type R, and he said he "did Jaguars", but that I had to phone him next Monday afternoon, and then agree a time to take the car.
About parts required, he said no problem, can get them in 3-4 days.

Now I had lost faith (even that he might not have a workshop manual), so I said I would phone him next week. (I won't)

So I took an Uber to the Jag dealer, got him to order in the sensor and the thermostat (of course he recommended the "2 tubes" also!), and hopefully they will be there Friday for my originally-booked service (which I will ask him to delay)

Voila! - I am now trying to resolve a "boot/trunk open light always on" issue.

 

Sounds like you've already decided on a plan, so that's good. As far as the independent shop, most likely he subscribes to a professional manual service like AllData, so don't automatically rule him out for that.

 

So you're going to DIY as a next step, that's good.

 

Not so much a "manual" issue, but that he was going away midweek on a rally, and could not give me appointment as we spoke, said I had to call him Monday mid morning to see when I could bring the car - and then I would have to wait several days for parts to arrive.

It's our only car, so time is immportant

 

My previous post was ambiguous, sorry.

Sorry, Mikey, I would love to DIY the heating issue, but don't have facilites to drain coolant etc., and I decided to bite the money bullet and get the Jag dealer to fit new parts without lengthy diagnostics and heating up the engine.

I am this afternoon DIYing an "always on" trunk ajar/boot open warning light. See

https://www.jaguarforums.com/forum/s...8/#post1765938

 

It sounds like he was bigging himself up on the website, hopefully the dealer will redeem himself.

 

Since the potential "independent" garage had not inspired trust on the phone, and told me to phone again in a week to make an appointment, I had no choice but to use the local Jag dealer
*see photo of independent garage at 10.30 am last week

I asked them to replace both temp sensor and thermostat to be safe.

On retrospect I should have asked for a quote beforehand, but as I say I had no choice.

The fixed the problem! - 2000 Euros - 2350 USD.

The reason for the large cost was down to one part!

Labour cost is high here - 130 Euros (150 USD) per hour - they took 2.8 hours- which seemed reasonable.

They said that Jaguar required that on thermostat replacement, the "exit tube" had to be replaced at the same time (repair warranty issue?)

The part alone cost 1222 Euros - 1436 USD.

I know this is an enormous charge for what could have been a much cheaper repair via an independent, but we don't have them here like you do in the UK or US.

So I was between a rock and a hard place.

The STR is our only car, 16 years old, owned from new, only 71,500 Km (just over 46,000 miles), and serviced annually. Beautiful condition inside and out!

There is nothing I could buy for less than 60,000 Euros (70,000 USD), even second hand, which comes anywhere near it in class, comfort, and personal pride! My wife agrees!

So, even at the cost of a couple of thousand a year, keeping the car going is the "professional golf shot" - for us! Of course if the gearbox or engine failed, then one re looks at the options.

Can I thank you all for your help, kindness, patience, over the last few weeks.

I learned a lo! And had some fun with my engine tester and the infrared thermometer.

Thanks again - David

 

Glad to hear you got it fixed, albeit at a large cost.
I can understand the bill being high due to the outlet pipe that runs under the SC, all that has to come off if I remember rightly, to get to it.
Did they change the thermostat tower for the metal one at the same time?
Plus with the low mileage that is on the car, it'll carry on for a good few years yet. Barring catastrophic mechanical failure that is, can't plan for that.
Now you can carry on enjoying your baby, savouring the ride, instead of looking at the gauge all the time.

 

David,

I'm glad to hear that it's fixed and that the advice here did not steer you in the wrong direction. Lucky car to have such a devoted owner.

I'm curious as to the exit tube part that had to be changed, not quite sure what that is. Is a part number shown on your invoice?