I used a Gates 33188S, the "S" means their premium line. An application you can find in Europe is a 1999 VW Golf with the 2.0 engine. You need the length when hot from the mounting flange to the "foot" to be 42-43mm. When heated, the thermostats usually move about 8mm, so you are looking for a cold distance of at least 34mm. The Waxstat brand sold at Jaguar dealers is only 32mm, that isn't long enough

 

Ciao Charles!

Thank you for your precious advice. I might add the heater valve and hoses to the list. It is pointless to overhaul a system and leave out titbits ... I am more inclined to replace the radiator, rather than keep the original, as the water bottle (box) on the LH side of the engine bay contains muck that will certainly be found also in the radiator. Besides, when you pass the finger in the water bottle/box, you can remove black paint (?) or something. And, having to replace it, I am more inclined to replace it with a more modern iteration. I am 'Jaguar-ignorant' so I tend to follow advice but when replacing, then doing so with a modern, aluminium, high efficiency, seems to be the consensus here.

Congratulations on your cars! Lovely!

 

Thank you, Jagboi.

Is this one a good thermostat? Do you know the serial or part number for the European 1999 VW Golf with the 2.0 engine thermostat? I have been looking but it is a bit confusing... if worse comes to worse, I can always order two from of these 'Gates 33188S' from Australia, but I would prefer to find something in Europe.

Thank you in advance for your help! Regards, Tommaso

 

No, those are the ones that are too short. I use Rockauto, they do ship to Italy and the prices are reasonable:https://www.rockauto.com/en/moreinfo...=2200&jsn=5858

 

Thank you Jagboi!

Perfect, I have sorted out my thermostat! Great. Of course I need two of these, correct? Do I need to replace the housing too or that is sufficiently reliable?

Can you recommend also a water pump? And a water bottle/box where air expands when it is hot (on the LH side of the engine bay). I found one at SNG barrat that is super expensive !

Thank you again, Tommaso

 

First, there's not really a problem, per se - the inline filter assembly was sub-par, so I just put a regular hose back on. If I can find a higher quality inline coolant assembly if its exists, I'll definitely post about it. If you're not inclined to work on cars, just follow what's in the sticky and directions from Grant/Greg/Doug/et.al. I don't mind the extra troubleshooting and maintenance on the mods I make - I like working on my Jag

Temp gauge is an addition I added after I removed the aux air assembly, seemed like a waste not to have something there...

Pics...

 

Yes, you will need two thermostats. The housing should be fine. Is there anything wrong with your water pump, like a coolant leak at the shaft? Water pump replacement on these engines isn't a routine thing, they generally seem to last the life of the engine. The expansion tank can rust from the inside, but SNG is probably as good as it gets. Again, if it isn't leaking or badly rusted, I'd clean it and put it back.

Often on the V12 cars you get a lot of debris like grass, leaves, etc gets sucked in-between the radiator and the AC condenser and blocks the radiator. It is essential to remove the radiator to clean all that out, so when you have the coolant drained plan on removing the radiator. I would also check the condition of the fan clutch, and if there is any doubt replace it. Then I'd put everything back together and see what the system does.

On my 6.0 V12 I have driven it in 40C temperatures and the gauge stayed right where it should simply by keeping everything clean and proper thermostats. The biggest difference actually was the thermostats, the gauge ran noticeably cooler when I changed to thermostats that extended far enough. I think you will find that more effective than a replacement radiator, assuming the original radiator is in good condition. Start small and cheap and replace the larger pieces only if necessary.

 

@ Pirk What does it measure and how did you install it?

@ Jagboi
On classic cars that I buy, and that I know nothing of their past, I have the habit of replacing one system at a time. The whole system. I prefer not to "start small and cheap and replace the larger pieces only if necessary". As you found on your radiator system replacement, you soon had a leak from the heater unit.
The expansion tank is rusting from the inside.

As for the radiator and fans, I have been convinced to go with a new aluminium radiator and two electric fans.

 

The XJS radiator is a bit of a beast IMO - I don't think it really needs upgrading. I'd echo ensuring the thermostats are working 100%, as is the self bleed system, thorough coolant flush & replacement, & electric fans instead of the engine driven viscous one if you can.

 

Not all electric fans are equal, so choose carefully. When I bought my car it had electric fans and they were fairly weak. I replaced everything with the OEM fan and then I could feel the air coming out from under the car when standing beside it when it was idling, and I could never feel any air movement with the electric fans. It ran at thermostat temperature with the belt driven fan, it was always hotter with the electrics. So if you choose to go electric, choose wisely.

 

I found tons of muck and rust coming off the neck of the expansion tank and the liquid itself, although very new and clean, contained debris. I can only imagine how badly it must have clogged the radiator. I think that the car was fully serviced before it was sold. But here we reach over 42°C in the shade in summer. Also, I try to listen to experts as I am not one. A few here recommend to do a whole system, one at a time, rather than bits and bobs across different systems. I like this advice as it matches my character besides the fact that it comes from experts. But, I agree with you, some items might be unnecessary to change. The challenge is understanding which ones....

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I am considering buying Alicool radiator with SPAL electric fans and custom made shrouds. Do you know this brand? can you recommend it? It was recommended by a member of this forum.

 

I have no experience with that brand of radiator or fans, so can't comment. If you do by an aftermarket radiator make sure that it has the transmission cooler, some don't.

 

Thank you. Yes, the website shows the option for the E Type so I will ask them if they will provide it also for the XJ12 unit.

 

There is a very good publication by an XJS V12 owner called Kirby Palm. He decided to document all the problems and solutions he found while maintaining his vehicle. It is a free PDF download from Kirby Palm's Jaguar XJ-S Help Book.
Runs to about 700 pages, and I read the lot. He has some very good info on the V12 cooling system. Would be worth reading.

 

This guy did a HUGE favour to V12 and XJ series owners. WOW! I will start reading it.

 

Can I just pop in to ask more about those ones that are too short? I think this is on the topic under discussion here, but if not, tell me to take it elsewhere....
It's coming up to five years since mine were replaced, and Grant (from memory) says they should be replaced every five years, so I'm thinking about getting some new ones if I need to order a new fuel pump or two anyway. However, you (Jagboi) recommend the Gates 33188S ones, which appear to be 82C ones. Extensive discussions on the Jag Lovers forum tend to devolve into people talking past each other, with no clear consensus. Or at least different clear consensuses depending on who's writing....

But, in general, it seems like 82C stats will make my car run a little cooler, and as summers here are not merely fairly hot, but exceedingly humid with all that implies for evaporation, I'm fine with experimenting with 82C stats next time. So a few questions....
1. The Gates have no jiggle pin, according to RockAuto. Does this mean they need a narrow hole drilled through at the 12 o'clock position? (And "narrow" is between 1.5 and 2 mm according to another post here, right?)
2. How much would a lower-temp stat affect emissions? Given that my mandatory vehicle testing takes place in summer, would there be any difference?
3. Some comments suggest older V12s have the 82C while the newer ones have the 88C. What is "newer" in this case? Post-facelift, or the 6.0L versions?
4. The OEM Waxstat 88C ones, not just the aftermarket, are definitely too short?
5. Are there any recommended 88C ones?
6. Bonus Q. How easy is it to replace stats yourself? If it requires draining coolant, I don't have any way of disposing of it safely (legally).

Any suggestions from anyone will, of course, be gratefully received. And again, if I'm butting in where I shouldn't, let me know.

 

I'll answer your questions by number, since I have not figured out how to insert an answer within your original text

1. Correct, they do need a hole drilled as an air bleed, and you have the correct size.
2. I don't believe it will affect the emissions at all, as the enrichment should be completely out by about 60C coolant temperature. That's extra fuel added to assist startup and cold idle, and the amount tapers off as the engine warms up.
3. I'm not sure when the change was, but if I had to guess I'd say mid 80's for the USA market, probably later for other markets
4. Correct, I have measured OEM Waxstat ones purchased at a Jaguar dealer and they are too short.
5. Since most of these seem to be American companies who make the thermostats the common steps have always been 180F and then 195F, which translates to 82C and 91C. I felt that 91 was a bit warm, but you could certainly try it. The part number for those is 33189S
6. It's not too difficult. You will have to drain some coolant, but if you put a shallow pan under the car to catch it, you can simply pour the coolant back into the engine when you are done. You would need new gaskets and either a 1/2" wrench or socket. I'm not sure if your car would have metric bolts on the thermostat housing, but I don't think so. You'd also need either a screwdriver or (typically) a 6mm socket to loosen the hoseclamp. I really like the ratchet wrenches with a flex head, they make the job easy.

 

Thanks very much, Jagboi. Very thorough, educational answers.

Looks like I might be giving the 82C ones a go next, as the way the temp needle creeps past the middle mark at stop lights in summer always unnerves me, even though it usually only creeps up a certain way and stops. That bit on the Jag Lovers forum where someone said something about you can always tell a V12 driver from the back by the way their head is crooked around to view the temp gauge dead-on makes me wonder if someone's been spying on me. As I have the OEM stats, it'll be interesting to see how much change there will be with the Gates. I'd ideally replace them with 88C ones to see how much difference a fully-opening stat makes, but it's not vital.

When I get around to this, I'm sure I'll be asking more questions like how much coolant to drain, but I'll start a new thread for that, I suspect. RockAuto has cheap prices but their overseas shipping is expensive, so I'll probably use another source. (Which is a bit of a heads-up to ascanio1 as well, actually.)

 

I noticed a significant difference with the Gates, it ran cooler and I could actually see the thermostats cycling as the gauge needle moved. I had also made sure that everything else in the cooling system was up to spec, so the radiator was clean inside and out, fan clutch was good and belts properly tensioned.

 

Everything else should be pretty good in my cooling system. The radiator was back-flushed recently, fan clutch passes the finger-spin test, and she's getting four new belts at the moment anyway.