When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Sorry to beat a dead horse with another one of these threads, but several of the older threads I found had outdated info, part numbers, or dead links.
I'm aware of Grant's thermostat fiasco writeup, and the ~41mm length needed for the bypass. The Tridon TT228-180 and Dayco DT18A aren't readily available in the US, and are available from Australia, but at exorbitant shipping prices.
What's the current recommendation for thermostats here in the US? I would prefer a 180-Deg over a 195. Looks like 160s are available as well, but I imagine that might play poorly with the EFI system going into closed loop and causing other undesirable issues, thoughts?
Just looking at some of the local parts places and RockAuto, it looks like I can choose from:
Motorad also has 170-Deg and 160-Deg versions of this thermostat with the same dimensions listed
Gates 33188- 180 Degree, Bypass Diameter 1.10", no Jiggle Pin. Can't find info on Bypass Length.
Can't find the 33188S version that was listed in some of the old threads, looks to maybe have been discontinued
Motorad 2033180- 180 Degree, listed as being "High Flow". Saw a couple threads mentioning these might be decent?
Napa's various thermostats:
THM 113 (180 Degree)
THM 160JV332 (160 Degree)
THM 170JV332 (170 Degree)
Stant 45398 SuperStat- 180 Degree, Bypass Diameter 1.092", can't find the info for the actual bypass length. Saw a few threads with people recommending these.
Stant 13398
I'm open to other suggestions. Like I said, I'd prefer a 180 thermostat over a 195. I'd even be open to the 160 or 170, if anyone has tried them and it doesn't effect EFI operation or anything else drastic. My initial thought it so go with the Stant 45398 or the Motorad 2033180, since the S-variant of the Gates is no longer available I think.
Also, while working on my parts engine that was on a stand, I noticed how easy it was to break the bolts for the thermostat housings. Was this a one-off or should I break out the torch on them before even touching them? Not sure how common it is.
Last edited by BuckleSpring; Jul 24, 2025 at 01:54 AM.
I changed them now and I set both of these to 88°C. Cooling without problems, we are now about 30°C, and even so I have the indicator on the clock below "N".
Regarding the screw on the house, I had them outside about 10 years ago and I had to heat them now (with an electric coil) otherwise I would probably have cracked them. And you don't want that.
I have looked at Gates Aust, no listing, not surprised, as Gates here is a low listed for some weird reason.
Dayco list that stat for SAAB 900, Landrover Defender 92 - 95 Diesel,, Disco Diesel 91 - 93, Kia Sorento 05 -09 Diesel, and 2.5 Petrol, Mazda RX7, and all the earlier RX's, Mitsubishi Diesel (many, many models).Nissan Diesel (many models).
Chev Captiva, 2011 to 2019. 2.3 Diesel.
I tried to copy the page, but this system does not like the format, and that is the end of my IT knowledge.
I have used RockAuto for bits for my 300c, as mobs here are useless at best. Worth asking them, maybe.
Last edited by Grant Francis; Jul 24, 2025 at 06:49 AM.
I have looked at Gates Aust, no listing, not surprised, as Gates here is a low listed for some weird reason.
Dayco list that stat for SAAB 900, Landrover Defender 92 - 95 Diesel,, Disco Diesel 91 - 93, Kia Sorento 05 -09 Diesel, and 2.5 Petrol, Mazda RX7, and all the earlier RX's, Mitsubishi Diesel (many, many models).Nissan Diesel (many models).
Chev Captiva, 2011 to 2019. 2.3 Diesel.
I tried to copy the page, but this system does not like the format, and that is the end of my IT knowledge.
I have used RockAuto for bits for my 300c, as mobs here are useless at best. Worth asking them, maybe.
Any thoughts on the Stant 45398 or the Motorad 2033180?
They're both the "premium" version from both of those brands. The Stant has the grooved piston for more precise coolant flow, and the Motorad has the very large opening for "high flow" (if that even does anything or matters on the V12). If neither of those seem suitable, I may go with the WaxStat from SNG like Roman suggested above.
Cant comment on part#’s as this was changed by a specialist when i bought the car years ago. However I was given option of factory temp or one that opens at a lower temp. I chose factory setting and no issues with cooling. 30C+ with AC on and gauge never goes higher than the N.
Any thoughts on the Stant 45398 or the Motorad 2033180?
They're both the "premium" version from both of those brands. The Stant has the grooved piston for more precise coolant flow, and the Motorad has the very large opening for "high flow" (if that even does anything or matters on the V12). If neither of those seem suitable, I may go with the WaxStat from SNG like Roman suggested above.
Did some more research, and the Stant 45398 might be discontinued? It's out of stock basically everywhere I've seen outside of Amazon (@~$15/pc).
When putting in the PN# on a few different sites, they all return with the Motorad 2033180. I learned Motorad bought out Stant back in 2022 and has been transitioning their products into the Motorad brand. So... It looks like I'm ordering the MotoRad and I'll measure it following the instructions.
If you need an application, ask for the 1993-95 Ford Crown Victoria.
I personally would not use the lower temp, as slighty hotter helps to boil off any condensation in the oil. Ideally, oil has a minimum operating temperature just under 80°C, and coolant operates a bit warmer than the engine oil.
If you need an application, ask for the 1993-95 Ford Crown Victoria.
I personally would not use the lower temp, as slighty hotter helps to boil off any condensation in the oil. Ideally, oil has a minimum operating temperature just under 80°C, and coolant operates a bit warmer than the engine oil.
We'll see, but I don't see why a 180 thermostat wouldn't be fine, lots of other people on the forum using them with no ill effects... Kirby's book states a 190F thermostat will result in a normal temp gauge a hair above the N, and a little below the N with a 180. I'll report back once they're installed (maybe next month?), assuming the bypass length is correct.
Last edited by BuckleSpring; Jul 27, 2025 at 12:54 AM.
Carby cars, including the V12, mostly ran 160 - 170 ish.
BUT BUT
That was before all this emissions nonsense, and engines were just that.
Emissions "junk" needs a spec temp to wrk. so they say. We misse all that hype until 88ish, had some air pump and EGR in the late 70's, but then nothing for ages. Most areas down here have zero emission testing, so putting ot back as Covenmtry intended is easy, and so simplified.
Less than 180 on a Fuel Infected engine will have the ECU over fueling a tad, MAYBE, and that is depending on the OE settings, too clever for me.
All my Jags, S2 Carby 6cyl, S3 EFI I6, S2 EFI V12, all the XJS ran that 180 stat, and NO issues ever. Remember, my Jags were, and still sort of are, DAILY drivers. The V12 ALL ran Efans, and NO emissions junk at all.
Winter, 2 to 11C mostly
Summer, up to 44c mote often than I like.
NO issues ever.
Those stats are NOT Jaguar specific, not much in that engine bay is.
Those listings I included are what I thought?? would be in your market, there are many more and ALL are Aussie cars, so useless to you.
Carby cars, including the V12, mostly ran 160 - 170 ish.
BUT BUT
That was before all this emissions nonsense, and engines were just that.
Emissions "junk" needs a spec temp to wrk. so they say. We misse all that hype until 88ish, had some air pump and EGR in the late 70's, but then nothing for ages. Most areas down here have zero emission testing, so putting ot back as Covenmtry intended is easy, and so simplified.
Less than 180 on a Fuel Infected engine will have the ECU over fueling a tad, MAYBE, and that is depending on the OE settings, too clever for me.
All my Jags, S2 Carby 6cyl, S3 EFI I6, S2 EFI V12, all the XJS ran that 180 stat, and NO issues ever. Remember, my Jags were, and still sort of are, DAILY drivers. The V12 ALL ran Efans, and NO emissions junk at all.
Winter, 2 to 11C mostly
Summer, up to 44c mote often than I like.
NO issues ever.
Those stats are NOT Jaguar specific, not much in that engine bay is.
Those listings I included are what I thought?? would be in your market, there are many more and ALL are Aussie cars, so useless to you.
Beer O'clock, see ya.
Yeah anything is better than what's going on currently. I'm planning a big overhaul to a lot of the car over the next couple of months. It's been running/driving for 7 years without an ECU vacuum switch, vacuum advance, temp gauge, fuel cooler (and therefore A/C), among several other issues that haven't been addressed.
Thermostats are original (as far as I can tell), one of them won't even fully open last time I checked. Hoses are all kind of getting hard, might try out one of those silicone kits.
Last edited by BuckleSpring; Jul 27, 2025 at 01:30 AM.
Went through similar.angst when replacing mine. Used Gates 33188S and I think they are still available.
Interestingly, my factory installed stats didn’t have the proper distance to fully close. With the new ones in place there was a big improvement in cooling performance.
Went through similar.angst when replacing mine. Used Gates 33188S and I think they are still available.
Interestingly, my factory installed stats didn’t have the proper distance to fully close. With the new ones in place there was a big improvement in cooling performance.
I went ahead and ordered the MotoRad 2033-180. The only place I'm seeing the S variant of the Gates is on Amazon (@$18.50/pc), listed as out of stock everywhere else, and the PN# doesn't return results on Gates' website, so I'd say it's been discontinued.
I'm going to stovetop test the MotoRad when it comes in and make sure the bypass length and opening temp are correct, I'll report back if they're any good whenever they arrive.
Kirby's book states a 190F thermostat will result in a normal temp gauge a hair above the N, and a little below the N with a 180.
all stock cooling on my ‘86, normally needle on temp gauge is just below middle of the N. Even when over 30C with air conditioning cranked, it will never go more than a hair over midway through the N.
factory thermostat temperature(not the cooler one)
The S on end of the Gates number meant a "superstat". It was supposed to be higher quality and longer lasting wax motor than the regular version (with no S at the end of the part number), but otherwise identical dimensions and performance.
The dash gauges are a GUIDE only, any of them. Pretty close, but NOT super accurate.
My 3 XJS's, and the one next door, same stats, same Efans, same gauge sender unit (Echlin), and all 4 had the gauge at different readings, with a Master mechanical giving 88c at the same time.
Oil gauge the same.
Volt gauge the same, thats why we always ask for volt readings AT the battery.
Nothings changed, the X300, S Types, X Type, all the same. Its always been that way since the makers went electric, as appposed to capillary gauges.
Same issues with the Series 2 & 3 6cyl cars, coz its the SAME stat.
As I mentioned, Jaguar Aust would not listen when I found that blunder waaaaay back. "Parts Managers are NOT Tech people, that is the Service Managers area", DUH.
I reigned a few eeks kater, enough was enough. That was not the first time with wrong spec parts.
They crack open at ~179F, and are fully open by ~195F in my stovetop testing with a thermocouple. I will say, they weren't kidding about the "High Flow" marketing, the opening is massive compared to other thermostats I've used.
From the bottom of the flange mating surface to the opposite side of the bypass mating surface looks to be just over 41MM when fully extended, maybe ~42.5-43MM. Yes they have an air bleed jiggle pin as well.
Should work pretty good once I get around to doing them, after figuring out this distributor debacle.
Really glad I decided to flush my cooling system and redo the thermostats. I cracked open both housings today (only breaking one bolt) and discovered 2 completely different thermostats. Neither OEM, 2 different temperatures, different brands and designs, etc. The one on the B Bank doesn't extend anywhere near long enough to close the bypass. Neither of them opened at their rated temp. Lots of sludge and silt came out as well after pulling the thermostats.
Current 5.3 Thermostat Recommendation
