Jaguar S-Type Thermostat Mod
 

I wanted to report that I installed this mod and did a preliminary drive this afternoon and it appears to be working well. It maintains the factory engine bypass loop for quick warmups and seems to have the temp stability of the inline thermostat mod.

I cannot take credit for this, as I saw discussion of this mod originally here: https://discoweb.org/index.php?threa...mod-3-0.95160/. I did however modify what the original poster did in a few ways, which I think improved it a bit. I managed to reuse most of the factory hoses. Using the VW Golf thermostat below meant no modifications to the thermostat itself were required.

Parts so far:
2004 Jaguar S-Type 3.0 V6 Thermostat Housing - like this: Eurospare AJ813558 (around $70 new, cheaper used) (do not use provided thermostat)
2006 VW Golf 1.9 Diesel Thermostat - 180 degree - alternate temp - used Stant 13378 (around $10) (other temps available)
Dayco 72287 - cut up for random bends - (around $13)
1-1/4 to 1-1/2 hose coupler (around $10) -> actually not needed, managed to fit upper hose over thermostat housing

This is not a final installation, but a good test start. I plan to redo this to get rid of the extra hose clamps (probably different upper hose). On the bottom, I replaced the original Rover thermostat with 3-way bleeder tee that was originally at the top (I have the Carrs 4x4 metal one). Will update as I get more experience with it.

https://cimg6.ibsrv.net/gimg/landrov...4ab691fe36.jpg

Revised the setup a little today. Managed to get rid of the connector on the top, which deleted several hose clamps, and ran the upper rad hose straight to the thermostat housing. I was able to fit the shroud with no modifications.

So far temperatures have ranged between 183 to 190 sitting in traffic with a/c on max.

https://cimg0.ibsrv.net/gimg/landrov...5d4f60f014.jpg

Yes, that's the typical ford setup from the factory twenty years ago. Mustang clubs were using these parts to help cool down hi horsepower engines. Using these models you can order replacement parts from any auto parts store, if you don't want to dig through a junkyard. The thermostat housing encloses the thermostat in two pieces. Different hose directions can be obtained with interchangeable housings from other Ford, Mercury,, Lincoln Jaguar, and Volvos models. The housings have one hose in and two hoses out. One (cold) is bypass, other is hot once thermostat opens.

Yes, same thing - it’s a very nice housing. I really like that the sealing method is an o-ring, so it is super easy to switch out to a new thermostat. I have also seen them used on eBay for around $40. The junkyard, like you said, is always an option too.

I am pretty happy so far. With the VW thermostat on a brief highway run later this evening it got up to 194. The engine in my Disco has a slipping sleeve that seems to become audible around 190. I am probably also going to try a 176 degree VW thermostat just to see how that responds. The VW 1.9 TDI engine is common, so there are a lot of alternate temperature options for the thermostat.

Hi buddy, how's this running now?

This modification has been good in my experience. It was running in the Disco since I made the original post. I can’t recall exactly, but I believe I ended up going back to the Stant 13378 180 degree thermostat and then added / enlarged the bleeder hole. If you were planning on doing this modification, I’d experiment more with what size bleed hole is needed. If the hole is large, it can slow the warm-up time. Alternatively, without a bleed hole, if I recall correctly, the temps would tend to overshoot the thermostat opening temp a bit, then come back down as it opened.



Overall though, I liked this setup. It was pretty clean after I adjusted the hoses. I believe that the highest temps I saw was around 204 in the middle of the VA summer in city traffic with AC on. Most of the time the temp stayed between 188 and 194 or so. The Ford / Jaguar housing with the VW thermostat was easy to change / swap out with an o-ring seal.

Cheers buddy. Similar temps to the stock 180. Just concerned about the hose sizes etc. I'd want a oem fit.

Can I ask, are you running an Electric fan setup, or clutch fan?

I can’t recall exactly what I did for hoses. I believe I mainly just used the factory hoses, cut to fit with the 3-way tee, plus the extra hose mentioned for some bends.

I feel like it seemed a little better - maybe a little more stable than the stock 180. But its been a while since had I one of the stock 180 ones.


Standard 2003 clutch fan with a Flowkooler water pump. I tried one of those severe duty clutch fans and I didn’t like the power loss.

Thanks Captain! I'm betting that using an Electric fan will have some added benefits over the clutch fan with this system too. We'll find out soon...:thumbsup: