I was getting the P0128 "Coolant Temperature Below Thermostat Regulating Temperature" code, so I checked out the thermostat and saw that it was stuck open. I ordered a new one and put the old one back in till the new one came in. While the old one was in I was on the highway and noticed the temp getting up to H and the red light came on. I imediatly pulled over to the side and let it cool down. I went on line with my phone while I was waiting and saw a writeup about trapped air pockets (since I pulled the thermostat). I got back out on the highway and turned the heater on full blast and that kept the temp down to the hashmark between the middle and H. I've put a new thermostat in now and it's still getting hot on the highway. I don't let it get to H. As soon as it gets to the third hashmark I turn on the heater. The thing is that when I'm in town doing stop and go it stays where it's supposed to, right in the middle.

I never got the overheating issue till I pulled the thermostat out.

Any ideas?

I'm supposed to go home and see the family in Texas for Thanksgiving and would like to take the Jag.

I tried to download the JTIS procedures from the JTIS21 win7 64 install method & new archives sticky, but but my computer keeps giving me a fault when I try to save it to my computer. Does anyone have the bleed procedures?

 

Ok, I've been searching this site for the last two hours (don't tell the Air Force) and I came across this little jewel:
"Remove the Supercharger cover and then open/remove the 19mm cap on the s/c coolant manifold. With that removed and the engine cool add some coolant and watch the coolant level in the s/c coolant manifold. Make sure the bleed valve is open on the expansion tank. When the coolant level starts to come up the threads on the s/c coolant manifold install the cap, close the bleed valve and cap on the expansion tank."
Does anyone have a picture of where the 19MM S/C bleed port is at on the manafold?

 

I was going to say that I have had issues with not properly bleeding the system on other cars and having them get too hot. Hope that resolves the issue.

 

When I did my thermostat (along with the pulley) I didn't use the S/C port to add coolant, I just used the expansion tank with the bleeder screw open. Anyways, you can't miss the S/C port:

 

When I get home tonight, I'm sure I'll be able to find it.

 

You'll need a hex bigger than you likely possess!

Generally people don't seem to need to remove that but also be aware that in effect you have 2 coolant circuits - engine & SC - and that only bleeds the SC one.

 

See https://www.jaguarforums.com/forum/s...charger-48852/ for removal instructions.

Either make a tool from a long bolt with a 3/4 inch hex head or buy a 19mm allen wrench socket.

 

But don't be surprised if it makes no difference as it's the engine (not SC) part of the circuit that is the one apparently giving the problem.

 

Thanks guys, I finally got the supercharger belt and installed it, I had to remove the expansion tank again, so I did the initial fill up, and idle with the heater on full blast. I had to get ready for work, so I didn't have time wait for it to cool. I'll check it out when I get home. I picked up a set of MM Allen sockets at Advances Auto for $30. They have 10mm to 19mm in the set.

Here's what I did:
I removed the vent plug on the expansion tank and then popped off the cap and filled the tank to the max (cold) level. Put the cap back on then started the engine with the heater on full blast. Waited for the coolant to maintain a small steady stream out of the vent plug and then closed off the vent plug. I let it idle for 5 minutes. I then increased the RPMs to 2000 for 2 minutes then let it idle for a couple of seconds. Started checking for heat (by touching). Felt both sides of the thermostat housing and both were warm. Checked the expansion tank and it was warm. Checked the radiator line (top passenger side) and it was warm. I felt the S/C plug and it stayed cool. I just picked up the 19mm and hadn't had a chance to pull the S/C plug. I'll do that when I get home.

Did I forget to do anything?

 

I do what youve done(the last time) and never have an issue and I DO NOT pull that SC plug they tend to leak after removal and Ive never had issue otherwise. BUT YOU NEED TO REPLACE THE TSTAT ASAP. JUST BECAUSE IT WAS STUCK OPEN DOESNT MEEN ITS NOT STUCK PARTIALLY CLOSED NOW

 

The thermostat is brand new. I replaced it on Saturday.

 

must have missed that, was it OEM? did you installed with the diddle valve up? and did you pop it off? I remove them as they cause surging and trap air pockets on the otherside of them. Generally a run hot while driving with good airflow is a sign of poor coolant circulation due to air pockets, slipping belt or water pump failure. Yours may not be a complete failure though at this point........that why you get some flow..just thinking outloud

 

Yes, it's a Jaguar OEM 190 degree thermostat. I have the needle facing the engine. I have both springs as well. Is the diddle valve the needle? You break that off?

None of the overheating issues happened until I messed with the old thermostat.

 

Yes i break that off and that needle/valve faces out not in and the hole is always to the top

 

So I've got the needle facing the wrong way? Where does the small spring go? It wont fit around the brass part.

So it's supposed to fit in the housing like this ( =I--

 

Are you talking about the one piece thermostat? My car has the one that comes in four pieces. This is the thermostat that I bought and the direction that I installed it.
S Type XJ8 XK8 V8 Thermostat New Jaguar Part AJ82697 AJ83525 | eBay

 

Hi mate, if you've followed the picture on the eBay link I believe you have got the thermostat incorrectly configured in such a way that it can't actually open fully. Image below is the correct arrangement with the 'pin' part fitting in the cast water pipe (the one that comes away when you remove the 3 bolts)




Hope that helps.

 

Ha ha....ya ever had one of those days you feel like you need to go back to school........yep I've got it facing the wrong way.....It just fit perfect so I thought it was good....

Thanks for all the help guys!!!

 

Yeah it fits both ways round the I took this photo for reference when I changed mine. That's what these forums are for glad we could all help :-)

 

Looks like I can return the 19mm hex head socket set since I never used it and it looks like I probably won't need to bleed the S/C seperatly.