Greetings my fellow XJS members. First of all I want to say how greatful I am to be associated with amazing fellows! In all my post you all have gave me support and suggestions to repair my wonderful 84 XJS V12.
Yesterday evening after work, it was only 90 degrees outside (cool day) I had to drive about 20 miles to check out a 2006 DTS V8 Northstar this guy wants to sell. About half way home I notice my temp gauge was reading above halfway but I didn't worry about it because it's a XJS. WELL, I had to go back down to the dudes house about 2 hours later and when I got there my car was running HOT! (Needle between the top and above normal).
I open the reserve cap and no gushing, luckly I had a bottle of antifreeze in my trunk(always prepared) and pour fluid in. It took half of the bottle when it started to gush. I put the cap on and rushed home! Got home and it was really hot! I kept the engine running, heater on, open the reservor cap and added water. XJS seems not to gush that much any more and I capped it.

Question. I want to bleed the system (Thank you DOUG! for the Steps)
But, I am wondering if I should replace the temostats? I am a long time believer if the car is running hot and if you dont hear any squeeking comming from the water pump it is best bet it is your termostat needs to be replaced. Am I right on this?

I have not looked at the car yet since I am work today, and I hope that when I do check my dip stick I hope I dont have a cracked block. But I know that is not the case.

Suggestions?

 

I suggest 2 new thermostats.

Alos 2 new pressure caps.

If the radiator internal cleanliness is unknown, then remove it and have it professionally cleaned inside and outside.

The hydraulic fan hub is also a suspect item.

 

I agree, get the CORRECT thermostats and replace your caps, then bleed the system and make sure there are no leaks.

Check to make sure the fan free spins after it heats up.

As far as this "gushing" thing you keep bring up. You realize that is boiling coolant right? The XJS does not have an expansion tank in the sense that it is a catch tank that simply overflows, it is hooked up to the rest of the system. You should never be pulling the cap off a hot car unless you want third degree burns.

It sounds like its losing water somewhere, triple and double check on this. You may also need to just bleed the system and it was appearing to take on more water and air was working its way out.

if the thermostats are wrong or not working properly, they aren't allowing coolant to bypass properly and the car is getting too hot. I would only by the jaguar part for these, as they don't cost much more and are a sure fire way to get the correct length. You block isn't going to crack from some overheating, the 5.3 is built.

 

Thank you Grant. I will go ahead and get some caps and thermostats. Radiator is clean. This should not be a hard job to take off a couple of therostats and bleed the system. fingers are crossed...

 

sidescrollin, thanks for your input. Fans work well and I really do believe my termostats are sticking. I will let you know. Thanks.

 

grant/sidescrollin:

wondering why you recommend new caps.

 

My 89 5.13 was heating up, bought a pair of new radiator caps from XK and now its right on normal, even on 97º day! Maybe worth doing before other more expensive fixes.
DickC

 

Isn't the expansion tank in the left wheel well behind tire?

 

Basically coz I am a Grumpy Old One Legged Jag Nutter.

The thermostats in ALL cars (badge on the bonnet means NOTHING) work VERY hard, and constantly.

I have alway replaced caps and stats at about the 5 year mark, or whenever a temp issue pops up.

The V12 getting HOT is not a matter to laugh about, it can cost you an engine in a heart beat. Caps and stats, are about $50.

 

Dont forget the stat gaskets (2 needed LH and RH are different) and GENUINE only here.

 

And like an old wrencher I used to know always told me, an oil change is a hell of a lot cheaper than a new engine...

 

BAD NEWS!
I was going to start bleeding and replacing my temostats when I told myself to start the car and double check if there is any leaks. Guess what. Yes, leaking was found under the water pump area of the car. Not from anywhere else. I thought maybe my hose might have a crack but to narrow to find out. Also tranny fluid was comming from radiator area (bottom left).
Trouble. So if I am right,
Disconnect the fan cowel assembly, take out the radiator.
Disconnect the water pump and replace it?
Replace both theromstats
Replace both caps.

Only issue I have is to figure if the water pump is bad or not. I didnt hear anything comming from that area. And it was hard to find were all that water was comming from in that general area..

I checked my dip stick and it looks clean as the day I changed it 2 months ago.

Help

What do you all think?

 

Sounds like the water pump seal is leaking. The fun never stops in XJS Land.

 

...and my wife told me to leave her (XJS) NOT! lol

 

Before you rip it apart, look carefully at:

1) The coolant cross pipe, this has the centre cap on its stand pipe. There is a hose that connects it to the TOP of the water pump, and is ALWAYS forgotten, coz you cannot see it. The coolant will run around the pump casting and out directly at the lower hose adaptor. Also check that pipe itself, especially the horizontal sections, as they do rot out, and get pin hoes in them. The 2 small (1"diam) hoses on each end are also suspect.

2) The lower hose itself.

3) The alloy adaptor for the lower hose TO the pump housing.

4) The pump itself. These are not a common failure item, well down here they are not, so its last on my list.

I strongly suggest, radiator OUT, professional clean (inside and outside). ALL, adn I mean ALL hoses replaced with new cal;mps, new stats, and gaskets, new belts. If the pump is suspected at all, obviously a new pump at this time would be smart.

Make up a simple pressure tester, and apply about 7psi to the system, this will quickly locate any leaks.

 

Thank you Grant. I am just a "home fix if I can guy". On the Pressure tester thing, I am not sure how to do that. But whatever it is I will for sure make sure the pressure is right.

 

remember caps don't have to fail catastrophically be flat out not work, they can partially work.

This means that they could not meet the pressure rating or not seal properly and pull a vacuum at shutdown. Over time air could be getting in or the coolant could be leaking out if the cap is not sealing properly.

 

i second grants "hose above the water pump" leak. It is possible for the pump to catastrophically fail, but usually they just start leaking from the weep hole once the seals go out.

That hose above the pump is really fiddly and deals with a lot of heat. It is high up enough on the front of the engine that a medium sized leak will be burned off and not leave much of a puddle.

It could still be the water pump though. Is there tranny fluid in your coolant or just the same area? Maybe just loose connection or leaky hose where it hooks into the radiator. Check the tranny, if there is a leak in the radiator the tranny will pull in coolant and become seriously damaged. sounds like you were driving it though, so it is unlikely. I believe the trans connections are on the right hand side, so you won't get things confused, but never forget the power steering on the left hand side can be filled with the same red trans fluid!

 

btw don't feel too at a loss with your XJS! the cooling system is the prime culprit for problems in the XJS and the most common thing to be ignored or in disrepair. Get it all fixed up and you won't have much to worry about after that.

 

As Grant said, renewing the hoses and clips an absolute must, rad bottom hose very likely to be going home. The hoses often deteriorate the most just by the worm drive clips for some reason, so the rest of the hose can look fine, but the hose still leak. Particularly all the small hoses that connect up the cross pipe to the stats and the pump. These are much much easier to do with the rad out.

As SS said, tranny fluid on the LHS is probably the PS hose or pump leaking. The return hose is just held onto a spigot by a worm drive clip, and the rubber often cracks up. This is the low pressure side so a length of hose can be cut out and a new bit spliced in using a barbed metal hose joiner and clips, quite safely. Same goes for the low pressure PS hose where it goes into the cooler from the rack.

If you do remove the pump and change it or the gasket, I strongly recommend lots of loctite on the fixings, as they can and do come loose. At least mine did, twice, once after a genuine specialist attached it.

Finally, as someone experienced recently, check that the pipe from the header tank on the inner wing, to the overflow tank in the rear of the LHS front wheelwell behind the wheelarch shield, is not blocked and that you can blow air through it. If not this may also be part of your problem as pressure in the system cannot be released.

Greg