Saturday after working a half day I decided to do maintenance on 99 xk8 with almost 100,000 miles.

There was a leak in one of the AC connections and my son who is the specialistin the family on AC's took care of that. While he was doing that I figured I do the secondary tensioners, plugs, and thermostat tower.

Tensioners installed with only a couple of minor problems. The crankshaft position sensor mount broke off so I replaced the sensor. The last person to have the cam covers off used a ton of silicone sealant and it took me 2 hours to get them cleaned up.

The thermostat tower was a chore because of the two bolts next to the intake manifold. I took a wrench and heated it with my touch and made a 90° bend. I used it to break the bolts loose and used needle nose pliers to slowly remove the bolts. I made the bolts 1/4" smaller to make it easier to get them back in.

The entire job took me about a day and a half. Took the car for a test drive and it feels so much more responsive on acceleration.

As I'm heading home dead tired my wife calls me. She is driving the 98xj8. She tells me check engine light is on , low coolant, low oil pressure, and restricted performance. I grab my tools and head to where she is.

I open the hood to try to see what the problem is. There it was, the hose from the radiator to the thermostat tower was off. There was about 3/8" of the tower broken off. The last person who put the screw type clamp on had put it too far on the end of the neck and over tighten it and today was the day it decided to break off.

I had enough of the neck left to be able to reattach the hose to get home. Filled it up with water and headed home. Got about three miles and it ovetheated again. Open hood to see that the connection to the resivoir had a pin hole in it and was shooting out steam. Put some JB weld on the hole and was able to make it home. A day in the life of a Jaguar owner. Now I have another project to take care of.

 

You are a glutton for punishment. The easy method to replace the thermostat tower is break the old one off with vice grips and use socket head screws and a ball drive for replacement. It's also important to replace the crossover pipe as they deteriorate and the hoses slip off.

You should receive an award from Jaguar for saving cars from the scrap yards.

 

That's what I get for not researching the forum first. Thanks for the procedure. I will use it when I do my wife's car. Do you have a good place to get the crossover pipe?

My award is when I get into my XK8 and drive it.

 

I believe I bought the pipe from sng barrett, but that was because I was buying some other things from them. I didn't go price hunting.

 

The easiest way to replace the thermostat tower assy is to remove the 10 intake manifold bolts and slightly lift the front of the plastic intake assy. (it will hinge at the throttle area)

Clean the debris from the cylinder head/intake area so the flexible gaskets have a clean surface to connect to (before you lift the intake!!!).

I keep new intake seals in case they leak but I have never had one fail in the thermostat tower replacement procedure described.

I install new ones if the intake is completely removed.

It is just the way I do it but people like to make special tools for different jobs.

bob

 

BobRoy, here is a good read on the way I did it.

https://www.jaguarforums.com/forum/x...ousing-119815/

Wayne

 

RJ, thank you for the info

Bob, thank you for your process. I don't like taking more things apart if I can. It seems like the more I take apart the more things I break. It only took me an hour to replace the tower, if I loosen the intake manifold and if I had a leak afterwards it would take me a lot longer. And I don't have the parts warehouse at my shop yet but I'm working on it.

Wayne, I got the idea of using my torch to heat up and bend a 8mm box end wrench at a 90° angle from your post. The thing is I should have bent an open end wrench to work the bolt loose after I broke it loose with the box end wrench. Thank you for your post and your ideas.

 

I can recommend the subtle & delicate approach to this problem :

 

How do you keep pieces of the tower from getting in the motor. I sure don't want pieces in my cooling system.

 

Stuff a rag in there, then vacuum the pieces out.

 

As RJ237 says .......... the material is brittle, but doesn't shatter - rather tears apart, so with a bit of care, there no danger of little bits getting into the cooling system.

 

For me this is the absolut easiest way......................
A simple solution with no risk.

 

I changed the tower on my wife's xj8 yesterday. I thought about all the ideas for the removal of the tower. When I did my xk8 last week the loosening of the two bolts was easy with the box end wrench I made. The difficulty was unscrewing it after it was broken loose. Last time I used needle nose pliers and that was really slow. Seeing Wayne's tools he made I took another wrench, this time an open end wrench, and used the torch again and made a 90° bend to it. Using these two wrenches I had the tower off in about 10 minutes.
I reinstalled the tower using RJ idea of hex head socket bolts. It would of worked but in all the tools I have I don't have ball head hex wrenches. So I took my torch again and bent a hex wrench to tighten the bolts. I think it would have been easier to put the origional bolts back in but cut off about a1/4" off the lenght. The whole process took me about an hour to complete. I have one more tower to do but this one will be a little easier because it's on the xk8 that I'm doing the engine work on. The intake manifold and heads are off so I should have plenty of room.

Next problem is that on my wife's xj8, I know its the wrong site but they are the same, the PO at some point switched to the regular green antifreeze. Looking into the resivoir it was clean with no gelling so it appeared they did a complete flush of the system before changing the fluid. But when I took the tower off I found sludge on the sides of the walls of the tower and inside the block. I'm thinking about doing a flush to the system and put back in the recommended coolant.

Another thing is after I did the tower and took it for a test drive the radiator hose that goes on the right side of the crossover pipe was almost off and leaking. After it cooled down I took the hose loose to fond the crossover pipe is also deteriorating. I have a good spare from one of my parts car to get it repaired for now. RJ mentioned an aluminum upgrade pipe but I a seach yesterday I couldn't find one, no even sng.

The car only has 72 000 miles do you think the use of the green coolant may have caused the deterioration.

 

I think it's just age related deterioration. I didn't realize I had suggested that there was a metal crossover pipe, sorry about that.

I would recommend changing that crossover pipe to anyone putting in a new thermostat tower or water pump. They don't cost that much, and again, the catastrophic loss of coolant could destroy the engine if the car is on the freeway and can't be pulled over immediately.

 

I rechecked the post RJ and you didn't mention an aluminum crossover pipe I just assumed that if it was a problem there would be an aluminum upgrade. My confusion.

I do plan to change waterpump also along with radiator hoses. They are starting to bulge.