Friends, thanks for looking. Last night was a nightmare. Was wondering if you could help me line up a plan to figure out what is wrong and where to start.

Background: Last 3 or 4 days, hear a noise like a jet engine on/off when cold, and changing from idle to driving speed. Goes away in a block or so. I kind of wondered if it was a belt issue.

Yesterday: Driving home highway speed, temp starts to climb. Pull over turn off, just as turning off, red overheating light comes on. While waiting for tow truck, I checked things out. Upper hose had collapsed. Restored when I opened the coolant resivour. The coolant was down about 1 pints. Added some, waited some more. Couldn't help but wonder if that was it. Was in a position to test, drove a block, all OK, 2nd block, steering started going hard, not charging message came on. Pulled over, temp started to rise again, waited 3hours for tow truck.

Checked things out this morning. Hoses collapsed, fluid level normal. Still shows not charging properly. I orignally thought fluid leak near the belt = slippage = hard steering & not charging properly. That should have cleared by now 10 hours later right? Opened hood, pushed down on belt, it moved 2 inches without a problem - that shouldn't happen right? Can a belt go bad by stretching or I'm I looking at a new tensioner (hope not).

Now I'm wondering if the belt slipping caused this or vice versa. I can only hope and pray that my radiator pressure tester has a connection for this car, I could test for a leak that way.

Every other car I've owned - collapsed upper hose = bad radiator cap. What might cause it on the XK8?

Well thanks for looking, I hope I can fix this myself. Look forward to your expertise and suggestions on where to start shooting this.

John

 

Sounds like one of the rotating components on the front of the engine has seized. Remove the belt and try to turn each one by hand to find it. After the repair, make sure you also replace the belt, which is likely damaged now.

 

Thanks I'll do that next. Bet its the water pump? Will follow up

 

The hose should NOT collapse. The cap should allow fluid from the atmospheric catchment tank to return to the reservoir as the system cools.

If the catchment tank is empty, then AIR should be pulled into the reservoir.

I think you have several faults.

bob gauff

 

OK, I'll get through this. The tensioner bolt head sheared off while I tried to release the tension. When I got to it, the belt was/is 1/2 off the track on the tensioner. My plan is to order a new tensioner right now.

I will have to cut the belt to remove it. I assume that moving the car 10 feet with the belt on and the tensioner bolt sheared is dangerous - will the tensioner pully stay put?.

So now my plan is to cut the belt, a new one is on order, see what's binding (rotate all pulleys by hand), pressure test. I can't think of anything that will be really wrong if I move the car 10 feet under its own power without any belt right?

Thanks for your input so far. Keep them coming.

John

 

Hey guys, let me double check. The diagrams sure look like you put the wrench in the tensioner's pulley that touches the belt. Did I mess up and it should be leveraged in the spring assembly below that pulley? I suppose not, that's how the tensioner attaches to the engine block, just want to be sure.

Good news, Auto zone has them by tomorrow.

 

Hi John,
+1 on WhiteXKR's post.

Yes you should use the wrench (I used a breaker bar) on the pulley bolt head to release tension on the belt - that's #1 on the attached pic.

Note that the pulley bolt is left hand threaded.

If you're not in too much of a hurry to get the car back on the road, you can just replace the tensioner pulley if you can get the sheared bolt out; check DaveinVa's entry in the non-OEM replacements sticky for the part no. Both the tensioner and idler pulleys can be replaced with the same metal one for a lot less $$$ than the OEM parts.

Hope this helps,
Mike

 

Michaelh, Thanks that confirms it, something was wrong with my tensioner. I did torque the pully bolt, that sheared it off. I'm happy to say a replacement is inexpensive, I've already ordered the entire tensioner assembly.

Have a good day. I'm going to go cut the belt off now.

John

 

I had replaced both the tensioner and the water pump so I am adding both my procedures to see if it helps you.

Link Water pump JagRepair.com - Jaguar Repair Information Resource
Link Belt Tensoiner JagRepair.com - Jaguar Repair Information Resource

 

Gus, I can use all the help I can get, thank you. This will help a lot. I too will replace both, while all the pulleys spin freely, the water pump has bearing issues, that I can hear when I start to spin it. In hindsight wish I understood why folks said loosen the water pump bolts before the serpentine belt. Your diagram explains why.

I tried my pressure tester today, can't mate it with the Jaguar threaded opening. I hope I can rent/borrow one from a local car shop. Just want to be 100% sure this isn't leaking too. Well everything is on hold until I can get my hands on a belt tensioner anyway. thanks again.

John

 

I have 'rented' coolant system pressure testers from 3 separate sources and none had a Jaguar specific connector cap. One had a cap that fit but it did not seal off the overflow bottle port. All contained an expandable universal connecter that worked just fine.

 

Test Point, thanks. Do you remember if the one that fit had a threaded connector or was it the twist on that other cars use, but you used that in the threads of the overflow bottle?

I don't want to harm my car's overflow resivour so I figured I'd ask someone who's been there before.

Thanks,

john

 

if your this deep into the water and looking at replacing the water pump{use the upgraded metal one } then go whole hog and replace the thermostat and tower with an aluminum one ... I would also replace the hose that is collapsing.... also look into the hose from the reservoir to the thermostat as the plastic gets very brittle and cracks I replaced mine with a rubberhose and clamps. it is not uncommon for that hose to develop a leak under pressure and not be noticeable due to the small leak evaporating on the housing of the thermostat.