Hey everyone, the name is Rath [2000 XK8/X100/AJ27] and over the last year I’ve basically become a master Jag mechanic... THE HARD WAY. However, I’m now at the end of my rope and I need help.

Here is exactly what I’ve replaced/fixed (mostly) in the last 30 days

1. Both Heads were worked over and machined, plus New Head Gaskets
2. Timing Chains and Tensioners (primary and secondary)
3. All 8 new Coils, and All 8 new Plugs
4. Radiator and Hoses
5. Primary Overflow Reservoir
6. Thermostat Housing Tower (aluminum upgrade) and Thermostat
7. Water Pump (upgraded to aluminum impeller)
8. 3 Oil Flushes and new Filters in the last 7 days
9. 2 Complete Coolant Flushes in the last 7 days
10. 8 Valves on the Bank 1 intake were bent and replaced (stems were all grinded and polished to match the resurfacing of the heads
11. Oil Pain and Oil Sump Strainer, completely cleaned out
12. Set Timing and Checked Timing no less than 4 different Times (AJ27 = VVT)
13. All 32 Valve Guides
14. Upstream Bank 2 O2 Sensor
15. Oil pump sump screen removed and cleaned inside and out

*AS A SIDE NOTE THE CHECK ENGINE LIGHT IS NOT ON*

**The current problem is beyond what I'm capable of diagnosing/fixing**
I was forced via a blown head gasket to commit myself to repairing this thing. I was in there so I chose to replace all timing components as well. The result of all the work I’ve done on this vehicle has yielded a car that performs poorly and runs no less than 15 degrees HOTTER than it ever has in the year that I’ve owned it. At a 10 minute idle at any ambient temp, The heat from the engine compartment LITERALLY feels like its on fire its so hot and 2 hours afterwards the heads are still hot to the touch. The OEM temp sensor reports temps at 208-210 and my on-board OBD-II monitor confirms the temps. It’s like the car is consuming itself from the inside and I cant stop it.

Any advice minus the aforementioned weak battery nonsense would be GREATLY appreciated, for I am now at the point of my Jaguar ownership where I’m ready to harm the car (on purpose) just to feel better for the time/work and money I’ve dumped into this seemingly bottomless pit

 

Some owners have reported that they mistakenly installed their new thermostat incorrectly (upside-down or backwards) which caused their engine to run significantly hotter....

 

Engine Temp. sensor? Air in cooling system? Are both radiator hoses hot, or just one?

 

Thermostat is doing its job for sure.... the upper hose gets hot 1st and then at temp opens!

ADDITIONALLY, the fans kick on when theyre suppose to.... low then high. Makes ZERO difference.

 

Jon, although i appreciate your comment, it was a little silly. Jiggle hole and thermostat placement was perpect.

 

I would try faultfinding with a laser thermometer. Scan each area to look for temperature drops, e.g. if temp is 208 at the temp sensor, what is it at the hose inlet to the radiator. What's the drop across the radiator? Could be as simple as a bad thermostat (even if new), same for the water pump. Assuming your coolant system doesn't have any blockages or restrictions, sounds as though it's not moving the water volume required to dissipate the heat via the radiator. Or, you may have a partially blocked radiator.

 

Come on Jon, Do you really think anyone with our expertise would make the installation upside down? I even checked my records, and only once did I do the installation backwards on 2/10/ 2017. That episode caused me to trash a brand new thermostat.

 

+1 to WooX4. From the Jag Engine Manual pic (below), there is obviously a fault somewhere.


Following Woox4's suggestion, you should be able to narrow the search area. If you're sure on your installation and the new parts, the next step is to check pipes for an air blockage. Running hot, the air turns to steam and will prevent coolant circulation. System is simple enough in the base XK8 to check temp. drops over the system, and/or pull hoses to see if the coolant is moving right.

From your description, with a quality installation, my bet would be restrictions in the engine cylinder heads which means a chemical flush.

 

Just another thought about our low volume pressurized coolant system. The coolant expansion tank, in the back of the engine bay, is familiar to all. There are two inlet plugs (one of which is closed and no longer used), and there is an outlet to the atmo tank hidden in the wheel well which vents high pressure. Is all that okay?

 

Timing is good? I've ran into heat issues on Miatas with no codes when timing was off a tooth and ECM was compensating with fuel mixture making it run hot....

Just throwing it out there - Not sure if it applies on these Jags, I'm just learning these cars...

--
Dusty

 

LOL, IM 100% capable of such a mistake. One only needs to meet my ex-wife to see how flawed I am. HOWEVER, ive been meticulous on this. Ive had the repaired heads off 3 different times, replaced/swapped thermostats twice, and replaced the waterpump 5 days ago. It made no difference, even with the metal impeller.

RETROSPECTIVELY, I cant help but wonder if the VVT on the intake is somehow a mismatch with the exhaust cams/valves. 100% POSITIVE (because I've timed and retimed/reverified) that the flats matched the crankshaft position hole. Because this is the AJ27, it timed of the rounded hole and NOT the triangle like the AJ26. Anyhow, with the flatts locked properly up, Im unsure if the outboard camshafts are able to creep and loose time. I mean is that not what the VVT does, CONTROL BOTH camshafts for optimal performance???

 

Woox4, oddly enough, I used my thermal imager last week to this very thing. Nothing stood out as different than anything else. Good idea tho, I like where your heads at.

 

DavidYau, Ive flushed the heating/cooling system 3 times since this adventure started..... Im being honest when I say, Ive not done a chemical flush. When the heads were sent out to be machined leveled, they came back spotless inside and out, with 32 brand new seats.

 

as far as secondary coolant plumbing and tank, they are ALL ok. I replaced that little tank about 6 months ago, IN FACT, the new generic radiator (made for the XK8/XKR) has that tiny, outlet on the top.... Its in the right side, right next to the power steering res. I've even opened that up and run it to the secondary inlet you speak of just to see if that made ANY difference. It did not. Not better, not worse.

 

I do think the VVTs are different. Thought I read somewhere that one was only two step and the other continuous timed. ECM may not know how to handle the data. Will try to track that thread down..

https://www.jaguarforums.com/forum/x...uestion-73211/
--
Dusty

 

RETROSPECTIVELY, I cant help but wonder if the VVT on the intake is somehow a mismatch with the exhaust cams/valves. 100% POSITIVE (because I've timed and retimed/reverified) that the flats matched the crankshaft position hole. Because this is the AJ27, it timed of the rounded hole and NOT the triangle like the AJ26. Anyhow, with the flatts locked properly up, Im unsure if the outboard camshafts are able to creep and loose time. I mean is that not what the VVT does, CONTROL BOTH camshafts for optimal performance???

 

I honestly have no intelligent response to your comment. I genuinely have no idea, ive not heard this before. I set the VVT counterclockwise to retard it. I do keep coming back to the timing though. As stated before, I timed this engine (AJ27) exactly the way it was suppose to be. Flatts up, and perfectly in line with the camshaft position sensor (flexplate circle) and camshaft hole.

 

My mistake - thought it was a 26 to 27 swap..

Only other thing that comes to mind is oil pressure - I know the VVT is tied to it. Stuck oil pressure relief valve?

 

I have some experience with the vvt, fighting it and getting it to right. I'll go back and read a few more of the entries to see what I can glean... also,, you could just pull the thermo and run it without one a while.

The first thing that came to mind for me was wondering whether you might have purchased, been provided/given and installed the wrong head gaskets...??? if the wrong ones are placed they will have a terrible effect on how water is flowing around through the cooling system. Blocking ports. Jus say'n

 

If it was that much out of time - to have exhaust going where intake/fresh air was supposed to be I think you would have serious trouble by now. It's an interference engine I think.

I know it's hard,,, but trust yourself that you have done MOST if not all things right. Second guessing every bolt turn will lead to worry that becomes counter productive to finding solution.