I just finished fixing two annoying issues with my XKR, and now I have another! P0128.

I gather this means I need a new thermostat + housing. I think the installation of this is relatively simple.

However, I am concerned about refilling and bleeding the system. JTIS says I need to refill the coolant with the expansion tank bleed screw open. When coolant comes out bubble-free, tighten the bleed screw. Then put the expansion tank cap back on.

OK, simple enough.

But then it says I need to remove the supercharger coolant filler plug and discard the washer, then run the engine for a little ibt and then top up the coolant through the supercharger fill port.

My question is--is messing with the supercharger coolant filler plug really necessary?!

 

Also, which parts do I need from this diagram?

2007 JAGUAR XKR Parts - Direct JPLV Porsche Parts.com

 

In the absence of an expert opinion, my guess would be: there are two high points in the system where air collects (expansion tank and supercharger), and you need to bleed both of them.

 

I think the first thing you should do is have your dealer reflash the ecm. There was a bulletin a while back to address this. The reflash will also address a fuel peculation issue. The only thing you will notice after the reflash is that the fans will stay running a few minutes after short drives.

 

Sounds simple enough. Do I really need to discard that washer? Where can I find the part number for a replacement washer?

 

Do you know where I can find the TSB for this?

I am a little skeptical of this approach. My X350 a while back had the same P0128 code, and changing the thermostat fixed the problem. However, the dealer charged me $600 to change a thermostat. Ain't going that route again.

 

So I'm guessing I need part #14 in the diagram and possibly #13 and 15. I hear people complain all the time about the plastic housing going bad. Is that the whole assembly (part #12)?

 

Apart from calling a Jag dealer & ordering it, dunno. Manufacturers usually recommend replacing washers, seals, etc. whenever they're disturbed - the cost is usually pennies, and the potential damage & hassle if they leak outweighs that. And, of course, they're assuming the work is being done in a Jag service centre with access to a full parts stock, so it's a no-brainer.

However, in my poverty-stricken past, or when I couldn't get replacements, I've successfully reused all sorts of components. A bit of instant gasket or Loctite to supplement the reused part's seal works wonders. There are some things that are designed for one-time use only - they compress and deform as part of their installation. Head gaskets are a good example. But I've even reused one of those, in a pinch…

If it's a pain to get a new washer, re-use the old one and just keep an eye on it for a little while to see if it weeps. Bung a bit of sealant on for insurance, if you like.

(sorry if this is an egg-sucking lesson)

 

I tried to order just the thermostat from Gaudin and they came back at me wtih it not being available. The only way I could get the thermostat was to order number 12 on your list, which is the coolant outlet assy , which included the thermostat as a part of it and also it had a new ECT sensor installed in it.

I'm glad they did not sell me just the thermostat because I found out my Real problem was the outlet assy had an internal crack that was the Real problem. I made a post on this a month ago or so.

The thermostat assy itself is composed of three distinct parts that are installed inside the cover of the coolant outlet assy.

Gaudin could not sell me just the thermostat, but maybe your local Jag dealer will have one.

I agree with the post just below this one.............replace the whole coolant outlet assy for your own good. Number #12 I believe from memory.

You need item #14 and #15 but not #13. The 13 is a oring b/t parts your NOT going to have to remove to replace just the thermostat.

EDIT: Your just going to remove the radiator hose from item #16, then unbolt the three bolts from item #16.............hold item #16 in your hand and unclock the thermostat assy from item #16............discard the old thermostat and put your new thermostat together with the other two parts that clock into the #16 (cover) and reassy the shebang.

Item #13 is used only if you replace the whole coolant outlet assy.

 

Get item 12 (the whole assy) or you will be back replacing plastic bits and pieces as they break.

 

Is that big un-numbered piece in that 12 assembly made of plastic?

 

Actually Alan, I had forgotten for a moment that you had an -R. On the pre-'07 -Rs is was aluminum, and plastic on NA cars.

On the XK NA it is also plastic, but I am not sure about the -R. If it is aluminum , you should not need to replace the whole assembly.

Sorry for the confusion.

 

Yes, the coolant outlet assy is made of PLASTIC that cracks due to heat fatigue.

When you take the thermostat cover off, the thermostat is attached to that cover (locked inside that cover with two ears). Then if you look carefully or even not carefully, you will see the aft end of the thermostat assy rests against a TUBE that is molded into the assy. This TUBE cracked on me which in turn cause an overheating problem for my XK. Just the opposite of the problem you have. I suppose your thermostat could be open all the time i.e. broke. Take but minutes to remove the thermostat cover and take a look at it and even maybe put it in boiling water to see if it opens/shuts.

Yep. That whole big assy is the coolant inlet assy.

 

I cleared the CEL code with my scanner, and it hasn't come back yet. I imagine the thermostat is still intermittently bad, but I think I can wait a little bit before I take action.

 

The other thing is does anyone know the side of the hex socket for the supercharger coolant plug bolt? It looks enormous and way bigger than anything I have in my toolbox.

 

I suspect it is still 19mm. I have the correct allen socket if you want to borrow it. You can also make a tool from a bolt with a 3/4 inch hex head.

 

Thanks, I may have to take you up on your offer. The CEL just came back on (I was expecting that).

I better just buy the whole assembly. Nothing annoys me more than having to do a job twice.

 

A few days later, the CEL went off by itself. Then a couple days ago (a couple weeks after this thread was posted), I got one of those bluetooth OBDII things and I've been playing with it. It said there was a pending code of P0128. I cleared it, and the next day it came back.

Then I did some more reading on it:

" What are Pending Codes?
OBD II Pending Codes are also referred to as “continuous monitor” and “maturing codes”. An intermittent fault will cause the computer to store a pending code in memory. If the fault does not recur within 40 warm-up cycles, the code will be cleared from memory. If the fault recurs a specific number of times, the code will then mature into a diagnostic trouble code (DTC) and the MIL or “check engine” light will turn on. "

Actron®

Does this mean I actually have a problem (why does it keep coming back as pending), or do I just need to let it run out 40 cycles?

 

Have you changed out the thermostat for a new one?

If not do it, engine temp is not something you shpuld play around and wait for it to fix itself.

 

Nope, haven't changed it. However, I did get this cool new bluetooth OBD2 thing and I have been graphing my engine coolant temperature for my daily commute and it doesn't appear to be anything unusual.

Scribbled out parts of the map to prevent a precision missile attack on the car. Ambient air temp was about 85ºF or so?

My commute is only 2.5 miles and about 5 minutes so I think maybe it's messing with the ECU somehow.