Just received five water pump bolts from a Jaguar Dealer. Since I could not wait, I have already installed the pump using Grade 10.9 bolts/
The bolts I received had the correct part number but, by my book, are 5mm too long - not enough thread and might bottom out if forced.
The bolts I removed were M6x50mm. The ones with the correct part number are M6x55 and would create a problem.
Anyone else seen this??

 

Perhaps either wil be OK:


JFB10610B was used from the get-go, and Heritage shows AJ... as the superseding part.

VIN A40265 was the intro of the 2004.5 MY. WP part # has changed over time but not at that VIN break.

Right to be cautious, though

 

Interesting michaelh! For sure need to be cautious. If you look at my picture, the M6x55 would have been a problem. Has there been a change in the pump design??

 

I did wonder if the design had changed and the body cast slightly deeper as a consequence. Quite a few part # changes over time since JLM20143:



So the thread in the block isn't recessed to accommodate the unthreaded part of the bolt?
I clearly didn't pay much attention when I changed my pump, and I haven't seen a TSB noting any difference.

 

No, thread starts right away - no recess. I assume that the pump I removed was original, but could have been after market. My new pump was the same depth/thickness for the bolts

 

Thanks.
So another Jaguar banana skin. Maybe a change with the MY intro - who knows?

This could be really frustrating if you can't re-use the original bolts for some reason, so good to know.

 

You are not kidding! I hade to "butcher" one bolt as the head stripped trying to remove it. So, I tried my local Jag Dealer who wanted $17 per bolt - close to $100 with tax for five.. Found them at a Jag Dealer in Florida for about $60 and ordered them. Patience is not my best side, so I bought nice M6x50 Grade 10.9 bolts locally for $0.72 each. That's what is now installed and properly torqued. So, now I also have my five $60 bolt set that is too long and will not fit. My friendly Jag dealer in Florida charges a 40% restocking fee😢
But the car is running and life is smiling again.😁

 

I am not a fan of these small diameter bolts in any length exceeding 10/15 mm because of the potential to twist and break mid shaft with just a hint of thread corrosion. Had it happen before with water pump and have since replaced these bolts with stainless studs and nuts.

 

I like the stud idea. However, I did like the after market M6x50 Grade 10.9 that bought and used . They had a 10mm socket head instead of the Jag 8mm. Not so easy to strip

 

That's crazy. Heritage quotes £3.81 and SNG US is $6.74 for OEM. My (only) local dealer always charges the same as Heritage and I even get 10% off that these days.

They're all M6x55, mind...

 

I was replacing my 2001 XKR water pump and took a set of pictures with some measurements in response to the questions above.
Not knowing the full history, I don't know if this is the original WP and WP bolts.

Old water pump - thinner old style 2-piece (30.5mm deep with gasket)
New water pump - fatter new style 1-piece (31.75mm deep w/o gasket)
New pump: ACDelco 252-800 Professional Water Pump Kit ( $57.78, Oct 2020, Link: )

Replacing the WP was dead simple since my WP bolts came out easily:

• Remove serpentine belts and WP pulley to improve view, I also removed the outer idler pully,
• Pressurize coolant system to determine the water leak source (see last pic)
• Order replacement water pump
• Drain upper coolant (I detached the fat upper DS hose and bent it down, catching the coolant in the orange funnel with almost no spillage)
• Remove electric fans (perhaps not necessary, but so easy to do and greatly improves access)
• Remove old water pump and clean engine WP surface
• Insert new WP, incrementally torque bolts (with anti-seize) to 8nm + 90 degrees in a chris-cross pattern
• Repressurize system to test for leaks (I used 1.2bar for 1 hour)
• Replace pullies, belts, fans and coolant
• Enjoy your leak-less XK!

Here are the various measurements:

2001 XKR Water Pump bolt as extracted & wire brushed. Was used with thinner old-style 2-piece WP and reused with new 1-piece WP



2001 XKR thinner old-style 2-piece Water Pump (with gasket)



2001 XKR thicker new-style 1-piece Water Pump (w/o gasket)



2001 XKR depth of Water Pump bolt hole



2001 XKR new style 1-piece WP (w/o gasket): WP bolt visible threads vs ~24mm depth of bolt hole



2001 XKR top of Water Pump bolt



Pressure testing setup (ignore the red arrow)

 

Well done. After reading about the recent problems several owners encountered while attempting to remove their factory water pump bolts, it is great to read about your trouble-free replacement job....

 

Shows that both your pumps use the 50mm bolt. Can't find anyone who needs the 55mm bolt😢

 

Well, you know, replacing a water pump is not exactly rocket science (TM). So, why o why should I look for instructions beyond the ones that came with the pump (Delphi from Rockauto). And barely look at those either.

One thing that became obvious to me as I proceeded is that the d@mn screws ordered from jag for the water pump (AJ88674) are too long (see below), 5 mm too long as discussed above and discovered by me later. That also became even more obvious when I found this thread!

Okay, that sucks, and it took a month to get them. How about just shimming up the heads using 5 mm of washers? Cut to chase: THIS DOES NOT WORK! Heads now impinge on pulley.

I did not go and cut 5 mm off and die 5 mm of new thread because that seemed ridiculous. So, on to new bolts. I will tell Jag heritage the issue hoping they they will fix this.

One of three immobilized. This is actually unusual in the time I have owned all three.


Bolts ordered from Jag (AJ88674) do not work for the 2001 XK8 water pump, they are too long. They don't work for the old two part pump either...

 

Ten minutes of looking produced no reasonable Jag alternative, which seemed even more ridiculous. So I cut and die'd the 55s into 50s. Took about 20 minutes. Fixed.


Note enthusiastic thread cutting. Length close enough for govt work. Old bolt extracted on left, new modified one on right.

 

Well done Dale....

 

Slightly OT, but what is the reason for replacing the bolts?

I re-used the originals when I did the job. I didn't RTFM properly, and just torqued them up to the stated 8Nm rather than the JTIS spec of 8Nm +90°.

 

I assume they are stretch bolts although I would not think that necessary in this particular application....

 

The +90° implies that, to me also.

I can see an issue with re-using the bolts and adding the quarter turn each time.

 

Adding some thread is a sensible, practical solution in a situation like this, but when stretch bolts are involved, I would suggest that the OEM threads will have been rolled to form, not die cut. Die threading an extension in those circumstances would likely create some potential stress points that could result in in tensile or torsional failure on stretching. Not so good!