A Tale of a 5 LTR XKR Supercharger Removal & Maintenance

[Popsjag]

I met Alan & Alison Manton at the JEC Caravan Rally, in Alderholt, in June 2015. He came along in his motorhome, towing a car trailer with an X308 on it – normal people would tow a Smart Car behind their motorhomes! Angie & I introduced ourselves (must have been the X308 that attracted us), started chatting and have been friends ever since. We have managed to continue to meet up at various JEC events and one particular event brought Alan’s XKR to my attention.

Angie & I had arranged to stay at Hurley Riverside Park, near Henley-on-Thames, along with like-minded JEC enthusiasts (arranged by Simon & Ann Cronin) to coincide with the JEC Windsor Castle event. Alan came along in their motorhome & Alison joined him later on that day, in the XKR. Upon arrival the XKR appeared to be unusually noisy under the body and when Alan lifted the bonnet to let us have a listen – you’d swear there was a couple of loose washers spinning around inside the supercharger!

Alan & Alison drove the XKR to the Windsor Castle event, for the day, and successfully back to the caravan park. The noise did not appear to get any worse during this period but they didn’t want to risk driving it back home to Storrington, so had it recovered by their breakdown company.

As far as I can ascertain, Alan had a garage replace the supercharger with another ‘supposedly’ good second-hand one but this appeared to be only slightly less noisy! At this point Alan lost some faith in the XKR and stored it away until such a time he could get it looked at again.
In the meantime, Alan knew that I was doing some work on my X350 XJR and had done some work on my supercharger (new doughnut coupling, 10% reduction pulley and fresh oil). As I had succeeded in doing this (you know what’s coming, don’t you!), Alan dropped some subtle hints about possibly ‘having a look’ at his supercharger for him. Now mates being mates, you don’t like to say no – but I did prewarn him that his supercharger was a totally different ballgame to mine, so it was going to be an interesting task for both of us (well he wasn’t going to get away with getting his hands dirty as well!).

As I live in North Wales and Alan lives in West Sussex, I would have to incorporate it within a holiday, so it was handy that Alan & Alison own a CS site near their home. This meant that Angie & I could take our caravan down and stop for a couple of weeks – which we duly did in April. The supercharger work was planned to commence smack in the middle of the 2 weeks holiday, so we could chill out and relax before and after said task.

On the day in question, I arrived at Alan’s house to find the XKR parked in the drive, bonnet up & tools laid out ready – and the sun was shining down on us. What more could we ask for (instructions, maybe?).

The first job was to start taking photos of various areas of the engine bay, so that we had references when the time came to put all the components (yet to be removed) back in their rightful place. The first part we removed was the Air Cleaner Outlet Pipe T-Connector (that connects between the throttle body and the air intakes), so that we could gain access to the supercharger belt tensioner. A short breaker bar (1/2” sq. drive with a 3/8” sq. drive reducer on the end) was inserted into the square hole of the tensioner and enough tension released to allow us to remove the belt from over the supercharger pulley – tight but manageable. We left the bar in situ to make it easier to refit the belt when refitting the supercharger (as we didn’t intend to rotate the engine during our ‘little job’) and the belt had been replaced when the previous ‘work’ had been done.

SAFETY NOTE – Disconnect the battery before commencing work. If you don’t, and you have disconnected the fuel pipes over the front of the engine, every time you open the driver’s door you will get fuel coming out of the open ends. It appears that the XKR primes the fuel system as you get into your car!

Next we disconnected the two top hoses from the Coolant Outlet Pipe (this ‘sits’ over the supercharger nose) as we only wanted to partially drain the coolant enough to facilitate the supercharger removal. This pipe can then be removed (2 torx set screws and a small pipe detached by squeezing the ends and pulling off). BE AWARE – inside the end secured by the 2 set screws, there is a small tube secured by 2 ‘o’ rings and this may drop out upon removal! We had the misfortune of misplacing this piece (we couldn’t find it anywhere when it came to refitting) and it is no longer available. Thankfully, in our case, Eurojags had a second-hand one available.

For reference Alan’s XKR is a 5.0L XKR with TVS Supercharger and that only the early examples of this breed have the small (lost) pipe - the design was swiftly upgraded.
The TVS has the Throttle Body at the front! Main benefits of a TVS over a Roots blower - The TVS runs much cooler and is 7 to 8% more efficient in similar conditions under 16psi boost.
Also note that the TVS twin screw has 4 lobes and 160/170 degree twist compared to the Roots 3 lobe assymetric.

Following this the water pipes going into the into the sides of the supercharger/air cooler (2 each side) were disconnected and cable-tied out of harm’s way, without putting any strain on them. Next we had to remove the metal fuel pipe (running across the front of the supercharger and throttle body) – remember to protect the open ends from any debris likely to fall in. It is not possible to manipulate the supercharger from under it, when it comes to removal.

On the throttle body there are 3 pipes to remove (2 on top of the body & 1 to the round black ‘actuator’). Then remove by unscrewing the 4 securing bolts and pull off, gently, towards the front of the vehicle and lay across the top of the engine (as this saved detaching the valley pipe). At this point you may decide to replace the valley pipe, but we chose not to because this had been replaced previously and had done hardly any miles since.

Moving to the rear of the engine we removed the pipe (one bolt) that is central to the supercharger and disappearing into the bulkhead (so it seems). This allowed us to unclip (6 clips) the plastic cover that holds more hoses in position, and a wiring harness! These are sitting in a u-shaped cradle, secured to the supercharger by 2 torx set screws. We removed these, unclipped the harness (2 cable ties) managing to get enough play to rotate the cradle from under the pipes and harness, and remove the cradle completely. Surprise, surprise – there was still yet another bracket to remove (3 torx set screws), that the cradle had hidden! After removing said bracket, we had 2 more hoses to remove (one on the lh side, which is a push fit and another on the rh side, which is attached by 2 torx set screws). There is also a further 3 torx holding this pipework assembly to the back of the supercharger – very awkward to get to, but doable.

We were now ready to remove the top cover off the supercharger – 23 torx set screws in total. Be careful – there is 2 long bolts (setscrews?) at the front end (1 per bank). These are a bit tight to remove (we undid them a quarter of a turn, sprayed them with wd40 and left them whilst we had a tea break!). Once the top was removed, we found 8 bolts securing the supercharger to the inlet manifolds (4 per bank). Before removing these we blocked the exposed unlet ports, in case we dropped a bolt or other small items down them by accident. Once this was done, we tied Kevlar rope through the vacant holes nearest the main supercharger body (4 holes) and secured it to an engine crane. We rechecked that there were no more hidden bolts and proceeded to lift the supercharger off the engine – worryingly, it seemed that we were lifting the engine as well! We tried some gentle persuasion with a pry bay under the supercharger (against the brace bars), but it didn’t want to budge.

At this point we decided to release the strain off the engine crane and double-check if we had missed something. So we had another tea break and tried good old Google, to see if we could be enlightened – but we didn’t seem to find anything to help us. So I phoned Mike Horlor to see if he could help, but although he could view some information, it wouldn’t let him download anything to forward to me. I then managed to download the XK workshop manual and spent a lot of time sifting through the pages – the pictorials were good but didn’t explain the removal process very well. As a last bid to obtain some better advice I phoned Rob Jenner, who gave me a couple of contacts that may be able to help. Unfortunately one was uncontactable that day and the other was not available until later in the day!

Then Alan had a light-bulb moment – he remembered he had the old supercharger in his garage and it might help us to see what the problem could be. Our doubts were confirmed – there were no more concealed bolts or attachments underneath the supercharger that could be causing any problems. But there are 2 hollow locating dowels that sit in the vee, so we could only assume that these were a very tight fit or even slightly corroded making removal difficult. So we tied the supercharger to the engine crane once again and tried to lift it, whilst gently levering in various areas, taking care not to do any damage. It still wasn’t going to give in and I think, at this point, Alan was getting a bit miffed (and he was a bit busy on and off because he runs his own business from home) and was very worried we were going to break the supercharger casing.

At this point, Alan took a break and went indoors to conduct some business, leaving me to carry on. I decided to take a risk (because we knew no bolts were holding it in) and put a bit more strain on the engine crane and use the pry bar with a bit more force (very risky on someone else’s car!). Thankfully, after manipulating each corner of the supercharger casing for a few minutes, it came away from the engine with a pop! But BEWARE – the valley pipe is held in place, to the underside of the supercharger, by 2 plastic clips – so don’t use too much force.

Once the Supercharger was placed gently on the work bench (large picnic table!), and Alan was cooled with a wet towel and another cup of tea, we then removed the left-hand and right-hand castings from the supercharger body (4 bolts each side) – mainly to make it lighter for us to handle whilst doing the necessary maintenance on it. Next we carefully removed the black ‘actuator’ (not sure of the correct name for the part) that attaches to the butterfly in the supercharger body. After this is removed, we could get to all the bolts securing the front snout to the supercharger body. This needed a little bit of persuasion to come apart (due to sealant between the machined faces), but once separated we found the reason for all the noise – a broken coupling spring!

After checking the shaft , for any play or damage to the bearings, we decided that the only ’wear and tear’ was the coupling and spring. The coupling was replaced with a doughnut from Powerhouse (who also supplied the oil refill kit we will use shortly). The mating faces were cleaned and new sealant applied (we don’t know if there should be sealant, but the flat surfaces were not 100% smooth, so we played safe) and bolted back together. A quick spin by hand, on the pulley, confirmed a successful fix.

We then removed the plug from the rear of the supercharger and left it standing on end, to drain as much out as possible, whilst we escaped for another cup of tea! Upon our return, we refilled it with fresh oil using a syringe supplied with the kit – but you do need to take your time or you’ll just waste the oil as it backflows out as fast as you try to fill!! Once done, don’t forget to put the plug back in and tighten it.

Now is the time to reverse everything we have done - i.e. refit the damn thing! The trickiest bit is to have the back of the supercharger lower as you replace it, to get it under the wiring harness and pipework, by the bulkhead. We also attached the cradle and rear pipes before levelling and lowering back down onto the inlet manifolds (as it gives you a little bit more room).

In the workshop manual, it advises to use special tools (screwed into the inlet manifolds – 2 per bank) to guide the supercharger back into position (they also hold the gaskets in place). We actually used the long bolts (one per bank) that were on the front of the supercharger (the ones that we advised maybe a bit tight to remove). We lowered the supercharger just enough to get the bolts in place, as a guide, then found we could let it just drop (lower) down onto the gaskets/inlet manifolds – USE NEW GASKETS.

All you need to do now is bolt it down and refit all the parts in reverse.

Don’t forget to refill with correct coolant mixture and bleed the system accordingly.

As far as I am aware Alan is pleased with the result and is now happily tearing up the tarmac in his XKR!

[Popsjag]

Some more pictures.

The middle one shows the old coupling, with a broken spring (hence the sound like washers rattling around!).
The blue doughnut is the replacement (no spring to worry about!).

The bottom picture is the supercharger being guided onto the engine. You will notice 1 of the long bolts mentioned in the write-up (there is another in the opposite side (bank)), to ensure it lines up with all the bolt holes.

[Popsjag]

Top picture shows the supercharger being lowered back onto the engine.

Middle picture shows the underside of the supercharger. Here you can see the locating dowels and the 2 clips that the valley pipe is secured in - so you have to be careful when removing said supercharger!

Bottom picture shows the front coolant pipe (it is upside down), with the small insert that we lost (?) and the 2 new 'O' rings.

[J44EAG]

You certainly are one for a challenge, Steve.

The TVS supercharger is a significant upgrade from our now well known and sometimes cussed Eaton M112 that several of us have worked on. Access is the main problem as those who have bitten the bullet and removed one (if only to get to the valley hose) will attest to. It seems the TVS unit is just as much of a problem when it comes to removal.

As I started to read your write up, my first thoughts were that of a failed coupling. The M112 also has a similar sprung loaded unit not known for its strength in the shock spring department. Like this TVS, my X350R is now fitted with one of the Lawson Smith (Powerhouse Automotive) up-rated doughnut couplings. Although very much stronger and with no spring to break, the modified coupling can only but be a positive fitment. The only downside, if any, is that the doughnut does tend to make the drive gear teeth chatter at idles speed. That disappears as revs are increased.

This issue appears quite common. Indeed, I saw one of these units in bits at Jagcare in Portsmouth which also had a noisy charger and a broken spring drive standard coupling.

The write up deserves to appear in the magazine, Steve. It would no doubt be well received.

Mike K

[mike020150]

I echo Mike K's comment that this work should feature in the magazine for wider coverage. It contains valuable info for members. Please send it to Nigel Thorley or Jim Mann. Mike.

[Popsjag]

I have sent Nigel this article (with more photos) a while ago, so I can only assume that he has plenty of other articles to use first.

[mike020150]

Excellent. Thanks Steve. Mike.