I’ve got a really baffling case here so I would greatly appreciate any help someone can give me.
Some background:
I own a 3.6 litre 1984 XJS Jaguar.
This motor had been under development by Jaguar for a few years prior to 1984 with a view to putting it in an upgraded xj6. Jaguar called it the AJ6 motor.
In around 1983 Jaguar fitted this motor to the XJS on a type of trial basis. Then in 1987 Jaguar released the XJ40 with this motor installed.
My Problem:
A month or two ago my power steering failed. So based on the understanding that my motor was essentially an xj40 motor I purchased an
XJ40 power steering pump.
However upon removing my pump I discovered that the drive dog used in my pump is different to the one in the xj40 one despite the fact that both pumps look identical externally and have the same part number
Despite exhaustive research I have not found anyone who has a pump with my type of drive dog.
These pumps work by having a removable coupling that connects the drive dog to a gear in the engine.
Upon removing mine, I discovered that this coupling that connnects the drive dog to the engine is different to the ones found on the xj40. I also discovered that my coupling was broken, which was no doubt the reason
why the power steering failed in the first place.
I cannot find this coupling (or adaptor as some people call it) anywhere.
So any advice, help, suggestions would be greatly appreciated.
I have both pumps. The original one from my car and an xj40 pump.
The coupler from my car is not designed
fit on the drive dog of the xj40 pump. Even if it could, mine is broken.
The only way the xj40 pump will fit onto my car would be to replace the cog or gear in the engine which the coupler connects to. But I don’t even know if this is possible.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
5
Different dog does not mean it won’t fit. This part was reviewed several times due to stresssss failure. The engine is the same in xj40 only offset may be different. You have obsolete ECU, different inlet and sensors (no MAF) when compared to later versions. Find first seven engine alphanumericals of your motor. As per Kirbert comment - pictures are highly recommended.
A guy from a company called British Motor Imports her in Oz has been trying to find this part for me so far without success.
However he did find a statement on Terry’s Jag Parts that states that my type of pump came from earlier 3.6’s and was replaced
by the one now found in Xj40’s. It also states that the parts are not compatible.
Despite the fact that the 3.6’s were only released in limited numbers, I still don’t understand why no one has this coupling.
A guy from British Motor Imports has been trying to source my type of coupling but so far without success.
I’ve included some photos in attachments of my style pump, the xj40 pump and the couplings.
You can see from the photos that the xj40 drive has two forks that are approx 55mm apart. These insert
into openings in the xj40 coupling which in turn mates up to what must be another pair of forks inside the engine.
The XJs one has a cylindrical head with two slots cut into it. These slots mate up to a 4mm wide metal bar that
is in the coupling. On the reverse side of the coupling there is another metal bar the same size that must mate up to
another slot on the drive gear inside the engine.(the drive gear in the engine is not visible)
One of the metal bars on my coupling has snapped in two places.
Information on the Terry’s Jag Parts website says the parts are not compatible.
So if you believe that the XJ40 pump can be made to fit can you please tell me how this can be achieved.
I’ve included some photos in attachments showing the differences between the xj40 pump and coupling and the XJS ones.
Since I have had this problem I have been wondering what other parts may be different to the xj40.
Which is why I found the contents of your previous message particularly interesting.
In your previous message you said that the ECU is obsolete in mine. Does that mean that
an xj40 ECU would not work in my engine and that replacements for the xjs one are unavailable?
Can you please tell me what you mean by “different inlet and sensors and (no MAF)”
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
10
The early 3.6 in the XJ-S has a completely different EFI system than the similar engine in the XJ40. As a result, those who have issues with the XJ-S are sometimes advised to replace the entire engine and EFI system with one from an XJ40, much more common, easier to get parts for, and reportedly a tad superior. Also note that the early 3.6 in the XJ-S has an issue with responding to wear in the engine, an issue that has been addressed by AJ6 Engineering with a modified ECU with a trim adjustment for wear.
As far as this coupling issue is concerned, this sounds like a job for John_john1! He’d probably need more info – some actual dimensions, or even better some parts he can handle – but perhaps he could work up an adapter coupling for early 3.6 owners.
The forks from the XJ40 pump would insert into two of the four slots of the
XJ40 coupler.
Remove one of the metal bars from my coupler.
Insert this into the engine side of the XJ40 coupler using the other two
vacant slots.
(I don’t know if this can be done as I don’t have an XJ40 coupler in front of
me). This bar would then slot into the two slots on the drive shaft of the
engine.
The forks from the XJ40 pump would insert into two of the four slots of the XJ40 coupler.
Remove one of the metal bars from my coupler.
Insert this into the engine side of the XJ40 coupler using the other two vacant slots. (I don’t know if this can be done as I don’t have an XJ40 coupler in front of me)
this bar would then slot into the two slots on the drive shaft of the engine.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
17
Yeah, I was thinking about something like that when I saw the pix, but didn’t know what the drive coupling in the engine looks like.
I think there’s a reason they redesigned it. Rather than put the old part back in, you might consider making a fork that fits both the XJ40 coupler and the 3.6 XJ-S engine, and make it out of unobtainium, something really hard and strong.
The drive part on the engine looks more or less the same as the one in the pump. Namely a cylindrical shape with two slots to
take the metal bar on the reverse side of the coupler.
I do agree that a fork arrangement attached to the drive unit on the engine would be a good way to go.I’ll give it some thought.
Thanks for the suggestion Kirbert.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
19
Makes sense. And I presume the coupling, if it were intact, would look pretty much the same on either side? Basically a fork stuck into a rubber coupler.
Is there any significant wear in the slot in the drive part in the engine? And BTW, which fork broke? The one on the engine side, or the one on the power steering pump side?
Here’s the one concern I have: On the old style coupler, each end of each fork fits into a rectangular opening in the rubber coupler. Hence, it is fairly securely held in place by the rubber. The new style rubber coupler has rectangular notches around the OD, so only three sides of each rectangular opening. The drive dog on the new pump is very securely held in place by the pump, and presumably the same would be true for the drive dog on the engine side in a newer engine. If you reuse an old fork or have a new fork fabbed, it’ll be held in place slightly less securely due to only being in contact with the rubber on three sides of each tine of the fork. It should work, I think, but it’s worth remembering that Jaguar originally felt it necessary to completely surround each tine with the rubber.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
20
I’ve thought of one idea that might make the drive fork a tad more secure: Make a new fork with four tines instead of two. The two inner tines would need to be shorter than the outer two so they don’t contact the center portion of the drive dog on the pump. But they could still fit snugly against the ID of the rubber coupler, thereby helping keep the fork centered.
By virtue of the fact that Jaguar upgraded the design of these pumps suggests that there must have been numerous
owners who experienced the coupler breaking. Maybe Jaguar ran out of replacement couplers!!!
My car has done around 140,000 miles and in view of the rarity of the earlier system I seriously doubt that
the coupler on mine was ever replaced before. So I can’t imagine the component being too weak.
I don’t know which side of the coupler broke as I had a mechanic remove the pump. The slots on the drive dog of the
pump and the drive dog on the engine has worn indentations on to both sides of the coupler metal bars where they mate together. This means that
they would not have been a perfectly snug fit into the slots on both drive dogs. This is where the metal broke. Each bar had already been weakened.
I think the most likely side for the bar to break would be the pump side as the pump responds to the turn
of the steering wheel. But this is only conjecture on my behalf.
There now seems to be a number of possible solutions to the problem but at this stage I’m favouring the easiest way out of the problem so I can sell the car. I’m concerned that if any other parts in the car fail I’ll have trouble getting replacement ones.
