New 1990 VDP Owner

Good afternoon everyone!

Well, I finally was able to get a jaguar, I’ve always wanted one and then found this and paid $350 for it. 1990 XJ6 Vanden Plas, of course it doesn’t start. Serpentine belt was broken when I got it, so I replaced that and tried to crank. It just turns real slow and doesn’t try to start. I checked the battery, it’s good so I imagine the PO put s push button start switch in for a reason! Anyhow, I quickly found these 4.0s are NOT fun to work on. I’ll check the ignition circuit and check for a voltage drop. It jus turns over real slow.

Glad to be here and look forward to reading through the archives!!

Welcome to Jag-Lovers but you are on the wrong list. I know your car is badged as an XJ6 but it is newer and has very little in common with the Series I, II, and III XJ6s and XJ12s discussed on this list.

You need to be on the XJ40 list where your car is discussed. XJ40 was an internal Jaguar project name for the new model that was introduced in the USA in 1988 and at other times around the world. The term “XJ40” is commonly used to distinguish your “XJ6” from.the much different earlier XJ6s.


Well, that’s interesting. I was wondering why I can very little information on this particular series and bading. I was able to source a repair manual for $27, so hopefully that will guide me along the way.

Thank you for the new information!

XJ40 is commonly used to refer to your version of the XJ6 but it is not universally used. So if you are looking for shop manuals or parts try using XJ40 but don’t be surprised if you find it only under XJ6.

I have no idea where in the world you live but there was a world wide transition period that stretched for sevetal years between when the XJ40 was first introduced and the Series III XJ6s and XJ12s were phased out, so make sure you are purchasing your items for your correct XJ6 model.

There is a “Model Guide” write-up with photos showing the differences between the XJ6 variants on the old site:


As usual, I moved the topic to #xj40 for you. It’s a common ‚mistake‘, no worries.

The XJ40 is basically a Series IV, but fundamentally different to the previous three generations as Paul wrote so it has its own list.

I’m just trying to get it to start! The serpentine belt was broken when I got it, so I replaced it, it cranks very slow with a good battery. I’m wondering if I have a starter issue, or wiring issue. I need to get it to crank fast enough to actually try to start.

Check all your ground wires are nice and clean and toght.

Feel for hot spots in the wires after cranking?
Battery connections tight? Does it want to catch? Is it kicking back?

Are you sure about the battery? These cars need quite a punchy battery and a FULL charge to start - if charge is below 11v or so the car won’t start even if all is well.

As mentioned above, check all the grounds are clean and tight and see if you are getting spark.
Does the rev counter register when you crank the engine?

Yes, I checked the battery, 12.6 + before cranking. The PO somewhere along the line has installed a push button start sequence, the key has to be turned on then I push the button to crank. It turns the engine over slowly, not near enough to even try to start. The engine sounds the same with or without the belt on, so I’m leaning to an electrical issue.

I thought the timing chain may have broke when the serpentine belt broke, but I don’t hear any slapping/knocking. I do have a slight grind sound when cranking, but I am attributing that to the slow crank. I’ll check the RPM gauge when cranking tonight.

It looks as though a power steering line blew in the engine bay and my distributor has oil on it. I’m wondering if some wires got covered in oil and are providing unwanted resistance in the circuit.

I’m new to Jag’s but not cars, so I just have to chase this ignition circuit down, find out why the PO installed a push button start, trace all the wires and see that’s going on.

I’d clean all the oil off but oil itself shouldn’t produce resistance. I’d focus on the slow cranking speed. That is if it actually is the speed that is causing trouble.

Do you have even compression when cranking? I assume you do especially if it is slow. Then it isn’t the chain.

The starter gets activated by the solenoid. Either that clicks or not.

I wish I could upload a video, it’s going to rain tonight so I won’t get to play with it much. I mean it cranks SLOW. I got about 200 rpm on the tach or less when cranking.

At least that removes the CPS from the equation if you have movement on the tach.
12.6v is base line but you need to actually check what the volts are when cranking the engine, it sounds from your description that there is a large voltage drop when cranking, as stated these will not fire below 10.5-11v

Not? The Mercedes goes down to 8.6V in the cold and starts perfectly…
So a second battery would clear this up? As in, twice the amps?

Sean, For 350 dollars lets have fun…Your car was a difficult car to say the least.
Lets take it slow since you worked on cars.

  1. Check your oil, make sure its not GLUE as that car ran 20/50 for the most part.
    You don’t want resistance.
    If good, your car should have the battery in the trunk.
    If so, remove the carpet and you will see the battery and a JOINING POST.
    Clean that post or remove it and just get or make a new one, they corrode and NO CURRENT GOES THROUGH…You will understand once you see it.
    Your car was a LOW point in service faults with MANY MANY relays.
    Ill bet if the oil is not SLUDGE clean that POST and you will get a surprise, your starter button is a cheater to bypass the wire.
    If that doesn’t work report back and we make a NEW button under the hood so we cut out the cables rear to front.

No the ‘90 will be in the engine bay.

Was it ?
I thought it moved to the rear or was that my v12 xj40?

Nope, no battery in the trunk :sneezing_face:

Good then check those connections
Make sure water doesn’t hit the fuses on the passenger wing
It was another weak spot