Jaguar XJ6 Diesel Conversion

MorrisCooper

Fado, fado it was all the rage to take big-engined petrol cars and replace the engine with a Nissan 2.8 diesel. I remember an XJS on diesel power many years ago and I knew of a couple of XJ6's also converted.

If you were to consider such a conversion nowadays, what diesel engine would you consider? Obviously it would have to be rwd and of large enough capacity to pull a large car. I've had suggestions of an Omega 2.5 as a donor but what else is out there that would be cheap to pick up.

quattro777

Was it a green XJS?

I remember back in the early 90's seeing one in Co. Galway which had a diesel of some sorts.

William Lyons was spinning in his grave.

trad

You have to remember in those days there was no NCT, so there was very little scrutiny of conversions.

Depending on what car you intend to convert you have to consider management systems on the car, abs systems, sufficient room to fit the engine, making up engine mounts, radiator hoses, clutch operating system, drive shaft modifications, exhaust mods, etc. You then have to consider the road tax implications. A 2.8 Nissan in a non classic car is getting close to a grand for tax.

Having said all that, Mercedes 250 /300 diesels should be in plentyful supply, reasonably powerful, available in auto and have a long life if properly cared for. Otherwise give API a ring and see what combinations of engines / transmissions they have available.

welder

Heres an XJ just as You described,with a Nissan diesel, on Donedeal at
the mo:

http://cars.donedeal.ie/for-sale/cars/931734

b.c

Remember seeing a mk2 with a diesel conversion in galway also in the early 1990s

mike65

Noooooooooooooooooo!

carchaeologist

I saw a Jensen interceptor recently with a 3 litre mercedes deisel fitted.Surely the whole point of having an interceptor is to have the 7 litre engine?

trad

carchaeologist wrote: »

I saw a Jensen interceptor recently with a 3 litre mercedes deisel fitted.Surely the whole point of having an interceptor is to have the 7 litre engine?

7mpg versus 30mpg - no contest. I once saw a rolls royce fitted with a 3.3 litre Nissan Patrol diesel engine and a towbar, just for badness.

carchaeologist

trad wrote: »

7mpg versus 30mpg - no contest. I once saw a rolls royce fitted with a 3.3 litre Nissan Patrol diesel engine and a towbar, just for badness.

Its still missing the point,its a classic,for occasional use(usually anyway).
Why wreck a good car to make it more economical,if you cant afford the juice dont buy the car.

sogood

carchaeologist wrote: »

Its still missing the point,its a classic,for occasional use(usually anyway).
Why wreck a good car to make it more economical,if you cant afford the juice dont buy the car.

Couldn't agree more. There are lots of cheap means of transport available, if thats all you want, but people who drive large/unusual/classic cars, usually have a lot more than mere A to B transport going on in their heads. I feel the same way about old cars that have been modified beyond recognition, whats the point? My car is as near original as is possible, with only a different radio/cd changer fitted. Part of the appeal for me (as a purist) is to have it as near to what it was like when it rolled off the production line.

carchaeologist

sogood wrote: »

My car is as near original as is possible, with only a different radio/cd changer fitted. Part of the appeal for me (as a purist) is to have it as near to what it was like when it rolled off the production line.

Yes,i tend to lean more towards originality myself,if i do fit a CD player,i will do my best to hide it so it cant be seen,leaving the original radio where it is.But,each to their own.

sogood

carchaeologist wrote: »

Yes,i tend to lean more towards originality myself,if i do fit a CD player,i will do my best to hide it so it cant be seen,leaving the original radio where it is.But,each to their own.

The CD changer is in the boot, so pretty much out of sight in there! Its a HUGE boot............boot...............boot........boot....boot

galwaytt

...the guy in Galway who did those, is still around, and still driving them. Usually has 3 or 4 in his driveway. Still !

Realistically, that genre of DIY diesels is very nearly an Irish thing, (I'm deliberately ignoring Cuba, ok........?), and is a TRUE classic, actually, being a very of-it's-time thing. Which is the whole point of classics, surely. They weren't all driven around in mind cond back then, you know......

trad

The idea of putting in a diesel instead of a petrol drinking monster is to have a useable classic. What's the point in having a classic that costs €50 everytime you take it out for a spin if you can make it affordable to drive and use it daily.

There was a guy in Tullow called Billy Watchorn who did diesel conversions. I drove a jag with a 2.8 nissan and also a BMW 730 that did 30 mpg on the devils fuel.

MorrisCooper

Getting back to the OP, what I'm trying to do is to take a very large, very thirsty Daimler DS420 which is used regularly all year around for weddings in all weathers. I've heard of XJ6 conversions and as it's the same 4.2 litre engine, what applies to one should apply to the other.

In terms of economy, I'm already running it on LPG which costs 97 cents/litre. It's cheaper but you lose a certain level of performance. When doing weddings though, performance isn't an issue. Also, I've had to replace auto gearboxes in the past and that can cost up to 2k including sending them to the UK for reconditioning. So now I'd even consider a manual and chucking the automatic.

Anything has got to be better than 12mpg and unreliable Jag engines.

So, what modern diesel would you suggest?

trad

There's a lmit to how "modern" you can go. Beside transplanting the engine "modern" diesel engines have complex engine management sytems, sensors etc.
For a big bus like you want to convert have a look at the mercedes 300 diesel multivalve up to 1996. No management system except a timer relay, automatic which should match up with your car and reasonably refined. Fit the mercs radiator to avoid cooling problems and with the Vee exhaust should match up without too much work to one side of the system and blank off the other.

Power steering might be an issue as I'm not faliliar with DS420's as might be brakes. I assume they are servo brakes as opposed to power brakes. I know a guy who did a lot of mercedes diesel conversions (petrol to diesel), not sure if he would be interested but I'll ask him.

MorrisCooper

Thanks Trad,

I had a W123 with knackered 250 auto converted with a W123 300D manual a few years and the only problem was balancing the propshaft as it was of different length.

My thoughts on using a more modern diesel would be that it would presumably be quieter.

Mycroft H

Why on earth would you replace the beautiful straight six engine, possibly one of the most magnificent petrol engines ever made with an evil noisey smelly diesel engine?

MorrisCooper

Simply for reliability and economy. The beautiful 6-cylinder petrol is unreliable and thirsty and I'm running a business. Also the Borg Warner Model 8 auto gearbox is expensive to repair, that is if you can find one to do the job for you. Daimler DS420s will never be collectors items so I'm not hung up on originality.

airnwater

I reckon use the ld28 nissan diesel as was fitted to loads of xj6s ,why not buy an already converted xj with rough body & use what ever is needed.

(Afaik in original form the xj & ds420 sumps are different,so might be an issue)

I also think some of those nissan diesels were automatics.

biggus

2.7 v6 twin turbo diesel and auto out of a crashed S-type or Xj . !!!

trad

biggus wrote: »

2.7 v6 twin turbo diesel and auto out of a crashed S-type or Xj . !!!

Management system and fuel system won't be compatable. The W124 multivalve engine is a 6 cylinder and much more refined than the 123 series 5 cylinder. I asked my buddy and he's not interested but said "you were on the right track".

My memory of LD28 powered jags ( I had one ) was plenty of black smoke but other than that not too bad to drive.

biggus

That's why he wants the whole lot out if a crashed one. ECU antitheft key the whole lot. would make a great project . I'd love to try it

trad

Great project but it's a working car so I'm guessing a week off the road is plenty. You would want a decent auto electrician to wire that one up,

biggus

5500 for the whole car

http://suchen.mobile.de/fahrzeuge/showDetails.html?id=115850272&__lp=2&scopeId=C&sortOption.sortBy=price.consumerGrossEuro&sortOption.sortOrder=ASCENDING&makeModelVariant1.makeId=12400&makeModelVariant1.searchInFreetext=false&makeModelVariant2.searchInFreetext=false&makeModelVariant3.searchInFreetext=false&vehicleCategory=Car&segment=Car&fuel=DIESEL&siteId=GERMANY&negativeFeatures=EXPORT&damageUnrepaired=ONLY_DAMAGE_UNREPAIRED&export=NO_EXPORT&customerIdsAsString=&lang=en&pageNumber=1

sogood

trad wrote: »

The idea of putting in a diesel instead of a petrol drinking monster is to have a useable classic. What's the point in having a classic that costs €50 everytime you take it out for a spin if you can make it affordable to drive and use it daily.

There was a guy in Tullow called Billy Watchorn who did diesel conversions. I drove a jag with a 2.8 nissan and also a BMW 730 that did 30 mpg on the devils fuel.

As previously mentioned, my original, undoctored, 6 cylinder, petrol, BMW 735 gets me between 25 and 28 mpg and I still have that lovely rumble/burble every time I pull away. It's just part of the package for me, but, each to their own.

101sean

I can't understand this strange desire to ruin good vehicles by fitting rattly diesels. Really smooth diesels have been only around for the last few years for prestige cars (current V8 Rangie/Jag engine for example) but need ecus and multiple sensors to run (inc CANBUS links to alarms and body ecus) . It's been done by speciasts to prove it can be done but at big cost.

A classic Jag engine should be reliable with regular servicing, electronic ignition and a good tune (inc with LPG). An auto transmission sholud be pretty reliable as well. The cost of a conversion would also pay for a hell of a lot of fuel.

A classic limo should purr up to the gate, not clatter.

MorrisCooper

101sean wrote: »

A classic Jag engine should be reliable with regular servicing, electronic ignition and a good tune (inc with LPG). An auto transmission sholud be pretty reliable as well. The cost of a conversion would also pay for a hell of a lot of fuel.

The critical word is should. Talk to anyone who uses an old Jag on a regular basis i.e. not for a lazy Sunday afternoon drive, and they will tell you that the maintenance costs are very high. I've had to had a B-W Model 8 'box rebuilt twice in 3 years. That's about 2 grand a go without adding value to the car, just getting it back on the road. Jag moved to the Model 12 autobox for good reason.

Surely with any diesel engine, you could strip back most of the modern ancillaries and have a glow plug system, a mechanical pump and still retain the soundproofing. With Minis, where my main interest lies, it is not uncommon to remove the electronics and fuel injection and replace them with good old simple carbs.

Purists look away. It's constructive suggestions I need, please.

bmoregan

MorrisCooper - A bit of a long shot but FYI...
I've been running a 1971 Series I XJ6 as my daily driver since 2000 (jeez - 9 years, time flies...). I'll post a pic when I get a chance. Anyway, a few years ago the engine had reached the point where something had to be done as I was almost putting in as much oil as petrol :-(
I sourced a "factory re-conditioned" engine in the UK (RobertHughes.co.uk - not necessarily cheap but doesn't sell junk) and got him to put it in over there. Zero engine problems and approx 18mpg since (yes, thats good !). The lump was 1250 STG but inevitably I got other work done at the time so labour was a lot more.

That said, my autobox is currently - as you say - vibrating like a string on Phil Lynnots bass and is not long for this world with the 2k+ price tag and associated hassle.

On the other hand - Is there any reason not to expect 20k/30k+ miles out of the recon'd box ? Have you experience to impart ?

MorrisCooper

The only knowledge I can impart is anecdotal. I have 2 Daimler DS420s, both with 4.2 engines and Borg Warner Model 8 autobox. One has never been found of reversing up a hill but will always manage it. The other lost reverse completely late last year and in the course of the drive home, lost all other gears bar Top. I sent the gearbox to Automatic Gearboxes in Middleton, north of Manchester and they rebuilt it. They had rebuilt it 18 months previously. I'm not making a comment on their work as after both rebuilds the gearbox worked perfectly but I am disappointed and down serious bobs that the gearbox has not been that reliable.

If I could turn back the clock, I would probably buy Beaufords or Regents which are basically vintage-looking but are based on either more modern Ford Sierras or London Taxis. There are 2 Regents for sale at 35k a piece on classiccarsales.ie but in the current climate, I couldn't justify the spend.

alias no.9

MorrisCooper wrote: »

Surely with any diesel engine, you could strip back most of the modern ancillaries and have a glow plug system, a mechanical pump and still retain the soundproofing.

The reason that modern diesel engines are quieter and more refined is because of the injection system. Strip that away and you have noisey old tractor engine. The major benefits of common rail come not from its basic concept of a single high pressure line feeding all injectors but from the ability of those injectors to be controlled electronically to open and close on demand. They generally function by injecting a tiny portion of fuel first (less fuel, smaller bang, quieter) and once that has ignited, injecting the remainder of the fuel directly into the flame front, sometimes this is done in multiple pulses over the length of the combustion stroke to give smoother power delivery. You lose the smoothness, refinement, power and economy if you replace this with a mechanical injection system. One engine you should consider is the 2.4 5 cylinder Fiat/Alfa unit which ranges in power output from 140bhp to 200bhp but due to depreciation of the car it's attached to, can be picked up for small money. I'm not sure how easilly it would be adapted for RWD.

MercMad

Actually the main reason the newer diesels are quiter IS down to the injectors themselves.Current cars are electronic, just like petrol injection and hence the ECU's whereas the older ones operated via fuel pressure.You needed a mechanical injector pump, like a small piston engine, to deliver the required fuel to the injector which would only open due to the pressure of the fuel from the delivery valve.This is what gave the engine its characteristic clatter.

Also the way diesel ignites causes a lot more noise, the direct injection engines being far noisier.

Since you dont need power I would stick with the 6 cylinder Merc engine and avoid all the complcations associated with any other.You should fit whatever box comes with it too !

the420g

I can't understand why a reconditioned BW 8 should fail within such a short time... unless it was poorly rebuilt, or (and this is important) the oil cooler wasn't thoroughly flushed out before reinstalling. If this is neglected, any bits of crap from your old gearbox will go straight back in, and ruin the new gearbox.

Similarly, the XK engine should be 100 percent reliable, and last many hundreds of thousands of miles, if oil is changed at the recommended 3000 mile intervals etc etc.

I am involved with the running of 4 Mk 8 Jaguars as wedding cars, home maintained to a high standard, which give NO trouble whatsoever... but admittedly... do use a little fuel.

Unless you do the conversion yourelf, fitting a diesel engine will cost far more than it would to rebuild the old 4.2, as with all modifications, there is a flow on effect..... touch something, and something unexpected won't work.... and it takes an age to get things like speedos working well.

Perhaps using parts from later limos.... like, as an example... a GM t400 gearbox would give better results?

If staying with Jaguar bits... perhaps the AJ6 engine as fitted to XJ40s is a decent option? These are very efficient, and totally bulletproof.... but again..... there will be agro in fitting...

... be careful modifying the cars too much... while most punters are using your cars for the looks..... its interesting to know how many people use the Mk 8s because they want an "authentic" experience.....

Aaron

Kevin_Herron

I'm not overly surprised about the Model 8 gearbox, they are nothing but trouble in my experience.
The Model 12 wasnt much different, the pull/push modulator was different and the sump was deeper on the Model 12? They were more or less identical apart from that?


The model 65/66 has proved to be the best of the Borg Warner, as fitted to the series 2 and 3 XJ6s respectively.
There would be a bit of jiggery pokery to get it to fit as its a longer box.


Also to be the best of my knowledge there is no difference in the DS420 and XJ6 sumps.

argosy2006

i once had a volvo 760 that was converted to a 2.8 nissan diesel,, it was crap.. engine was useless,, there really not meantto be in cars ,there a nissan cabstar or patrol jeep engine,, noisey and slow and uses a lot of fuel, which is silly when thats what u were trying to avoid by fitting it,,,
i also had toyota cressida diesel,, which got crashed,, so i got a petrol cressida and coverted it using the diesel cressida engine,, straight swap, very easy,,
any toyota diesel is good start to use as a donor,,4 cylinder ,,, don't use 6 cyliner engines, there to noise,, unless the merc 250d or 300d,, there a quite diesel,,,250d is 5 cylinder i thing,,they are the ideal choice for me

maidhc

Here is an interesting link for ye:
http://gas2.org/2009/09/04/more-power-more-mileage-more-style-mercedes-mods-80s-190d/

Mercedes themselves transplanted a modern CDI into a 190E.

Clintmincy

I have seen the xj6 on donedeal which "Welder" mentions in this thread. Has anybody been to look at this car? What is it like?

I had a Daimler Double Six and I am very curious about running such a car on diesel. The car I had was badly rusted and I am weary of this with such cars.

The xj6 on donedeal is running with a Nissan 6 cylinder diesel 2.8litre - I am thinking you would do well to get 30mpg - what you think? Does this engine have a timing chain not a belt? Are these engines good and reliable?

Your feedback would be gratefully appreciated. Thanks