Which is better - 2.25 petrol or 2.25 diesel?

[Lost Landy]

Iam rebuilding a exarmy 2A and keeping it as stock as possiable.
I plan to do a lot driving around the Top end/Gulf country. My question is do i stick with a petrol 2.25 or go with a 2.25 diesel?
I have both motors and will rebuild the one that I will fit into the Landy.

2.25P good points:
I have played/worked on them for over 10 years & iam very familiar with them.
Very reliable easy to service/maintain.
Bad points:
Fuel economy could be a hell of a lot better.
Shorter range.

2.25D good points:
Great sluging power.
Better fuel economy that the petrol motor.
Very reliable easy to service/maintain.
Longer range
Bad points:
I have never owned or worked on one.
If the injector pump has any dramas how hard are they to fix??
Not as common as the petrol motor.

Guys any advice would be greatly appreaicted.

[RobHay]

....plus diesel is more readily available up the top end as well........I think for sheer ruggedness and reliability you can't go past the diesel.

My thoughts on the matter.

[Shonky]

If you have both then I'd go the diesel. I don't think I'd ever bother removing a good petrol to drop in a diesel, but from a clean slate I wouldn't hesitate.

[isuzurover]

I changed from a 2.25P to a 2.25D. Wished I had done it years ago and would never go back. With a few tweaks a 2.25D can perform as well as a stock 2.25P and use 30-50% less fuel at the same time.

IMHO they are simpler to work on than a 2.25P. As for the injector pump, the CAV DPA is quite a good little pump and has been used on a whole range of engines - even Kubota tractors!

I have replaced all the seals on the pump myself. Not too hard. I don't know if my pump has ever been rebuilt since it was made in 1979. They go for a long time if you keep the fuel clean.

If you are worried though you could always carry a spare pump and a couple of spare injectors.

Downsides:
If overheated the injector nozzles will crack and may fail completely.
The precombustion chambers can drop out of the head if not properly peened in or overheated.
The engine which donated IP and ancillaries to my rebuilt 2.25D had both of these issues - it had been fully rebuilt (head resurfaced - no peening) - then overheated (I suspect). This resulted in one of the precombustion chambers trying to punch a hole through a new 0.040"OS ACL piston.

Some early 2.25Ds also had problems with snapping cranks apparently...

In my case, I have never had any issues at all with mine. The only time mine has stopped has been when I have run a tank dry, and needed to bleed the IP to get it going again.

[JDNSW]

I think Ben has just about covered it. In general I prefer diesel, but like Shonky I would think twice about swapping a good petrol for a diesel (unless I got given a good diesel engine!). Also, Ben comments that you can bring the performance of the Diesel up to that of the petrol with a few tweaks - but similar tweaks can put the petrol ahead again! Unfortunately, I don't know of anything that will get you reasonable mileage from the petrol engine!

The one big advantage the petrol engine has over the diesel is that it will stand abuse much better (mainly because it has the same mechanicals but less stressed). For example, run it out of water? probably no dramas if you let it cool. Neglect service? It'll keep running, although life will be shortened. Dirty fuel? Clean system out and good as new (Don't try that with the diesel!)

But still, overall, I would prefer the diesel.

John

[Blknight.aus]

oh I dunno, with a good filtration system you can run the diesel on near on anything....

and as for out of water killing them, nope, I ran mine near on out getting up to townsville for the cape trip.

The petrols got a bit more top end and more torque but the diesels got it nailed for the spread of torque and fuel economy, they also dont mind getting wet.

[fraser130]

I wouldn't hesitate to go the diesel, just think, NEVER do plugs, leads, points, timing or carbies again.
Just oil and filter changes, and put in fuel.
I've had both, and would never go back to a petrol car.
There's also the better fuel economy.
It's all win.

My 2c

Fraser

[korg20000bc]

I'm thinking of the doing the same thing. Fortunately, I located a series 3 diesel with 4 spare engines. Grouse.
Is the bulkhead different in a petrol 2a to a diesel 2a?

[Lost Landy]

Iam sure all 4cyl fire walls are the same wether petrol or diesel. Half your luck finding 3 diesels I still have to go down Tamworth way to get mine lol.

[Blknight.aus]

the 2.25 P+D use the same block.

The bulkhead is the same.

Its a drop in conversion with the addition of rivnuts for the fuel filter shifting the the throttle and getting the exhaust on.

Theres some electrical work to be done but its not much and mainly relates to the startermotor.

[korg20000bc]

Thanks Blknight.
Do you know of any conversion walk-through links at all? Having trouble finding a good resource.

[Blknight.aus]

get someone to take a photo of a diesel engined series

look at your series 2.25 petrol engine bay

make whats in the photo appear in the engine bay after youve bolted the the engine to the bellhousing and engine mounts.

Thats what I did.

[Sleepy]

get someone to take a photo of a diesel engined series

look at your series 2.25 petrol engine bay

make whats in the photo appear in the engine bay after youve bolted the the engine to the bellhousing and engine mounts.

Thats what I did.

Here's a start:

https://www.aulro.com/afvb/images/imported/2009/09/862.jpg
https://www.aulro.com/afvb/images/imported/2009/09/863.jpg
https://www.aulro.com/afvb/images/imported/2010/01/1273.jpg


I can get more detail if you want.

[Blknight.aus]

now you know where the big bits go.

put them there and then work out how all the little pipey bits hook it altogether (remember wires are just pipes for electrons)

If I can convince MR scanner to work I'll scan the fuel system and electrical schematic for the diesel.

[Sleepy]

now you know where the big bits go.

put them there and then work out how all the little pipey bits hook it altogether (remember wires are just pipes for electrons)


I love all this technical chatter! :-)

[isuzurover]

Thanks Blknight.
Do you know of any conversion walk-through links at all? Having trouble finding a good resource.

Get hold of a genuine SIIA shop manuel - or better still, a parts manuel...

The hardest part is silver soldering a return line fitting into the tank(s).

[Blknight.aus]

nahh just t piece the breather.

or fit a combinded diesel fuel sender/pickup.

I have the OEM manuals once youve got all the big bits into place then it becomes usefull.

The schematical layouts dont do a lot for you till you know where all the big bits go and digging through each individual section to find the individual drawings of the components is a PITA.

of course having them side by side as you strip one part out of the doner to install it in the reciever is by far the easiest way of doing it.

[isuzurover]

nahh just t piece the breather.



The t-piece would have to be in the cab. Much easier to just solder or silver solder a steel or copper pipe into the top of the tank. Or drill and tap a hole to fit a cut down pickup.

[Jojo]

As said earlier, the engines are basically the same, so a swap should be not too difficult to perform. But, also as already mentioned, with a functioning petrol engine I would think about it twice. Doing the swap I mean.
Although I am a Diesel-man and honestly prefer a Diesel over any petrol powerplant I have to admit that the 2.25l Diesel will give you a new perception of speed. Or rather the opposite. It will give you the relevation of slowness. The 2.25l petrol is by no means a rocket, but the Diesel will bring this to another dimension. Sure, you'll get some more low-down grunt, but the petrol isn't that bad in this respect either. In terms of fuel economy there is surprisingly little difference between them, unlike a Tdi in comparison to, let's say, a V8. Of course a lot depends on how you want to use the car. Travelling in Diesel-only country will of course push you towards an engine swap, do you want to preserve the vehicle to go on shows, you may wish to keep it as original as possible, although the Diesel was fitted to many military models overseas. In the end, however you decide, it's horses for courses.

Cheers

[Lost Landy]

The curent motor that is in my 2A is a POS holden 202 witch in my view is unsuitable for waht i want.
There for I have a clean slate to stat off from lol.
If the diesel motor is quicker then my 2 litre IOE series 1 motor then ill be quite happy with the performance.

[isuzurover]

As said earlier, the engines are basically the same, so a swap should be not too difficult to perform. But, also as already mentioned, with a functioning petrol engine I would think about it twice. Doing the swap I mean.
Although I am a Diesel-man and honestly prefer a Diesel over any petrol powerplant I have to admit that the 2.25l Diesel will give you a new perception of speed. Or rather the opposite. It will give you the relevation of slowness. The 2.25l petrol is by no means a rocket, but the Diesel will bring this to another dimension. Sure, you'll get some more low-down grunt, but the petrol isn't that bad in this respect either. In terms of fuel economy there is surprisingly little difference between them, unlike a Tdi in comparison to, let's say, a V8. Of course a lot depends on how you want to use the car. Travelling in Diesel-only country will of course push you towards an engine swap, do you want to preserve the vehicle to go on shows, you may wish to keep it as original as possible, although the Diesel was fitted to many military models overseas. In the end, however you decide, it's horses for courses.

Cheers

I would disagree with you on a number of your comments.

They are certainly no rocket, however a good 2.25D with improved breathing will keep up with a good 2.25P. My 2.25D has beaten equivalent vehicles with 2.25Ps up hills a few times - both driving flat out.

IDI engines are not as economical as DI engines, that is of course true. However the 2.25D has great economy. On a recent trip from Brisbane-Perth, heavily loaded, I was averaging 11 l/100km. When I had a 2.25P, I was getting 18-20 l/100 for similar driving.

I can get as low as 9l/100, whereas the best I ever got from the petrol was 17.

I removed a recently rebuit 2.25P which went like a train for a 2.25D and never regretted it.

[JDNSW]

I would disagree with you on a number of your comments.

They are certainly no rocket, however a good 2.25D with improved breathing will keep up with a good 2.25P. My 2.25D has beaten equivalent vehicles with 2.25Ps up hills a few times - both driving flat out.

IDI engines are not as economical as DI engines, that is of course true. However the 2.25D has great economy. On a recent trip from Brisbane-Perth, heavily loaded, I was averaging 11 l/100km. When I had a 2.25P, I was getting 18-20 l/100 for similar driving.

I can get as low as 9l/100, whereas the best I ever got from the petrol was 17.

I removed a recently rebuit 2.25P which went like a train for a 2.25D and never regretted it.

I agree on the fuel economy. Best I have ever got with a petrol 2.25 was around 25mpg - and that was on a swb. When I had a lwb diesel, on one occasion I got 36mpg from it, and rarely got under 30mpg.

John

[Brad110]

What is the weight difference, or is it negligible.

[isuzurover]

What is the weight difference, or is it negligible.

Bugger all. From memory the manual lists the diesel as ~50 kg heavier. I did not change or reset my springs between 2.25P and 2.25D.

One thing I will add to my previous comments, is not to expect a 2.25D to live any longer than a 2.25P. In fact because they are essentially the same engine, a 2.25D could be expected to need ring/bearing and head rebuilds more frequently. Purely since they have the same rev range, but the Diesel has higher pressures/stresses, plus the addition of soot to increase the rate of engine wear (better filtration , more frequent oil changes and/or oil analysis should help).

[Johnno1969]

After all that, you hardly need any more convincing - but I'd go for the diesel too. I have had one for twelve years and have loved it (alright, I have spent a fair bit of that time out of the country and not actually driving it, but that's not the point). I turfed a Holden six out of the Landy in 2001 and, faced with the cost of reconditioning a motor I opted for the 2.25D over its petrol mate. It lugs beautifully, gets 30mpg and has been perfectly hassle-free. The petrol engine is wonderful and probably more resilient given some of the points already outlined, but sort out a nice diesel and take care of it and it's all happy days...

John

[Ypsilophora]

Sorry about hauling the old thread up from the depths [bigwhistle]
Just wondering if you guys who did the 2.25p to 2.25d swap got an engineers cert to go with it, or did you just stick it in an wing it?
Luca

[JDNSW]

I don't think any state requires such a certificate where you are changing the engine to one that was sold in the same vehicle, although where there were other changes in the one that was sold (e.g. the Six has larger brakes) you need to make these other changes as well. And note that the maximum load and towing weights change slightly.

[Ypsilophora]

Ah... interesting, so for a 2.6 to a 2.25 you also wouldn’t need a certificate? Despite modifications needed to engine mounts + different bell housing?
Cheers

[Blknight.aus]

Ah... interesting, so for a 2.6 to a 2.25 you also wouldn’t need a certificate? Despite modifications needed to engine mounts + different bell housing?
Cheers

not so. if the chassis didnt come with the engine then you cant just drop it in without engineering for at least the welds, the 2.6 also had different brakes to the 2.25 (in some cases) However... Its a lot easier to do and have an engineer sign off on it because its already been done and approved so its not a huge amount of hoop jumping.

[sharmy]

I had a diesel swb back in the 70's and my wife managed to do the impossible. She thought she would see what it would do and egged on by her sister flattened it down a long (very long) hill and got booked for SPEEDING.

[Cap]

I had an interesting discussion with a friend that has the 2.25p. We both have 2a 88s... On the same roads (we took a evening drive) he said he needed to shift constantly (twisty roads) using 2nd and 3rd gears, whilst I was basically on 3rd most times. The diesel has some great torque range, and makes for a lazy shifter, its like driving an auto. Whilst I have not driven his 2.25p as yet, and he hasnt driven mine, it was interesting that he said he hasnt got that range of torque.

We also discussed fuel economy and he said he would be on average around 25/100! I told him on my initial calcs that I was about 12/100 or less. However, going up hills I seem to run out of steam a bit, but again cant compare to petrol just yet.

Of course I am biased as I am a diesel guy, I have two 300tdi discos also :)

[mick88]

How's the 2.25 Diesel's for noise?
I am partial to petrol engines in the series vehicles.

Cheers, Mick.

[JDNSW]

Noise is not really the issue - vibration, especially at idle is. (And, of course, this rattles everything loose on the vehicle). But you won't tell the difference in engine noise over the wind and tyre noise at road speeds anyway.

[whitehillbilly64]

What engine oil for a 2 1/4 Diesel ?
Same as my S3 petrol, which I use Castrol 20/50 when on special at Autobarn/Super Cheap.
Or do I need something 'special' ?
Thanks.

whitehillbilly

[67hardtop]

I use Castrol rx super 15w40 diesel oil.

[101RRS]

Same as my S3 petrol, which I use Castrol 20/50

For a new engine or one that is in good condition, in my view 50wt is too heavy - better with 40wt - different in an older engine that is starting to get a bit smokey and rattly.

[whitehillbilly64]

Its in a 75 S3 109, sitting for many years with no fuel cap.
Managed to fire it up after cleaning fuel tank, sedimentor, rebuilt lift pump, new fuel filter.
Think I should give it a oil change. Have a few ltrs of 20/50 hence the question.
So I must use a diesel oil ? Or would the Castrol 20/50 mineral oil be ok to run it on.
Thanks for you comments. Here and else where.

whitehillbilly

[gromit]

For a new engine or one that is in good condition, in my view 50wt is too heavy - better with 40wt - different in an older engine that is starting to get a bit smokey and rattly.

I think 20W50 would have been used in period, possibly individual oils for summer & winter would have been specified.
Added to this the viscosity numbers have a tolerance so a 40 from one manufacturer and a 50 from another could be very similar if the 40 is at the high end and he 50 at the low end.
I'm running all mine on Castrol 20/50, cheap at Kmart although their automotive section seems to be getting smaller & smaller.



So I must use a diesel oil ? Or would the Castrol 20/50 mineral oil be ok to run it on.


From memory Diesel oils contain more detergents although talking to an oil blender some years back I found that earlier diesel oils contained less detergent.
Shouldn't be a problem running on 20W50.
Penrite suggest it isn't a problem as long as the oil meets the spec. for the engine.
Knowledge Centre | Penrite Oil (https://www.penriteoil.com.au/knowledge-centre/Miscellaneous/242/can-petrol-engine-oils-be-used-in-diesel-engines/407)

Being so old the spec. of any modern 20W50 will be higher than originally specified.

Colin

[whitehillbilly64]

Thanks Colin.
Repco has the filter. Thought was a different type as per the 2.6 Rover, but looks common to the S3, Short fat type not long skinny.
Probably not politically correct.
As for starting a Diesel, are glowing the plugs like a choke on the petrol ? Or does the system have a 'running rich to start' function on the pump ?
Not had anything to do with Diesel motors before, even though the old man was a Diesel fitter in the UK RAF.
Another 'strange' question. Why would you use 'start ya bastard' on a Diesel Engine ????
Thanks.

whitehillbilly

[Lionelgee]

Thanks Colin.

Not had anything to do with Diesel motors before, even though the old man was a Diesel fitter in the UK RAF.
Another 'strange' question.

whitehillbilly

Hello WhiteBilly,

One of those - "it depends" answers in relation to the diesel engine start up. My long wheel base 2.25 litre Series 3 diesel needs the glow plugs for the first start of the day. After that it starts straight away for any restarts - without the glow plug stage. I also have a Series 2A which a previous owner fitted an early 1B Toyota diesel into. Even in the middle of a Queensland summer it needs glow plugs to start or for any restarts later in the day.

Kind regards
Lionel

[gromit]

As for starting a Diesel, are glowing the plugs like a choke on the petrol ? Or does the system have a 'running rich to start' function on the pump ?


A diesel is compression ignition and pre warming the combustion chamber helps with initial starting when the engine is cold.
Direct injection can be started without glowplugs typically but an indirect injection diesel requires use of the glowplugs.

My Isuzu powered Series III requires use of glowplugs even on a hot day, on a cold day by pushing the 'pull to stop' control it alters the pump setting which also helps.
My Defender can be started easily without using the glowplugs, even in the cold weather in the High Country.
We have two TDV6 Territory's and they prefer the use of glowplugs. Start immediately after using the glowplugs, quite a few revolutions before it will start without and it then emits unburnt diesel for a few seconds. So the glowplugs save wear & tear on the starter motor & battery, SWMBO still doesn't quite get this so her Terri is cranked over multiple times and leaves in a cloud of white smoke !

It's a bit like starting your lawnmower or whipper snipper. Once you've worked out a starting technique it's straightforward.


Colin