Can I replace T25 1.6/7 diesel with VW Caddy 1.9 sdi AYQ

[Jean Claude Damn Van]

Hi
I'm living through a classic nightmare. My beloved T251.6/7 straight diesel has died and needs replacement.
Is there a tech wizard out there who can tell me if a 1.9 sdi diesel out of a VW caddy code AYQ is a possible replacement? I know where a good one is at a reasonable price.
If it is possible are there any significant issues to bear in mind if i undertake such a task?
Desperate for any answers or advice.
While I,m at it does anyone have a 1.9 diesel 1y engine for sale?
Many thanks
JCDV

[davegsm82]

Short Answer, yes it's possible.

Long Answer, Yes it's possible but it's going to require a fair bit of fabrication.

Explaination; Your 1.6/7 is a revvy little beast, built back in the days before direct injection, designed to give reasonable economy at high revs. The 1.9SDi was designed to deliver it's power lower down in the band. If you bolt the 1.9SDi on to your gearbox, it will work but won't be revving within it's 'happy place'. Cue; early engine wear and the possibility of thrown rods etc.

My genuine advice is, replace it with something better from the same Era, i.e. a Turbo'd AAZ (AAY is non turbo I think?) or similar. Becuase;

1) Your 1.6/7 is cable throttle, the AYQ is Fly-by-wire, which means you either have to make a hybrid from the two diesel pumps to create a mechanical pump for the 1.9 or install all the electronics associated with the AYQ and have an electronic throttle.

2) The AYQ is not compatible with your engine mounts. They changed the mounts after the 1Y/AFN series, i.e. when the oil pump changed to being chain driven rather than direct-drive.

3) AAZ = More power and better economy if driven correctly.

These aren't massively problematic if you know/are someone mechanically competent with lots of spare time who's handy with a welder.

I installed an AFN in my bus along with a flipped A4/Passat box. Cost me way less than a grand but I did ALL the work myself apart from buying the adapter plates from ultimate engineering and getting the gearbox cut down by 15mm externally. Took me 5 days from driving onto the ramps with a 1.6 and off with a 1.9 (not including weeks of prep-work to the engine/box/loom).

Please feel free to ask anything else you need to know, while I'm new to this game, I'm still fairly familiar with the VW early diesel stuff.

Dave.

[Jean Claude Damn Van]

Many thanks Dave for your comprehensive answer
I had my doubts. I'm trying to find an aaz or a 1.7 ky unit which is the original now deceased engine. so far it seems finding the holy grail would be easier!
I may pick your brains as I go along. if that's ok.
JCDV

[davegsm82]

Absolutely no problem.

There's an AAZ in a yard near me, no idea what condition or anything but my AFN came from the same place and is sweet as a nut.

Where are you based?

Also, what catastrophe became of your 1.7? They're usually as tough as old boots.

Dave.

[Jean Claude Damn Van]

Hi Dave
I'm in Manchester.
Had a leak in the cooling system. Engine started to overheat but warning light did not come on so thought I,d got away with it and hoped it would just be a gasket or valve replacement, I was touring in Wales so just shut it down and had it towed back to Manc to the garage I use. When they opened it up it appeared that some small element (forget what they called it) had separated from the inside of the head and dropped into one of the cylinders it really did look like a mess of molten metal. Unlucky!

I've been researching whats involved in converting to the AAZ unit on Brickwerks and it seems more complicated than i thought as the deceased engine was non turbo i'll need new exhaust system, manifolds and other issues related to oil volume, gears, and different mounting angles to be overcome. I'm not a mechanic, and whilst the mechanic I use is very competent and experienced, I don't think I can afford the cost of his time to do that sort of conversion.
So I think the only viable solution is to replace rather than convert. so the task is to find a 1.7 KY!!! which I think might be more difficult than finding any of the others. But once found being a 'KY' it should slip in easily.....If you pardon the pun!
So quite a fix as I use the van daily for work and family business.
Many thanks for spotting the AAZ Dave but I feel it may be better to try and keep this little nightmare as simple and economic as possible.
Your continued interest and any thoughts you may have will be well appreciated.
Thanks
JCDV

[davegsm82]

Oh Dear, yea the LED in the dash is a bit of a double edged sword, from what I remember (and I may be wrong) but I think the light is only a coolant fluid low indicator, I only ever had it flash when the coolant was low... and when it wasn't low.... and when the capacitor inside the dial was failing...

Also, I'm not so convinced by the temperature senders since, they're so high up in the block that if you ran out of coolant they would be so slow to respond that they might not give adequate warning before your pistons turn to liquid

There's not a lot that could drop into a combustion chamber, there's only a few 'removable' parts in there, i.e. the Valves, Glow-plugs etc (injectors are indirect). I wonder what it was?

I guess you're right, a KY would be a simple operation to swap, but it all depends whether you're happy with the KY as it is. I didn't like the JX to be honest, it was really thirsty and although I'm sure it would be reliable, I preferred to refit something which wasn't screaming it's nuts off just to keep up with B-road traffic. As it is now, my AFN engine in the T25 can out-pull a Citroen C1 off the line. Not exactly blistering speed but compared to the JX it goes like a stabbed rat. 38-40MPG is nice too.

I can't imagine that mounting angles would be an issue, your gearbox should already have the appropriate mounting positions, they should be the same as the KY since the 1.6D right the way through to the early TDi's (1Y and AFN) including the KY, AAZ (AAY?) share the same block. My AFN used the same mounts as my JX.

Gearing Ratio's - shouldn't be an issue, you won't be making the most of the AAZ's power but I can't see why it would be an issue, people go from JX to AAZ and keep the same gearbox, some just fit larger wheels for a slight improvement in ratio.

Fair enough, you'll need a new Exhaust, but... ECP have the Turbo downpipe for £40 at the min, I just bought one. Also they do the backboxes, I think that was only about £60. Other than the expense of the replacement engine and Exhaust pipework, I can't forsee any major hurdles. If you buy a replacement engine usually it will come with manifolds, but I think you'd need a JX exhaust Manifold and possibly an intake manifold too, again not impossible to find just slightly more expense. Saying that, if you DID know someone handy with a welder then they'd be able to knock up some new mounts in no time which would allow you to use the manifolds and turbo that come with the AAZ.

I think you're going to struggle finding a replacement KY, if it's only 1 cylinder which is trashed then you might be able to get the head repaired (built up and milled back to shape) and buy a new/used piston to replace the knackered one.

You should definitely give it a bit of thought

Dave.

Hi Dave
I'm in Manchester.
Had a leak in the cooling system. Engine started to overheat but warning light did not come on so thought I,d got away with it and hoped it would just be a gasket or valve replacement, I was touring in Wales so just shut it down and had it towed back to Manc to the garage I use. When they opened it up it appeared that some small element (forget what they called it) had separated from the inside of the head and dropped into one of the cylinders it really did look like a mess of molten metal. Unlucky!

I've been researching whats involved in converting to the AAZ unit on Brickwerks and it seems more complicated than i thought as the deceased engine was non turbo i'll need new exhaust system, manifolds and other issues related to oil volume, gears, and different mounting angles to be overcome. I'm not a mechanic, and whilst the mechanic I use is very competent and experienced, I don't think I can afford the cost of his time to do that sort of conversion.
So I think the only viable solution is to replace rather than convert. so the task is to find a 1.7 KY!!! which I think might be more difficult than finding any of the others. But once found being a 'KY' it should slip in easily.....If you pardon the pun!
So quite a fix as I use the van daily for work and family business.
Many thanks for spotting the AAZ Dave but I feel it may be better to try and keep this little nightmare as simple and economic as possible.
Your continued interest and any thoughts you may have will be well appreciated.
Thanks
JCDV

[colinthefox]

You might also like to consider the AEF engine as a replacement. As fitted to Polos and Skoda Felicias from 1998-2003 ish, it is similar in many respects to the 1Y. It uses many of the bits you already have, and will be happy with the existing gearbox. You could then think about putting in a longer top gear at a later date, as there is plenty of torque available.

Take a look at this http://www.brick-yard.co.uk/forum/16cs- ... page1.html" onclick="window.open(this.href);return false;