JX Engine Mods

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Spailpin Fanach
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JX Engine Mods

Post by Spailpin Fanach »

Hi folks. 

Just wondering. I recently spent a week in Co Mayo and Co Sligo, both hilly counties. My 1989 1.6TD JX T3/Type25 could charge up steep hills doing 70km/h and 3,000 RPM. This was in 4th or 5th gear and when I already had a good head of steam up.

It was a very different story when starting from a stopped position or in 1st gear. Then, if the hill was steep, I couldn't get the revs up high enough to engage the next gear. I kept crawling up in 1st gear with the engine making a terrible racket and the revs creeping up to the 4000 mark. I'd change up to 2nd and the revs would drop real low and the engine would stall. I'd usually admit defeat at that point and find a different route. On one occasion, in Westport, I was parked on a steep hill and  broke an alternator belt trying to get up the hill.

The engine itself is rock solid with a fairly recently installed new cyclinder head, turbo diesel and reconditioned gearbox. The timing belt was changed 4,000km ago. It also has power steeping

Is there any remedy to this? I read somewhere about possible mods for the JX engine. I think I remember something about an oil radiator or inter cooler or something similar.

Thanks
1989 LHD VW T3/Type25 1.6TD JX Westfalia California poptop, 5-speed. 


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syncroandy
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Re: JX Engine Mods

Post by syncroandy »

It sounds like you're not getting sufficient turbo boost and possibly timing/fuel could benefit from adjustment. Getting a boost guage would be a useful start. Then assuming all the mechanicals are healthy it should just be a matter of setting the engine up following the workshop manuals. Servicing often gets neglected so things like valve clearances (which need shims swapping) may be well out of spec. I used to have a JX then a 1.6 GTD, but that was a long time ago now. I think I still have some of the old diesel tools kicking about if you are short of any.
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clift_d
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Re: JX Engine Mods

Post by clift_d »

I have the JX workshop manuals in PDF format - if you still need them drop me a PM.

We can only normally power up hills with our JX if we have a good head of steam up already, and it's a short grade. Otherwise we frequently need to drop down a gear (or two) and calmly motor up. For steeper climbs we drive using the rev counter rather than speed - if that makes sense. We usually settle in a gear that keeps the engine around 2200 rpms - it's near the peak torque of the engine (see image below), and we've also found that it doesn't risk overheating the engine as much.

Image

Adding an oil cooler probably won't improve the engine performance, but is one of the things that is generally seen as beneficial in terms of extending the life of a JX. An intercooler can improve boost performance, but your stalling issue sounds like you have other underlying issues you need to sort out first.
1988 LHD T25 1.6TD Westfalia Club Joker Hightop syncro

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Oren Kipnis
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Re: JX Engine Mods

Post by Oren Kipnis »

To my own opinion, any penny spent on a JX is worthless.
For the long run, and investment of a TDI upgrade will pay itself back in a more leisurely drive and a 15-20% better fuel consumption. Once done right from the beginning, you should have a trouble free motor for years.
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clift_d
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Re: JX Engine Mods

Post by clift_d »

Oren Kipnis wrote: 07 Sep 2021, 11:48 To my own opinion, any penny spent on a JX is worthless.
For the long run, and investment of a TDI upgrade will pay itself back in a more leisurely drive and a 15-20% better fuel consumption. Once done right from the beginning, you should have a trouble free motor for years.
"Once done right from the beginning..." being the key phrase here :run

TBH there are a lot of reasons why keeping your JX in good order might be a better option, not including the £££s a TDi conversion can cost. In the UK the primary reason might be to retain the option of historical vehicle status when your van hits 40 years old, which would give you exemption from VED, MOT and Emission charges. Also TDi engines have a reputation for being quite hard on gearboxes, so there's that cost to consider as well.
Last edited by clift_d on 09 Sep 2021, 08:48, edited 1 time in total.
1988 LHD T25 1.6TD Westfalia Club Joker Hightop syncro

Spailpin Fanach
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Re: JX Engine Mods

Post by Spailpin Fanach »

syncroandy wrote: 07 Sep 2021, 09:35 It sounds like you're not getting sufficient turbo boost and possibly timing/fuel could benefit from adjustment. Getting a boost guage would be a useful start. Then assuming all the mechanicals are healthy it should just be a matter of setting the engine up following the workshop manuals. Servicing often gets neglected so things like valve clearances (which need shims swapping) may be well out of spec. I used to have a JX then a 1.6 GTD, but that was a long time ago now. I think I still have some of the old diesel tools kicking about if you are short of any.
Thanks. That's very kind of you. Thing is, I'm not at all mechanically competent. I'm learning though. 
 
1989 LHD VW T3/Type25 1.6TD JX Westfalia California poptop, 5-speed. 


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Dueller
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Re: JX Engine Mods

Post by Dueller »

I tried to mod my JX but couldn't find enough info on it to give me confidence

Simon Baxter has posted as far back as 2006 i think it was when he first started out and he modded his JX to 100bhp

Plenty of info about on the GTD mods, the fuel pump has the saucer on top for visual difference, the JX is a fuel efficient economy pump so a bit different, the GTD was in Golfs and Passats so more modded articles about

The main thing is the fuel delivery internals so you need the fuel governor mod doing, can be done at home on GTD

Here's some links i discovered over that time:

https://forums.tdiclub.com/index.php?th ... di.275682/
http://www.brick-yard.co.uk/forum/the-d ... 33228.html
http://www.brick-yard.co.uk/forum/t3-en ... rum21.html
http://vwdiesel.net/forum/index.php/topic,645.0.html
http://www.brick-yard.co.uk/forum/jx-bo ... 91498.html
viewtopic.php?t=109141
http://vwdiesel.net/forum/index.php/topic,3649.0.html
http://vwdiesel.net/forum/index.php/topic,32848.0.html
http://vwdiesel.net/forum/index.php/topic,5843.0.html
http://vwdiesel.net/forum/index.php/top ... #msg188075

I planned an AHU conversion and modded one for fitment that i still have from my old Golf, wired and turbo relocated to work with JX exhaust, brackets from Tim at Ultimate Engineering if you fancy a conversion that's part done  :D

Good luck with it
1989 Crewcab 1600TD JX - Gone to Romania
1989 Caravelle 1.9 AutoBox

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sweetaswesty
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Re: JX Engine Mods

Post by sweetaswesty »

We took the expensive option of a proper 1z TDI conversion with a refurbed and upgraded gearbox to match (higher final gear).
But it was a hard choice not just because of the cost. In the end for us the pros outweighed the cons.
The pros being a stronger more powerful engine better matched to the van; reliability (our JX was a pain in the proverbial); improved economy, an altogether easier driving experience cruising at motorway speeds, going up hills, just pootling along nicely keeping up with the traffic,etc.
The cons being the odd custom part or set up, an electronic box and immobiliser instead of simple mechanicals (maybe that’s a plus also?), and maybe gearbox wear to come?
Legend has it the JX is a gutsy reliable little engine, but ours wasn’t and we gave it chance after chance. I feel a twinge of envy when some one says they’ve got a good one. Though according to our PO we actually had one too.
1991 Westfalia California Hightop1.9tdi

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