JX to AAZ Conversion

[keeno]

I have installed many oil coolers to Splits and Bays and have found that between the chassis rails is ideal. I custom fabricate a small scoop ( approx two inch in depth) and this seems to work extremely well. To be honest, even without a scoop and just working by convection will be more efficient to a watercooled T25 than the oil cooler directly in front of the radiator. On a Syncro we are fairly limited due to clearance issues when off-roading and the fact that a prop gets in the way of things! On 2 wheel drive between the chassis rails is good. You can always fit a 12 V pull or push fan to increase efficiency.

I will have a good look at my Syncro to come up with a solution for mounting an oil cooler this week.

[v-lux]

Those rough calculations are only taking into account the thermal efficiency of the air. To be more accurate you would need to factor in the heat transfer between the two radiators also. The engine cooling radiator being much larger with a higher potential for heat loss.

What would be a mistake would be to mount the two radiators with a gap between them, this would certainly lessen the potential for efficency of both radiators.

Given that there is only a relatively small portion of the coolant rad covered by the oil rad, I would expect there to be very minimal effect on efficiency.
The coolant rad being generally cooler and larger it will bring the temp of the oil rad down quickly, meaning that the exiting air temp would only be high for a short time until things balance back out.

Thermostats for both cooling systems will also effect the dynamics, depending on when each one opens/closes in relation to each other.

At least that's how I see it....

[H-G]

Interesting to read your comments regarding the Oil Cooler; I have read the literature from MOCAL that came with it and they suggest that it goes in front of the radiator, and that while there will be a small reduction in the efficiency of the radiator, it is more than compensated by the benefits of cooler oil flowing into the heart of the engine. Furthermore, we also need to bear in mind that there is also 8 meters of black pipework running the length of the van which also cools the oil. The MOCAL literature does state that the oil cooler must go as close to the radiator as possible to ensure that there is no turbulent air created between the two coolers as this will have a detrimental impact to the cooling effect of the air through the radiator.

I am sure that the facts and figures posted go some way to show the loss of cooling, however, if this is the area suggested by the supplier, MOCAL, who fit these coolers to high performance vehicles, I will follow suit.

Turning to the installation, we got back from our holiday on Thursday and spent a couple of days unpacking etc. I managed to get on to the bus yesterday and finally finished the installation and drove the bus for the first time in far too long.

Fitted the oil cooler adaptor plate on to the filter mount and then connected the pipes. I cut them a bit shorter and ensured that the pipes were pushed fully home and also used a couple of jubilee clips as a belt and braces precaution to ensure that they don't pop off. A new oil filter fitted as the standard JX filter is too long and narrow to fit with the adaptor plate fitted - instead a filter for a T4 is used. I couldn't find any info regarding the amount of oil needed to fill the oil cooler so put in 2 litres (1/2 to fill the filter and 1 1/2 for the cooler); removed wire to the fuel cut-off solenoid so that the engine wouldn't start and then cranked a few times to pump the oil around the, now, extended system. Connected the wire and started the engine - the oil light went out after a couple of seconds. With the engine running, a good look around the adaptor, filter and cooler to check for leaks and found none - Happy Days.

While I was fitting the adaptor, I drained the water from the cooling system as I needed to fill using anti-freeze. Normal way, removed the pipes at the bulkhead, the bottom of the water-bottle and undid the bleed valve on the radiator. When everything has stopped dripping, reconnect the pipes and fill; 8 litres of anti-freeze gives a 50/50 (approx) mixture ratio. Ran the engine until warmed fully and then fitted the pressure cap. Allow the pressure to build and then turn off. Leave for a couple of minutes and then bleed at the radiator to remove any air from the system. Check of levels and make sure that the overflow tank is filled.

Air box fitted with a new filter - I found that I needed to adapt the plastic brackets to create enough clearance as the cylinder head is closer to the nearside bulkhead (AAZ is slightly taller then the JX). A bit of a squeeze to get everything back together, but it all fits as it should.

A big smile on my face now as it is effectively finished - there is the engine cover to do, but I am going to use the one from the donor van. I took it out for a bit of a drive - felt good to be driving the bus again. Got everything up to temperature. The engine pulls a lot more strongly than the JX and from lower revs. It also seems a lot smoother than the JX as well. I have not yet taken it out on the public roads as the insurance has lapsed, but I am looking forward to a good ride out next week.

As a result of the work I have a pile of spare JX parts which I will list on the 'For Sale' Link. I will be going to VANFEST if anyone out there wants any of the bits taking down there. I will be camping in the Splitterz Club site; if anyone is considering a similar conversion and wants to look/chat about what I have done here, come and look me out.

Many thanks to everyone that has assisted with advice and parts and for reading this thread. I have learnt much and I hope that this will assist anyone who is considering a similar conversion.

[reddwarf]

Sounds really great. Very helpful post.

[H-G]

Thanks for your comment Reddwarf. It was written in the hope that someone out there may find it useful.

[H-G]

Likely to be the last post on this thread, however just thought that I would update the forum after the first 'real' run out since completing the conversion.

Went over to Malvern from Huntingdon for VanFest at the weekend so a last check of fluids and to make sure there were no leaks we set off. Decided to go cross country rather than the motorways so that there would be a little less stress on the engine. Ran very smoothly no over heating in any way. It would appear that the oil cooler is making a significant contribution to the cooling of the engine as the temp needle took up position just underneath the LED whereas with the JX it would cover the LED. A slight rise when going up hill and but only up as far as to cover the LED. One stop on the way to collect the family; fully loaded no problems at all.

On the way home we took the motorway all the way home - cruise at 60 - 65 and again the temp held steady just below the LED. Hills cam and went with them needing to be quite significant to slow progress. We did develop a 'buzz' at idle and I have tracked this down to the snorkel vibrating in the rear 1/4 panel. Nothing to worry about and will be fixed at the next servicing when I remove the airbox. As for fuel economy, I did 275 km on the way back from Vanfest and used approximately 2/5 of a tank of diesel - about the same as I was doing with the JX.

I have seen a couple of threads asking if it is worth it. I have been very lucky in that I have managed to pick up the majority of the parts needed for the conversion from a donor vehicle. Notwithstanding this, the conversion was relatively straight forward and while the benefits will never set the world on fire, there are noticeable benefits. Less gear changes, Don't have to plan ahead so much for hills and I would say that it is smoother and quieter than the JX.


In summary:

If your JX is running fine then I would suggest that you leave it; if you find yourself with a broken JX and you want a hassle free upgrade, replace it with an AAZ.

[HarryMann]

Well done Ian, and thanks for the fullness of reporting, will try to make sure it gets into the Tech Archive for permanence eventually..

Whilst the installation of your oil cooler looks top notch, I would worry about the effect its location would cause on your water radiator.

Well, this is very std procedure, on the assumption that:
1) the oil is cooled as priority (and only a fraction of the water rad area is covered);
2) the hottest water is at the top of the main rad;
3) the combined heat taken out of the engine is higher with an oil cooler, despite its positioning (think of the radiator being extra thick just at the bottom >> greater total heat rejection)

Additionally, someone's done the sums, as nearly all modern vehicles stack the air conditioning rad > oil cooler > water radiator in that order closely stacked, sometimes 4 of them (intercooler). This is what we saw on the new T5 production line at Hannover during the 25Y Syncro visits.

There really is nothing quite like a a full dynamic head of air (total pressure) going through an oil cooler, have tried several fan based arrangements and the biggest reduction in oil temp I saw was about 5 degrees. That was before the fan(s) got blocked with mud, after about 3 fans I gave up replacing them and settled on the theory that 'some' heat must be rejected from the oil, though the temp gauage didn't confirm it...

..until I put one up front, with 3/4" bore pipes

Clive