285 Maxidyne.

One for Mrs Mack, or anyone who wants to jump in.
Working for Jetspress during late 70's to mid 80', we bought (brand new at the time) a pretty stock standard R model although had the quad headlight type bonnet.
Had the twin air cleaners, we knew it as an 'air-to air' 285 engined truck, straight 5 speed box.
Only one we had in our division, put it on Syd-Adel express, replaced a 237 F model Maxidyne, never got to have a wheel of it myself, I was running North at the time, so didn't cross paths with the permanent drivers very often.
Did however ask one of them what they thought of it, said it was geared the same as the 237 F models, running Adel, right up on its weights all the time, still only doing 100 kph and not real brilliant if running into a headwind across the Hay Plains! May have been a different story if geared up a bit, instead of being up on max revs to maintain a decent road speed, letting the engine work at its optimal lower rev range and try and get a bit of economy out of it.
Management thinking would most prolly have been that if they were geared up, drivers would only want to still drive them flat stick for hours on end!
And they used to run 24 hr tachographs and woe betide you if you tried to either 'forget' to either put one in or run one over its 24 hrs!
Just about this time, Maynes traded most of Jetspress and Mayneroads 237 Maxi's in on the only just released 320 2 valve 'Cool Power' R models and the 285 went along with it, unless it went to another of Maynes companies.
The 320's went on the Syd-Bris express with a driver change at Glen Innes.
Syd-Melb- Syd and Syd- Adel were run one out straight through.
Had a few problems with the first batch of 320's, camshaft lobes chewing out, they also had that weird 10 speed box which I always reckon was a 'mongrelized' version of the venerable old and proven 5 speed Maxidyne.
Seemed to glue a two speed PLUS reverse onto either the front or rear, think it was the back, anyhoo, gave 10 forward speeds and five reverses.
Air operated, bit like a Spicer knob set up.
Funny the next batch that turned up had the 350's with a 9 speed range change box, much the same as Fullers 9 speed but with a lot lower reverse ratio.
Had seen a few of these 285/5 speed jiggers around, yet Mack didn't seem to persevere with this setup for to long.
Not sure if the 285 was upgraded to the 300, but the 320' a were rated as Thermodynes, I.e the silver engine (and dog) as opposed to the 285 gold editions.
Last ones I drove were the 350/4 valves, underpowered even then on Syd-Bris Express on the New England.
Lots of hills up there!
And we were running one out, the Change over having been scrapped.

Must be heaps of blokes who have done a few miles in these beasts, as I said, I never got the chance to drive a 285 /5 air to air, would have liked to though!
Dave

The 285 was by almost everyone I have spoken to regarded as a good goer
Worked well and pulled hard

Gearing on most Australian sold Macks was pretty slow but they lugged pretty hard

Also I reckon in this era the speed limit for trucks was 80kmh
Not many were driven to that

10 and 12 speeds are as you describe, 2 speed split and reverse on the rear and a 12 speed has deep reduction on the front

Most Mack drivers prefer these to the 5 speed

All 285 and 320's are known to me as a coolpower, anything with the tip turbine was called cool power

Interesting (to me anyway) I had quite a long phone conversation with Kiwi Mack bloke on Saturday night and a coolpower over there was chassis mounted intercooler and the tip turbine was Econodyne

Thats what I was told, it was the otherway around in Australia

Great memories and thanks for sharing with us all

Paul

Mrs,
Thanks for the correction, I always thought that the 'Econodyne' guernsey was given to the 350 4 valve engine.
Seems I recall that they were released in the R model which had the ' swept back' grille as opposed to the previous 'flat' front?
Must have been out in about 1987 as I moved job and location just as the last batch arrived.
Of course I could be totally wrong in all this, have trouble sometimes remembering what I had for lunch yesterday!
I did have a photo I posted here many years ago of a float parked out at the Birdcage on the Sturt Highway with a HD41 on its way to Olympic Dam.
R model looked to be pretty new at the time, got talking to the driver for a few minutes as they were getting ready to chop off.
It was a 285 Maxidyne with the 5 speed Maxitorqe box
backed up with an air change 4 speed Spicer.
Don't know what diffs had, other than the axle shaft extensions were the cone type as compared to the flat type that we were running on Highway diffs.
Looked to be a 'camel back' suspension, but again, much heavier than the norm.
Photo shows HD41 with Dolly and 4 axle float.
Think it was Swishy who told me that it was some wire rope cable set up, hadn't come across them before, myself.
Dave

Dave I feel your more than likely correct about the Econodyne

I can't even remember if I have had lunch some days, let alone what it was

Paul

Interesting stuff fellas... back in the day, I always thought that the 285's, 300's etc would have pulled christ off the cross- but thats just what I heard and read, I never drove one, I must say.
Even the 237's went ok, I thought, but once again that was probably in the era where bigger motors and higher speeds were just beginning. Mine gets along OK, but with a load on it's bloody slow compared to the trucks of today. Back when Dad had a 711 in his R model, (I think they were 210HP?) gee, the 237 would have been bloody amazing compared to the 711, which could only be described as gutless, but honest....really was pretty damn slow.

From my limited knowledge, the 350's were the first of the four valve engine? And they were "econodyne's". I reckon the last of the R models had them, with the air to air intercooler in front of the radiator, then the R model finished and they morphed in to the "Valueliner", which had the swept back headlights. I think Mack started to lose its way a bit around this time, (only my impression tho) perhaps as other trucks got more power than 350HP from a 6 cylinder, and the europeans started showing that you could actually have some comfort in a truck- and the 1990's Valueliner cabin was really still just a hangover from the mid 1960's Flintstone cabin! Albeit with a little more legroom, but still not much, and a plastic dash...

Here's a question for you tho-
I've just bought a 285 Mack engine Ex army, as the poor little 237 in my R model is getting tired and using oil- The 285's (etc) all had the two airc leaners, I believe the left hand one was purely for the tip turbine, which was only to cool the after/intercooler? (what is it called?) Am I correct in thinking this?
SO- the question is, do I need that second air cleaner? I reckon I've seen a bloke just bring air up to cool the after/intercooler from under the front of the truck, but I'll have to investigate further.
Aside from that, I'm of the belief that the 285 will slip directly in to where the 237 is?
Thoughts please!
Cheers
Rich

This is not the engine I bought, but it looks the same (well this one looks a lot tidier than mine...) - it's green, and it's in a box!! Apart from that, I know nothing... will it be good or stuffed, that is the question......



And now I'm just showing off. can't have too may Mack pics tho eh. This was a tank we took up to my brothers place near Mansfield. Fair bit of breath-holding, but we got it unloaded with a bit of crossing of the fingers..

prodrive wrote:

Interesting stuff fellas... back in the day, I always thought that the 285's, 300's etc would have pulled christ off the cross-

I;'m inclined to agree Rich. I had one & It punched WELL ABOVE It weight...

Here's a question for you tho-
I've just bought a 285 Mack engine Ex army, as the poor little 237 in my R model is getting tired and using oil- The 285's (etc) all had the two airc leaners, I believe the left hand one was purely for the tip turbine, which was only to cool the after/intercooler? (what is it called?) Am I correct in thinking this?
SO- the question is, do I need that second air cleaner? I reckon I've seen a bloke just bring air up to cool the after/intercooler from under the front of the truck, but I'll have to investigate further.
Aside from that, I'm of the belief that the 285 will slip directly in to where the 237 is?
Thoughts please!
Cheers
Rich

MY Rememberer says That you need the 2 Aircleaners....

Reckon Hayseed is correct in saying that the two air cleaners would have to be plumbed in.
Although my rememberer has been known to be awry quite often, so I wouldn't like to be betting the farm on it!
Leave that to others who know or can remember more!
Dave

https://www.hcvc.com.au/forum/attachment/41062
The Maxidyne with the 3 oil filters was there ESI model .................... Extended Service Interval

it had a huge sump
the oil was kept too cool, they had a fibre glass pad across the front of the sump to try and keep the heat in the oil
we kept the 3 oil filters idea and fitted a smaller sump so it fitted in with our other truck service intervals

cya

Second air cleaner?

Yes it uses the second aircleaner to suck fresh air in and blow (in the case of the R model) straight over the air to air intercooler and back out over the passanger side front wheel under the mudguard

As to is it needed or not

Well lots of different thoughts here
I have seen coolpowered motors in US B models and the intake pipe isnt even there, just the tip turbine sucking straight from the engine bay
The first US coolpowered trucks had a second air cleaner mounted under the bonnet and they sucked the air from a bonnet scoop aircleaner doohickie




NewZealand was still using this setup into t he 80s on some trucks

Apparently these were trialed in Australia and clogged to quickly
Im gunna call 100% b.s. and urban myth to that
I have spent thousands upon thousands of hours on farm tractors with the air intake under the bonnet working in worst dust conditions than any truck ever would and this doesn't happen

The most common air intake world wide was from what I can see, a double intake, a pipe in a pipe




Even the rubber duck truck from the movie convoy was for the most part one of these, 3 trucks were used in the filming, plus a few more bits of trucks



I feel the two aircleaner set up used in Australia was more gimic than what was needed

Mack purists will be swearing at their phones or keyboards reading that bit

So like all things, I dunno my ass from my elbow about any of this stuff

And Swishman is spot on about the sump on a ESI motor, 50 litres of oil
Maybe 51 litres, but flipping huge

I have never experienced the motors oil running to cool, these motors are very cool running motors, at least that's what I have found
Even up on the gross weights approaching 100 ton on a 45° C day climbing a big hill they dont get above 70° C

Don't let anyone fool you, these were a little motor with a huge heart that punched well above their weight
They put Mack well and truely in the history books as great motor builders, plenty of E6 Mack motors did well over a million miles with out rebuilds at all which for that era was almost unbelievable

The E9 V8 was garbage compared to the E6, it went well but didn't last, just like V8 Macks before it
Anyway I'm getting off topic now

Paul

Prodrive,
I have no experience with ex-Army Macks but when I bought Ex Army Morris engines (they were used to drive the generator, etc. in Centurian tanks) I found that the clean and tidy ones were rebuilt by the Army to strange sizes but the dirty ones were used ones on their way to be reconditioned.