automatic oil cooler

Submitted: Thursday, Jan 16, 2014 at 11:05

ThreadID: 105835 Views:2797 Replies:4 FollowUps:8

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kman1

hi all,
I have just replaced my tow vehicle which was a falcon au automatic wagon with a prado 3l turbo diesel automatic 120 series.I had an automatic oil cooler fitted to the falcon should I do the same with the prado.I will be towing a 15' caravan at 1300 kg agg.Maybe in the future I may buy a bigger van.
kman

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Reply By: Ross M - Thursday, Jan 16, 2014 at 12:09

Thursday, Jan 16, 2014 at 12:09

For the same reason you had one on the Falcon you would also fit one to the Prado.
If buying a bigger van then anytime there is more slip of the torque converter there will be more heat being created in the auto so, YES. Unless the Prado already has one.

AnswerID: 524602

Reply By: Member - Frank P (NSW) - Thursday, Jan 16, 2014 at 12:28

Thursday, Jan 16, 2014 at 12:28

G'day kman,

I have a 120 Series 3L turbo diesel auto Prado from new and tow 2200kg. When it was newish I asked my dealer about a tranny cooler and was told
"Toyota specify max towing loads for a standard vehicle taking into consideration local conditions. Toyota hasn't fitted a cooler, you don't need one and we don't recommend you fit one."

Some years later I fitted a Scangauge and got codes for transmission temperature. I was alarmed to find the tranny fluid almost always in the 90 to 100 deg range while towing, and regularly 130ish on hills. I've had the ATF overheat light come on once on a long climb in the Border Ranges NP, temp then was 150.

I have fitted a fan-assisted cooler. I decided on the fan assistance because a lot of our hard work is done at slow speed with not much natural airflow. Temps are on average 20 deg less than before. For me, the indications are that it is essential and should have been there from new, contrary to Mr Toyota's advice.

Heat is the enemy of auto transmissons. With your 1300kg a cooler is probably not essential, but certainly desirable. Your future bigger van may make it essential.

Member Toyocruiser has a blog of his DIY fitment to a 150 Series here if you're interested.

Cheers

FrankP

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Follow Up By: Member - bbuzz (NSW) - Thursday, Jan 16, 2014 at 13:43

Thursday, Jan 16, 2014 at 13:43

Hi Kman,

I have had two Prado diesels; 2003 and 2008; and put a 2nd hand Landcruiser oil cooler on both of them.

They are relatively cheap from the wrecker, you usually get to pick which one you want (least damaged) and any auto tranny place will fit them up for you. I used the Central Coast 4x4; they are good guys and easy to deal with.

There are two types - 80 series is a thick one (5cm?) and the later ones are skinny (3 cm?).

I have had both.

They fit in quite well to the RHS of the grille and look OME.

Good for piece of mind.

bill

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Follow Up By: olcoolone - Friday, Jan 17, 2014 at 09:43

Friday, Jan 17, 2014 at 09:43

90-100 deg is a safe operating temp for auto trans and even up to 130 for short periods, at 150 it starts getting critical.

Don't think of an auto trans as an engine.

FollowupID: 806388

Follow Up By: Ron N - Friday, Jan 17, 2014 at 15:04

Friday, Jan 17, 2014 at 15:04

The important thing to remember is that oil coming out of a hard-working automatic transmission on a hot day with a heavy towing load, might be around 130 deg C - but some internal components in the transmission can be running at temperatures up to 600 deg C!

The oil operating temperature of your automatic transmission is best kept in the narrow range of 80 deg to 110 deg C.
At 120 deg C oil temperature, the oil in contact with the exceptionally high operating temperature components, is starting to break down with heat.
Oil breakdown affects the oil additives and reduces the oils ability to lubricate and protect the transmission.

We use temperatures of a maximum of 130 deg C with heated oil baths, to install interference-fit bearings in earthmover transmissions.
Bearing manufacturers warn that temperatures in excess of 130 deg C affect bearing steel characteristics - and that means reduced life.

Any automatic transmission repairer of note, will tell you straight-out, that constant high automatic transmission operating temperatures (over 120 deg C) is a good way to give them plenty of work!

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Follow Up By: Member - Frank P (NSW) - Friday, Jan 17, 2014 at 18:15

Friday, Jan 17, 2014 at 18:15

Ron,
"Oil breakdown affects the oil additives and reduces the oils ability to lubricate and protect the transmission."

I presume that would be indicated by the colour of any removed fluid.

The manufacturer of my vehicle says the tranny is sealed for life and has no need of routine ATF replacement in normal circumstances. I'm a bit sus about that. However they do specify a heavy duty maintenance cycle. After any arduous trip I always get an ATF fluid change done - well it's a partial change, 4 litres in a system that contains more - but that's the heavy duty service cycle that the manufacturer recommends.

On one change I had them keep a sample of old fluid after a particularly hot and hard trip. No ATF warning lights on that trip and no Scangauge, but knowing what I now know I suspect temps got up into the 130-ish area a number of times and would have regularly been around 100. It was black in the bottle, though if you poured it out you could still see a tinge of red.

I have not yet done a colour inspection after installation of the cooler. That will be an interesting exercise.

Cheers

FrankP

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Follow Up By: olcoolone - Friday, Jan 17, 2014 at 21:21

Friday, Jan 17, 2014 at 21:21

Thats why there are many different spec trans fluids on the market ranging in price from $10 to $200 per litre.

Some vehicles have to use a high spec oil for the temps they run.

Heating and cooling interference fit parts is nothing new and in most cases we are talking contraction or expansion of 0.05mm, when fitted to another part in most cases they have the same contraction or expansion as the other part meaning the fit tolerances will be the same maintaining the bond no matter what temp.

The surface area loading is enough to maintain the bond of the two parts.

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Follow Up By: olcoolone - Friday, Jan 17, 2014 at 21:24

Friday, Jan 17, 2014 at 21:24

Frank don't go by the colour of the oil or seat of the pants analysing, send to an oil sampling lab and they will tell you everything you need to know including future damage.

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Follow Up By: Member - Frank P (NSW) - Friday, Jan 17, 2014 at 21:50

Friday, Jan 17, 2014 at 21:50

Thanks olcoolone, I won't be doing any DIY analysing, just curious to see the difference if any.

Having said that, for some time the trans does tend to stick in 4th and not shift up to 5th sometimes until I flick the shifter from D to 4 and back. That brings about an instant, smooth change. I have wondered if the high temps have had anything to do with that - varnished valves or some such - even though it has had regular off-schedule ATF changes.

Apart from that little foible, it is faultless.

I have been procrastinating, thinking I'd wait until something more definite came up and then take advice on an overhaul and modified valve plate.

After the next tough trip I will consider sending off an ATF sample for analysis as you suggest - the result may spur me into some kind of action - no doubt at great expense :-(

Cheers

FrankP

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Follow Up By: olcoolone - Saturday, Jan 18, 2014 at 08:12

Saturday, Jan 18, 2014 at 08:12

Oil testing is not that expensive.

Have a look here, never used this mob but it will give you an idea.

http://www.oilcheck.com.au/technical/transmission-oils.html

This is the only true way of finding out what's happening and how the oil is coping.

If more 4x4ers did oil sampling they might find they have been wasting BIG money on unnecessary oil changes.

There are many reasons why a trans may not shift right.

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Reply By: Member - Toyocrusa (NSW) - Friday, Jan 17, 2014 at 21:40

Friday, Jan 17, 2014 at 21:40

Hi. I had a 2005 V6 petrol model and it had an auto cooler fitted standard from the factory. It was a small unit fitted in front of the radiator, LH side. It may pay to check. My current 2012 D4D did not so I fitted an after market one. I wrote a blog on fitting it if you need any ideas. Regards, Bob

AnswerID: 524699