Trans Cooling Option

[The Stranger]

I have fitted a huge engine oil cooler and an oil temp gauge to the trans. The cooler is at least double the capacity of any trans cooler I could find, but still I hit 110c up the Brynderwyns and 125c up the Mangamuka gorge when towing.

I note that cooling only really happens to any degree when the TC is locked. When towing I always use OD. This does load the engine a bit more but it allows the best cooling of the trans. This leads me to assume that most heat is generated in the TC and unfortunately that is sandwiched between a hot engine and a hot transmission.

The TC and flex plate are essentially a large centrifugal fan, but they are starved for air flow so I removed the metal plate that closes off the bottom of the bell housing as a test.

This has resulted in a decrease of 10 degrees in the trans oil temperature - in general. I say in general because I haven't had the chance to test it yet with a load.

So - is this good or bad? I only use the vehicle for towing and beach launching, not four wheel driving as such. Certainly if it keeps the trans cooler whilst towing it's good. Possible down side is debris entering there, but what real harm is likely to result should the cover remain off?

[Budore]

Place a piece of fine wire mesh over the hole. That should stop a lot of debris getting in and still allow the air to circulate.

HTH

[crazyclark31]

That doesn't seem right to me as my safari has only got a 25row cooler and i have no issues keeping it cool even when towing the digger or wood(3cube wet). I never tow in o/d unless it empty trailer etc.
Is your cooler running through the rad as well? Running stand alone works best.maybe need to get t/c checked

[Dirtydog]

Check to make sure its not airlocked, as it may be affecting it.

[The Stranger]

That doesn't seem right to me as my safari has only got a 25row cooler and i have no issues keeping it cool even when towing the digger or wood(3cube wet). I never tow in o/d unless it empty trailer etc.
Is your cooler running through the rad as well? Running stand alone works best.maybe need to get t/c checked

I don't use the std cooler at all as when my trans blew I went to flush the std one and it was choked, so I won't do that again. TC and trans are fully reco'd, lines were flushed and full synthetic fluid so should be in good nic.
Are you running an oil temp gauge on your auto?
If so what are you getting?

The temps I outline are max and pretty grueling hills with a loaded boat - but then this is the time I need most cooling and that I want the least problems.

[The Stranger]

Check to make sure its not airlocked, as it may be affecting it.

If by air locked you mean no flow, then this isn't a problem. If it is restricted flow then I'm not sure how one would know as there definately appears to be a good flow of oil.

[Dirtydog]

air lock asin there is a void in the cooler, and oil is only going through 1/4 instead of all of it, resulting in nowhere near the same cooling efficiency.

[crazyclark31]

Its never been into triple figures but pretty close. Normally sits mid seventys and climbs to the nineties when towing into head wind/BIG loads.
don't actually check exact temps more just glance to make sure its not high as.

how is your cooler mounted. Have been a few threads about were to have inlet/outlet to prevent airlocks. also having a decent gap between the cooler and the radiator heaps with flow as well.
I also have a water spray setup for it that i can use when i'm giving it heaps. Haven't really needed it for a while though.

[The Stranger]

Its never been into triple figures but pretty close. Normally sits mid seventys and climbs to the nineties when towing into head wind/BIG loads.
don't actually check exact temps more just glance to make sure its not high as.

how is your cooler mounted. Have been a few threads about were to have inlet/outlet to prevent airlocks. also having a decent gap between the cooler and the radiator heaps with flow as well.
I also have a water spray setup for it that i can use when i'm giving it heaps. Haven't really needed it for a while though.

Thank you, very interesting. There is about 20mm between the cooler and radiator - which is of course way more than say a normal trans cooler which is often close coupled. The engine fan pulls a lot of air through both the cooler and radiator so when lugging up a hill I doubt any heat is transferring from the engine radiator to the trans cooler.
I have inlet at the bottom so as to push air up and hopefully ensure fluid fills the entire cooler before exiting the outlet at the top.

I had a large trans cooler on it prior to using an oil cooler and this unit is a definite improvement. The system seems to work fine for normal use, holds it to 50-55 on the motorway and 60-70 around town. It's towing up big hills where it can generate more heat than it can clear.

My oil temp sensor is on the oultlet line. Where is yours please?

[The Stranger]

air lock asin there is a void in the cooler, and oil is only going through 1/4 instead of all of it, resulting in nowhere near the same cooling efficiency.

Seriously - how would I know?
All seems to be working fine - as noted only big hills towing a decent load give me any issues. It just seems that in those situations when the EGTs are maxed for a sustained period leading to a hot engine that the trans generates more heat than can be disipated.

[Dirtydog]

wel ya never know, its allways one thing to make sure about either way, but if the in is at the bottom and out is at the top it should be fine.

I dont even run it on the factory radiator cooler and ive never had problems with mine at all.

i do need to get an egt guage and an oil temp guage, but ive neverhad it overheated, still smells fine.

maybe a spacer between the radiator and the cooler could help?

that way if there is any radiant heat from rad it would be slightly insulated.

[crazyclark31]

is that on the outlet of the cooler or the trans? Mine is just before the cooler. Prob not the best place to be honest.

[Dr_PC]

Go see the guys that rebuilt it, get them to check the pressure flows and also where the gague is plumbed in

[Dirtydog]

mine is straight from the trans to cooler, then back to trans.

[jaza]

what car ya talking about? terrano td27?

[Dirtydog]

yea, td27, never had a problem with it, and it used to tow horses around all the time no worries.

also drove over the milford road every fourtnight no worries.

[The Stranger]

what car ya talking about? terrano td27?

Isn't everyone on here a mind reader?

Good point. Yes a D21 with a TD27.

[jaza]

Mine heats up to up bombays etc under load ive replaced everything new reco trans, radiator ,external tran cooler, new water pump and thermostat and it still gets up to 3/4 on the gauge under load.

[fullthrottle]

According to the manual, the 'normal' Auto fluid temp will be 50-80c

Not much help I know, but might pay to ask a trans expert about what temps are acceptable under load.

[tallsam66]

Maybe the issue is using OD ,, you want engine to rev a bit ....using OD maybe be making it labour & increasing temps.

[fullthrottle]

Maybe the issue is using OD ,, you want engine to rev a bit ....using OD maybe be making it labour & increasing temps.

Good point. How fast would you be travelling and at what sort of revs. Anything is going to heat up when there is not enough air being drawn through the cooler. One reason why I got rid of that stock fan.

[The Stranger]

Maybe the issue is using OD ,, you want engine to rev a bit ....using OD maybe be making it labour & increasing temps.

Intuitively 4th (OD) is not good, and testing confirms this. When I disable the TC lock functionality and use the OD switch the trans temp skyrockets. So in that sense you are correct.

However as noted I get best cooling when TC is locked (say 5th) and I can't lock the TC without using OD, so must run with OD on to get good cooling.

So having said OD is bad - the reality here is that it never spends enough time in 4th to cause a problem as the TC locks real quick when it gets to OD and the trans cools promptly as a result.

Also as noted the issue only exists when towing on long steep hills. At this time it is moot if OD switch is on or not as it is usually in second gear anyway. This is of course also where the air flow through the cooler is lowest - but I doubt airflow alone could solve this as I had an auxiliary fan on the trans cooler for just these occasions and that didn't do anything.

I would bet that having the ability to lock the TC when in lower gears would get rid of the issue entirely.

[The Stranger]

I would bet that having the ability to lock the TC when in lower gears would get rid of the issue entirely.

Turns out it is pretty easy to lock the TC in any gear.
Now to test if this helps the cooling when towing.

[fullthrottle]

OK, taking an educated guess I would say that all the heat is being generated by the two halves of the torque converter continuously slipping (so to speak) while not in lock-up state.

---Quote, from a doc Pete gave me---
The torque converter can be looked at as being two separate halves, one coupled to the engine and the other to the gear box.
The two halves are connect by the transmission fluid, which transfers the spinning motion generated by the rotation of the crank shaft in the engine through to the half connected to the gear box.
When lock up occurs, a clutch locks the two halves of the torque convertor together, making a direct mechanical link from the engine to the gear box.
By doing this, the loss of power created by the fluid coupling is eliminated.
-----------------------------------------

I'd be interested to hear how your tests went and how you got it to work. Direct drive power from engine to transfer without the loss of power via the TC would be great. I'm sure thats how the drag racing boys do it
Basically a manual with no clutch

[wjw]

OK, taking an educated guess I would say that all the heat is being generated by the two halves of the torque converter continuously slipping (so to speak) while not in lock-up state.

---Quote, from a doc Pete gave me---
The torque converter can be looked at as being two separate halves, one coupled to the engine and the other to the gear box.
The two halves are connect by the transmission fluid, which transfers the spinning motion generated by the rotation of the crank shaft in the engine through to the half connected to the gear box.
When lock up occurs, a clutch locks the two halves of the torque convertor together, making a direct mechanical link from the engine to the gear box.
By doing this, the loss of power created by the fluid coupling is eliminated.
-----------------------------------------

I'd be interested to hear how your tests went and how you got it to work. Direct drive power from engine to transfer without the loss of power via the TC would be great. I'm sure thats how the drag racing boys do it
Basically a manual with no clutch

It toyotas you just have to switch the correct solenoid and voila.... you really want it setup so if you touch the brake it disengages though.

[The Stranger]

It toyotas you just have to switch the correct solenoid and voila.... you really want it setup so if you touch the brake it disengages though.

I'd be interested to hear how your tests went and how you got it to work. Direct drive power from engine to transfer without the loss of power via the TC would be great. I'm sure thats how the drag racing boys do it
Basically a manual with no clutch

There is a post around (by Diesel Boy if I recall correctly) describing how to disengage the TC lock. I just modified that mod with a 3 position switch and put 12v down the wire to the solenoid as wjw says. Position 1 is normal, 2 disengages the lock and 3 engages it.

So far, as one would expect gear changes are harsher when locked and if you lock up with engine revs to low it bogs the engine pretty bad - but that's simple to avoid and there doesn't seem to be a problem even at say 50 in 3rd. One benefit is increased engine breaking, which when towing or off road can be an advantage and should allow quicker cooling too.

Towing is going to be interesting, but haven't tried that yet.

[The Stranger]

There is a post around (by Diesel Boy if I recall correctly) describing how to disengage the TC lock. I just modified that mod with a 3 position switch and put 12v down the wire to the solenoid as wjw says. Position 1 is normal, 2 disengages the lock and 3 engages it.

So far, as one would expect gear changes are harsher when locked and if you lock up with engine revs to low it bogs the engine pretty bad - but that's simple to avoid and there doesn't seem to be a problem even at say 50 in 3rd. One benefit is increased engine breaking, which when towing or off road can be an advantage and should allow quicker cooling too.

Towing is going to be interesting, but haven't tried that yet.

Another update for the sake of completeness if anyone is thinking of this mod (adding manual TC lock).

This drops the temperature very significantly. Going up Scenic drive (sans trailer) the trans oil would hit about 85c. Selecting 3rd and locing the TC 60c. It has never cooled up hill before, but now will.
It also cools much quicker on the down hill with the TC locked.

Haven't towed the boat yet, but a couple of trailer loads of firewood have seen significant reduction in temperature - at least 10c. Previously I couldn't get cooling at 50 kph when towing - It wouldn't heat up, but it wouldn't cool either. With the TC locked it cools at 50kph with a trailer no problem.

Needs a bit of care.
You don't want to lock with the engine below about 2500 rpm as the drop in revs may take it out of the power band and it pays to lock on a trailing throttle i.e. get up to speed then back off the accellerator before locking.
Gear changes are very rough when the TC is locked, so I plan on avoiding that situation too as all shock load is going through the drive chain. But I believe with a bit of careful use it is very effective and won't cause any damage.

[fullthrottle]

Nice job. A good outcome and interesting mod that can be done.

There is a trans shop up Taupo way I believe that specialise in supplying upgraded springs etc so the trans will handle slamming into gear while the TC is locked. Doesn't sound nice for the rest of the drive though.