GQ TD42 Auto....Trans Cooling Questions

[grunta11]

Hi Guys,
I'm pretty new to this forum, if this topic has been covered feel free to tip me on searching this out for myself.

Recently acquired GQ TD42 NA auto. Vehicle totally stock everything apart from a 2 inch lift. Bit of a blank canvas at present so planning on future Turbo with all the usual bolt on touring accessories to come, 33's, roof racks, steel bars, winch. etc, towing camper trailer and general offroading.

Looking for information regarding keeping the Auto cool, reliable and up to the job.

Curious about the idea of bypassing the trans cooling duties from the radiator and installing an external cooler. Removing the possibility of water contamination is an obvious plus.
A unit was recommended to me is 280 x 300 in size. My concern is the amount of airflow blocked out from the engine's radiator with a cooler in front. Removing the load of cooling the tranny from the engine's radiator is great, but to place the cooler in front of the rad half robbing it from airflow seems counter intuitive. Im led to believe the radiator is only just up to the task as it is.......(?)

a) Does an external trans cooler compromise the radiator enough to worry about?

b) With bypassing the trans cooling, is it rational to suggest the worthwhile options of heavier duty radiators available for improved engine cooling to counteract the above?

c) Does the Nomad valve body and/or manual convertor lock up make a worthwhile difference in relation to operating temps?

d) Does anyone have engine and transmission temp readings of before and after any of above modifications?

She's a keeper so I'm willing to spend the $$ on improvements that are worthwhile.

Thanks for any additional info or feedback.

[jff45]

The trans fluid lines through the radiator are more designed to get the trans up to operating temp rather than cooling the fluid but there is obviously heat exchange and that isn't always a good thing if the trans is worked hard and has a tendency to overheat.
I'm a big believer in removing those lines from the radiator, especially in a higher mileage vehicle, because if there's an issue the cost will hurt.

Trans cooling radiators don't block air flow very much. Big spotlights do..
I don't know GQs at all but 3.0 litre & 4.5 GUs have factory fitted trans coolers. I mounted a big Davies Craig cooler with my 4.5 and have kept it with my 4.2 turbo conversion.
I had the factory cooler plumbed in series with the Davies Craig but I've since removed it because the trans was running too cool.

A Nomad valve body is good but they're expensive and really aren't worth fitting on a high mileage trans.
A manual lock up for the TC is a very good idea if the trans heat is being generated by the trans continually slipping in and out of normal lockup. This happens a lot when towing.

You don't mention the history or mileage of your vehicle. If the trans is currently working well, you should drop the pan and inspect the magnet for debris. If ok, wash the strainer and flush the whole unit with synthetic fluid. The synthetic works better with higher temps.

Here's a pic of when I had the 2 coolers on my TB45

...

[grunta11]

The trans fluid lines through the radiator are more designed to get the trans up to operating temp rather than cooling the fluid but there is obviously heat exchange and that isn't always a good thing if the trans is worked hard and has a tendency to overheat.
I'm a big believer in removing those lines from the radiator, especially in a higher mileage vehicle, because if there's an issue the cost will hurt.

Trans cooling radiators don't block air flow very much. Big spotlights do..
I don't know GQs at all but 3.0 litre & 4.5 GUs have factory fitted trans coolers. I mounted a big Davies Craig cooler with my 4.5 and have kept it with my 4.2 turbo conversion.
I had the factory cooler plumbed in series with the Davies Craig but I've since removed it because the trans was running too cool.

A Nomad valve body is good but they're expensive and really aren't worth fitting on a high mileage trans.
A manual lock up for the TC is a very good idea if the trans heat is being generated by the trans continually slipping in and out of normal lockup. This happens a lot when towing.

You don't mention the history or mileage of your vehicle. If the trans is currently working well, you should drop the pan and inspect the magnet for debris. If ok, wash the strainer and flush the whole unit with synthetic fluid. The synthetic works better with higher temps.

Here's a pic of when I had the 2 coolers on my TB45

...

Thanks for the info JFF,
Regular service history indicating trans servicing traveled 290K, radiator replaced 12 months ago with OEM.
I'm not swapping my LF 240 blitz currently fitted to my Prado and change over to an LED light bar just for the airflow factor.
How does one know ya trans running too cool, do you run a trans temp gauge?
cheers.

[tuckertrucker]

Trans temp gauges are a must if youre putting the trans under any load so you can keep an eye on it. Before I fitted my gauge I used to feel the centre console heat up, not I know that it's at 105c when the console gets that warm.....
Ive got a 92 GQ Safari (NZ model) and after a costly trans rebuild a few years back I now have an external trans cooler mounted in front of the radiator. Temps are much lower now, and the engine temp hasn't been affected at all. I used to push 95c quite easily before the rebuild and cooler, now I'm lucky if I break 85c.

[jff45]

Yes, the trans temp gauge is a must. I had readings as low as 60C on the highway with TC locked. That's what I consider too low.
The factory trans temp light comes on at 140C and that's way too hot even for synthetic fluid.
Before I fitted the big cooler, I could get readings up around 100C. 80C is an ideal temp for a trans.

I haven't had a chance to try mine with the TD42T engine that I've just swapped in but I expect it to be slightly higher since I removed the TB45 cooler. I'll fit a thermo fan if I need to.

If you're handy with tools, another option is fitting a TransGo shift kit into the valve body. They cost around $140 on Ebay and would be a good option before flushing fluid to synthetic.
The Nomad valve body sells for around $1200 these days. Don't know how they justify the price..
I'm only running a Nomad valve body now because I got it very cheap from a damaged trans and had to overhaul it. I honestly don't feel a big difference between the Nomad and the TransGo shift kit.

[tuckertrucker]

I haven't had a chance to try mine with the TD42T engine that I've just swapped in but I expect it to be slightly higher since I removed the TB45 cooler. I'll fit a thermo fan if I need to.


Have you got a thread open somewhere where I can check out your truck and all the mods you've done????? So far as I've read around the forum YOUR truck must be a machine!!

[jff45]

I did the thread on Patrol 4x4. I have the same user name there. There are quite a few pics.
It's a standard TD42T engine with the original HT18 turbo. I added a modified intake manifold and an Ebay intercooler.

With apologies to the OP for the hijack, here's a pic..
...

[tuckertrucker]

With apologies to the OP for the hijack, here's a pic..
...
Yeah sorry 'bout that. I'll head over and have a look. Thanks

[grunta11]

Trans temp gauges are a must if youre putting the trans under any load so you can keep an eye on it. Before I fitted my gauge I used to feel the centre console heat up, not I know that it's at 105c when the console gets that warm.....
Ive got a 92 GQ Safari (NZ model) and after a costly trans rebuild a few years back I now have an external trans cooler mounted in front of the radiator. Temps are much lower now, and the engine temp hasn't been affected at all. I used to push 95c quite easily before the rebuild and cooler, now I'm lucky if I break 85c.

Hi Tucker trucker,
just so i understand you correct.... you used to push 95 before the rebuild and now your lucky to break 85.......was it your engine or your trans your refering to there?
either way thats bloody good news!........
appreciate you taking the time for input.

[grunta11]

Yes, the trans temp gauge is a must. I had readings as low as 60C on the highway with TC locked. That's what I consider too low.
The factory trans temp light comes on at 140C and that's way too hot even for synthetic fluid.
Before I fitted the big cooler, I could get readings up around 100C. 80C is an ideal temp for a trans.

I haven't had a chance to try mine with the TD42T engine that I've just swapped in but I expect it to be slightly higher since I removed the TB45 cooler. I'll fit a thermo fan if I need to.

If you're handy with tools, another option is fitting a TransGo shift kit into the valve body. They cost around $140 on Ebay and would be a good option before flushing fluid to synthetic.
The Nomad valve body sells for around $1200 these days. Don't know how they justify the price..
I'm only running a Nomad valve body now because I got it very cheap from a damaged trans and had to overhaul it. I honestly don't feel a big difference between the Nomad and the TransGo shift kit.

Hey JFF now thats the kind of real world info i was hoping for, great tip re transgo kit, gives me some direction to take with some confidence of it all being worthwhile. thanks!

PS; re highjack - not a problem! :-)

[jff45]

I think that with 290k kms the trans should be considered as being in the latter part of its life. Even fitting shift kits, etc can't make up for the inevitable larger tolerances the clutch packs would now have. That's just due to typical normal wear in its lifetime.
That doesn't mean that it won't last quite a bit longer if it's looked after with good fluid and temps and driven with the care that older transmissions require..

I would still drop the pan and inspect the magnet, wash out the strainer and flush it all with synthetic fluid. Castrol TransMax Z is one of the better fluids but a more cost effective (which I'm now using) is the Nulon Multi-vehicle synthetic. You can get it in 20 litre drums.

[tuckertrucker]

Hi Tucker trucker,
just so i understand you correct.... you used to push 95 before the rebuild and now your lucky to break 85.......was it your engine or your trans your refering to there?
either way thats bloody good news!........
appreciate you taking the time for input.

No worries mate, it was the trans. Shouldve been more clear lol. When really powering it and loading it (especially in OD) it would easily break the 100 mark. Highway temps and general use would push their way to about 95. But now I can load her up on the hills and I'm lucky if it breaks 85.
Cheers, Dylan.

[tuckertrucker]

I think that with 290k kms the trans should be considered as being in the latter part of its life. Even fitting shift kits, etc can't make up for the inevitable larger tolerances the clutch packs would now have. That's just due to typical normal wear in its lifetime.
That doesn't mean that it won't last quite a bit longer if it's looked after with good fluid and temps and driven with the care that older transmissions require..

I would still drop the pan and inspect the magnet, wash out the strainer and flush it all with synthetic fluid. Castrol TransMax Z is one of the better fluids but a more cost effective (which I'm now using) is the Nulon Multi-vehicle synthetic. You can get it in 20 litre drums.

Haha, when my trans spat the dummy I wasnt too educated in towing with autos - I'm amazed it took four years for it to happen now..... costly lesson to learn.

[grunta11]

No worries mate, it was the trans. Shouldve been more clear lol. When really powering it and loading it (especially in OD) it would easily break the 100 mark. Highway temps and general use would push their way to about 95. But now I can load her up on the hills and I'm lucky if it breaks 85.
Cheers, Dylan.

Hey TuckerT
What rpms does yours sit at 100 klicks cruise?
Mine with new 33`s at an indicated 100 is just under 2000 rpm. My diff is in possible need of a new crown wheel/pinion set and was thinking of maybe i should consider a ratio swap from 3.9 to 4.1 to keep her in the ideal cruise rev range - especially if I'm towing the camper trailer and a car load of gear.
Its not yet turbo`d - thats a near future mod.
i realise the front has to change too,.

[grunta11]

I think that with 290k kms the trans should be considered as being in the latter part of its life. Even fitting shift kits, etc can't make up for the inevitable larger tolerances the clutch packs would now have. That's just due to typical normal wear in its lifetime.
That doesn't mean that it won't last quite a bit longer if it's looked after with good fluid and temps and driven with the care that older transmissions require..

I would still drop the pan and inspect the magnet, wash out the strainer and flush it all with synthetic fluid. Castrol TransMax Z is one of the better fluids but a more cost effective (which I'm now using) is the Nulon Multi-vehicle synthetic. You can get it in 20 litre drums.

Thats pretty sound advice jff, cheers.