Auto temps

[mrkrss]

Hi
Just a question for those who have fitted manual radiators and an additional trans cooler to their auto surfs. What temperature does the trans fluid best do its job at? I just had a temperature gauge fitted to the trans pan during a transmission service (as recommended by the trans shop), and asked the guy if it would run too cold as my surf has a manual radiator in it and only has an additional trans cooler. He said any time they fit an additional cooler to a vehicle, they always disconnect the factory radiator cooler pipes, and connect them straight to the additional cooler. He suggested the trans would come up to temp long before the engine coolant warmed the trans fluid up. (if I had the auto radiator fitted). However, on my setup, the gauge barely goes over 50 degrees celcius, and it takes a reasonable time and distance for it to get there...(maybe 10-15mins, 10-15km). I live in NZ, so we don't have the extreme temperature variations like some countries, I guess we'd get down to -5 degrees and up to maybe around 35 degrees. The trans changes gear smoothly and doesn't "hold" onto gears as someone suggested it may if the trans fluid had too high a viscosity. I haven't tried towing yet to see how much hotter the fluid temp gets, I imagine it will though. But is the fluid capable of doing what it needs to when its reasonably cool? Has anyone had any problems with their transmissions when running this setup, or am I over analysing the situation. Many thank-yous in advance.

[europa88]

Hi mate

At 50 degrees thats pretty much as cool as you would want it but ok, Toyota reckon on 80 degrees or there abouts as optimum temps for transmission fluid. It can, and will if you tow, get a lot higher I have seen 115 degrees on a long incline towing on a hot day. I have a similar setup to you but have an oilstat in the line which switches the trans fluid through the additional tranny cooler at 80 degrees which gives me quick warm up and good cooling.I have never had the built in transmission temp warning light come on and I believe this comes on about 120 to 125 degrees centigrade.

Cheers

[mrkrss]

Oil Temp

Ok, yeh I did read a post where someone had mentioned the radiator cooler was good for getting the trans up to operating temp, and was also good at stabilising the temperature too, rather than have it move up and down alot with slow/fast driving. When I talked to the trans shop guys, they said if you fit 2 trans coolers, they should be fitted in parallel, so the oil can take the path of least resistance, rather than in series where there is a risk of creating a back pressure, reducing oil circulation. By fitting a thermostat in the oil line to the cooler, does that create any problems pressure wise in the transmission. Oil that comes out to be routed to the cooler would obviously stop until the stat opens to let it flow. Does that affect the trans at all? I just assumed the transmission relied on oil flow out one pipe and back in the other during operation. Although thinking about it, I guess the water coolant system operates the same way doesn't it. Thanks for the replys.

[europa88]

No problems at all!

In fact the stat (Mocal) recirculates the fluid by offering a path of least resistance untill 80 degrees C is reached. then opens up (gradually) to flow to the trans cooler.

[mrkrss]

Overheats

Bugger.
Here I was thinking I had my problems all fixed. I bought and fitted a fan to my auxiliary trans cooler, and had the wife try it out towing 2 horses, which I guess combined with an 800kg float, ends up being close to 1800kg. Towed fine, with the trans temp reaching around 65 degrees. So off we went up north to pick up 30 bales of hay for the winter, and admittedly, there were some pretty knarly hills to drag the trailer of hay over, I'm guessing maybe 900-1000kg all up, and sure enough, the cooler and fan couldn't cope. Fortunately the temp gauge I had fitted, warned me that the trans was heating up, so 5-10mins at the saddle of the hill soon had the temp back down again. But the scary part, was the sudden flick of the engine temp gauge halfway up the next reasonably large hill. Normally it sits just under half. Suddenly it was just over half. So an immediate stop, and shut off of the engine. And it smelt quite warm. Another 10-15 min sit at the side of the road, and off we went again with no further problems. I'm concerned because I have a manual radiator fitted in my truck. I can only assume I need to give the cooling system a flush and maybe look into replacing some of the hoses that are showing signs of deteriorating. Otherwise i hate to say it, but maybe a Nissan Safari might be a better wagon for towing??? Its a real shame as the surf definitely feels nice to drive whilst towing. Very stable and has plenty of grunt.

[stormforce]

I pulled a trailer with a surf on it which a total weight of 3t.I met up with Vince(bushwhacker) and drove to his place in Wales.The hill to his place on top of what they call a mountain was about 2m long i think it was or there abouts and i just about got to the top when i had to stop as the temp was in the red and atf warning light on.I let it cool down for a bit and then carried on with no probs since.

[MattF]

So an immediate stop, and shut off of the engine. And it smelt quite warm. Another 10-15 min sit at the side of the road, and off we went again with no further problems.

One shouldn't turn the engine off. Just pull over, park and pop it in neutral. You need coolant flowing around the engine to cool it down.

[europa88]

When it's sorted, the Surf is a competent tow machine.
Sure you can get it hot if you abuse It (not that im suggesting any one did). I take long inclines slowly and at no more than 2500- 2700 rpm. Since intercooling it and transmission mods ie. Not running transmission fluid through the rad, together with a new rad from Roughtrax. I can now take some hills with the aircon on!
My transmission temps still get to 115 degrees but soon come down. An aftermarket gauge shows my coolant temps at top hose to just nudge 100 degrees at peak. I think a large (Huge) tranny cooler is the best way to go and check the coolant route is in tip top condition.

[MattF]

No problems at all!

In fact the stat (Mocal) recirculates the fluid by offering a path of least resistance untill 80 degrees C is reached. then opens up (gradually) to flow to the trans cooler.

Just noticed this post. At last, someone has done it the correct way. Nice one.

[europa88]

Just lucky I guess Matt!

Cheers

[wishbone]

Can I ask for more details about the mocal setup ? I have an extra trans cooler to fit before my trip to spain so could maybe incorperate this into the install..

Thanks,
Rob

[europa88]

Hopefully these attached diagrams will help. The waxstat I used has push on connections, to be used with hose clips. I bought mine from Demon Tweeks, but they are widely available.

[MattF]

Just lucky I guess Matt!

I'd forgotten you'd done it, to be honest. Then I remembered when you were originally asking about the mod, yonks ago, over in the modifications forum. Glad to hear it's still performing like a good 'un.

[wishbone]

Hopefully these attached diagrams will help. The waxstat I used has push on connections, to be used with hose clips. I bought mine from Demon Tweeks, but they are widely available.

Thanks for the info They look pretty easy to put in with the cooler. I think I'll be getting one soon.

Rob