Auto box okay at 60mph but getting hot at 70mph

[Lorin]

231758397507 ebay number. Had a quick look no doubt you can find them cheaper somewhere though my wifi is pretty crap out here. I belive you can get 2 types. Ones that record the highest temp and ones that change with the temperature so can be reused. Hope that makes sence

Great idea, thanks for that. That may well be a good way to get some max temps across various parts of the transmission. Cheers.

Check the viscous fan for rub marks , i had this problem though i had to go a little bit faster than 70 to distort the fan cowl allowing it to rub .

It's only my auto box that is getting hot Shayne. The general cooling system is operating as it should, including the ATF cooler in the bottom of the radiator.

 

[Shayne]

Yes i just thought it was something simple to check it took me ages to work out what was going on and i still can't believe such a light touch of plastic on plastic increased the load on the engine/gearbox enough to cause overheating .

 

[Jon Wildsmith]

Maybe worth checking the torque converter temperature through the access hole in the bottom of the bell housing and if it's high what's the engine block / head temperature like at the back to rule in/out heat soak from that.

 

[Lorin]

Maybe worth checking the torque converter temperature through the access hole in the bottom of the bell housing and if it's high what's the engine block / head temperature like at the back to rule in/out heat soak from that.

Cheers Jon I'll do that

 

[Dave2000]

Apologies if this has been said, and assume my cooling system/rad/pipes and so forth is all ok.

I run just an electric engine cooling fan. My car in stock form the fan stays off until around 65 -70 MPH, @circa 40 degrees C if I try and hold 80 MPH for around 10 -15 minutes though the fans first speed comes on for awhile then goes off then repeats, as long as I stay at 80, go back to the 65-70 and it never comes on unless climbing a long steady hill. Even when it is 30C outside the temps still rise when you start to push a little harder, I do have a modified temperature gauge that actually moves with engine temperature, not the stock offering that sits neatly in the middle of the scale until your near overheating. I can watch the gauge rise if I push a little harder, the fan switches though are a known temp so this is not speculation it is fact.

So remembering that the power to push vehicles goes up by a factor of IIRC 8 then this proves that the stock cooling system needs a little help at higher speeds, even the stock viscous will come in at speeds circa 70 - 80, it seems the 80's shape puts quite a bit of load on the cooling system at higher speeds. So on mine I blocked all the air gaps between the bumper and radiator, in effect preventing any air hitting the front of the car escaping from bumper to rad face for example, this actually stopped the fan coming on until holding at least 90 for n extended time. So check around the radiator for the sponge that fits between the rad and car body, it normally rots away, also the plate between the chassis rails (protects the fan belts from intrusion underneath) seems to have an effect if it is not there. The reason for that I am not sure, but it affected mine but again only at the higher speed.

So, you could have a weak viscous, and/or the blocking sponge is missing?

Next, have you had the exhaust route relocated, I have seen some lift the exhaust up nearer the transmission fro ground clearance, the result is more radiated heat nearer the gearbox.

I am no expert on auto trans and Jon has made a good point but, the cooler receives fluid at idle from the front pump right and during all times the pump is operating? I do not recall seeing a valve or anything in there that would interrupt the cooler flow when the converter locks up, absolutely open to this being challenged as it is a long while since I pulled one apart.

Those are just a couple of thoughts Lorin.

regards

Dave