[Misaeus]

after a hour or so in the highway or under heavy traffic for long time, my engine overheats.

when it occurs, the 1st to 2nd shift is intermitent but if i rev it up the 2nd engages, but i cant shift into 3rd.

if i stop and wait for some 30 minutes the problem disappears.

if i drive for short time or in light traffic the trans operates correctly.

i know i have to fix the engine overheat, but the trans problem is related. i think the trans overheats also...



68 Road Runner, built 440, built manual valve body 727 forward pattern, 2800 converter, 3.55 gears.


i read somewhere that when the 727 are under heat, the steel trans pan flexes and obstruct the filter/sump and the trans not work properly.

any opinios on this?

an aluminum pan can solve this situation if its true...

i have an engine oil/trans fluid cooler combo. it measures 13.5 x 12.5 in the finned area, but the trans portion is the smallest with 13.5 x 5.
i 'm thinking in use it in line with the trans cooler of the radiator.
is it ok or i need a bigger trans cooler?

can i connect the two lines of the combo cooler to make it work as a single bigger trans cooler?
the inlets/outlets are different in diameter but i dont know if the inner tubes are also different. from the outside they look the same...


if i buy a bigger trans cooler and i use the current cooler for the engine oil, can i use the remaining small line for another accessory like power steering or even the fuel line?

thanks in advance

[dave-r]

There are many things that can cause this. But as it only happens when too hot I suspect it is low fluid pressure causing it. Maybe problems with the pump when the engine is hot?

It the valve body bolts are loose that would have the same effect.

I would fit a deeper trans pan and run the fluid through the radiator cooler as well as the extra cooler. the cooler the trans the better it will work and the longer it will last.

You HAVE to sort out your engine temp problem first though. You need a bigger or more efficient radiator. One of those big aluminium jobs work well but paint it matt black with correct radiator paint as this improves the cooling a lot.
Also use a stock type fan as well if you can. One of the clutch type. For AC cars too as they were bigger fans. And fit a fan shroud.