View Full Version : Auto Transmission runs very hot

27-04-2010, 03:53 PM
When my EL engine is cold the auto gear shifts are fine for a while. Once it gets to normal temperature after about 20 min it starts thudding up to second and slipping a little into third.

Engine temp guage reads normal but when the transmission fluid out pipe is wrapped in foil with an oven thermometor it reads 155 celcius. Is that way too hot?

I have a big aftermarket cooler fitted but that doesn't help.

I had fluid done a year ago but they didn't change filter. Can tranny filter clog and cause overheating? I hear old fluid loses it's cooling properties over time too.
Plan to change filter and fluid this weekend.
Will check fluid pump is working while I am at it.
Any other ideas?

27-04-2010, 10:31 PM
Fluid done? Was it a service where they change the tray but didnt change the filter?

You probably need a full flush, thats a 10-11 litre job

28-04-2010, 09:23 AM
"Fluid done" meaning they don't remove the tray at all but only drain the old fluid and top up with new (probably leaving a whole lot of old fluid in the torque convertor).

29-04-2010, 06:12 AM
yeah am having same with my EB.
console seems hotter then normal and metal on shift almost too hot to touch.
took off return pipe from cooler to transmission,it doesn't go thru the radiator.
oil seem to be flowing ok maybe pump is getting old.i know the box is.
changed oil/filter 18 months/about 10,000 so oil is a red colour.i've learnt now when they do a service they changed all the oil and not just the 3.8 l like the manual says.

29-04-2010, 09:24 PM
your problem is that the bands need to be either renewed or adjusted which is causing the slipping also when an automatic transmisson changes to often it heats up faster

01-05-2010, 10:33 PM
Is the torque converter locking up? Solenoids sometimes stick, and with no lockup you would be getting a lot of slippage, generating heat and causing trans failure.

A talk with a reputable auto trans place might be beneficial.

02-05-2010, 02:56 AM
I have had erratic S7 solenoid operation, caused by an intermittent failure in the internal wiring loom, and to be honest, the only noticeable symptom was higher engine speed. When the box locks up, at around 70 kph in top under light throttle application, the engine drops around 250 rpm. This follows as you accelerate, and the failure to lock up was only noticed because at 100 kph the rev counter was reading just over 2000 rpm. Limp / self protect mode did not occur in this condition. I would tend to agree with Heathmurray and have the bands adjusted correctly, particularly if the ATF is discoloured - dirty brown to black - and smells mildly burnt or worse. Do agree with talking with a specialist if your woes persist, as my next thought would be a possible problem in the clutches as the friction linings are the major sources of heat in the box.

03-05-2010, 10:14 AM
Thanks for everyones contributions.

I was all set up to do a service myself but couldn't get past step 1, taking the tranny fill nut off @#$%!!@#. Totally stripped the nut so will buy a pipe wrench to try otherwise will have to get mechanic to blow torch it or weld a socket to it or something.

An auto tranny specialist say the 1st to 2nd thud is usually caused by a dodgy solenoid. He reckons the 155 c running temp is not unusual.

The concept of "lockup" in new to me but it makes sense because the tranny specialist mentioned that sometimes top gear is not achieved (which I take as laymens terms for "lockup"). see http://www.kichline.com/chuck/fiero/TCC.htm

The tranny fluid is dark brown and smells burnt so it is definitely running hot.

Is the S7 solenoid easy to replace or does the whole tranny need to come out?

03-05-2010, 04:44 PM
from memory #5 solenoid shift first to second hard/rough second to third long . cost around the 200 mark ..
get to it by removing pan, losening solenoid before lowering value body leaving front row of bolts.bolt lenghts may differ'
value body needs to be lower only to replace solenoid .

i put a bottle or 2 of LUCAS STOP SLIP[ thick stuff ] in as well for an older worn box.

03-05-2010, 05:40 PM
The S7 solenoid which activates torque convertor lockup is the only solenoid not in the valve body. It is situated in the body of the pump - big job to replace. Lockup means that the box is no longer in a state of 'fluid drive' but is now an electrically activated no slippage solid drive unit - it saves fuel and is more efficient.

04-05-2010, 09:15 AM
The S7 solenoid which activates torque convertor lockup is the only solenoid not in the valve body. It is situated in the body of the pump - big job to replace. Lockup means that the box is no longer in a state of 'fluid drive' but is now an electrically activated no slippage solid drive unit - it saves fuel and is more efficient.

Did a test drive to check my lockup last night by counting the gear changes from a standing start under constant acceleration. My tranny does in fact kick into the fabled 4th gear which I understand is actually the lockup engaged by the S7 solenoid. That's a relief. Won't need the whole lot pulled apart to replace it.

The mechanic is attacking my stripped tranny lug nut today. They just phoned to say the s5 solenoid is dead and have quoted $745 for replacement solenoid, filter and flush . Plan to do it myself later this week. Got some solenoids out of a wreck so I will probably replace s1 to s6 while I am at it (I will check each solenoid part number to make sure the replacements are correct). Hope this eliminates the problem otherwise a major overhall is in order.

04-05-2010, 10:50 AM
4th gear is just that - 4th gear. Lock up is is a state that occurs in 4th gear. They are not the same thing.

04-05-2010, 12:03 PM
Yeah you have 4 gears and then lock up, a further drop of about 500rpm when on gentle throttle and cruising speed

10-05-2010, 02:04 PM
Doh! :thinking:Thanks for the heads up on it being a four speed box. Tested the gear changes again from a standing start a few times and found the lockup (5th gear) does engage. Hooray! No need to pull the whole tranny out.

Serviced the tranny myself over the weekend and put in a replacement S5 solenoid from the wreck of a 2000 model falcon which is interchageable with my 1998 model ($80 secondhand rather than $200+ for a new one. Of course there is always the risk it too is faulty or may fail soon). Put 14 litres of new fluid through to flush out the old crap from the torque converter via the connections to my aftermarket cooler. No significant metal particle build up in the sump.

I can see now why it's much easier to pay for a mechanic but I'm glad I did it for the experience and the savings (cost $300 in materials all up rather than $745 by mechanic for parts and labour)

Running temperature on the tranny fluid out pipe is now 125c rather than 155c and the gear changes are smooth and silky. No more clunk from 1st to second and no more slip from 2nd to 3rd. Taking a road trip this weekend to see how the temp and gear changes are after a long haul.

Thanks all for your advise everyone. I found this forum to be a great source of info and support.

17-05-2010, 11:31 AM
After 3 hour road trip my tranny is running perfectly. No thud from first to second and no slip from second to third. The temp of the tranny fluid out pipe is 150 celcius which is still a bit of a concern because I read the fluid starts to burn at 120 celcius.
http://www.exploroz.com/Forum/Topic/50251/Automatic_Transmission_Fluid_Temperature_Gauge.asp x
Might try a synthetic fluid next time which has higher burn temp.
Anyway replacing the s5 solenoid and changing fluid and filter has fixed my main gear shifting problems.