Something getting hot

[big-yin]

I need a little help on something that’s bugging me on my 99 4.7 auto. If I use 2nd gear (or D) at 40mph going up a nearby mountain for maybe 3-4minutes steady part throttle I can smell oil like something overheating. Can drives fine on full throttle, nice and smooth not clunking which I had on previous 4.2 so thinking more torque converter maybe?

Any thoughts very much appreciated.

 

[Dave_S]

Sounds like transmission belt slipping - had that on an automatic XJ a few years back - first sigh was a burning smell under heavy load...

 

[big-yin]

Thanks for comment - is that something that needs a gearbox specialist or a normal garage can do ?
It’s fine for long journeys btw only on this particular route does it show itself.

 

[Michael80]

Hi,

It sounds like the gearbox oil is getting warm as may be the torque converter hasn't locked up yet.
You wont get torque converter lock up in second so this will make the oil get hot.
it may be worth checking the oil level and colour, could also change it if you haven't for a while.

 

[big-yin]

Thanks, it does do it if I’m in drive too so maybe the gearbox oil just needs replacing. That will be easiest and something on my list of things to do anyway. Thanks.

 

[karl2000]

You've selected drive but I wonder what gear it's actually in when its chugging up the mountain? Probably not high enough to get lockup.....

 

[Dave_S]

I had an auto gearbox guy look at mine - only needed adjustment apparently (I'm not sure what exactly they did TBH!).

 

[uHu]

1
A synthetic ATF will handle high temperature better than a mineral one, and much better than an old ATF.
2
Check level, at normal operating temp, with engine idling.
3
If the oil (atf) cooling is configured as standard, with atf going through the bottom of the main radiator, and a separate oil cooler at the front, it should be able to handle 3-4 minutes at high power without LU, but not high power for a long time (w/o LU). Some cars are modified, by rerouting the atf cooler lines to circumvent the main radiator, in order to avoid catastrophic atm failure in case of radiator failure (water in atf). This mod will reduce the max cooling capacity, and prolong the atm heating up period at cold starts.

 

[big-yin]

Thanks for comments, i've booked it in to local garage to have transmission fluids replaced. I've had since end october so don't know when it was done last. Will test again after and take it from there.

 

[Dave_S]

Just recalled... on the XJ we also later fitted an aftermarket ATF cooler (as we were doing heavy off roading, oversize tyres, etc) - never had a problem after this.