RPM's when towing???

Hi guys and gals.

Can I ask please , does anyone else have the same sort of experience when towing a TT, except I've never towed with an EXpy before so here goes.

I have a 98 EB 5.4 with about 70K miles on it, bought it last year for towing. It has the H6 axle so I believe thats the 3.73 lsd. The trailer is a Trail Lite 19', at @4000lbs loaded up.

I tow at about 55 to 60 mph and the engine is pulling about 2400rpm in 3rd, OD is off. Is this sort of rpm normal for that speed and trailer weight. I dont want to go faster anyway, cant afford the gas!

ANy comments welcomed.

Thanks.

 

Yes. Sounds like she's right in the sweet spot at that RPM, too.

 

So having the motor running at that rpm for a few hours wont do it any harm?
Its so different from not being loaded up.
I keep an eye on the oil pressure and temp gauges and they dont seem to change either from when its not towing.
So no worries then.
Thanks for the reply.

 

well pay little attention to those gauges as they are fake it is just a fancy idiot light if the engine is between190 to 220 it will read normal than after 220 it reads redline then the oil will read right in the middle unless the pressure drops below 10 psi keep in mind the modular engines like to rev out and with the load you pull you can turn the o/d on unless it hunts for gears then turn it back off

 

Your engine would not have any problem running 3500 RPM all day long. Steady state is very easy on an engine. The hardest part is start and warmup. Alot of people are skidish of towing in 4th gear, do yourself a favor and install a Tranny Temp gauge and then do as you please. Just don't let the trans hunt and what ever you do try to keep the time the converter is not locked up to a minimum. If it is not locked up let off the gas a little and it will lock then add some more gas. Takes a little practice but will pay off in the life of the trans.

Dave

 

Thanks fellas, though I must ask Dave, how do you know or feel when the converter is locked up.? I never heard of this , I just assumed the converter remained somewhat viscous, not acting like a standard clutch at any time.

 

That's what the O/D button does... it engages/disengages the TCC (Torque Converter Clutch). It locks the flexplate to the input of your tranny. If you are in the right RPM range/load it should be fine to leave it on. If you are low in the RPMs while towing, the TCC will be continuously going on and off.

 

OK
thanks for that info, probably the only time I`ve left the OD on is when going downhill, coasting relyy.

Thanks.

 

As far as telling when the converter is locked you will be able to note that from RPM. Under normal driving what when the trans shifts into 4th under a slight load after another second or two it will drop another 2-4 hundred RPM as the torque converter locks up. One way to play with this is after a shift if you goose the gas and RPM jumps a little the converter is not locked if slight taps of the gas only yield a little intake noise then it is locked. There is a solonoid and valve that enages a servo to basically lock the converter to the input shaft some vehicles do it in the converter and others due it by means of 2 input shafts one inside another. A very common problem for the 4r100 and predecesor E4od is an error code for converter clutch slipage. As far as towing is concerned turning off OD only stops it from shifting into 4th gear. It used to be vehicles only locked the converter in overdrive but not the case anymore. All the precautions and warnings about trans damage and towing are related to heat. When the Torque converter is acting like a fluid coupling and trading RPM for torque it is is creating a tremendous amount of heat. Some will mention 4th gear as not being as strong in design as the first 3 but the trans will have down shifted way before that threashold. Hope some of this helps.