Hello, I'm new to FTE. I have a 1990 F150 4x4, 5.9L, EOD trans, 3.55 gears. I'm pulling a camp trailer that ways about 5200 lbs loaded. When I am pulling the trailer down the freeway, the truck runs cooler out of O/D but runs at about 2600 rpm. When I do run with the O/D on, it runs at 1800-2000 rpm but hotter. Is it ok to run at the higher rpm without any adverse affects on the engine and or drive train?
Any thoughts would be great. Thanks

 

Could define "hotter"? If you are referring to the factory temperature gauge then consider it as an indicator the engine is running and putting out heat, beyond that it is well known to be very inaccurate.

 

hope you will forgive a very minor hi-jacking of this thread ...

rla ... will an aftermarket gauge cure the problem you are talking about, or is there a problem with the sending unit as well ? also, what years suffer from the "wonky gauge syndrome" ? i have an '89 and a '94.

 

An aftermarket temperature gauge is the only sure way to know the true engine coolant temperature. I am most familiar with the OBS trucks (1992 - 1996ish), I know firsthand how bad the factory gauges can be. Other folks on this forum can chime in for the earlier models.

 

My apologies. I do realize that the factory gauge can be just a relative "temp". I have replaced both sending units, but I do plan on installing an auxiliary water temp gauge and a trans temp gauge. I guess the main question at this point is if it is ok for the engine to operate for long periods of time running at 2800 rpm's? also another point to address is the fact that when I put it into O/D, it is right at the verge of wanting to down shift but not quite. Plus it "pings" just a tiny bit if it starts to lug down. That's why I leave it out of O/D.
Thanks.

 

I would investigate why the truck is pinging under load. What is the base timing? Could you please verify what engine and transmission you have? (there is no 5.9L or EOD transmission in a Ford). What size tires are you running?

Is there harm in running ~2600 RPM...no, other than it will use more fuel.

 

The E4OD trans is well known for generating a lot of heat and that often does lead to trans failure, so if you are seeing a significant increase in operating temp while towing I'd suggest you install an aux trans oil cooler and temp gauge ASAP and keep the trans out of OD all the time except easy cruising on level ground or downhill.

 

Thanks, Apparently the trans is an E4OD (like the other gentleman said) I am not sure how the timing is set. My first thought was low quality fuel. I probably will continue to not use O/D. My tires are 31x10.5 (slightly larger than stock)

 

Yep, I found out that they can generate heat(the hard way) It has been fixed and yes, an Aux trans cooler and gauges are soon to come real soon.
Thanks for the info.

 

your right it's a 5.8L, Sorry.

 

NEVER tow in overdrive! The only bad thing about the engine running higher rpm is burning more fuel. Your trans will thank you in the long run