I recently bought a new trailer and have some requests and thoughts. First, my truck has a 460 w/5spd, aftermarket ignition, I think its a dui but not sure and a KN stock replacement filter (previous owner installed). I put a 3 in catback flowmaster exhaust kit on last year. The tires are 265/16 toyo open country's.

My first question is; is there anything I can do to improve my mileage aftermarketwise to the engine other than a cold air kit (in the plans)? I get about 6 mpg in fourth at 60-65 mph and taching around 2600-3000k towing. I used to have 2400lbs 12 ft slide-in camper and was able to run in 5th all day long and get between 8 to 10 mpg with no heat buildup in the tranny, but I found out this is not possible wth a 5500 lbs trailer. Common sense departed me on my first trip and I came very close to seizing up my tranny. I know, I know, NO TOWING IN O/D!! I assumed that only applied to automatics. I owe a large debt of gratitude to a tranny shop in Camden NJ, but I will post more on that in another thread.

This leads me to my second question. In light of my recent dumba**
experience, I am considering fabbing a oil cooler for the gearbox large enough to tow in fifth. Has anyone tried this? I have been a mechanic for about 18 years so putting it together does not faze me, but is it worth it and does anyone think it will work? I don't have much towing experience so I have nothing to base my assumptions on. My last assumption almost cost me bigtime!

Thanks to anyone who can help me.

I is a so sorry if this too long...

 

One thing, do you have a bed cover? When towing my 28 foot enclosed car hauler, I have found my mileage drops about 25% and you really feel the trailer when the bed cover is in place. Take the cover off, the trailer feels lighter and the mileage goes back up. I think the cover, while it helps aerodynamics a little when not towing, screws up the aerodynamics when towing.

As for the 460, well...they are not known for sipping fuel. A cam swap to move your max torque to the range you tow in (2000-4000) would help.

 

there most likley is nothing you can do to improve the towing. tires are the only thing I can suggest. Getting to more of a highway tire, make sure it is E-rated LT type tires and that may help.

But expensive.

 

nope, no bedcover my camper is 28 ft as well and mama still needs the bed for,as the famous sage George Carlin once said, "MORE STUFF!" I didnt consider a cam but that is a good Idea. We are not adverse to looong trips so even a 1-2 mpg improvement is good on the pocket.
And thanks for your service, I am a former Marine and new Guardsman.

 

yep,my tires are E rated LT's. When I bought it, the previous owner had 285/16 D's on it and they were junk. So I swapped em for the toyos, i am very happy with their performance. We went through Philly in a bad storm
towing the camper with lots of traffic (very high pucker factor for a newbie camper tower!) and they never gave me any surpises or scares. Any thoughts on the oil cooler ? Our old 815s had something like it and I don't remember any problems with overheating.

 

Gear swap would be desireable considering what is in there right now.

 

What gears are you running now? What is your rpm range when running down the highway? 460's dont like to tow at under 1500-1600 rpm's and do best between 1500 and 2500 rpm. Cam timing can affect mpg's as well as aerodynamics. The more ignition timing advance you can run without detonation the better it'll run. You should be able to drive down the road in o/d the same as with an automatic. You might want to install a trans temp gauge and keep it below 210. Several friends of mine towed enclosed car haulers that weighed in the 7000 lb range with 460's with no problems. They all towed in o/d, but they never bogged the engine nor overheated the engine or transmission. All seemed to get in the 9-10 mpg range.

 

Never heard of overheating a manual transmission...do you have a temp gauge?

 

I've overheated manual trannies before, just not on the highway. It was on the track.

 

I think a temp gauge is your best bet for now. Keep an eye on it for a couple trips and see if the trans is overheating. If it is you may want to try some synthetic oil in engine and trans. Other than that I'm not too sure how you can cut fuel consumption with a 460.

 

sorry to take so long to reply, Uncle Sam called. I have never had any problem with a stick overheating, so this threw me for a loop as well. I'm not sure what the ratio is, but I know it's stock, as is the 5 speed. The overheating may have been caused by my lack of experience towing and the goofy hills between Hartford CT and the NY state border. THEY SUCK! After them we never really allowed the tranny to cool off. I also went back and refigured the mpg figures and got around 7-8 mpg in 4th. I am going to install a temp gauge and switch to synthetic tranny fluid and engine oils very soon. the next long trip, I am going to try some things and see if I can narrow down the cause of my problem. I am also going to try the timing advance. I will post my results, It might be helpful to someone?

 

if you were to install a water injection kit you could prob handle more timing especially when loaded. the cooler cylinder temp resists detonation. as long as you don't get silly and use way too much theres no harm and it helps keep the combustion chamber clean(which also lets you use more timing) and reduces valve depoisits. most manuals now use oil coolers, i think even my 03 disel with 6 speed manual had one, so a cooler seems like a good idea ifworking hard in hot weather.even if you can pull a hill by flooring it, its easier on the tranny to drop a gear and generates less heat

 

I will look into water injection. I have no experience with it. I was downshifting on the hills, but maybe not soon enough, this is what confuses me, when I took my slide-in to Nova Scotia a few years ago and there were plenty of long hills and the tranny never showed any sign of getting warm. I know that carrying is different than towing but there was still a heavy load on the truck and I never had any problem. I am not trying to get better mileage towing, I am just trying to not get hammered on my mpg. I am glad I asked because nowI have plenty of different options to look at.

 

The newer 6 speeds do have coolers so maybe there is something to the heat problem.

 

does your tranny make any humming or howling in different gears since you got it hot. gear oil actually lubricates quite well in some tests even when its smoking. thing is for it to get that hot i'm wondering if some bearing is maybe starting to let go. in 4th which is direct drive the input is connected straight to the output of the tranny, in overdrive power transmission is input to countershaft to output, when towing there is considerable more torque try to push the 2 shafts apart. in other words much higher load on the bearings and gears which = more heat. even if you can control the heat the old trannies were not really designed with heavy enough gears and bearings to stand up to sustained heavy towing in OD, for that reason i would try to stay out of OD unless on flat ground