I just bought a 1998 34-5Y Wilderness, 36' footer, triple slide fiver. It weights 10,500 LBS dry so it should be around 12,000 loaded. I used to have a 2002 bumper pull Wildcat 30BHSS that weighted 7600 LBS dry so about 9000 LBS loaded. So the difference is about 3000 LBS. Pulling with the old bumper pull, I would hit 1200 degrees easy going up some hills and then it would down shift into fourth and the EGT would lower a bit. Pulled the fiver this weekend to go camping and I would barely hit mid 800's. On the hills that it would down shift, the temps were about 850 and it would downshift. I do not understand this at all. The fiver pulls 10X better than the bumber pull. Fiver's are suppost to pull better than bumper pull's do, but this does not explain the difference in EGT to me.

I have gone this same route camping over a hundred times. I have been fishing this lake since 1993. I take the same route everytime so I familar with certain hills. There is one hill that I always take at 55 MPH and it is one that always makes the EGT rise fast with the old bumper pull. This same hill I only hit about 870 or so.

I have thought that maybe my J/A probe may be bad. I just remembered that a have a brand new never used probe at home. I will replace it before the next trip to see if the old probe is bad.

From what I understand (and someone can help me with this) the reason why a 5er pulls easier is because of where the towed load is placed. Because the weight is on the rear axle rather than behind it, it makes the trailer tow easier, ie the truck has less work to do. Even though the trailer is heavier the work is easier due to the load being in a better place (this making any sense?) That would be why the EGT's would be lower.

Another thing, I don't know how tall your TT was but the fact that the 5er is closer to the roofline of the truck, the airflow is better. The air doesn't hit a dead spot over the bed then have to try and break over the TT iself. If you look at the profile of the truck and 5er hitched up you can see how this would be.

I have heard a lot of people say that towing their 5er was a lot different and easier than ever towing a TT. I know that my dad's 9000lbs TT tows like crap so I am looking forward to towing a 5er here soon (hopefully buying my own) It is 9.5 feet tall and sits so high up that the air hits it like a brick. I normally run about 950 EGT when I tow this trailer and I hit 1300 once when I passed up a Ford while going uphill at about 80 mph. So your EGTs actually sound about right. I bet you got better mileage this last trip as well? That is how I am guessing that the others towing 5ers get the mileage they do when they tow heavier trailers than I am.
My 2 cents

the axle conditiions may contribute as well, if the TT had poor or even had a bad bushing or 2, it would add alot of parasite drag. and the new 5er would have none. Combined with other theories, this could easily add several hundred to the EGT.

I see now the 5er is older, but stranger things have happened

Thanks for your input guys. I will also check to make sure the probe has not worked it way out. Another guy mentioned that his probe worked it ways out and the EGT temps started to show less degrees. When I went with the J/A, I took out my analog guages go I could put my tweeters in the A-pillar. I wish I had just moved the analog guages to a different spot.

It was the probe. It backed out of the manifold.