I know this is related to a van but I figured since the Dodge van and Dodge truck have almost identical drivetrains, you guys might be able to help, and I dont think the van guys understand what im asking.

I have a 98 1500 with a 5.9l and it has a lot of trouble maintaining speed while in overdrive when pulling my trailer. The slightest hill or even gust of wind makes the van downshift to 3rd, so I find myself driving in 3rd almost all the time and getting about 5mpg. Ive had a couple ideas on how to fix this problem, one of which was to throw a supercharger on and the other was to swap out the differential with one that had a higher ratio, like maybe a 4.10. I figured that a new diff would be a lot cheaper. Is this a good idea? Does anyone know what the ratio of a stock diff in a 1500 is? and does anyone have any other ideas?

 

That is just how these trucks or vans in your case are. Stock gears in most are 3.55's. 4.10'3 would be great for towing the supercharger would add more more power but then you'd burn the tranny up trying to pull loads with a high gear and lots of power.

 

To put it bluntly, the problem is that you're trying to tow in OD. This builds a lot of heat and is bad for the trans.

 

yep, never use overdrive when you are towing. Heck, I hardly use OD ever!

 

...... plenum gasket,, and check the cat

 

So this is a conversion van? How much taller than stock is it? How large is your trailer? How much does it weigh?

Like everyone else has said... Never tow in O.D. Its bad news. That said, your 5.9l only had 245hp stock and that was when it was new and in its prime. If its not 100% you can't expect to be at that number. You can only expect so much from it...

 

Ya, I dont think im gonna put supercharger on it. This is my first mopar vehicle and to be honest, im really not a fan of the tranny. everything else has either met or exceeded my expectations. The odd thing is that I used to tow this exact same trailer with the exact same equipment, with my 2000 4runner (3.4L V6) and it never had this problem.

? The cat is fine. How would replacing the plenum gasket help?

My van actually does just fine in overdrive on a completely flat surface and has never had a problem with overheating. The reason this is such a problem is because this is my bands tour van and when we're on tour we really cant afford the bad MPG's.
My van only has 80k miles on it.
With the pop top, my van stands at about 7.5 feet tall. so about a foot taller.
My trailer is an 8' x 6' x 6' and fully loaded i would guess that it weighs about 2-3k lbs.

I wish I would have bought a diesel

 

Trust me, your MPGs arent that great anyway. Towing even the small pop up you are not getting great MPGs, so taking it out of overdrive wont hurt you that bad.
Then just take it out of overdrive on the hills. NEVER go down a hill in overdrive while towing the trailer!!!