betsycam

Ok, first of all, be kind - I'm a gal and not a gear head, though I've done a few things on my own with this truck.

So, it now has about 177k on it, with about 70 or 80k on a rebuilt transmission. The fuel pressure gauge has been reading normal.

I changed the transmission fluid and filter about 2500 miles ago. I don't use the truck often, just for hauling livestock to the sale and such. Sometime after that, I noticed the transmission slipping, going around 45 mph. I was close to home to turned around and came back. Found the trans fluid was low so added more (checked level in N, of course). That seemed to take care of the slipping at the lower speeds, but I noticed at 60-65 mph that the rpms would dip slightly now and again. Warning bells in back of mind...

Yesterday it was hot, about 107F, and I was heading out in the truck on the highway when I noticed the drops in RPM around 45 mph again. Aborted trip and came home. Checked fluid level and it was still ok, though low ok. Added more.

Now, once in a great while in first gear the engine will gulp like it's not getting enough fuel, and then even out again. I have the FASS lift pump and pressure is good, so not sure what that is about. We'd replaced the injection pump a lot of miles ago, hoping it isn't that. Just last week I put the OEM air box back in, since the aFE BHAF is old and rather gunky. Maybe it's where we live but it gets soiled fast.

My final concern is that the old gal just doesn't do as well with fuel economy as it used to. Hanging out around 14-15 mpg not towing, country driving.

I am about to take her in to a tranny guy, but I don't want to head there if there's a chance there is something else that is causing these little RPM drops.

Thoughts?

jrs_dodge_diesel

I bet your ground wires need to be cleaned. Dirty grounds can cause electrical noise, which can in turn cause the lockup clutch to lock and unlock. It is controlled electrically by the PCM. This happened to my truck, and is a common problem on our Rams. Mine did it about 9 years ago and hasn't done it since I cleaned the grounds.

Try cleaning the ground wire connections first, there are 6 key places to clean. The first two are both negative terminals on the batteries. The next two are the wire connections going from the battery negative terminals to the body/chassis grounds, which are near the batteries. The last two are the ground connection on the PCM, and the wire that connects from there to the chassis. A wire brush and a small piece of sandpaper is all you need.

You were on the right track with the low fluid for your low speed slipping.

betsycam

Thanks, Jrs

So, not knowing about the noise problem until looking on this forum, I took it to be diagnosed. The tranny guy hadn't a clue about the noise problem, said option 1 was a rebuild for $2600 in house, or a remanufactured tranny for $3600. He then said I could limp along on it as is for awhile, that it wasn't bad.

Thankfully, I finally remembered to check here and saw a thread about the noise issue. Then I saw your reply to me.

About four months ago, the truck was dead, took a lot of effort to get it to jump. But after that, it started fine. This problem came up after that. I don't drive it often so don't recall the timing other than that this started after that.

Turns out our batteries are from 2012!

So, bought two new batteries, but on to the next problem. Two of the battery clamp bolts broke from corrosion, the ones outer-most ones closest to the body, so ordered new ones, There's a lot of corrosion so I wanted to remove the battery trays and clean them, and put the good bolts in place of the broken ones . Well, you can't seem to do that without removing the trays due to not being able to get those metal clips the bolts thread into in place without removal. Now I've run into how to remove the trays. The tray on the driver side has exposed bolts that I can undo (if I can ever get them unfrozen!). The other tray has what looks like a flat piece of metal with two flat studs or something, no bolt to undo. How am I supposed to get that undone? Are those Dorman fasteners? I don't know why they are different between the two trays other than that I had a front end accident where the shop probably put in a 1500 fender, since it no longer has the studs the air box fits onto!

Anyone have a link for a video on how to remove that type? Or a pictorial?

Why does it always seem to be more difficult than it needs to be?!!!

betsycam

Ok, to update....bad batteries. I recalled that earlier in the year the truck was dead and took a lot of effort to jump. Didn't have any trouble with starts after that, especially since we don't use it often. But, the bells went off after reading about the "hunting" issue. Checked the dates on the batteries and holy cow, 3/12! Forgot we got new batteries and alternator five years ago!

So, two new batteries, and cleaned the grounds and battery boxes while at it. Immediate fix! To think a tranny guy was going to do a rebuild...thankfully he blurted out that I would be ok using it the way it was for awhile, that it wasn't "bad." His conscience getting to him, perhaps?

So glad this place exists! Thanks, again, Jrs!