keithb7

My '98 24V Cummins sees about 6,000 - 7,000 miles per year. I tow my RV in the summer. I run Caterpillar DEO 5W40 full synthetic oil. I change my oil annually. Every October just before winter. I take an oil sample in about April, and another in Oct at the time I drain the old oil. I send it in to a lab for analysis. The lab tells me what's going on with my oil and engine internals. Oxidation is a good one to watch, aside from wear metals. I have no concerns and am not guessing when to change my oil.

Just following up to say that I added a second small bottle of friction modifier and the symptoms are gone. I had added one at the time I changed the diff oil. Apparently its not enough. I also took an oil sample in December and sent it in for analysis. I last changed the diff oil in June, I think. The oil sample came back good. I am in good shape again it seems.

I am attempting to track down a driveline vibration. Seems to be happening when accelerating from a stop while turning left. Unknown history of diff and drive line maintenance. I Changed the diff oil in July. Not many miles use since June. Will take a diff oil sample soon for analysis. This weekend I drove at hiway speeds for about an hour. No issues. Got home and immediately used a laser thermometer to check u-joint and diff housing temps. Ujoints all seemed fine and no hot bearings. Rear Diff housing pumpkin measured about 100F. Housing near pinion recorded about 120F. Is there something maybe going on with a pinion bearing? Any idea on normal housing temps after a good drive? Looking for any clues as to where to look from here. Thx.

Hi folks, I am looking to tap into the tranny oil on my 98.5 47RE transmission. I am unsure where to thread in the gauge temperature probe. I would rather not be reading oil temps after it has been though the cooler and is re-entering the tranny. I was thinking it would be better to read the hot oil as it exits the tranny. No? I was under the truck today looking around for a test port plug. On the RH side I see these two plugs as shown in the photo. Am I even on the right track here? If so, which one is preferred? Thanks, Keith.

Ya, you guys are right. Thanks for the reminder. I was pulling a long steep hill towing the trailer. 2x I pulled over, part way up, to let the fuel pressure build up to 17. Sat for a while at idle to cool down the VP. It helps probably, but it ain’t right, nor the solution. Enough screwing around. I’ll order up the mechanical pump, off the crank pulley.

Just a follow up report. Two week vacation towing a 23 ft travel trailer all around. Trailer is probably 6,000 lbs loaded up. Lots of driving. Lots of hills. Hiway speeds too. ISS Pro fuel gauge that I installed and trust, gives me readings. 60-65 mph on flat nets me about 12 psi. Lots of hills (up and down) and winding roads. Backing off the throttle for corners and down-hills, fuel pressure quickly goes back to 14-16 psi. At idle maintains about 17 psi. Pulling hard up steep hills, watching all my gauges, I back off throttle and gear down. I maintain 10-11 psi. 10-12 lbs boost. 1,000F EGT. Stock engine and newer stock turbo. So far the Herko is hanging in there. VP-44 temps? I have no idea. I do go over 14 psi fairly often. Guessing it’s doing an adequate job cooling.

So far no problem here. Been running the Herko since March. Lots of towing. Depending on the load I’m towing it maintains 10-12-14 or so psi at 65 mph. Not awesome but certainly better than the stock Carter pump. I’m saving pop-cans to get the mechanical pump off the crank. Hopefully my VP holds out. Lol.

I had heated up my old rotors and had a caliper of unknown age seizing. So I had some vibration but it felt different. I installed new rotors, calipers and pads. If the couple of studs were not quite seated properly I was thinking they were the culprit. As mentioned I am going back in to install new wheel bearings with new studs. Thinking I should press in the new studs. Ensuring they are fully seated.

I recently performed my first rotor swap on my 98.5 2500. I pounded out the wheel studs with a single hit of a 5lb sledge. Easily came out. I swapped the wheel bearing assy over to the new rotors. Used same sledge to set the studs back in the same wheel bearing housing. A few studs did not want to set back in place flush. I whacked ‘em a few times and carried on. Thinking I’d pull ‘em right thru when I torqued the lug nuts up at wheel installation. Well I’m still cranking a few nuts tight. I’ve been test driving and get a slight vibration when braking. I have driven, braked and got hubs warm, then retorqued 3X. Seems I am almost there as the vibration is improving with each retorque. What is the correct procedure? A hydraulic press I assume? To seat the wheel studs in the bearing hub properly, the first time? I’m goin back in as I decided to order up new front wheel bearings. Mine appeared original. I ordered new NGK USA built bearings. Came with new studs too. I’d like to seat them right this time. Also I read 175 ft lbs on the centre nut for bearing pre-load. Plus a little more to align the cotter pin. Seems high but I have limited experience with the truck. I’m used to 3-4 ft lbs on other light vehicles I’ve owned. This Torque is right? Just double checking. I appreciate your experience Thx.

My 98.5 does have the rear load sensing valve. I will consider unhooking it and strapping the lever in the uppermost position. My trailer brakes are in great shape. I took them apart. Inspected cleaned and adjusted. They are nice and tight. I can lock the trailer brakes up using my electronic brake controller. I chose a hitch with anti-sway bars It too doubles as a weight distribution type hitch. Upon installation I did not tweak it to max transfer more weight to the front axle. The tongue weight is still nicely loading up the rear suspension. I chose the anti-sway type hitch to minimize the sail-like effect of trailer walls at hi-way speeds. I was driving a 2017 F-250 today. It has a digital inclinometer. I can’t vouch how accurate it is. It reads in degrees. I drove up my problem-hill today. Average reading was around 6 -7 degrees. However some spots registered 8 degrees. Converting degrees to % slope, that converts to 11% - 12% average. Up to 13% slope at a couple points. No wonder my rotors warped pretty much immediately after a trial run down. Second run down I manually worked the trailer brakes to have them do more of the work, sooner. I can’t take it any slower going down. Gravity wants to pull you at a fixed rate. As mentioned: in first, auto tranny...not gonna do it. I just ordered a set of heavy duty commerial tow grade rotors and pads. New up-rated calipers too. I’ll replace all and also the wheel bearings. All are cooked anyway. Barring this, the next step I am prepared to take is obtaining a lighter trailer. There’s no accounting for the decision to alllow this goat trail to be built, and passed as a drivable road.

I agree guys my 24V eats up normal driving conditions. Hwy or city roads. However, try a 10% grade down hill for 3 miles towing a heavy load. Auto tranny dropped into first gear. Keeping your speed at under 30 mph...I have found the limits of a stock truck. Everytime I hit the brakes this week I am reminded.

Yes my truck is 4x4. Posi-lock?How does that look? I’m unsure. How could I get 2 wheel low? Thx.

I towed my 1938 Plymouth car over 450 or so miles of hiway at various grades over the weekend. I towed an 1800 lb trailer loaded up with a 2800 lb car as well as as additional 400 pound engine block. I was very impressed. The auto tranny was just fine on normal roads and hi-ways. I switched off the OD when climbing hills. Braked and geared down on descents. No issues with brake heat due to excessive breaking. The only issue seems to be the darn steep winding hill near my house. It’s cooking my breaks. It is too winding and steep to lay off the brakes, and descend safely. Otherwise the auto tranny and the 24V 5.9 are certainly adequate for my needs. Dang.

If I have 3.55:1 rear end, and first gear is 2.45:1 is my final ratio 6:1 when in first gear? If I had 4.10 gears, and retained the same tranny, in first at 2.45:1, is my new final drive ratio 6.55:1? Hmm. I wonder how much effect that may have on the hill, both up and down?

John you make some real valid points. The tranny gearing is likely suspect. I have the 47RE. First ratio is 2.45:1 Like you said, hardly ideal. Rear end diff ratio I am not 100% sure. I'll get under there and see diff tag. My tires are stock. Engine is stock.