Engine selection? - Diesel Forum

Bill Wincapaw · 09-26-2008, 07:26 AM

Hey guys
I looking at buying a ( used) Class 6 for towing
I've been reading alot about the 3126(B) dropping valves and being expensive to maintain and the 5.9 being underpowered in this size truck. My question is that my 1995 F-800, 2000gal fuel truck had a 175hp 12v 5.9 w/6spd DD eaton tranny. I was satisfied with the performance with that truck even when loaded ( 65mph cruise on flat Fla roads). So what makes the newer, higher HP 5.9s that bad?, is it towing that puts the hurt on them??? I believe the max I'd be towing with my next truck would be about 30k lbs and that would not be constant. Please don't anyone think I'm flaming either engine I'm just courious for opionions from those who have/had either engine

Bill Wincapaw · 09-29-2008, 06:54 AM

Wow
55 hits and no opinions, I did not realize this question was such a stumper. I guess I've posted it in the wrong forum???

nevrenufhp · 10-04-2008, 01:47 PM

It would probably get more attention in the "General" section.
The early 24 valve Cummins 5.9s are the ones that were bad, the common rail engines arent bad at all. If they have an aftermarket lift pump(look up FASS), then they would be 50 times better in reliability. A 5.9 can haul 30k, just wont be going up hills very fast, but it'll get there. The 3126 does have an iffy track record. Some guy swear by them, some despise them. If I had the time & cash, I'd get the F7-850 with a blown 3126, then swap in a DT466....but that's just me.

CATTC · 10-05-2008, 07:47 PM

with routine maintenance (valve adjustments and oil changes @250 hours) 3126B's are OK IMO and experiance...one of our customers who has a 1000 units (3116, 3126 and C7) after doing valve adjustments at the recomended intervals went from averaging 1 engine w/dropped valves per month to none in the last 6 years...Maintenance isnt free but it sure is cheaper than failures and unscheduled downtime....

kaquinn · 10-18-2008, 11:25 PM

i like the cat 3126 it dose well i installed an edge chip and a PAC brake. the PAC brake was a waste of money! though i am told they have a new model now. the 5.9 has lots of potential and they are cheap to build up but Ive never had a 650 w/5.9! my 650 has a 7speed 210 it is defiantly a torque monster!

97FordCTD · 11-29-2008, 03:33 AM

I don't know much about the CAT, but the 5.9 can be made into a powerhouse pretty quick . If you are looking at the 24V Cummins check the block for the mold stamp. If it has a 53 on it RUN! It is very common for the 53 blocks to develop a crack on the rear passenger side below the freeze plugs. Other than that the VP44 injection pump is know to let guys down after 100-140K miles. These are the two issues I know of with this engine. The 12V is my favorite but the 24V can be tuned electronically so you actually have more control over your power level, in other words turning the power on for the hills or passing and back off for the fuel economy and highway. I will say again though, the 5.9 can make all the power you'll ever need!

kaquinn · 11-30-2008, 12:23 PM

the only problem Ive Had w/ the cat was the oil cooler leaked and it was fixed under warranty, while there the valves were adjusted! other than just normal maintenance! i went across the scale @ 32,000# (dint tell DOT)with it before i chipped it and it pulled fine up the rolling hills where i was traveling i was quite impressed that was the most i ever had on it that i can say i had a slip for what i weighed!