Cat 3126 Questions

ds1450

Expert Expediter
I am used to running as DT 466 at about 1800 rpm and that gave me about 70mph.

Just test drove an fl70 w/cat motor and ran 2200 rpm for about 65 mph. Is this normal with this Cat motor??/ How is the fuel mileage???

Dave
 

LDB

Veteran Expediter
Retired Expediter
That seems way too high. It sounds like it's geared for city use at 45-50 mph not highway use.

Leo Bricker
OOIDA 677319
truck 4958
73's K5LDB
Support the entire Constitution, not just the parts you like.
 
G

guest

Guest
Dave

Yes, that is about right. I have had 2 trucks with a 3126 Cat motor in them and they both ran at 2200 rpm's at 65 mph. As far as fuel mileage it can range from 8.9 to 12 mpg it depends on how fast you run, and what rear end you have in your truck. Mine has 373 rear ends. Another thing is how heavy your truck is.

I think if you keep up on your PM's, this is a great motor to have. Mine has over 700,000 miles on it. I have used Lucus motor oil with every oil change since day one. I change the oil every 12,000 to 15,000 miles. Keeping the service up on your truck is the name of the game. You have to spend money to make money. Remember "most people don't plan to fail, they fail to plan" that's what I live by.
 
G

guest

Guest
>That seems way too high. It sounds like it's geared for city
>use at 45-50 mph not highway use.

No, that is what they run at Leo. And if he ran 55 mph it ran at 1800 rpm.
 

LDB

Veteran Expediter
Retired Expediter
I'd go insane. I have enough trouble accepting my MB900 turning about 1675 at 65mph. I've spec'd the new one with a double overdrive. At 1400 rpm overdrive 1 gives about 62mph and overdrive 2 gives about 71mph. 2200rpm??? I'd think the engine was blowing up and I'd probably blow up too.

Leo Bricker
OOIDA 677319
truck 4958
73's K5LDB
Support the entire Constitution, not just the parts you like.
 

ds1450

Expert Expediter
RE: Cat 3126 Questions/Change Gear in rear...

... or leave it alone?. Talked to a couple of Freightliner dealers and they say that motor built in (1976) can run all day at 2200rpm and be just fine. Kind of un-nerving. It's not hauling a lot of weight (Expedite) owner claims 8 - 10 mpg. I like to run a bit faster and I am worried about fuel cost and of course wear and tear on the engine. How much to re-gear the rear end. Would lower profile tires make a differance?? Thanks for all of the replies.

David
 

ds1450

Expert Expediter
RE: Cat 3126 Questions/Change Gear in rear...Hiogh

Meant to say... would higher profile tires make any differance... not lower...

Thanks
 

raceman

Veteran Expediter
RE: Cat 3126 Questions/Change Gear in rear...Hiogh

I have had two and they run at 2200 and run very well. The one I am driving now has over a half million and running great. I change my oil every 8000 to 10,000. Always use CAT filters. Trust me do not save the few bucks, use CAT. There is enough difference it will cost you.

I am to the point of getting 11MPG


Raceman
OTR O/O
 

TheGoodGuy

Expert Expediter
RE: Cat 3126 Questions/Change Gear in rear...Hiogh

I'll bet your FL70, has the six speed transmission. If so, the 3126E will turn awfully high. LDB 10-04 on the going insane.

Our FL70 has the 7 speed Spicer and the motor turns 1675 at 65 MPH. With the 250HP 3126e it has just enough power to get out of its own way. It averages anywhere between 9 and 11 mpg, depending on load and terain.

The Spicer is probably by far the worst transmission that has ever seen truck service(except maybe in school buses).Ours has been rebuilt twice in 2 1/2 years, and was never designed for long distance OTR application.

I have great respect for the little engine in our truck, it has been reliable(knock on wood), the only problem is I don't get to see it very often(only if I steam clean it), due to the fact that its always coated with oil from its numerous leaks.

I'm presently shopping for a new surplus engine.
 
G

guest

Guest
RE: Cat 3126 Questions/Change Gear in rear...Hiogh

With the Eaton 6 speed and 4:65 rear end I'm at 2000 rpm at 65mph. I wonder why you guys are at 2200 rpm at that speed?
 
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