CAT 3126: looking for opinions

Tags · Jan 2, 2016

I have a friend that is looking at a used 2001 6 wheel dumptruck with a CAT 3126 motor with 300hp. The truck only has 31000 original miles on it. I have heard that motor can have some issues, is it something to stay away from or is it an ok motor? Thanks for the help....

Catback · Jan 2, 2016

3126B? Mechanical or hydraulic?

I have two B's and they purr like kittens. The key to these engines is keep the oil clean, and no severe (or any) upgrades/mods. They like to run the way they were built, and will easily run 500,000 miles if taken care of, and not modified.

Tags · Jan 2, 2016

Thanks for the reply. Not sure about mechanical or hydraulic. How would I tell? I did peek at the engine tag and dont remember seeing a "b" anywhere after the 3126, but I could be wrong. There was some oil weeping on the drivers side I believe along (I think) the valve cover and have heard this was common.

Delmer · Jan 2, 2016

300hp is on the high side for that engine, isn't it? The 3116 had a bad reputation in the higher HP versions.

Tags · Jan 3, 2016

The tag on top of the motor states 300hp and I'm sure I've never seen or heard of them rated for more than that...

Nige · Jan 3, 2016

Tags said:
The tag on top of the motor states 300hp and I'm sure I've never seen or heard of them rated for more than that...

Give the Serial Number. That will remove all doubt about what model it is,

Catback · Jan 3, 2016

Tags said:
Thanks for the reply. Not sure about mechanical or hydraulic. How would I tell? I did peek at the engine tag and dont remember seeing a "b" anywhere after the 3126, but I could be wrong. There was some oil weeping on the drivers side I believe along (I think) the valve cover and have heard this was common.

The injectors.

If memory serves, all 3116's are mechanical, and all 3126's are hydraulic. So it is a moot question of mine.

The B is a later version of the 3126.

My 3126's do not leak a drop. If yours is leaking that would invite a thorough perusal of the engine and maintenance records.

If properly maintained (in the past and future), and the oil is regularly maintained and no severe mods are done on the engine, and if the price is right, I would not hesitate on the engine.

Both of mine were installed with both block and intake heaters, and start easily in cold weather. The only "major" engine work I've done on them was to replace one turbo...and that was a breeze.

Any good mechanic will tell you that all diesel's (engines, for that matter) have their share of problems...none are immune. Some are clearly worse than others. I have one DT466 and two 3126 B's, and they are, in my experience, both dependable and durable workhorses. All my heavy trucks were purchased used and were/are well maintained.

Delmer · Jan 3, 2016

Tags said:
The tag on top of the motor states 300hp and I'm sure I've never seen or heard of them rated for more than that...

Yeah, that's my point. The 3116 came in trucks at 170hp, up to around 300, from what I've read in marine forums it had a terrible reputation at high HP (boats run full power more than trucks or equipment). An engine that size rated at 170hp is more immune to driver abuse than 300hp.

I believe no less than Cmark corrected me that both the 3116 and 3126 came in either mechanical or electronic versions.

Nige · Jan 3, 2016

From a brief scan the 3126 Truck Engine is available in arrangements from 190-350BHP. Thay all appear to use the HEUI system but I may be wrong on that.

Tags · Jan 3, 2016

Nige said:
Give the Serial Number. That will remove all doubt about what model it is,

Nice, thanks for the reply, I could kick myself for not snapping a pic of the tag so I'd have the number....I'll be looking at the truck again on Tuesday so it'll have to wait till then.

Catback, thank you also for the info. The drivers side of the engine is damp for sure and looks like something maybe weeping more than a constant leak. The truck will be brought to a local heavy truck mechanic we use and will get the once over before purchase. I am not sure of any maintainance records as the owner has been away and will be back Tuesday. Again thanks for the help!

Cmark · Jan 3, 2016

Delmer said:
Yeah, that's my point. The 3116 came in trucks at 170hp, up to around 300, from what I've read in marine forums it had a terrible reputation at high HP (boats run full power more than trucks or equipment). An engine that size rated at 170hp is more immune to driver abuse than 300hp.

I believe no less than Cmark corrected me that both the 3116 and 3126 came in either mechanical or electronic versions.

Yes. Early 3126 engines used the MUI system but I don't think they were ever offered as a truck engine, only marine and industrial.

Shimmy1 · Jan 3, 2016

In college they told us that the only reason they created the 3126 was so Cat could market the engine to other truck manufacturers. Apparently GM had exclusive rights to the 3116 as a on-highway engine.

Tags · Jan 6, 2016

Had another look at the truck today and took it for a ride, drivers side of motor is damp with oil for sure, don't think its a big deal but somebody here may have something different to say bout that. I also snapped a pic of the engine tag

.

Cmark · Jan 6, 2016

Those printed tags are tightly controlled by Cat, so if the serial number on the tag matches the one on the block, and if the engine hasn't been modified, you can take the information on it as gospel.

Knepptune · Jan 7, 2016

We had one awhile back and it was by far the most temptermental engine I've ever been around. Ours was in freight liner chassis with a boom truck mounted on it. Weighed about 49k. When that engine decided to run right it pulled that truck around like a champ. But that was when it ran right. Some days it would hardly get out of its own way. Some days it would leave a big puddle under the engine. Some days it wouldn't leak a drop. I still scratch my head when I think about that engine. You definitely never what you were going get till you hit the key. If it started instantly you knew you where gonna have a good day. If it would barely start you knew you were gonna be slow lane most of the day. It still doesn't make any sense to me how it could run so differently from one day to the next.

Nige · Jan 7, 2016

The engine's a 3126B ratedcat 300BHP for use in Paccar products. Everything about the engine based on the Serial Number seems kosher.

Tags · Jan 7, 2016

Nige said:
The engine's a 3126B ratedcat 300BHP for use in Paccar products. Everything about the engine based on the Serial Number seems kosher.

Thanks for the info Nige, once again you've been helpful to someone you coulda ignored. The motor is in a Peterbilt so that's good to know it's where it's supposed to be.

blowerman · Jan 7, 2016

Ive owned several and while injectors, leaking water pump, turbo etc, have needed addressing, the motors are decent. While dated now, you'll be ok buying it,

Nige · Jan 7, 2016

To get the exact date of manufacture someone else will have to chime in. For some reason my tablet does not want to play when I get into SIS-web.

Edit..... Build Date 25th of July 2001 in Greenville NC.

driveshed · Jan 10, 2016

Hi Nige
Iam also looking at a Ford F700 with a 3126 cat in it , the year is 2002 but its got 570ks on .Iam going to see it this week the guy that owns it has all the service record and it only did small local deliverys . I did read that the 2008 3126s had more problems than the older one. Are they a good motor to rebuild if not bably damaged.
Thanks
Driveshed

CAT 3126: looking for opinions

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