1999-2003 CAT 3126 Specs (Weight, Oil Pressure, Torque)
The CAT 3126 Engine has been around for quite some time. But you want to know the specs to make sure you are getting an engine that will not fail on you at the most critical moment. You need to make sure with the 3126 as it has been around for over 20 years.
The engine comes in several different HP ratings. The ratings go from 170 to 330 HP over the different versions of this diesel motor. Regardless of its horsepower level, this is a workhorse of an engine that should last for some time, even used.
To learn more about this engine and its specs, just continue to read our article. It contains the best information possible so you can see if this used motor is perfect for your driving or towing situation. Take a few minutes to see how this information helps you make that purchase decision.
Complete 3126 CAT Engine Specs
Here are the specs for this engine when it is in top shape:
- Horsepower- ranges between 170 and 330
- Peak Torque- 420 to 860 lb ft @ 1440 RPM
- 6-Cylinder, 4-Stroke-Cycle Diesel
- Bore — in (mm) . . . . . . . . . . . . . . . . . . . . . 4.33 (110)
- Stroke — in (mm) . . . . . . . . . . . . . . . . . . . . 5.0 (127)
- Displacement — cu in (L) . . . . . . . . . . . . . 439 (7.2)
- Aspiration . . . . . . . . . . . . . . . . . . . . . . . . . . . . ATAAC1
- Compression Ratio 175-300 hp . . . . . . . .. . . . . 16:1
- Rotation (from flywheel end). Counterclockwise
- Cooling System2 — gal (L) . . . . . . . . . . . . 3.5 (13.2)
- Lube Oil System (refill) — gal (L) . . . . 4.75 (18.0)3
- Weight, Net Dry (approx) — lb (kg) Including Flywheel. . 1295 (588)
CAT 3126 Torque Specs
Here are some of the torque specs for different engine parts:
- Rod Bearing Torque & Main Bearing Torque- 35 to 45 Ft/Lbs + 90 degrees
- Cylinder Head Torque & Intake Manifold Torque- 10 to 20 Ft/Lbs
- Exhaust Manifold Torque- 29 to 37 Ft/Lbs
- Firing Order- 1-5-3-6-2-4
- Intake Valve Lash- .015” cold
- Exhaust Valve Lash- .025” cold
- Piston Protrusion- +.020” to +.035”
- Piston Orientation - Bearing notch goes to the right of the engine
These torque and other specs are for the CAT 3126, 3126B, and 3126E engines.
3126 CAT Engine Injector Torque Specs
For the fuel injector hold down the specs are as follows- torque shoulder bolt between 44 to 62 inches lbs, then the socket head bolt to 79 to 133 inch lbs. Then the injection actuator pressure sensor should be torqued between 70 to 106-inch pounds.
The intake manifold should have its bolts torqued between 16 to 26 Ft-Lbs. If you want to see a complete set of torque specs for a variety of sparks then look over this diagram:
It provides you with a complete list of torque specs along with special instructions for exceptions to the rule underneath the table. There are manuals available to double-check any figures and specs but they may cost a little bit of money to download or have sent to your home.
3126 CAT Engine Oil Pressure Specs
There seem to be several readings that you should be aware of when it comes to oil pressure.
- Low idle- is about 18 psi
- Regular idle - is about 30 to 35 psi
- Driving- between 55 & 60 psi
- oil pressure at the injectors- 870 to 3,300 psi.
Just so you know, you need oil pressure to get fuel to the engine. The oil pressure runs the injectors and when that disappears, the injectors will not work. If you are running about 18 psi at low idle then you should be doing fine.
Another thing to know is about the oil pressure gauges. It is being reported that accurate oil pressure gauges are useless with this engine. It seems that once the oil pressure drops to unsafe levels, the electronics shut the engine down rendering the gauges worthless as there is no power to them and no il pressure to monitor.
3126 CAT Engine Oil Cooler Torque Specs
The torque specs for the engine oil cooler are not to be found on those normal websites that provide all the other specs for this engine. We did find some websites that offered the information in a PDF file.
However, those files are not free unless you sign up for a month free trial. We did not check to see what the access would cost in case we forgot to cancel our free trial.
Most websites offering a number of specs for this engine leave that component off their lists. We found some good lists but for some reason, no one wants to mention the torque specs for this specific part.
CAT 3126 Marine Engine Specs
Here are the specs for one version of this engine:
Caterpillar 3126B "CAT" Marine Diesel engine rated
- 450 HP@2800 RPM with Transmission 2.5:1
- H/E cooled (bullet proof) ZF IRM-280-1
- Transmission ratio 2.5:1
- I-6, 4-Stroke-Cycle-Diesel
- IMO I emissions levels (2000-2010)
- 7.2 L (442 in) displacement
- 2800 rpm
- 110 mm (4.33 in) bore x 127 mm (5.0 in) stroke
- Turbocharged-aftercooled aspiration
- Electronic governed
- Heat exchanger
- Cooling System Refill Capacity: 28 L (7.4 gals) /Lube oil system: 25 L (6.6 gals)
- 250-hour oil change interval
- Counterclockwise rotation
- SAE No. 3 flywheel housing with SAE No. 3 flywheel (126 teeth)
- Compression- 15.5:1
- Coolant capacity- 7.4 gallons
- Oil capacity- 6.6 gallons
3126 CAT Engine Weight
The weight seems to depend on the application. For regular trucks and RVs, one 3126 weighed in at 1295 pounds or 588 kg. For the 3126 marine engine, the weight registered at 1592 pounds or 722 kg.
The weight may vary depending on the version of 3126 you want to buy.
Misc. Torque Specs
1. Main bearing cap bolts
- Install the bearing caps with the sequence number to the right. The order is 1 through 7 (front to rear).
- Apply "SAE 30" engine oil to the bolt threads (6) and face of the washers.
- Tighten bolts (6) on each bearing cap.
- Tighten to the following torque. ... 54 ± 7 N·m (40 ± 5 lb ft)
- Tighten bolts (12) on each bearing cap again.
- Tighten the bolts by another one-quarter of a turn. ... 90 ± 5 degrees
2. Connecting rod bolts
Use the instructions that follow to tighten the connecting rod cap bolts:
Before installing the rod cap, clean the mating surfaces of the connecting rod with compressed air or a steel brush. Ensure that there are no loose particles that remain from the process that is used to fracture the rod.
Note: Lubricate the seating faces of the rod cap bolts with 4C-5593 Anti-Seize Compound or engine oil before installing the bolts.
- Install new connecting rod cap bolts (5).
- Tighten each of the cap bolts to the following torque. ... 70 ± 5 N·m (50 ± 4 lb ft)
- Place an index mark on each connecting rod cap bolt and tighten each of the cap bolts for an additional 120 ± 5 degrees (1/3 of a turn).
3. Crankshaft pulley
- Torque for four bolts ... 200 ± 25 N·m (150 ± 18 lb ft)
4. Flywheel
- Torque for eight locking bolts ... 120 ± 20 N·m (90 ± 15 lb ft)
5. Exhaust manifold
- Apply 5P-3931 Anti-Seize Compound to the threads of bolt (1) through bolt (12).
- Tighten bolt (1) through bolt (12) in a numerical sequence.
- Tighten the bolts to the following torque. ... 4 ± 1 N·m (35 ± 9 lb in)
- Tighten bolt (1) through bolt (12) in a numerical sequence.
- Tighten the bolts to the following torque. ... 45 ± 5 N·m (33 ± 4 lb ft)
- Lock the tabs and bend the tabs (13) over the flat of the bolt heads.
- Tighten the studs (14) to a torque of 35 ± 5 N·m (26 ± 4 lb ft).
Some Additional Words
A good diesel mechanic will be able to provide you with the specs for those 3126 versions not mentioned here.
