Cummins 6BT Overhaul Kit for 5.9L Engine Rebuilds
A 6BT5.9 nameplate does not point to one universal overhaul kit. Cummins used multiple piston designs, CPL groups and application arrangements across 6B, 6BT, 6BTA and 6BTAA engines. The correct package must be built around the engine serial number, CPL, piston identification and the machine shop’s measurements.
4BTdiesel supplies configurable 5.9L overhaul packages for industrial equipment, generators, marine engines, commercial vehicles and other 12-valve B-series applications. Send the identifiers below and receive a quotation with the proposed kit scope, sizes, availability and packing list stated in writing.
Verified B5.9 platform data: Cummins’ published 6BTAA5.9-G13 generator specification identifies a liquid-cooled, inline six-cylinder engine with a 102 × 120 mm bore and stroke and 5.9 L displacement. That specific G13 configuration is turbocharged and charge-air-cooled with a 16.5:1 compression ratio. Rating, aspiration details and compression ratio can vary by model/CPL, so the G13 value must not be generalized to every 6BT.
Source: Cummins B5.9 Series Specification Sheet (6BTAA5.9-G13) →
Prepare these five items for matching:
- Engine Serial Number (ESN) and CPL from the data plate.
- Exact model: 6B, 6BT, 6BTA, 6BTAA or QSB5.9.
- Piston crown/marking or the old piston part number.
- Main- and connecting-rod bearing size after crankshaft measurement.
- Required repair scope: in-frame, complete/out-of-frame or machine-shop package.
Choose the Correct 5.9L Kit Family First
The model family narrows the search, but it does not finish the fitment check. Use the three paths below to tell us where to start.
6B / B5.9
Naturally aspirated 5.9L. Common in industrial, construction and generator applications. The CPL and piston number still determine the correct piston kit and gasket package.
Send: ESN, CPL, data-plate photo and piston marking.
6BT / 6BTA 5.9
Turbocharged or turbocharged-aftercooled 12-valve engines. Industrial, automotive, marine and genset arrangements can use different CPL and piston groups.
Send: ESN/CPL plus the equipment or vehicle application.
6BTAA / QSB5.9
Later aftercooled or application-specific versions. Do not assume an early 6BT kit fits because the displacement is the same.
Send: complete nameplate, control/emissions information and old piston photos.
These paths are identification starting points, not a fitment guarantee. The approved quotation and final packing list control the order.
Cummins QuickServe says to use the most recent piston part number first when identifying a MidRange overhaul kit. If the piston number is unavailable, use the engine CPL. Cummins also provides a B Series CPL lookup tool. Read the official MidRange selection method.
What a 4BTdiesel 6BT Quote Will Confirm
A useful quotation should let your technician and purchasing team see exactly what is being supplied. We build the quote around the information available instead of hiding every variation behind one generic product image.
| Quote Item | What Should Be Stated | Why It Matters |
|---|---|---|
| Engine match | Model, ESN/CPL basis and application notes | Separates early 6B/6BT, 6BTA, 6BTAA and QSB arrangements |
| Piston package | Piston reference, quantity six, rings, pins and retainers | Bowl, compression and emissions versions are not automatically interchangeable |
| Bearing sizes | Main and rod bearing size: standard or confirmed repair size | The crankshaft measurement—not the engine name—sets the bearing size |
| Gasket coverage | Upper, lower or full gasket package and major seals | In-frame and out-of-frame scopes use different sealing parts |
| Bore repair | Whether liners/repair sleeves are supplied and whether machining is required | Some sleeves are semi-finished and cannot be installed as a drop-in part |
| Commercial terms | Brand/condition, availability, handling estimate, shipping, warranty and exclusions | Prevents a low headline price from being mistaken for a complete rebuild package; Cummins Genuine-kit coverage does not automatically apply to an aftermarket kit |
In-Frame, Complete or Machine-Shop Package?
Choose the repair scope after teardown and measurement. A larger kit is not automatically a better purchase if the crankshaft, bore or cylinder head work is still unknown.
| Repair Scope | Best Used When | Typical Supply Direction | Items Often Added |
|---|---|---|---|
| In-frame package | The engine remains installed and the crankshaft/block are serviceable | Six piston/ring groups, rod bearings, main bearings when required, upper gasket set and oil-pan sealing parts | Front/rear seals, oil pump or selected cooling parts |
| Complete / out-of-frame package | The engine is removed for a full reseal and dimensional inspection | In-frame components plus upper and lower gasket coverage and additional seals | Rod bushings, cam bushings, valves/guides/seats |
| Machine-shop package | The block, crankshaft and head are being machined | Configured around measured bearing sizes, piston/bore plan and head work | Repair sleeves, oversize pistons where supported, valve train parts, oil and water pumps |
If your shop has not measured the crankshaft or decided the cylinder-bore repair, request a provisional quote first and finalize the sizes after inspection.
Typical Six-Cylinder Kit Contents
| Base Rebuild Components | Available by Configuration | Normally Quoted Separately |
|---|---|---|
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The quotation is the specification. Photos show the type of package; they do not override the confirmed line items and packing list.
Shop 12 Related Cummins 6BT Components
These currently available 5.9L B-series components are a sample of the parts that may accompany a 6BT overhaul or major repair. Each product has its own application range, so verify the ESN, CPL, old part number and machine configuration before ordering.
Cummins states that MidRange B3.9/B5.9 kits contain the mandatory parts for a basic overhaul—piston rings, pistons, bearings, gaskets and cylinder liners if applicable—while other components are selected after inspection. Cummins training further classifies 5.9L as a parent-bore platform with salvage sleeves available, not as an 8.3/8.9L-style wet-liner engine. This is why “six liners included” must not be assumed unless the quotation identifies a machining/sleeve repair. Sources: Cummins Engine Overhauls and Cummins Parts Professional 67, page 20.
Shop 6BT, 6BTA and 6BTAA Parts
Compare pistons, bearings, gaskets, fuel-system and supporting parts already tagged for 5.9L applications. Final fitment still requires the engine identifiers.
Working on the four-cylinder 3.9L?
The 4BT has a separate fitment and machining path. Do not reduce quantities in a 6BT list and assume the remaining parts match.
Why ESN, CPL and Piston Number All Matter on a B5.9
Cummins’ official MidRange reference groups B5.9 overhaul kits by piston part number and CPL. The table below reproduces five of the published groups so a buyer can see the scale of the variation; it is not a complete fitment table.
| Piston P/N | Cummins Overhaul Kit P/N | Published CPL Examples |
|---|---|---|
| 3906223 | 4955757 | 596, 691, 714, 791, 802, 845, 960, 1403, 1433 |
| 3907163 | 4955758 | 729, 761, 804, 807, 856, 938, 943, 947, 948, 949, 950, 994, 1160, 1163, 1168, 1189, 1245, 1266, 1279, 1288, 1289, 1440, 2049, 8736 |
| 3907156 | 4309177 / 4352520 | 599, 600, 698, 713, 742, 792, 834, 912, 940, 961, 962, 983, 998, 1209, 1518, 1519, 1523, 1524, 2530 |
| 3928673 | 4955761 | 629, 1902, 1948, 1961, 1962, 2014, 2015, 2016, 2071, 2147, 2292, 2296, 2303, 2373, 2417, 8085, 8444 |
| 3957795 | 4309178 | 2678, 2846, 2943, 8058, 8105, 8111, 8148, 8149, 8265, 8266, 8267, 8337, 8483, 8492, 8604, 8623 |
The same Cummins guide also lists B5.9 piston references 3922687, 3930187, 3919041 and 3917619 in additional CPL/kit groups. Use the current ESN parts catalog to check supersessions and the exact build before ordering.
That is why a seller can advertise “fits 6BT5.9” and still send the wrong piston or gasket arrangement. We use the following hierarchy:
- ESN identifies the engine build record.
- CPL narrows the performance and component configuration.
- Piston number or clear piston-crown photos confirm the combustion hardware when the engine has been rebuilt before.
- Machine-shop measurements set bearing and bore sizes.
- Application flags automotive, industrial, generator and marine differences that may affect seals or accessories.
Reference: Cummins MidRange Overhaul Kit Quick Reference Guide. CPL examples are identification aids only; final compatibility must be checked against the specific ESN and supplied parts.
Bearing Size and Bore Work Must Follow Measurements
Do not order undersize bearings because the old shell is marked that way, and do not order standard bearings because the crankshaft “looks good.” Ask the machine shop to record:
- Main-journal and rod-journal diameters at multiple points.
- Taper, out-of-round and surface condition.
- Block bore diameter, taper and out-of-round.
- Piston-to-wall clearance for the selected piston.
- Whether a repair sleeve is required and the finished bore specification.
- Deck and cylinder-head work that could affect gasket selection.
Official Cummins option data demonstrates why sizes must be tied to the exact build. For 6B5.9 CPL 1165, option PP1165-02, the parts list shows:
| Component | Standard Reference | Repair Options Listed for This Exact Option |
|---|---|---|
| Connecting-rod bearing | 3901170 standard | 3901171 (0.25 mm), 3901172 (0.50 mm), 3901173 (0.75 mm), 3901174 (1.00 mm) |
| Engine piston kit | 3802170 standard | 3802172 (0.50 mm), 3802174 (1.00 mm) |
| Piston-ring set | 3802050 standard | 3802052 (0.50 mm), 3802054 (1.00 mm) |
This is a documented CPL 1165 example, not a universal 6BT size menu. Another ESN/CPL can use different part numbers or supported sizes. See the Cummins B Series option parts catalog, pages 67–68. We only add a repair size after the machine shop measures the crankshaft/bore and the ESN-specific catalog confirms the option.
Industrial, Automotive, Marine and Genset 6BTs Are Not One Application
| Application | Information to Add to the Quote Request | Common Ordering Risk |
|---|---|---|
| Construction / industrial | Machine make/model, arrangement photo, rated power and data plate | Ordering by “6BT excavator engine” without the engine build data |
| Generator set | Generator model, speed/frequency, standby or prime rating | Assuming a vehicle CPL and genset CPL use the same piston package |
| Marine | Marine rating, cooling/exhaust arrangement and engine plate | Leaving out marine-specific sealing or accessory differences |
| Automotive / 12-valve truck | Vehicle year/VIN plus engine ESN, CPL and piston identification | Buying by vehicle year alone after an engine swap or previous rebuild |
| 6BTAA / QSB5.9 | Complete model, emissions/control information and piston photos | Treating every 5.9L B-series engine as an early mechanical 6BT |
Send This Information for a Buildable Quote
- One clear photo of the complete engine data plate.
- Typed ESN, CPL and exact engine model so unclear digits can be checked.
- Photos of the piston crown, bowl and any readable piston number.
- Old bearing-shell markings plus the machine shop’s measured journal sizes.
- Required scope and any parts already purchased.
- Delivery country, postal code and required arrival date.
If the plate is missing or unreadable, include block casting marks, injection-pump details, equipment information and photos from several engine angles. Review our Cummins engine serial lookup guide before submitting the request.
From Identification to Shipment
- Fitment review: we compare the supplied ESN/CPL, piston and application information.
- Scope confirmation: you select in-frame, complete or machine-shop coverage and confirm bearing/bore sizes.
- Written quotation: review line items, brand/condition, exclusions, availability, shipping, warranty and packing list.
- Pre-shipment confirmation: resolve any remaining identifier or measurement questions before the kit is dispatched.
- Receiving inspection: compare labels, quantities and visible parts with the approved packing list before opening sealed packages.
4BTdiesel supports worldwide parts supply from its China warehouse. Actual handling and transit times depend on configuration, stock, destination and carrier, so the quotation should be used for the current estimate.
Cummins QuickServe records the engine’s original build by ESN and provides the engine-specific parts catalog, dataplate information and service literature. Cummins also defines the CPL as the basic parts and timing specifications required for a given performance/certification configuration. See the official Cummins ESN/CPL guide, pages 4–6.
Inspect the Kit Before Opening Sealed Packages
Rebuild kits have stricter return conditions than ordinary service parts. The current 4BTdiesel policy states that opened rebuild kits are not accepted for return and that eligible returns may involve a 15% restocking fee and return-shipping charges.
- Match every carton label and part number to the packing list.
- Count six piston/ring groups and verify visible piston markings.
- Check main- and rod-bearing size labels.
- Confirm the upper/lower gasket scope and major seals.
- Report discrepancies before opening sealed internal packages or beginning installation.
Read the current Shipping and Returns Guide before ordering.
6BT Overhaul Kit Questions Buyers Ask
Will one kit fit every 12-valve 5.9 Cummins?
No. “12-valve 5.9” describes a broad engine family. The ESN, CPL, piston group, application and machining sizes are needed to approve a specific kit.
Can I order a 6BT kit before the engine is torn down?
You can request a provisional quote, but bearing sizes and the bore-repair plan should remain unconfirmed until inspection. Finalize those items before shipment.
Are cylinder liners included?
Only when listed in the quotation. Some repair sleeves are semi-finished and require machine-shop boring or honing; they are not automatically drop-in liners.
Does a 6BT kit fit an ISB5.9 or QSB5.9?
Do not assume so. ISB and QSB applications can use different pistons, controls and component arrangements. Submit the full model and ESN for a separate match.
Are the turbo, injectors and injection pump included?
Not in a standard internal-engine package. They can be quoted separately after their part numbers and condition are checked.
Why is there no single fixed price on this page?
A low in-frame package, a complete gasket-and-piston package and a machine-shop package are different products. The price should follow the confirmed piston group, bearing sizes, optional components, brand and shipping destination.
Request a 6BT 5.9L Overhaul Kit Matched to Your Build
Send the data plate, CPL, piston identification, bearing sizes and repair scope. We will return a configuration you can compare line by line before ordering.
Primary Technical References
- Cummins B5.9 Series / 6BTAA5.9-G13 Specification Sheet
- Cummins B3.9 and B5.9 MidRange Overhaul Quick Reference Guide
- Cummins Bulletin 5600511, B5.9 Overhaul CPL/Piston Reference
- Cummins B Series Option Parts Catalog, CPL 1165 Example
- Cummins Parts Professional 67: MidRange Overhaul Kits and Parent-Bore Engines
4BTdiesel is an independent replacement-parts supplier. Cummins names and part numbers are used only for identification and compatibility reference. Confirm the quoted brand, condition, warranty and complete contents before payment.
