Model: 6BT
Part Number: 4919951
Brands: Cummins
Engine Model: 6BT, 6BTA, 6BTA5.9, B5.9 series
Engine Type: Diesel
Scope of application: trucks, buses, agricultural machinery, construction equipment, generator sets, marine engines
Cummins lists more than one cylinder liner number for the 6BT and 6BTA, and 4919951 sits alongside 3904166 in that group. The two are close relatives, but they are not always interchangeable in a given block, because the bore preparation and the O-ring sealing arrangement were revised across production. That is why we ask for the old liner or its measurements rather than accepting a model name as sufficient.
Measure the outside diameter, the flange thickness and the overall length of the old liner before ordering. Those three figures identify the variant faster than any catalogue lookup, and they can be taken with a caliper on the bench in a couple of minutes.
Start with the block, not the parts book. Check whether the bore has a machined step for a flange, measure the bore diameter at three heights, and note whether the block has been bored oversize during an earlier rebuild. An engine that has already been through one liner replacement may now take a different part number than the original build sheet lists.
The liner is the working surface for the piston rings. It has to hold combustion pressure, pass heat into the coolant and seal against the head gasket at the top. A liner that is round, correctly finished and set at the right height does all three; one that is oval or set low will fail at the gasket even if the rings seal perfectly.
Oil consumption and blow-by are the usual complaints, and both appear gradually. A ridge at the top of ring travel is the point of no return: it cannot be honed out, and the liner has to be replaced.
The liner must go in square. Pressing or driving at an angle distorts the bore and produces a liner that will not seal, and the damage appears as coolant loss weeks later.
Protrusion is the only thing that lets the fire ring crush onto the liner top. Measure it on every cylinder and compare the figures across the block; uneven protrusion is a common cause of head gasket failure on engines that were assembled carefully everywhere else.
Wet liners vibrate against the coolant and pit when coolant chemistry is neglected. Correct mixture, the specified inhibitors and a system free of air are the only defence. On engines used seasonally, check the coolant before the season starts rather than after a liner has pitted through.
Order the liner, piston and ring as a matched set where possible. A liner honed for one ring type may not suit another brand, and mixing parts is the most common cause of oil consumption after an otherwise correct rebuild.
Run at varying load, increasing gradually, and change oil early. Holding full load immediately glazes the bore and leaves the rings unseated, and the engine then uses oil for the rest of its life. Check the coolant level and the head bolt torque after the first heat cycle.
Liners are supplied oiled and wrapped because a bare bore corrodes quickly in a damp workshop. Keep them packaged until the block is clean, and never polish surface rust off with abrasive paper, which destroys the honed finish the rings need in order to seat.
Not always. Compare the old liner dimensions and the bore preparation.
Not every B series block does. Check for a flange step at the top of the bore.
Yes, the correct set for the bore is supplied.
Possible, but a full set keeps compression balanced.
Browse the Cummins cylinder liner category, and pair the liner with the Cummins 6BT cylinder liner 3904166 or the Cummins engine parts range.
Cummins Cylinder Liner (4919951). This liner is the wear surface for the rings and a sealing surface for the coolant. Its protrusion above the deck is what allows the head gasket fire ring to crush and seal.
Check whether the block takes a liner at all before ordering. Some engines in this family are parent bore, and a liner is not the answer there.
The part number is the reliable identifier here. Where the old number is unreadable, measure the component and compare it with the drawing rather than guessing from the engine model.
Measure protrusion on every cylinder with a dial gauge and record the figures. Uneven protrusion produces a head gasket failure that looks like a gasket fault.
Ordering note. Photographs of the actual unit can be sent before dispatch on request. That is the cheapest way to avoid a return when a casting revision is in doubt.
Related reading: Cylinder Liner Cavitation: Causes, Symptoms and Prevention
| We Are 30 Years Diesel Engine Parts Supplier | |
| Brand | EPID |
| Warranty | 12 Months |
| Condition | 100%New |
| More Models | Weichai: 6BT, 6BTA, 6BTA5.9, B5.9 series, and other Weichai series. |
| Shipping | By sea / air / express (DHL, FEDEX, TNT, UPS, EMS) |
| Packing | Standard exporting packing or as required |
| Payment Term | L/C, T/T, Western Union, Trade Assurance |
| Delivery Time | 3-7 days (depend on order) |
| Selling Point | 1. On-time Delivery 2. Genuine Quality Assurance 3. Professional Supplier |
The liner is the working surface for the piston rings. It has to hold combustion pressure, pass heat into the coolant and seal against the head gasket at the top. A liner that is round, correctly finished and set at the right height does all three; one that is oval or set low will fail at the gasket even if the rings seal perfectly.
Oil consumption and blow-by are the usual complaints, and both appear gradually. A ridge at the top of ring travel is the point of no return: it cannot be honed out, and the liner has to be replaced.
The liner must go in square. Pressing or driving at an angle distorts the bore and produces a liner that will not seal, and the damage appears as coolant loss weeks later.
Protrusion is the only thing that lets the fire ring crush onto the liner top. Measure it on every cylinder and compare the figures across the block; uneven protrusion is a common cause of head gasket failure on engines that were assembled carefully everywhere else.
Wet liners vibrate against the coolant and pit when coolant chemistry is neglected. Correct mixture, the specified inhibitors and a system free of air are the only defence. On engines used seasonally, check the coolant before the season starts rather than after a liner has pitted through.
Order the liner, piston and ring as a matched set where possible. A liner honed for one ring type may not suit another brand, and mixing parts is the most common cause of oil consumption after an otherwise correct rebuild.
Run at varying load, increasing gradually, and change oil early. Holding full load immediately glazes the bore and leaves the rings unseated, and the engine then uses oil for the rest of its life. Check the coolant level and the head bolt torque after the first heat cycle.
Liners are supplied oiled and wrapped because a bare bore corrodes quickly in a damp workshop. Keep them packaged until the block is clean, and never polish surface rust off with abrasive paper, which destroys the honed finish the rings need in order to seat.
Browse the Cummins cylinder liner category, and pair the liner with the Cummins 6BT cylinder liner 3904166 or the Cummins engine parts range.
Not always. Compare the old liner dimensions and the bore preparation.
Not every B series block does. Check for a flange step at the top of the bore.
Yes, the correct set for the bore is supplied.
Possible, but a full set keeps compression balanced.
EPID supplies diesel engine parts for Weichai, Baudouin, Yuchai, Caterpillar, Sinotruk, FAW Xichai and Cummins engines. Every order is checked against the original part number before packing, and our team can identify a part from a photo of the engine plate. Ask for a quotation with your model and quantity and we will reply within one working day.
