Motor Grader Engine Rebuild Cost: Cat, John Deere, Komatsu (2026)

Motor grader engine rebuilds are among the most expensive repair decisions in a road-building or grading fleet. The engines are large, access inside the hood requires significant disassembly, and the machines themselves carry high replacement values. Here is what the work costs on the most common production graders, and how to decide whether to rebuild or replace.

Motor Grader Engine Rebuild Cost Ranges

Production motor graders run Cat C6.6 through C9.3 engines, John Deere PowerTech 6068 and 6090 units, and Komatsu SAA6D107E and SAA6D114E engines. All are industrial diesels in the 145-215 hp range with long rebuild intervals and strong reman support.

• In-frame rebuild: Cylinder liners, pistons and rings, rod and main bearings, head gasket set, valve train service. Engine stays in the machine. Cost: $9,000 to $24,000 depending on engine model and scope found on teardown.
• Full out-of-frame rebuild: Engine removed and fully disassembled. Crankshaft ground or replaced, block line-bored, heads rebuilt, all wear surfaces measured and reconditioned. Cost: $17,000 to $44,000.
• Reman exchange (installed): Core engine out, remanufactured long block in, with warranty. Cost: $24,000 to $52,000 installed depending on engine model and dealer vs. independent shop.

For a quote on your specific machine before calling shops: EquipBook's free repair cost estimator covers engine rebuilds on common motor grader makes and models.

Cost by Model and Engine

Model	Engine	In-Frame Rebuild	Full Out-of-Frame	Reman Exchange (installed)
Cat 120M	C6.6 ACERT (145 hp)	$9,000-$15,000	$17,000-$32,000	$24,000-$40,000
Cat 12M / 140M	C7.1 ACERT (155-174 hp)	$11,000-$19,000	$20,000-$36,000	$27,000-$44,000
Cat 140K	Cat C7 (175 hp)	$11,000-$20,000	$20,000-$37,000	$27,000-$45,000
Cat 160K	C9.3 ACERT (215 hp)	$13,000-$24,000	$24,000-$44,000	$32,000-$52,000
John Deere 670G / 672G	PowerTech 6068 (180 hp)	$10,000-$18,000	$19,000-$34,000	$26,000-$42,000
John Deere 770G / 772G	PowerTech 6090 (215 hp)	$12,000-$22,000	$22,000-$40,000	$30,000-$48,000
Komatsu GD655-5	SAA6D107E-1 (178 hp)	$10,000-$18,000	$19,000-$34,000	$26,000-$42,000
Komatsu GD675-3A	SAA6D114E-2 (200 hp)	$11,000-$21,000	$21,000-$38,000	$28,000-$46,000

Ranges assume shop rates of $100-$160/hr. In-frame labor: 50-90 hours. Full rebuild: 100-170 hours. Reman includes engine-out, installation, and startup commissioning. Costs rise if crankshaft journals are worn beyond regrind limits or if turbocharger damage is found during teardown.

Signs a Motor Grader Engine Needs Attention

• Blue or gray smoke under heavy load. White smoke on a cold start is normal. Persistent blue or gray smoke when the machine is grading on grades or running the blade at full cut is oil burning past worn rings or valve seals. On Cat C7.1 and Komatsu SAA6D107E engines, this typically starts in one or two cylinders. A cylinder compression test confirms the pattern before you commit to a repair direction.
• Oil consumption beyond normal service intervals. A motor grader burning a quart or more of oil between normal service checks, with no external leaks visible on the ground, is burning it internally. Track consumption over two or three service intervals to establish a rate before deciding between an in-frame rebuild and a more conservative approach like valve stem seals and injector sleeves.
• Power loss on grades. If the grader struggles on inclines it used to handle in a higher gear, and the torque converter, transmission, and hydraulic system check out, the engine is not producing rated output. Turbocharger boost pressure test and a compression check across all cylinders will identify whether the issue is fuel system, air path, or mechanical.
• Coolant disappearing without external leaks. On Cat C7 and C7.1 engines, head gasket failure is the most common cause of unexplained coolant loss. Coolant entering the combustion chamber produces white smoke with a sweet exhaust smell. Shut the machine down immediately. A head gasket job caught before bearing damage runs $4,500-$8,000. Running the machine on coolant-contaminated oil turns it into a full out-of-frame rebuild at three to five times the cost.
• Metal particles in oil analysis. Most grading fleets run oil sampling on their production machines. A sharp rise in iron particles above historical baseline is an early warning of ring or liner wear. Aluminum spikes point to piston skirt breakdown. Act on the trend, not just the threshold. Catching it early is often the difference between an in-frame job and a full reman.
• Crankcase pressure at the breather. A steady stream of gases from the engine breather under load, rather than the occasional light puff, means piston rings are no longer sealing the combustion chamber. This is the clearest in-field indicator for an in-frame rebuild on Cat and John Deere production graders.

In-Frame vs. Full Rebuild vs. Reman: How to Decide

The in-frame rebuild makes sense when the block and crankshaft are within tolerance. The shop pulls heads, does a bore measurement, replaces liners, pistons, rings, and bearings, and the engine is back to factory spec without removing it from the machine. This is the right choice when the problem was caught at the early warning stage and the crankshaft journals are not worn.

A full out-of-frame rebuild is required when the crankshaft needs grinding or replacement, the block needs line boring, or the engine was run with contaminated oil long enough to damage the main bearing journals. The engine comes out, everything is measured, and only the components that need replacement are replaced. Cost is higher but the result is a fully reconditioned engine rather than an engine with rebuilt upper end and original crank clearances.

A reman exchange is the fastest path back to work and carries a warranty. It costs more than a rebuild but the machine is down for 2-4 days rather than 2-3 weeks. On a machine generating $2,000-$4,000 per day on a road contract, the reman premium can pay for itself in reduced downtime inside the first month.

Does the Rebuild Make Financial Sense?

The core question before approving any engine repair is whether the machine is worth the investment. A 2016 Cat 140M3 in good working condition is worth $180,000-$230,000. An $18,000 in-frame engine rebuild is 8-10% of that value. If the machine has 10,000-14,000 hours, the hydraulic system and tandem drives are in good shape, and the circle gear is not worn out, the rebuild is straightforward.

A 2005 Cat 140H at 20,000 hours with circle gear wear, tandem seal leaks, and an engine needing a full reman at $40,000 is a different calculation. The combined deferred repair cost may approach the machine's current market value, and a replacement makes more sense than stacking expensive repairs on an aging grader.

Get a free motor grader valuation at EquipBook in under 60 seconds. Then use the free repair cost estimator to price the engine job on your specific machine. Those two numbers together make the repair-versus-replace decision clear before you write a check.

See also: motor grader hydraulic pump replacement cost, motor grader final drive replacement cost, and motor grader repair costs overview for the full picture of major repair categories on production graders.