New vs. Remanufactured Cylinder Heads: What Changes

A remanufactured cylinder head reuses the original casting: it's cleaned, crack-checked, machined and rebuilt with some new parts, then usually sold on a core exchange. A new head is a casting that has never been in an engine, built with all-new valvetrain parts. The casting is the real difference. It decides the crack history, how much machining margin is left, and whether you owe a core.

What is the difference between a new and a remanufactured cylinder head?

The casting is the one difference you can't machine away. A reman head starts life as somebody's used head. It has already been heat-cycled for however long that engine ran, and it may have been decked once or more before the current rebuilder got it. A new casting has never been heat-cycled and still has its full machining margin.

Everything else in the comparison follows from that: what gets inspected, what gets replaced, what can be salvaged, and what paperwork comes with the part. Here is how the four grades of head you'll be quoted line up, with the warranty term TTM puts on each grade of engine component.

What does a remanufactured cylinder head actually include?

It depends on whose program built it, and "reman" does not guarantee an all-new valvetrain. The OEM programs publish enough detail to show the range.

Cummins ReCon is a good example because Cummins spells it out. Every ReCon cylinder head is pressure tested twice for casting defects in the water and fuel jackets, every valve is vacuum tested, and the combustion face is precision ground. Valve guides, injector sleeves, collets and spring retainers are replaced on every head regardless of condition. Valves are replaced only if they fail Cummins spec; the ones that pass are reconditioned and reused. Injector sleeves go in metal-to-metal, with no sealant, by an automated process that sets injector protrusion.

Cat Reman says its process restores cores to match the OEM performance specifications of new Cat products. Parts are cleaned in media matched to the material and inspected. According to Cat's reclaim and salvage overview, cracks in specific areas go to salvage technicians for approved salvage processes before the head moves on to machining.

Two OEMs, two sets of reuse rules. That's why the first thing to ask any reman seller for is the replaced-parts list.

Rebuilt, reconditioned, remanufactured: which one is on your quote?

Read the word on the quote carefully, because the tiers are not interchangeable. Caterpillar states plainly that reman is not the same as rebuilding, refurbishing, repairing or reconditioning.

In everyday shop use, a rebuilt or reconditioned head is a repair. The shop fixes what's worn or out of spec, sometimes welds a crack, and sends it back. There's no common process behind the word, so the result depends entirely on that shop's standards. A remanufactured head is supposed to come off a defined line with set inspection, machining and testing steps.

Don't assume reman means no welds, either. Some sellers say it does. Cat says its reman program applies approved salvage processes to cracks in specific areas. Both statements can be true for different programs, which is the point: the label tells you less than the paperwork does.

TTM's warranty reflects the tiers. Remanufactured components carry 12 months, reconditioned components 3 months, and good used, tested and inspected components 30 days.

Where can a remanufactured head cost you later?

Three places: what inspection can't see, how much machining margin is left, and the core. None of them show up in the price comparison on the day you decide.

Inspection finds today's cracks, not the casting's history

Magnetic particle inspection (Magnaflux) and pressure testing find cracks that exist the day the head is on the bench. They don't tell you how many heat cycles the casting has already been through, or how it was treated before it got there. That isn't a claim that reman heads fail. Cat's Reuse and Salvage Guidelines for cylinder head assemblies say a head that meets the guideline can be expected to give normal performance until the next overhaul; get the current version through your Cat dealer or SIS. The point is what you know. A new casting's service history is zero. With a reman, you're trusting someone else's inspection and their reuse rules.

Every deck cut uses up machining margin

Each resurfacing takes the head closer to the OEM minimum height, and a head already below that minimum gets scrapped. You usually don't know how many times a reman casting was cut before the current rebuilder got it. Removing deck material also moves the valves and injector tips relative to the deck, so valve recession and injector protrusion need to be confirmed against the OEM service manual after any machining, whoever did it.

On the 3406E and C15, a CAT C15 spacer plate (6I4421) sits between block and head, so head, plate and block surfaces all add up in the stack. Before any head goes on, check the liner and deck dimensions for that whole stack against the Cat service manual for your serial number. If nobody checks, a geometry problem can show up later looking like a failed head gasket.

Cores, freight and waiting

Most reman heads are sold on core exchange. TTM's core rules show what that means in practice: the core comes back within 30 days, drainable, uncracked, with mounting surfaces intact. Hold your old head up against that list. If it came off because it cracked, it may not qualify, and the core charge you planned to get back stays on the invoice. Add return freight on a heavy casting and the days the core spends in transit and inspection before the credit posts. TTM's new heads carry no core charge, so none of that applies.

What should you ask before buying a reman head?

Ask for answers in writing. A seller running a real process will have them; a seller who can't answer is telling you something too.

1. Which parts were replaced? Get the list. Valves, springs, guides, seats, seals and injector sleeves: new, reconditioned or reused?
2. Was it pressure tested and vacuum tested? Water and fuel jackets for casting leaks, valves for sealing.
3. What is the head height after machining? Compared with the OEM minimum for that casting.
4. Was any crack repaired, welded or salvaged? Where on the casting, and under whose salvage rules?
5. Are the injector sleeves new? And was injector protrusion set and checked?
6. What is the warranty, and what voids it? Length, what's excluded, and how a claim is handled.
7. What are the core terms? Return window, condition required, and who pays freight.

When does a new head make more sense than a reman?

Buy new when the casting itself is the problem or the unknowns cost more than the price gap. A good reman is a fair buy when the paperwork is solid and your horizon is short.

Buy new when:

• The old head cracked rather than just wore, so your core may not qualify anyway
• You're keeping the truck through another overhaul cycle
• You want one invoice, with no core charge, no return freight and no core credit to chase
• You want to choose the valve material

A good reman is defensible when:

• It comes from a documented program with a written 12-month warranty
• You're selling or trading the truck soon
• Your old head is clean, uncracked and will qualify as a core

Treat a rebuilt head with a welded crack as a stopgap unless the shop can show you what was repaired, where on the casting, and under which OEM guideline.

On valve material: TTM's new heads come in stages. Stage 1 uses standard OEM-style valves, Stage 2 upgrades to Inconel exhaust valves, Stage 3 uses Inconel intake and exhaust valves, and Stage 4 adds a fire ring where offered, such as the Cat C15 / 3406E / C16 universal head. A reman exchange usually ships whatever valve spec the program uses. Check each product page for the stages offered.

Why did the old head fail? Check this before installing any head

Find the root cause first, new head or reman. If the engine is still overheating or a liner is out of spec, the replacement head can fail the same way.

On the Cat C15, C15 ACERT and 3406E, the usual signs are coolant loss with no outside leak, white smoke, overheating under load, bubbles in the coolant and milky oil. Causes include thermal cracking between the valves or injector bores, a deck warped by overheating, head gasket erosion and injector bore wear. Cracks between the exhaust valves are a common find once the head comes off.

On a Detroit Series 60 pushing coolant out of the overflow with white smoke, work in order:

1. Rule out the EGR cooler.
2. Pressure test the cooling system.
3. Pull the intake manifold and look for coolant in the intake ports.
4. If a head gasket blew, check liner height and counterbores before any head goes on.

Fix whatever cooked the first head, or you'll be buying a second one.

Head bolts, gaskets and the labor you only want to pay once

The removal and installation labor is the same whichever head you buy, and no head warranty pays for it. TTM's warranty excludes labor, diagnostics, removal and installation, towing, freight, downtime, lost revenue, rental equipment and driver costs. So the cheapest head is the one that only goes on once. Get your shop's labor quote for your engine and weigh the price gap between heads against paying that labor a second time.

Plan on new head bolts and a new gasket set with either choice. Head bolts on torque-to-yield designs are single use, which is why TTM sells head bolt kits separately; confirm the bolt type for your engine in the OEM service manual. Get the bolt specification, torque values and tightening sequence from that manual too; they aren't printed here. TTM carries a CAT C15 head bolt kit for 3406E, C16 and C18 and a Cummins ISX15 / X15 head bolt kit, along with kits for other engine families.

TTM warranty and core terms, in plain words

TTM new heads carry a 12-month warranty against defects in material and workmanship unless the product page says otherwise, and no core charge. Remanufactured components and long blocks also carry 12 months, reconditioned components 3 months, and good used, tested and inspected components 30 days. The full terms are on the TTM warranty page.

Coverage is voided by improper installation, inadequate cooling, fuel contamination, over-fueling, overheating, low oil or coolant, skipped break-in or non-OEM fluids. That's another reason to find the root cause before the new head goes on.

If something goes wrong, notify TTM within 72 hours of detecting the issue, and don't tear the engine down until TTM authorizes it in writing. Cores, where they apply, come back within 30 days, drainable, uncracked, with mounting surfaces intact.

Which new TTM head fits your engine?

Start with the engine serial number; it's the fastest way to confirm which head your engine takes before a torn-down truck is waiting on the wrong casting. A few of the new loaded heads TTM carries:

• CAT C15 cylinder head 2239250, 3406E / C15 ACERT universal, new
• Cummins ISX15 cylinder head 4374091, X15 SOHC, new
• Detroit Series 60 DDEC V 14L Stage 2 cylinder head 23538858, new

TTM also carries new loaded heads for the Cummins N14 and ISX dual cam, Cat C13 and C12, Detroit Series 60 12.7L and DDEC VI 14L, Volvo D13 and Mack MP8. Search ttmdiesel.com by engine or part number, or call with the serial number.

If you'd rather order the head and supporting parts together on a Cat, see the Caterpillar 3406E / C15 / C15 ACERT cylinder head replacement kit and check the product page for exactly what's included.

TTM also runs an in-house cylinder head shop and diesel machine shop in Houston. If you're weighing a new head against your own, call (713) 675-2435 or email sales@ttmdiesel.com with the engine serial number and what you found when the head came off.

Frequently asked questions

Is a remanufactured cylinder head as good as new?

A head from a documented reman program is machined and tested to OEM specs, and Cat says its reman process restores cores to match the performance specifications of new Cat products. What reman can't change is the casting, which has already been heat-cycled and possibly decked before. If the old head cracked or you're keeping the truck long term, a new casting removes that unknown. For a shorter horizon, a good reman with a written warranty is a reasonable buy.

What is the difference between a rebuilt and a remanufactured cylinder head?

A rebuilt head is a repair: the shop replaces what's worn or out of spec and may weld cracks, so quality depends on that shop. A remanufactured head goes through a defined program of inspection, machining and testing, and Caterpillar says reman is not the same as rebuilding or reconditioning. Even reman programs differ on which parts are always replaced, so ask for the replaced-parts list before you buy.

Do I have to return a core on a remanufactured head?

Usually, yes. Most reman heads are sold on core exchange, and the core charge comes back only if your old head qualifies. At TTM, cores must come back within 30 days, drainable, uncracked, with mounting surfaces intact. A head that came off because it cracked may not qualify. TTM's new heads carry no core charge, so there's nothing to send back and no credit to wait on.

Can I reuse my head bolts?

Not on a torque-to-yield design, and most of the engines TTM works on use one. Those bolts stretch once and are single use, so plan on a new set every time the head comes off, whether the replacement head is new or remanufactured. TTM sells bolt kits for the Cat 3406E, C15, C16 and C18, the Cummins ISX15 and X15, and other engine families. Confirm the bolt type, torque values and tightening sequence in the OEM service manual for your engine.

Does resurfacing a cylinder head cause other problems?

It can if nobody rechecks the geometry. Cutting the deck uses up height above the OEM minimum and moves the valves and injector tips relative to the deck, so valve recession and injector protrusion need to be confirmed afterward. On a 3406E or C15, which use a spacer plate, the head, plate and block surfaces all affect the stack. Check every dimension against the OEM service manual before the head goes on.

Can a C15 head with cracks between the valves be reused?

Techs disagree. Some say Cat has approved reinstalling heads with cracks between the intake valves; others won't run a cracked head at all. Don't settle it by opinion. Cat publishes Reuse and Salvage Guidelines for cylinder head assemblies with the measurements that decide whether a used head can return to service. Check them through a Cat dealer or SIS, and replace the head if it doesn't meet the guideline.

Are remanufactured cylinder heads welded?

Sometimes. Some sellers say reman means no welds, but Cat's reman program applies approved salvage processes to cracks in specific areas, and rebuilt heads may carry welded cracks too. Whether a repair is acceptable depends on where the crack is and on the OEM's salvage rules. Ask the seller in writing what salvage or weld repair was done to the casting before you buy.

Sources

• Cummins ReCon Cylinder Heads (Cummins QuickServe)
• Cummins ReCon Parts Training (Cummins QuickServe)
• The Remanufacturing Process (Caterpillar)
• Lifecycles of a Cat Reman Component (Caterpillar)
• Engine Remanufacturing: Reclaim and Salvage (Caterpillar)
• Cat Reuse and Salvage Guidelines: Cylinder Head Assemblies

Written by the TTM Diesel Tech Team, Houston, Texas. Published October 22, 2026. This article was researched and drafted with AI tools by TTM Diesel and checked against the sources listed before publishing. Confirm specifications in the OEM service manual for your engine serial number.