Guides

Engine Gasket Sets: Head Set vs Full Set vs Bottom Set

By the Agroparts engine specialists · Last updated: 6 July 2026

A head gasket set covers everything above the block for a top-end job: head gasket, valve cover, manifold and injector seals. A bottom set covers the lower end: crankshaft seals, sump gasket, and the timing cover gasket. A full set combines both for a complete rebuild. Order by the job you are doing, and remember head bolts come separately.

What each engine gasket set contains

A head gasket set, also called a top set or de-carbonising set, holds the gaskets and seals you disturb when you remove the cylinder head. That means the head gasket itself, the rocker or valve cover gasket, the intake and exhaust manifold gaskets, and the smaller seals around injectors, glow plugs and the thermostat housing. Many sets also include the valve stem seals. What it does not include is the head bolts, so order those alongside the set. You use a head set for a head skim, a valve job, or any repair that lifts the head and leaves the bottom end sealed.

A bottom set, or bottom-end set, covers everything below the head gasket line. It includes the front and rear crankshaft oil seals, the sump (oil pan) gasket, the timing cover gasket, and the oil pump and pickup seals. Some engines add main bearing side seals here. You reach for this set when you drop the sump, replace the crank seals, or refresh the lower end without touching the head.

A full set, sometimes called a complete set, is the head set and the bottom set together in one box. It seals the engine end to end for a full strip and rebuild. A few suppliers label the combined kit a conversion set, but on some ranges that term names a narrower kit, so confirm the contents against the part number rather than the label alone.

Contents vary by engine family and even by build date within a family. Two engines that share a block can take different injector seals or a different rear main seal design. Before you order, an Agroparts engine specialist confirms the correct set by engine number or OEM code, so the box matches the engine on your bench. We have rebuilt hundreds of diesel engines with Emmark parts and have been an authorised Emmark distributor since 2018, so a set matched to your engine number is the norm here, not the exception.

How to choose the right set for the job

Start from the job, not the symptom. If you are pulling the head to skim it, fix a blown head gasket, or do valve work, the head set carries every seal you break going in and coming out. Buy a full set here and you leave unused bottom-end gaskets on the shelf. Order your head bolts at the same time, since the set will not contain them.

If the head stays put and the work is underneath, the bottom set is the match. A rear crank seal leak, a weeping sump gasket, or a timing cover reseal after a front-of-engine repair are all bottom-end work. You keep the top end sealed and avoid disturbing a good head gasket.

For a full teardown, an overhaul, or an engine you are rebuilding on the stand, order the full set. It costs less and moves faster than buying a head set and a bottom set separately, and it puts a fresh gasket at every joint you open. A rebuild stalls fast when one small seal is missing.

One rule saves the most returns: match the set to the engine, not just the model. Log the engine number and, where you have it, the OEM gasket code. Agroparts cross-references more than 13,000 OEM codes against our Emmark range, so a specialist can confirm the correct set before you commit the order.

Why the wrong set costs you a second job

A missing gasket stops a rebuild dead. When the box lacks the one seal you need at the point of assembly, the engine sits open, the bench is tied up, and the machine is off the field waiting on a part. In busy season on tractors, harvesters or construction machinery, that lost day is the real cost, not the gasket.

The same logic applies to head bolts. Most diesel engines run torque-to-yield bolts that stretch on first tightening and are single-use, so they are not part of a gasket set and cannot be reused when you refit the head. Order your head bolts together with the gasket set so the job is not held up at the last step, waiting on a fastener you assumed was in the box.

Reusing an old head gasket to keep going is a false saving too. Once crushed to its clamped thickness and heat-cycled, it will not seal reliably again. A reused head gasket can let combustion gas into the coolant or coolant into a cylinder, which shows as white exhaust smoke, pressurised coolant, or oil and water mixing.

Ordering a full set to be safe when you only open the top end has its own cost. You pay for bottom-end gaskets you never fit, and part-used sets are hard to return cleanly. Getting it right the first time comes down to the part number: when a specialist confirms the set against your engine number before dispatch, you open one box and find every seal the job needs. We back orders with a 12-month warranty and 365-day returns, so a confirmed part is a covered part.

Signs you need a gasket set, and which one

White exhaust smoke and coolant loss with no external leak often points to the head gasket letting coolant into a cylinder. That is top-end work: plan on a head set, and have the head checked for flatness while it is off, since a warped deck will fail a new gasket fast. Order the head bolts with the set so the refit is not held up.

Oil and coolant mixing, seen as a mayonnaise-like film under the oil cap or oil in the coolant, can come from a failed head gasket or a cracked head. On some engines an oil cooler or a lower gasket is the culprit. Confirm the source before you order: a head gasket fault means a head set, while a lower oil cooler seal may sit in the bottom set.

An oil leak from the back of the engine, near the bellhousing, usually points to the rear crankshaft seal. That is a bottom set job, and it is worth doing with the gearbox off, since access is already open. A weep from the front pulley area points to the front crank seal, also in the bottom set, alongside the timing cover gasket.

A full rebuild, high hours, or an engine already stripped takes the guessing out. Order the full set and reseal every joint at once, and add the head bolts to the order. Whichever way the diagnosis points, an Agroparts specialist confirms the exact set by engine number or OEM code, checks availability on that part, and quotes delivery before you order.

Frequently asked questions

What is the difference between a full set and a bottom set?

A bottom set seals the lower end only: the front and rear crankshaft seals, the sump gasket, the timing cover gasket, and the oil pump seals. A full set adds the head set to that, sealing the engine end to end for a complete rebuild. Choose a bottom set for work under the head, and a full set when you strip the whole engine.

Does a head gasket set include the head bolts?

No. A head or top gasket set contains gaskets and seals only, and the head bolts are ordered separately. Most diesel engines use torque-to-yield stretch bolts that are single-use and must be replaced when you refit the head, so order them together with the set to avoid holding up the job. Ask an Agroparts specialist to confirm the right bolts for your engine.

Can I reuse a head gasket if it looks undamaged?

No. On most diesel engines the head gasket is a single-use part. Once it has been clamped to its final thickness and heat-cycled, it will not seal reliably again, and a reused head gasket can leak combustion gas, oil or coolant. Fit a new head gasket every time the head comes off.

How do I order the right set the first time?

Give the engine number, and the OEM gasket code if you have it. Agroparts cross-references more than 13,000 OEM codes against our Emmark range, and a specialist confirms the correct set before you order. Contact export@agroparts.ro or WhatsApp +40 758 366 275 to check availability, then we confirm delivery: 24 to 48 hours in Romania via GLS, or tracked FedEx across Europe with the quote confirmed first.