Head Gasket Thickness: What to Confirm Before Ordering

A quotation that says only “head gasket for this engine” leaves an important question unanswered: which version? A distributor needs enough information to order the requested part. The workshop needs to establish why that part is correct for the engine being assembled. Keeping those responsibilities clear avoids turning a familiar-looking gasket into an unsupported replacement decision.

What determines the required thickness?

Start with the engine code and the repair information for that exact version. Do not choose a gasket from vehicle model and displacement alone. Record the existing part reference when readable, but ask the workshop to confirm the selection rather than treating the removed part as approval.

Elring explains that diesel engines may offer several gasket thicknesses, with selection based on piston protrusion measured to the manufacturer’s specifications. Its brochure uses the largest applicable piston-protrusion result to select the gasket from the corresponding product information. This describes a selection principle, not a measurement procedure or a set of limits for every engine.

For purchasing, request the workshop’s selected gasket reference and the repair-information reference used. Where a measurement-based selection applies, retain the relevant results and the selected grade together. The buyer should not invent a thickness from incomplete measurements or substitute a generic internet chart for the workshop’s applicable instructions.

What do holes and notches actually tell you?

Elring describes holes or notches as identifiers for gasket thickness in the relevant range. Photograph the identification tab and the complete gasket, then match the marking to the exact catalog entry. A count without an engine reference and product range is incomplete information. Do not assume that the same count means the same thickness across different engines.

Ask the supplier to state the manufacturer, full part reference and thickness designation used in its catalog. If two proposed products use different references, request a documented cross-reference for the exact application. Keep this separate from the question of whether the gasket physically resembles the old one.

A useful photo set shows both faces, the identification tab, any readable reference and the overall hole layout. Photograph packaging separately so the label can be matched to the item. These pictures support identification; they cannot establish an unrecorded dimension or prove that a gasket is suitable after machining.

Does machining mean you should order a thicker gasket?

Do not approve that substitution on machining history alone. Victor Reinz’s cylinder-head installation guidance requires observing the manufacturer’s minimum dimensions for the block and head, as well as the specified gasket thickness. The appropriate response is to check the permitted repair and selection rules for the engine.

Ask the workshop to record which component was machined and its resulting dimensions against the applicable limits. If the proposed gasket differs from the original reference or grade, request the technical basis before approving the purchase. A thicker gasket should not be used as an undocumented workaround for an unresolved repair decision.

Thickness selection also does not replace checking the sealing surfaces. Our separate explanation of cylinder-head flatness and surface finish addresses those different questions. This article does not provide machining allowances, surface specifications, tightening instructions or clearance limits.

Build one order record that both sides can check

Use the following fields as a purchasing record. A blank field should prompt a specific question, not a guessed value. For a multi-engine order, keep one record per engine version and selected gasket reference.

• Engine: code, vehicle identification where relevant, and the workshop’s confirmed version.
• Selected gasket: manufacturer, full reference, catalog application and thickness designation.
• Selection basis: applicable repair-information reference and the person who approved the selection.
• Workshop evidence: measurement record where required, machining history and any unresolved question.
• Visual evidence: complete gasket, marking tab, readable references and packaging label.
• Commercial scope: quantity, package contents, destination and whether any proposed substitute needs separate approval.

Send the record with the inquiry, then ask the supplier to confirm the quoted reference in writing. If the reply offers an alternative, compare the application and selection basis before accepting it. Add the agreed reference to the purchase order so a later packing or receiving check has a clear target.

What can the buyer check when the shipment arrives?

Compare the delivered reference, visible grade marking and quantity with the approved order. Record the packaging label and the item together before passing them to the workshop. If the reference or marking differs, hold that item for clarification and preserve the original packaging.

These are identity and order checks, not an installation release. The workshop must still follow the applicable engine and gasket instructions. For a shipment containing an engine or major assembly as well, use a separate receiving-inspection record; do not let a correct gasket label stand in for the rest of the inspection.

Frequently asked questions

Can I order the same marking as the removed gasket?

Use it as an identification lead, then have the workshop confirm the required grade. Retain the old reference and photos, especially if the engine’s repair history is unclear.

Can I select thickness from a photograph?

A photograph can show a readable reference or grade identifier. It cannot replace required measurements or the applicable catalog and repair information.

Should the quotation include a numeric thickness?

Ask for the exact catalog designation and its stated thickness information, where provided. Avoid an isolated number without a manufacturer and part reference.

Technical references and image credit

The technical basis is Elring’s Cylinder-Head Gaskets, page 28, and Victor Reinz’s Practical Tips: Preparation and Cylinder-head Installation, page 14. These general publications do not establish the correct part or repair limits for a particular engine.

The cover is an illustrative edit of Sonett72’s public-domain gasket reference. Unrelated pieces and the editorial number were removed; the gasket was rotated for the cover. It does not identify a thickness grade, a diesel application or a NANXI product.