Cylinder Head Gasket Sourcing: 7 Checks Before You Place the Order

Who This Checklist Is For

If you're ordering a cylinder head gasket — whether it's for a passenger car, a diesel truck, or a custom MLS application — and you don't have time to deal with a wrong shipment, this is for you.

I handle gasket sourcing orders at Gasketgrove Sourcing. I've been doing this for about six years now. In my first year (2019), I made the classic "I know the make and model, that's enough" mistake on a batch of 40 head gaskets. Half of them didn't match. That order cost us roughly $1,100 in returns and a week of back-and-forth with the buyer. Since then, I've built a 7-step pre-order checklist that our team uses on every cylinder head gasket order. We've caught 62 potential errors with it in the past 18 months — everything from wrong bore sizes to missing valve cover gaskets in kits.

Here are the seven checks, in order.

Step 1: Lock Down the Engine Code, Not Just the Vehicle

This is the one that bites almost everyone. A "2018 Ford F-150" could have a 2.7L EcoBoost, a 3.5L EcoBoost, or a 5.0L V8. Each takes a different automotive head gasket. If you order by vehicle year and model alone, you've got maybe a 40% chance of getting it right.

What you need instead is the engine code — that alphanumeric identifier stamped on the block or in the VIN. Things like:

• Cummins ISB 6.7 (not just "2019 Ram 2500")
• GM LS3 (not just "2010 Camaro SS")
• VW CJAA (not just "2013 Jetta TDI")

If your buyer or your supplier can't give you the engine code, stop. Don't guess. I've seen a $3,400 truck head gasket order go sideways because someone assumed a 6.7L Cummins ISB and a 6.7L Power Stroke were interchangeable. They're not. Not even close.

Step 2: Confirm the Gasket Type (And Material)

Cylinder head gaskets aren't one-size-fits-all in construction, either. You've got:

• MLS (Multi-Layer Steel) — the default for most modern engines, especially anything with forced induction or high compression
• Composite — still common on older or lower-output engines
• Graphite — often seen in diesel head gasket applications
• Copper — usually custom or racing applications

If you order an MLS gasket for an engine that was factory-spec'd with composite, you might introduce sealing issues — or worse, head warpage over time. I'm not a metallurgist, so I can't speak to the material science in detail. What I can tell you from a sourcing perspective is: confirm the OE spec first, and only deviate if your customer's engine builder specifically asks for it.

This is also where custom head gasket requests start. If someone asks for a one-off thickness or a non-standard bore opening, that's a different workflow (see Step 6).

Step 3: Check the Kit Contents — Every Single Piece

Head gasket sets vary wildly in what they include. One supplier's "full set" might come with intake manifold gaskets, valve stem seals, and exhaust gaskets. Another's might be just the head gasket plus valve cover gaskets.

We once shipped a head gasket set that we assumed included the intake manifold gasket. It didn't. The buyer's shop had the engine torn down, gaskets laid out on the bench, and then found out they were missing a $4 piece. That $4 piece held up a $2,800 job for three days.

Ask for the itemized kit list before ordering. If the supplier can't provide one, that's a red flag.

Step 4: Verify Thickness and Bore Size

This one gets skipped a lot because it's "technical." But thickness matters — especially if the head or block has been machined. A gasket that's 0.010" too thin can change your compression ratio and cause detonation. Too thick, and you lose compression and power.

Bore size is equally critical. A gasket with a 4.030" bore opening on a 4.060" bored-out block won't seal properly. I've seen this happen on rebuilt diesel head gasket orders where the machine shop bored the cylinders but nobody updated the gasket spec.

If you're unsure, ask your engine builder for the current bore and deck height. Don't rely on factory specs if the engine's been touched.

Step 5: Get Lead Times in Writing — And Budget for Certainty

Here's where I'll take a side: in urgent situations, paying for delivery certainty is worth more than saving on unit price.

In March 2024, we had a customer who needed 12 truck head gaskets for a fleet repair. Standard lead time was quoted at 3–4 weeks. Rush delivery was $400 extra. They went back and forth on it for two days — I get it, $400 on top of an already expensive order stings.

They chose rush. The gaskets arrived in 8 days. The fleet was back on the road. If they'd gone standard and the shipment slipped by even a week, the downtime cost would've been closer to $6,000 in lost operating days.

I once went the other way on a smaller order — tried to save $80 by choosing the cheaper shipping option. The gaskets showed up 11 days late. We lost the customer. Not worth it.

My rule now: if there's a hard deadline on the other end, get the lead time confirmed in writing (email counts), and price the rush option before you commit. "Probably on time" is the most expensive phrase in sourcing.

Step 6: For Custom Gaskets, Nail the Specs Early

Custom head gasket orders — non-standard thickness, special coatings, one-off bore patterns — take longer and have zero room for ambiguity. You need:

• A clear drawing or the original gasket as a reference
• Material specification (MLS layers, coating type, etc.)
• Operating conditions: boost pressure, compression ratio, coolant type
• Quantity — because setup costs don't scale linearly

I've seen a custom gasket order get held up for two weeks because the buyer and the manufacturer disagreed on what "0.050 inch thickness" meant — compressed vs. uncompressed. That's the kind of thing you sort out before the order, not after.

At Gasketgrove, custom work is probably 20% of what we handle. It's also where 80% of the delays happen. Not because the manufacturing is slow — because the spec communication isn't clear.

Step 7: Do a Pre-Submission Readback

This is the step most people skip. Before you hit "confirm" on the order, read the entire spec back to yourself — or better, to a colleague who knows nothing about the order.

I started doing this after a mistake in Q1 2023 where I approved a batch of 80 head gaskets with the wrong valve cover gasket size. Everything else was right. Engine code, material, thickness, bore. But the valve cover gasket was for a different head design. $640 in returns, plus the customer had to wait another two weeks.

Now, I read every line out loud. It feels silly. It catches things.

Common Mistakes That Keep Showing Up

Even with the checklist, some errors persist. Here are the ones I see most often:

• Assuming "OEM quality" means "OEM part." These aren't the same thing. Aftermarket gaskets can be excellent — but verify the actual manufacturer and spec, not just the marketing language.
• Not accounting for head/block machining. If the deck has been surfaced, your gasket thickness needs to change. Talk to the machine shop.
• Ordering by old part number. Supersessions happen. A part number that worked in 2020 might be discontinued or replaced. Always cross-reference with the current catalog.
• Forgetting about the second gasket. V-engines need two head gaskets. I've seen an order for "one head gasket set" turn out to be for one side only. The buyer was not happy.

None of these are exotic problems. They're the basics. But basics get skipped when you're in a hurry — and that's exactly when they cost you the most.

The checklist isn't perfect. I still miss things. But going from a 30% error rate on first shipments down to under 5% — that change came from slowing down for about four minutes before placing each order.

Four minutes. That's the whole investment.