Collection: Head Gaskets
Head Gaskets
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Head Gaskets
A blown head gasket will sideline a 13 HP engine just as fast as a thrown rod, and the fix costs less than lunch. We carry head gaskets for the Honda GX160 through GX390, the engines bolted to most gas pressure washers on the road today. Read the model stamped on your crankcase, then call 301-519-9274 if you want us to confirm the match before you order.
How a Head Gasket Fails on an Air-Cooled Engine
Car mechanics look for coolant in the oil. Honda GX engines are air cooled, so the symptoms are different and easy to miss. Here is what a leaking head gasket looks like on a pressure washer engine:
- Hard starting when hot, with the recoil rope feeling soft on the compression stroke
- Oil weeping from the seam between the head and the cylinder, usually caked with dust into black grime
- A faint puffing or ticking sound at the head seam under load
- Noticeable power loss, since escaping combustion pressure is power you paid for and did not get
To confirm it, run the engine and brush soapy water along the head seam. Bubbles mean combustion gas is escaping past the gasket. A compression test tells the same story with a number. Most failures trace back to heat. Grass clippings and dirt packed into the cooling fins, a lean carburetor, or long runs at full load will cook the gasket until it loses its crush.
Doing the Job Right
Replacing the gasket is a one-hour job on a GX engine if you follow a few rules. Scrape both mating surfaces clean with a plastic or brass scraper, not a screwdriver, because gouged aluminum will leak again. Never reuse the old gasket once the head has been off, even if it looks fine. The crush is gone. Snug the head bolts by hand, then torque in a crisscross pattern in two stages. The small block engines (GX160 and GX200) use M8 bolts torqued to roughly 17 ft-lb, while the GX240 through GX390 use M10 bolts at roughly 26 ft-lb. Verify against the Honda assembly manual for your exact serial range. Finish by checking valve lash, 0.15 mm intake and 0.20 mm exhaust, since you disturbed the top end. Keep track of which bolt came out of which hole. Some engines use different bolt lengths and swapping them strips threads.
Head Gasket Fitment by Engine Model
| Engine | Typical Rating | Gasket | Price |
|---|---|---|---|
| Honda GX160 | 5.5 HP class | GX160 head gasket | $1.99 |
| Honda GX200 | 6.5 HP class | GX200 head gasket (metal) | $2.99 |
| Honda GX240 | 8 HP class | GX240 head gasket | $18.00 |
| Honda GX270 | 9 HP class | GX270 head gasket | $18.00 |
| Honda GX340 | 11 HP class | GX340 head gasket | $18.00 |
| Honda GX390 | 13 HP class | GX390 head gasket | $18.00 |
Prices can change. Call ahead and we will check availability on the spot.
From the Field
Order the gasket before you pull the head, not after. Any top-end job on a GX engine, whether it is carbon cleaning, a stuck valve, or a leaking seam, ends with a new head gasket, and a two dollar part should never hold up a five hundred dollar machine for a week. The other counter advice we repeat daily: blow out the cooling fins every time you change the oil. Nearly every cooked gasket we see started with fins packed full of debris. If your engine is already apart, look at our cylinder head components and camshaft and crankshaft parts so one teardown covers everything.
Related Parts
- Honda engine parts
- All engine parts
- Cylinder head components
- Pump gasket kits
- Carburetor components
- Engine air filters
- Recoil start assemblies
- Muffler accessories
Local crews can pick parts up same day at our Gaithersburg, MD store.
Frequently Asked Questions
How do I know which head gasket fits my engine?
Find the model code stamped on the side of the crankcase, near the base of the cylinder. It reads GX160, GX200, GX240, GX270, GX340, or GX390. Match the gasket to that code, not to horsepower, since clone engines borrow HP ratings loosely.
Can I reuse a head gasket if it looks fine?
No. The gasket seals by crushing when torqued the first time. Once compressed it cannot crush again, and a reused gasket almost always leaks within a few hours of runtime.
What are the signs of a blown head gasket on a pressure washer engine?
Power loss, hard hot starts, oil weeping at the head seam, and a soft feel on the pull rope. Soapy water brushed on the seam while running will bubble where gas escapes.
What torque do Honda GX head bolts take?
Roughly 17 ft-lb for the M8 bolts on GX160 and GX200 engines, and roughly 26 ft-lb for the M10 bolts on GX240 through GX390. Torque in a crisscross pattern in two stages and confirm the spec in the Honda assembly manual for your serial range.
Do I need to adjust the valves after replacing the head gasket?
Yes. Set lash to 0.15 mm on the intake and 0.20 mm on the exhaust with the piston at top dead center on the compression stroke. Skipping this step causes hard starting that gets blamed on the new gasket.
Will these gaskets fit clone engines like Predator?
Often yes, since most clones copy the GX160, GX200, or GX390 architecture. Measure your bore or call 301-519-9274 with the engine specs and we will tell you straight whether it fits.