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How to Change a Head Gasket

How to Change a Head Gasket

Oct 20th 2019

How to Change a Head Gasket

Yamaha Raptor 700 top end gasket kit
Top-end gasket kit for a Yamaha Raptor 700 ATV, including head gaskets

The idiom, “blown a head gasket” is used to describe whenever someone is having themselves a major temper tantrum in response to a negative reaction. It basically means to “lose one’s cool”, which is exactly what happens when a head gasket fails on an internal combustion engine. A blown head gasket can leak vital fluids such as coolant and oil which can result in overheating and, in turn, catastrophic irreparable engine failure.

Blown head gasket? Probably.
Coolant and oil mixing inside the engine is often the tell-tale sign of a blown head gasket

Head gaskets are engineered to be durable enough to withstand the extreme heat and pressures of an internal combustion engine, but they’re not intended to last forever. To ensure that your engine keeps its cool, you’re going to need to periodically inspect the head gaskets for wear and degradation. If you possess a fair bit of mechanical aptitude but have never attempted to change out your own head gaskets before, we’ll show you how in 4 easy steps.

NOTE: The following instructions are for common applications. However, some makes and models require the engine to be removed from the chassis in order to access the cylinder head. If you do not have the experience and the resources, you should not attempt to perform this job yourself and instead, seek assistance from a professional mechanic or a qualified service and repair center.

YOU WILL NEED:

  • Shop manual for your exact make, model, and year of motorcycle or ATV
  • Ratchet and socket set
  • Gasket scraper
  • Combination wrenches
  • Torque wrench
  • New gasket
  • Gasket dressing

STEP 1:

Remove the exhaust headers, fuel tank, fairing (if equipped), and any obstructions so that you can access the engine. For liquid-cooled engines, drain the coolant. Be sure to set aside the removed parts in a safe area away from the working space to prevent damage and/or loss of said items.

STEP 2:

Loosen the cylinder head bolts and remove the cylinder head. Most likely, the old gasket will tear and leave behind bits of itself stuck on the head and the engine block. Use your scraper to remove this debris and be sure not to let it fall into the cylinder or back up through the head. Be extremely careful to not use excessive force or hardened scrapers to remove the old gasket material. You run the risk of causing deep scratches and grooves that will prevent the gasket from forming a correct seal, thus leading to engine damage.

TIP: For V-twin or V-banked engines, it might be a good idea to change out both head gaskets as both will likely have aged the same.

STEP 3:

Apply a light layer of gasket dressing to your new gasket and place it on the surface where the engine block meets the cylinder head. Don’t be sloppy and do not overapply the gasket dressing the excess can spew back out and clog the intake and combustion chambers. Be sure to install it in the proper direction and alignment as a malaligned gasket will be just as ineffective as blown or severely degraded one. Pay attention that the gasket lays flat and that there are no bends or gaps. Reinstall the cylinder head and tighten the bolts to the proper torque specifications as per your shop manual.

TIP: It may be difficult to acquire replacement gaskets for vintage or extremely rare engines. Race-Driven stocks a wide array of complete gasket kits for popular domestic and foreign motorcycles and ATVs, including certain classic and vintage models. However, if your exact make and model is unlisted and you cannot procure the necessary replacement gasket, you may have to fabricate your own out of blank gasket material sheets. These are available at your local auto parts store.

STEP 4:

Replace exhaust headers, fuel tank, fairing (if equipped) and any other obstructive components that were removed back in Step 1. If your engine is of the liquid-cooled variety, refill the engine coolant to the specifications as noted in your shop manual.

TIP: At this point, you might want to run your engine for a few minutes and check for fluid leaks and vacuum leaks. To learn how to check for engine vacuum leaks, click here to check out our previous entry on the subject. If no leaks are found, you can run your engine for 15-20 minutes so that a proper heat cycle occurs. This will help the gasket and gasket dressing “cure” and be ready in time for normal operating use.

1971 Honda CB750
Honda's famous inline 4-cylinder 750four engine out of a 1971 CB750