GM 6.6L Duramax Diesel – How To Choose The Correct Head Gasket

GM 6.6L Duramax Diesel - How To Choose The Correct Head Gasket
GM 6.6L Duramax Diesel - How To Choose The Correct Head Gasket

So, The GM 6.6L Duramax diesel seems to be causing a lot of controversy. Consequently, One big issue is, what the is correct head gasket is for this application.

As a result, Many installers are just picking the thickest gasket available to avoid any clearance issues. While, Hoping that performance and reliability will not suffer.

Above all, To maximize performance and longevity there is a proper gasket to use on the GM 6.6L Duramax Diesel. Consequently, After you have confirmed the piston protrusion. Therefore, Using the wrong head gasket on this engine could cause engine damage.

GM 6.6L Duramax Diesel - How To Choose The Correct Head Gasket
GM 6.6L Duramax Diesel – How To Choose The Correct Head Gasket

Important Note:

The left and right cylinder head gaskets are not interchangeable. As a result, Improper placement of the cylinder head gasket will block coolant and oil passages. Hence, Blocked coolant and oil passages will cause severe engine damage. But, It is physically possible to install the head gasket “flipped” end-to-end. The gasket markings should be up when correctly installed.

As a result, GM offers three different thickness head gaskets depending on the amount of piston protrusion the engine has.

There are also different head gaskets for the left and right bank of the engine. Also, Measure piston protrusion to confirm you are picking the correct gasket. Therefore, Always check both sides as they are not always the same.

Use a dial indicator on the deck surface and check the piston in two different locations on each bank.

Piston Protrusion Tool
Piston Protrusion Tool

Finally, Place the pointer right above the piston pin centerline to prevent inaccurate readings. As a result, Of the piston rocking in the cylinder bore. Rotate the engine through (TDC) while noting the maximum reading on the dial indicator.

Obtain the maximum value of protrusion for each bank of cylinders. Determine your gasket options using the information below.

GM 6.6L Duramax Diesel - How To Choose The Correct Head Gasket
GM 6.6L Duramax Diesel – How To Choose The Correct Head Gasket
Gasket Selection
Gasket Selection

GM 6.6L Duramax Diesel – How To Choose The Correct Head Gasket

NOW THAT YOU ARE COMPLETELY CONFUSED, WHAT DO YOU USE ?

Well , Felpro has solved that problem for you, It is your choice but this is what most people are using.

26401PT
26401PT

FEL-PRO #26401PT (LH) AND 26402PT (RH)

Accommodate all model years as well as OE grades “A,” “B” and “C” and overbored blocks

26405PT
26405PT

FEL-PRO #26405PT (LH) AND 26406PT (RH)

.010-inch thicker gaskets accommodate blocks that have been overbored and deck milled (all grades & model years)

PDF Version Of The Felpo Information Including Torque Specs

Fel-Pro-IS-Duramax-6.6L-Diesel-Flyer

Conclusion

So, The GM Duramax 6.6 diesel is a great engine. But, If you keep it long enough, you will probably be replacing the head gaskets at some point. So, If you are using aluminum heads, with a iron block, sooner or later you will have head gaskets issues. Finally, Now you go to order parts and you are confronted with a bunch of choices.

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