Aftermarket Gaskets

[Cavalry]

I need to pull the upper end on my L345. For the cost of just the head gasket I can get all the top end gaskets. Are there problems with aftermarket gaskets or should I stick with OEM?

 

[bosshogg]

I would have zero issues with using aftermarket gaskets.

 

[Breeze]

That's a tough question.

The OEM head gasket is produced to the exacting requirements of your Kubota engine and while a knockoff might function just as well, I wouldn't want to do a second tear down to repair a blown gasket and risk engine damage in the process. For me, that would be like jumping with an aftermarket parachute.

While I'm sure you realize it, most gaskets are just softer stuff to bed metal to metal assemblies with very low pressures seen, to maintain a seal. The head gasket sees it all, coolant, lube and combustion pressure.

Sidebar: I still recall being faced with my first Detroit twelve cylinder head which was six cylinders long, 300 lbs. or so, and had a jag of o-rings in addition to the gasket. Just lowering this beast into place, on an angle, was going to be hard enough, but how the heck to keep all those o-rings seated. Help?

Up steps a more seasoned tech with a small can of Crisco in hand, daubed each o-ring with some hydrogenated vegetable oil and bam! As soon as she heats up the first time, the Crisco disappears. One pinched o-ring and you would be in deep, deep water. (This job was done on the deck of a 156' Ocean going Research Vessel, in situ, as they say)

Best of Luck

 

[Eric McCarthy]

I don't see any shame in an aftermarket gasket and a bead of RTV around the edges...

 

[Breeze]

I don't see any shame in an aftermarket gasket and a bead of RTV around the edges...

RTV applied to the block around the edges of a head gasket?

A head gasket is actually three separate gaskets, each with its own pressure requirements.

#1 Seal Combustion Gas within each cylinder and valve chamber.
#2 Seal water galleries from external or internal leakage.
#3 Seal lubrication galleries from external or internal leakage.

Each of these three types is repeated in multiple locations on each head.

Most modern head gaskets are MLS, Multi layer steel and include a sealing coat. I can't say for sure this is what Kubota uses as I've never replaced a Kubota head. Gaskets require a very smooth surface on the block and head, especially for MLS types. They also require flatness of around .002 to seal at the recommended torque. The gasket's thickness is also critical to maintaining proper combustion chamber pressure, especially on a diesel engine. If for instance you shave either the head or block to regain flatness, you would need to shim the gasket to keep volume the same. Kubota makes five different head gaskets for the engine in my L3700, Marks 15, 20, 25, 30 and 35. They recommend measuring piston protrusion and based on the measurement, using one of these five gasket thicknesses. These make using shims unnecessary but it is very important to use the correct Mark to insure correct combustion chamber volume. The Kubota workshop manual says nothing about using sealer in replacing the gasket which implies, "don't do it".

Some applications with some gaskets, a spray on coat of sealer is sometimes used. The resulting coat is extremely thin, say less than .002. Generally it is recommended however not to use additional sealer but to insure the surfaces are free of flaws and flat.

Applying a coat of RTV around the perimeter of the mating surfaces would guarantee blow by of combustion gas and leakage of both oil and coolant because the internal sealing rings would not be compressed properly when the head was torqued in place.

Don't mean to bust your chops but this is just plain bad advice.

Back to the OP's original question, who can say what you get with an aftermarket head gasket. The one you pay dearly for, from Kubota, will be the correctly engineered gasket for their engine.

You pays your admission and you takes your chances.