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What causes DR650 base gasket leak?

35 posts in this topic

Some DR650 owners claim that too much engine oil can cause base gasket leak. I am wondering how the extra oil in the sump can result in an increase in oil pressure to cause the leak. Maybe some of you here who are more mechanically inclined can better explain the reason behind it. :thumbsup:

Thank you all in advance.

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Still don't get it. I thought the oil pressure is determined by how fast the oil pump is rotating, as long as the oil pickup is completely submerged in the oil.

The only thing that I can think of is that when the piston rod comes in contact with the oil in the sump, it will make big oil splashes inside the engine and introduce air bubbles into the oil; but one will have to grossly overfill the crankcase in order for that to happen. In this scenario, I would expect less oil pressure in the oil lines due to the introduction of air into the system.

Any thoughts???

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If there is much oil in the crankcase, the pulsations in crankcase pressure will be higher. So theoretically this can cause a leaking basegasket. But for a leaking basegasket to happen in the first plase, it has to be a weak one to begin with.

Unfortunately the pre 2003 have a weak basegasket. Not that they all go leaking, far from it. But it happened too often so Suzuki decided te design a better one.

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It starts to make more sense now. With more oil (non compressable) and less air (somewhat compressable) volume in the cranks case, all gaskets will have to endure greater (air) pressure when the piston travels downward.

Is the crankcase vented at all?

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Yes (they always are afaik). But the question is if the venting system can keep up with the pressure pulses.

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Crank case is vented to the airbox. The concept is very similar to the suspension. If you add more oil to your forks you have less air in that sealed area and it increases the internal pressure.

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what everyone said is true....the crankcase pressure properties of a big 650 single, vibration, temperature, and poor gasket design leads to leaking/failure. Excess oil exacerbates the problem. Warpage, a common source of gasket failure is non existent.

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The problem of base gasket failure is caused initially from the expansion of the cylinder as it heats up while the engine case is still relatively cool. In this design the cylinder is sandwiched and floats between the head and case. Everytime the cylinder warms and cools, there is movement between the case and cylinder that eventially will fracture or break a conventionally made paper type gasket.

New gasket technology is using a pressed stainless steel material coated with a heat activated sealer that is tear and break resistant. The sealer remains somewhat flexable and will allow a small amount of movement while still affording a seal. These new gaskets will also fail in certain applications but are much better than anything previously used.

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All this talk of oil pressure, air pressure, etc. is fine, but the bottom line is that if the gasket for the pre 2003 DR650s was any good we wouldn't have the leaks. The new gasket doesn't have the problem regardless of oil level.

Flea

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All this talk of oil pressure, air pressure, etc. is fine, but the bottom line is that if the gasket for the pre 2003 DR650s was any good we wouldn't have the leaks. The new gasket doesn't have the problem regardless of oil level.

Flea

But the question was what causes the leak.

My 2001 hasn't leaked yet.

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For those who have not had a leak in the pre-2003 models, please post the mileage on the bike.

I am wondering if it's just an isolated problem for a few of us, or if it's an epidemic for all pre-2003 owners. I have my eyes on my gaskets everyday after reading all the leaking threads on TT.

Sorry, I am hijacking my own thread.

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mine leaked at about 3ooomiles.

fixed with black rtv hi temp.also vented crankcase to atmosphere.

when it gets rebuilt i will get the new gasket.......

see fix in archives MZRATT

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Do pre-03 Euro mdels have the leaking gasket problem as well ? I never heard of it in the reviews I read about the bike

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Do pre-03 Euro mdels have the leaking gasket problem as well ? I never heard of it in the reviews I read about the bike

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Due to the fact that DRs run lean from the factory and therefore run hotter, could this factor contribute to a leaking base gasket?

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I have a 2002 that leaked. I was lucky enough for it to happen under warentee. I'm sure I put too much oil into it. I just add 2 qts and I'm done.

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Allowing your crankcase vent hose to become clogged can raise crankcase pressure too, It is an easy item to overlook

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Some DR650 owners claim that too much engine oil can cause base gasket leak. I am wondering how the extra oil in the sump can result in an increase in oil pressure to cause the leak. Maybe some of you here who are more mechanically inclined can better explain the reason behind it. :confused:

Thank you all in advance.

The weak link in any properly designed engine concerning crankcase pressure is the rubber seals.... not the gaskets. Suzuki just goofed with the cylinder base design on this bike. Either the span is too large between securing bolts or the cylinder casting expands and contracts more than engineers anticipated. That is why they had to come up with a steel base gasket. I have a question though.... I hear the new base gasket is laminated steel. Hopefully they were able to keep the thickness the same as the paper gasket or there goes some of our limited compression ratio. :confused: I knew there was a good excuse to install the high comp piston when I get around to fixing the leak. :confused:

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