Yanmar Saildrive Oil

[Captain Bill]

I have just had the second failure of the front main oil seal on my Yanmar SD40 saildrive in a little over 2 years. Prior to the last failure I had changed the oil in the drive and used Quicksilver High Performance Gear Lube. The service manual for this drive is for several models and specifies a number of acceptable 80W-90W oils. The manual calls for High Performance Gear Lube for the 4T model of the drive (mine is not the 4T model). The chart on the specifications page says the High Performance Gear Lube is acceptable for the other models. A chart found later in the manual does not make this statement. When I had the drive repaired last time one of the other specified products was put in by the shop. I had the boat hauled in April and the saildrives were completely drained for 3 days while on the hard so little to no residual oil should have been present in the drives. I again used the Quicksilver High Performance Gear Lube as it was easy to obtain. Now 2 months later the main seal is gone again.

Is anyone aware of a compatibility issue with this product and the Yanmar oil seals?

[ggray]

What are you calling the front main seal ? The seals around the output shaft? Is the measure of failure water intrusion ?

I have SD20s, and use Amsoil synthetic,

[Captain Bill]

This is the oil seal around the input shaft (pinion). There is no water intrusion just lots of 90w coming out of the bell housing. I was Lucky I happened to smell the oil and shut down the engine. Lost about half the oil in the unit. I had only looked at it an hour before and there was no issue. Hopefully I managed to shut it down before serious damage was done. At least there were no bad noises coming from the drive. I needed to use it for 15 minutes to get it docked. Even though I filled it to the full line before starting it again, after docking there was no oil on the dipstick and a lot in the trap below the engine so the seal has had a major failure. I have ordered the parts for a repair but they won't be here for 3 weeks. It almost seems too much for just a leaky oil seal, but there's not much else in that part of the drive. About the only other possibility I can think of is that the bolts that hold the oil seal assembly in place have failed and the whole assembly has come loose. I guess I'll see when I get it apart.

Have you had good luck with the Amsoil?

[ggray]

I thought that was the seal you were talking about, but hadn't heard of one failing before. If the SD40 is unvented as the SD20 is,maybe pressure is pushing the seal out ??

I've sensed that marine gear lubes don't have as tough a job as say a truck gear lube. It doesn't have to deal w/ high temps.

The Amsoil seems to be doing fine. I just hope it does as claimed...deal with water dilution.