My gearbox on my Hunter 34 has gone dry by the end of each season which is about four months. I put not more than 50-100 hours on it per season. I can't seem to find any oil leaking from the gear box. Befor I pull the gear box out, I wanted to continue to use the boat for this season. I check the oil lefel in the gear box and top it off ever two weeks. I was wondering if I should use a transmission sealer or extra heavy oil in the gear box to top the leak. any suggestions? Is this a problem with Yanmar gear boxes?
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My '92 37.5 is doing great
I have had the 37.5 since 1992, and the gear box has never used a bit of oil, and I never had to refill it. The only time I put new trani oil in it is during an oil change. What year is your boat, and what oil are you using? Are you using Chevron ATF?
I have had the 37.5 since 1992, and the gear box has never used a bit of oil, and I never had to refill it. The only time I put new trani oil in it is during an oil change. What year is your boat, and what oil are you using? Are you using Chevron ATF?
Ours uses 30wt motor oil
The transmission in our H'31 2GM20F engine uses 30 wt motor oil. I think that you have a 3GM30F and it also uses motor oil. I would continue to fill it up like you have been doing and have it resealed after the seasion is over.
The transmission in our H'31 2GM20F engine uses 30 wt motor oil. I think that you have a 3GM30F and it also uses motor oil. I would continue to fill it up like you have been doing and have it resealed after the seasion is over.
In my Yanmar manual
I have the Yanmar engine manual for my 3HM35F. It calls for ATF oil, which is Automatic Trani Fluid for cars. I use Chevron ATF.
I have the Yanmar engine manual for my 3HM35F. It calls for ATF oil, which is Automatic Trani Fluid for cars. I use Chevron ATF.
Use Synthetic ATF
Hi: I have been down this road a few times. My first thought is that if the gear has been run dry it may not live long. As for where it is going I can't help however. The gears are under tremendous pressure. They tend to create a lot of heat as well. I found that draining, flushing out all the worn sediments and then putting in a high performance ATF has helped me greatly and the gear sounds much better. I used Redline ATF which is available and most speed and custom racing shops. It is designed to handle high heat which will remain a constant viscosity regardless of the heat which could help in slowing leaks. Regular ATF will thin at high heat and leak faster and will burn as well.
Hi: I have been down this road a few times. My first thought is that if the gear has been run dry it may not live long. As for where it is going I can't help however. The gears are under tremendous pressure. They tend to create a lot of heat as well. I found that draining, flushing out all the worn sediments and then putting in a high performance ATF has helped me greatly and the gear sounds much better. I used Redline ATF which is available and most speed and custom racing shops. It is designed to handle high heat which will remain a constant viscosity regardless of the heat which could help in slowing leaks. Regular ATF will thin at high heat and leak faster and will burn as well.
Be Careful
Some Yanmars share the trans fluid with the regular oil reserve of the engine (I think, please correct me if I'm wrong). So if the oil level drops, it could be due to engine oil consumption rather than the trans.
Some Yanmars share the trans fluid with the regular oil reserve of the engine (I think, please correct me if I'm wrong). So if the oil level drops, it could be due to engine oil consumption rather than the trans.
Correct oil
This forum made me look in my official Yanmar service manual... Models: 1GM10(C), 2GM209(F & C), 3GM30(F&C) and the 3GN35(F&C) use 10w-30 motor oil in the transmissions, not transmission fluid! Even the v drive models use 10w-30, motor oil. Hope this helps.
This forum made me look in my official Yanmar service manual... Models: 1GM10(C), 2GM209(F & C), 3GM30(F&C) and the 3GN35(F&C) use 10w-30 motor oil in the transmissions, not transmission fluid! Even the v drive models use 10w-30, motor oil. Hope this helps.
Correct oil
You need to make sure you are using the correct oil for the transmission. I don't all the manuals at the tips of my fingers but I would follow up with a good mechanic and have him/her go ove rthe transmission with you before you have a serious problem Charlie
You need to make sure you are using the correct oil for the transmission. I don't all the manuals at the tips of my fingers but I would follow up with a good mechanic and have him/her go ove rthe transmission with you before you have a serious problem Charlie
Get the engine manual
I highly recommend that you purchase a copy of the engine manual for your Yanmar. They are very inexpensive and will give you the exact info you need. One big benefit for the manual is that when you are out cruising, your engine may die and you have to call a local mechanic. They may be a great mechanic, but they might not have the manual for your engine model. So, buy a copy, if not for you, then for them to use.
I highly recommend that you purchase a copy of the engine manual for your Yanmar. They are very inexpensive and will give you the exact info you need. One big benefit for the manual is that when you are out cruising, your engine may die and you have to call a local mechanic. They may be a great mechanic, but they might not have the manual for your engine model. So, buy a copy, if not for you, then for them to use.
I see all different answers, so I took a picture
Since I am seeing all the different answers, I decided to take a photo of a page in the manual. This manual is for all Yanmar GM or HM engines. As you can see, the oil type is not based on the engine, but based on the trani, which makes sense. The trani type for the GM and HM engines can be either KM or KBW. You can find the gear type on a metal tag on the side of the trani. I have no idea what is the correct trani oil for other engines.
Since I am seeing all the different answers, I decided to take a photo of a page in the manual. This manual is for all Yanmar GM or HM engines. As you can see, the oil type is not based on the engine, but based on the trani, which makes sense. The trani type for the GM and HM engines can be either KM or KBW. You can find the gear type on a metal tag on the side of the trani. I have no idea what is the correct trani oil for other engines.
Different Tranny's, different oil
This is from the Yanmar Manual: Transmission Type 1GM10, 2GM20(F), 3GM30(F) KM2-C: SAE #10W-30, CC class .25 L KM3-A: SAE #10W-30, CC class .3 L Transmission Type 3GM35(F) KBW10E: Dexron-ATF .7 L Transmission Type 1GM10, 2GM20(F), 3GM30(F) KM2P: SAE #10W-30, CC class .3 L KM3P: SAE #10W-30, CC class .35 L Transmission Type 1GM10V, 2GM20(F)V, 3GM30(F)V KM3V: SAE #10W-30, CC class .8 L These transmissions were changed in August '85 based on your serial no. KM2P 1GM10 03413 and after Aug. 1985 KM2P 2GM10(F) 03567 and after Aug. 1985 KM3P 3GM30(F) 01888 and after Aug. 1985 There is a chart in the manual that says to use the "Same lube oil as for crankcase" We have always used the same oil as in our engine. This originally was 30W and we have recently switched to multi-grade 15w-40. I would not suggest that anyone switch to a pure synthetic oil on an older engine. The oils quite often will cause an "OLDER" engine to weep. If you start out with these oils it tends not to be a problem. For some reason Yanmar has never recommended synthetic oil for these engines. That may have changed with the newer engines, but I would check first.
This is from the Yanmar Manual: Transmission Type 1GM10, 2GM20(F), 3GM30(F) KM2-C: SAE #10W-30, CC class .25 L KM3-A: SAE #10W-30, CC class .3 L Transmission Type 3GM35(F) KBW10E: Dexron-ATF .7 L Transmission Type 1GM10, 2GM20(F), 3GM30(F) KM2P: SAE #10W-30, CC class .3 L KM3P: SAE #10W-30, CC class .35 L Transmission Type 1GM10V, 2GM20(F)V, 3GM30(F)V KM3V: SAE #10W-30, CC class .8 L These transmissions were changed in August '85 based on your serial no. KM2P 1GM10 03413 and after Aug. 1985 KM2P 2GM10(F) 03567 and after Aug. 1985 KM3P 3GM30(F) 01888 and after Aug. 1985 There is a chart in the manual that says to use the "Same lube oil as for crankcase" We have always used the same oil as in our engine. This originally was 30W and we have recently switched to multi-grade 15w-40. I would not suggest that anyone switch to a pure synthetic oil on an older engine. The oils quite often will cause an "OLDER" engine to weep. If you start out with these oils it tends not to be a problem. For some reason Yanmar has never recommended synthetic oil for these engines. That may have changed with the newer engines, but I would check first.
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