Yanmar 3GMD or 3GM30 Water Freeze Cracks

[westwinds]

I am looking at a sailboat to buy on the Great Lakes, but am worried about inadequate winter preparation resulting in freeze cracks for the Yanmar 3GMD or 3GM30. From what I have read, these two engines are essentially the same except the 3GM30 has a somewhat larger cylinder bore. So if you have experience with either engine I would sure like to hear from you. The question I have is where would I be likely to find freeze cracks on the block? I would expect along the side of the block, or the back? Also, what about the head? I would expect cracks there also, but have no idea where to look. What about water cooled exhaust manifold? Any experience on crack repairs?

[Badsanta]

I would think you could find cracks anywhere. Check for water in oil, rust stains. Have them start it and check for leakage. I would not trust one with a crack even if repaired. My 3gm30f has antifreeze in the motor and I flush the fresh water heat exchange and exaust with pink potable antifreeze. The motor is an expensive replacement. It would be cost effective to hire someone to check it out. Good luck

Sent from my SM-G860P using Cruisers Sailing Forum mobile app

[colemj]

Why search for cracks? Just fire up the engine and take it for a spin under load. You will find out if it runs well or not - if not, walk away. No way to fix a cracked block that you will be comfortable counting on afterwards.

Mark

[westwinds]

I had another look at the Watkins 32 sailboat today. The engine was winterized by taking the hose loose from the water intake and running a 50/50 percent mixture through the water pump and capturing what came out the exhaust. The problem with this is that little circulation occurs through the block and head because the thermostat is not open. I remember seeing warnings here on cruisersforum about doing it this way; however, I did not see any cracks. There was also an oil leak that came off the engine near the bell housing. I thought at first that it was likely a rear main seal, but there was also oil on the side of the engine. With the engine tipped up at the front to align with the propeller shaft, on reflection, I think the oil came down the side of the engine from the rocker arm cover, then flowed along the pan to the bell housing and then dripped down from there. However, the real problem with the sailboat was that water was seeping from the keel on the front port side about six inches down from the bottom of the hull five days after pulled from Lake Michigan. The water had a black coloration.

[Vasco]

Originally Posted by westwinds

I had another look at the Watkins 32 sailboat today. The engine was winterized by taking the hose loose from the water intake and running a 50/50 percent mixture through the water pump and capturing what came out the exhaust. The problem with this is that little circulation occurs through the block and head because the thermostat is not open. I remember seeing warnings here on cruisersforum about doing it this way; however, I did not see any cracks. There was also an oil leak that came off the engine near the bell housing. I thought at first that it was likely a rear main seal, but there was also oil on the side of the engine. With the engine tipped up at the front to align with the propeller shaft, on reflection, I think the oil came down the side of the engine from the rocker arm cover, then flowed along the pan to the bell housing and then dripped down from there. However, the real problem with the sailboat was that water was seeping from the keel on the front port side about six inches down from the bottom of the hull five days after pulled from Lake Michigan. The water had a black coloration.

I believe this way of winterizing is fine for engines that are not raw water cooled. I have had both and with the raw water cooled engine always removed the thermostat when winterizing. With fresh water cooled engines simply dipping the intake hose into a bucket of antifreeze is fine.

[Cheechako]

As well as mentioned above, check the coolant level before starting etc. Look for coolant color in the bilge. Run it long and hard and look for leaks as well as loss of coolant after.

[westwinds]

Originally Posted by Vasco

I believe this way of winterizing is fine for engines that are not raw water cooled. I have had both and with the raw water cooled engine always removed the thermostat when winterizing. With fresh water cooled engines simply dipping the intake hose into a bucket of antifreeze is fine.

I believe you are right. On raw water Yanmar 3GM the manual says to drain the penstock for the block, and head. The water pump is drained by taking the back plate off.

[westwinds]

By the way, had a friend taking a lot of pictures and on review, found a major crack in the aft part of the keel. What makes me uneasy is that I did not spot these cracks while looking over the hull. I just did not look low enough as I was looking for impact damage higher up.