A25 Motor Mount replacement with Isoflex mounts

[Burton]

"Slow Motion" was in need of new motor mounts. The shaft alignment was quite good, but the Yanmar 3JH3E shook like crazy. Yanmar recommends changing mounts every few years, and I can see why. The mounts are rubber and steel, like on your Ford F-150 or whatever, and the only thing that sticks the rubber to the steel is the rubber's vulcanizing to the steel. The rubber was pulled away from the steel on every mount. The steel looked to be mild steel, heavily rusted. In fairness to the Yanmar mounts, we think the boat sat unused for 18 years. And whoever did the Yanmar install did a horrible job-- the engine had to sit farther back than the Volvo, and the rear mounts had to sit on the section of the engine bed where it is angled. They had to build the engine beds up, and just used pieces of King Starboard--flat, and let the mount take the abuse of the angle on the rear mounts. No wonder the rear mounts tore in two.

I built proper bed blocks, all epoxied in, etc., for the new mounts. What to buy? After calls to three northeastern Yanmar dealers, I found they had no interest in bothering with selling me anything. (Had to get a new stop solenoid, filters, fanbelt, etc., too.) As to mounts, I never even could get a return call for a price. On eBay were some...over $200 each. For mounts that looked like they were off any old V-8? I started looking. (On a related note, the customer service rep at Mack Boring was very helpful as to a prop issue. I'm sure they'd be disappointed that the dealers they sent me to had such bad customer service.) I found Isoflex on the 'net. When I called Isoflex the customer service was as good or better than I have ever had in buying things. And, the price was much less than what was on eBay. Bank America thought this purchase suspicious and blocked my card payment to them. Isoflex was kind and patient.

The new mounts are beautiful and an engineering masterpiece. Isoflex designed these mounts after a certain sailboat race near Australia where a bunch of boats were knocked over and the engines pretty much fell out of their beds. (I suspect they were held with only the vulcanizing, like our stock mounts.) These Isoflex mounts are made so that this sort of damage cannot happen. They are a direct replacement for the factory mounts. The central adjustment bolts are not set in the standard black rubber we often see, but some sort of polymer or something. The mounting base allows adjustment for left/right, front/back.) The shake is now gone, and we could not be more pleased. I can't recommend these mounts highly enough, and if I was to order a new engine I would definitely pay less for Isoflex mounts, and get a superior product.

[Bob Noodat]

Good information, thanks for that. Confirms what others have written on Isoflex for Yanmars. Also confirms what I have found with Yanmar North America.... I wonder if the parent company in Japan realises what a lousy agent they have over here: a pity considering what great engines and equipment they build, and how much of it I own.

[DesertAlbin736]

Interesting. We have a Yanmar with engine mounts that are 30 years old. Shakes a bit when idling at less than 1,000 RPM. Smooths out at 1,000 RPM & above & we have the Aquadrive unit. Since it does have Aquadrive not sure if those mounts are stock Yanmar or something else.