Yanmar 6ly2a-stp 440 problems

We had a well cared for 2004 with 260 hours eat it. 30k down the tubes. The insurance company denied the claim. They claimed microscopic corrosion. No lie. I was spitting nails and it wasn't even my money.

I have had a couple of guys say if you adjust the values every 150 hour ,they run ok. any comments on the valve adjustments?

Sorry, but this boat is lightly used. The owner bought it after having it surveyed, and put something like 20 hours on it before it blew. We did have the valves adjusted on the other motor though since this happened, but I'm just holding my breath (and we got a different insurance company). One thing I will say, and it goes for any motor, make sure the hours match the years in use by at least 100 per. Motors don't like not being used. So today, with a 2004, I'd like to see at least 900 hours.

Hi,

If the valve clearance is reducing every time you check it remove the head and see what's going on after the second adjustment. I would also be tempted to reduce the time between checks if at all concerned.

It could be the seats wearing down or and most likely if the engine group is known to drop valves the valve stem will be stretching, it can only stretch so far before failure.

NYCAP, Did the "experts" tell your client if the valve head fell off or if it were knocked off by the piston?

BTW, My Nissan Patrol sat in my garage for 37 months, it started up straight away and has run flawlessly for the last 4 months. Not all engines are the same.

My 28 has done only 60 hours since 2008 long story, bit smokey on start but once warm good, trawling long hours little smelly not so much smokey.

I hear its important to only use the coolant they recommend ( red/orange )

Mine are 240 4lh

Hi,

If it hasn't been done yet I would suggest a valve lash check for peace of mind, a low HP one might not have the same problems as the higher output ones but it would be good peace of mind if everything was good when you checked.

The valve head broke. The metallurgist's magnified photo showed a speck inside the break that the insurance co. hung their hat on. Looked to me that the valve probably got hung up and came down at a slight angle causing the break. The motor was clean as a whistle inside and out.

Great information, I apperciate all the good advice!

My situation was similar. My understanding is that not all Yanmars are affected this way. As someone else mentioned, having the valves checked and adjusted on a routine basis is key.

I am back up and running and the engines are running great, better than ever. I had fantastic support from my dealer.

A speck inside the break, if not exposed to air would more likely be the result of poor metal or a poor casting of the metal.

I know that; you know that; our mechanic knows that. The owner was advised and recommended that he sue the insurance company. I know he changed companies. but from there it's not my business.

NYCAP....I would be interested in knowing if there was any furher response from YA or if this is an isolated incident. I have a 440 getting close to 400 hours and am a bit concerned.

Thanks
Robert

The owners didn't pursue the matter any further. We had no problems with the second motor, but it only got about an additional 50 hours the following summer and almost none since because I was out of commission last summer.

I am currently interested in a boat powered with this 6LY2A-STP. There is a lot of negative info on the web on this motor, mainly directed at the valve train . I contacted the local distributor, Mack Boring. I have learned that serial numbers M56928 (circa 2005) and below are subject to failure of the intake valves due to the material the valve was constructed of. A remanufactured head (with inconel valves) is approx $3,000 plus a $700 gasket set and 8-10 hours labor.

Has anyone heard the same or otherwise?

Hi,

You could always knock this cost off the price and look at it as a maintenance item especially of the engine has done a few hours and is approaching half life a top end overhaul might be a good idea.

An alternative would be to ask the guy who offered the re man head how much to replace the valves/seats/guides in yours.

The labour and gasket set will be the same and you get your same casting back.

MAN tracked down the owners of motors and offered a free piston replacement.

You would think Yanmar would at least give you 6 new intake valves at no cost, they're $112 a pc, it would be something. My concern is that even after the new top end how desirable of an engine is this 440 and then you always have to worry about resale. But being able to prove the new top end with updated intakes should help on the resale..

Hi,

Are the valves offered by Yanmar the same as the ones that have failed or are they the same as the ones in the re man head you were offered.

Considering that they add up to $672 that leaves a lot from the $3000 to replace the seats, machine and lap the exhaust valves or you could replace them all and still have some cash left over.

The new intakes are inconel, the original problems ones were not. The reman head is fitted with the inconel valves. The gasket kit would then be all that is needed and, of course, a trustworthy machine shop.

It would be wise to change the valve seats as well with new ones, instead of trying to lap the old seats to the new valves.