timing belt on yanmar 315

[sail410]

My engine has 900 hours but is a 2002. Should I change the timing belt (5 years or 1200 hours)? Has anyone done it on a 28TE and if so what was the approximate cost? Which is more important the age of the engine or the hours?
Thanks in advance for your help,
Bill I.

[loubennett]

Better to be safe than sorry. Follow the recommendation from Yanmar (5 years or 1200 hours). My mechanictells me this is one of those engines that sustains significant damage if the timing belt breaks with the engine running. Plus you will be stranded.

[JackK]

In talking with Ken Hilton of Standish Boatyard, he told me to replace the timing belt at 1,000 hours.
I am at 800 hours on my '03 28 TE. Anyone done this yet? How much (time & $$) is involved?

Jack

[loubennett]

I apologize for my terse response earlier today. I was using my iPhone and long messages are not its strength. As with most marine engines, the Yanmar 315 was adapted from an existing automotive engine. In this case (according to my mechanic) it is a Toyota diesel engine that is (was) used in the Land Rover. Yanmar has adapted it for marine use. As with most automotive engines, it has a fiber reinforced timing belt. If the timing belt breaks, the result is likely a collision between the valves and the pistons resulting in bent valves, damaged pistons, or both. Many (maybe most) deisel engines have a timing chain that is designed to last the life of the engine, eliminating the problem. Yanmar's recommendation of changing the timing belt at 1250 hours is reasonably consistent with the standard 60,000 to 75,000 miles recommended for most cars. I'm not entirely sure about the age criteria. It seems to make sense that a fiber reinforced belt does not maintain its strength indefinitely, even without use. Its a question if five years is a reasonable number. I'll try to get some opinions from my colleagues who are more versed in flexible composite structures and I'll let you know. Until I have better information, I would follow Yanmar's recommendation. It may be conservative, but the consequences are too great to risk. Remember, you only have to use your boat 250 hours per year and the dilemna goes away.

[RobS]

On the 28TE engine box models there is just enough clearance between the timing cover and the rim of the deck cutout. Depending on your install you may or may not need to move the engine to get the clearance you need to remove the cover. The tensioner should be done at the same time. I have heard of this on more than one application but more than likely it can be done with the engine in place. Mine was done due to age, not hours. It was done at 440hrs and 7 years. It looked identical in condition to the new one that replaced it but I would not recommend pushing it beyond the change-out specs.

[earlcarlo]

I replaced both timing belts on my 2001 31TE Express and the labor is the big expense. It took around 6.5 hours per engine. If your engine has a lot of room in which to work then it could take less. It is very important to have the tensioner replaced with the belt. I bought the boat last year and the engines had 245 hours and the Yanmar mechanic that surveyed the engines highly recommended that I replaced the belts as soon as possible. Compare to a rebuild, replacing the belt is cheap.

Below is a break down from my boat. You'll have to add what your mechanic charges per hour. Hope this helps.

Labor 6.5 hours/engine
Tensioner around $180.00/ea
Belt around $100.00/ea
Gasket $ 5.00/ea

[jleonard]

Is this engine's coolant circulation pump mounted inside the timing belt cover? If so then it would be wise to replce it when you do the belt since you are already in there.

[RobS]

Is this engine's coolant circulation pump mounted inside the timing belt cover? If so then it would be wise to replce it when you do the belt since you are already in there.

It is not

497-9795_IMG.JPG

497-9793_IMG.JPG

[Murrelet]

I have a 2000 31' TE w/ twin Yanmar 6 lp-ste's
I just changed out the timing belt and tensioner on both engines. It wasn't very difficult.
Make sure the keys are out of the ignition or batteries are turned off,
Remove the aluminum coolant passage that wraps around the front of the engine, it would be an easier job if you didn't have to take that off, because it dumps most of the coolant out. After that take the plastic timing belt cover off and rotate the engine until it is at BDC (line up the marks on the cam pulley and injection pump pulley) I found and adjustable C-clamp to compress the belt tensioner to allow the belt enough slack to remove and replace it. I'm sure Yanmar sells a special tool for this but a small clamp will work. The tensioner has two bolts that come off easily.
Just make sure the engine is still in time after the new belt goes on (verify the line up marks.)
Replace the plastic cover
Gently clean the coolant passage gasket mating surfaces and install a new gasket, I used a little bit of aviation gasket sealer to hold the metal gasket in place while reassembling it. Fill with coolant. You should be good to go.

The starboard engine on my 31 is a bit easier to change, as you can access the front of the motor easier through the hatch below the steering helm, this motor took me about 1.5 hrs to change and the port took me 2.5 hrs.

A shop manual will guide you along also.

Hope this helps.
Ryan

[joe.baar]

Ryan,
Thanks from all of us for your exceptionally detailed, clear and encouraging instructions for this work. Even those of us who aren't mechanically very bright will find this very useful. Moderators, I nominate Ryan's post for stickie status. RobS's photos also clarify the issue really well.

[afrayedknot]

Ryan - Thanks so much for the detailed info on changing the timing belts and tensioner on the Yanmar 315. Having read your post, I know this is something I can do myself. Do you have any suggestions as to where can I get the necessary parts and a copy of the service manual you refer to? Thanks, Bob

[Murrelet]

Bob,
I went to www.yanmarmarine.com and clicked on the 'find a dealer' button. I found one in Juneau close to where I live, he ordered everything right away. But then again he had to order from his supplier in Seattle. So it might have been faster for me to order direct. But I was supporting a business in Alaska so it made feel good.....
Most Yanmar dealers should have the parts and service manual.
Ryan