Really tight alternaotor/belt fit on Yanmar 3JH5E - how do you fit it ?

[aidancoughlan]

Following on from another recent thread ....
http://www.ybw.com/forums/showthrea...is-sound-from-alternator-area-alternator-belt

... I've tried to replace the belt with a cogged belt, but struggled. The fit is *really* tight. I've loosened the bolt at the foot of the alternator (on which it pivots), and the bolt on the alternator arm (on which it moves in/out), but there is no way I can push the alternator close enough to the engine to allow the belt to fit around the last pulley. There is a rubber pipe just behind the alternator which is preventing it going in the last half centimetre on the adjustment arm.

I've also tried removing the alternator completely from it's "footrest", then placing the belt around the alternator pulley (which is possible with a little difficulty), but the angles and the space is such that getting the alternator back into the position where it's "foot" rests so I can through-bolt it on again is tricky - I've not been able to achieve it by and, and I'm reluctant to resort to a hammer.

The alternator is a Hitachi L180-03C 80amp which comes standard on those engines.

I've had this problem before when the boat was located a long way from home , and I and resorted to an on-site mechanic to replace the belt - they elected to use a smooth belt rather than the Mitshubishi toothed belt I had as spare on board, I wonder if this was the reason. However, french marine (where I got the belt) assured me that this is the right belt.

I've attached a couple of videos here, hopefully it will be obvious what I mean.
Is this level of difficult in replacing a belt normal, or is there something amiss ?

 

[Plum]

Following on from another recent thread ....
http://www.ybw.com/forums/showthrea...is-sound-from-alternator-area-alternator-belt

... I've tried to replace the belt with a cogged belt, but struggled. The fit is *really* tight. I've loosened the bolt at the foot of the alternator (on which it pivots), and the bolt on the alternator arm (on which it moves in/out), but there is no way I can push the alternator close enough to the engine to allow the belt to fit around the last pulley. There is a rubber pipe just behind the alternator which is preventing it going in the last half centimetre on the adjustment arm.

I've also tried removing the alternator completely from it's "footrest", then placing the belt around the alternator pulley (which is possible with a little difficulty), but the angles and the space is such that getting the alternator back into the position where it's "foot" rests so I can through-bolt it on again is tricky - I've not been able to achieve it by and, and I'm reluctant to resort to a hammer.

The alternator is a Hitachi L180-03C 80amp which comes standard on those engines.

I've had this problem before when the boat was located a long way from home , and I and resorted to an on-site mechanic to replace the belt - they elected to use a smooth belt rather than the Mitshubishi toothed belt I had as spare on board, I wonder if this was the reason. However, french marine (where I got the belt) assured me that this is the right belt.

I've attached a couple of videos here, hopefully it will be obvious what I mean.
Is this level of difficult in replacing a belt normal, or is there something amiss ?

Looks like you have the wrong length belt.

Www.solocoastalsailing.co.uk

 

[ctva]

Agree, with the alternator loosened, the belt should slip on / off easily.

 

[peteK]

Yes looks the wrong size,take it too a motor factors and get a toothed belt a bit bigger.

 

[RichardS]

The cogged belts on my Yanmars are exactly like yours and mine are exactly the Yanmar specified size. It's rather fiddly but the way I do it is similar to what you are doing which is to lever it onto the start of the alternator pulley with a small screwdriver and the turn the water pump pulley (ideally get someone else to assist) so that the entire belt and all the pulleys move around and drag the belt over the rest of the pulley.

Once it pops into place in the pulley groove it will be fine.

Richard

 

[aidancoughlan]

Thanks for all the replies folks ...

It appears the belt is the right size ( double-checked the part number), and was supplied by a Yanmar dealer for this engine.

Turns out this problem was posted before on a different Yanmar engine , and the answer is in the manual

"The engine is a Yanmar 4jh4, I could get the original belt off but no way could I fit the new one, there just wasn't enough movement by loosening the alternator, the handbook says " loosen the water pump v-belt pulley to change the belt" not sure what this means, is there a short cut or dodge I can use?"
Read more at http://www.ybw.com/forums/showthread.php?370604-Replacing-alternator-drive-belt#R9uCJclSELsPQsbf.99

Another owner of a similar engine posted

However, new Yanmar supplied belts are usually too tight to fit over the pulleys
Read more at http://www.ybw.com/forums/showthread.php?370604-Replacing-alternator-drive-belt#G5LjB6wQsFofGxK7.99

The advice therein was

Presumably loosening the water pump pulley will allow a little extra slack to slip the belt over the alternator pulley.
Read more at http://www.ybw.com/forums/showthread.php?370604-Replacing-alternator-drive-belt#R9uCJclSELsPQsbf.99

Slacken the bolts that hold the pulley on to the water pump drive flange. That'll allow the belt to be fitted. Tighten the pulley bolts againbefore adjusting the belt tension.Read more at http://www.ybw.com/forums/showthread.php?370604-Replacing-alternator-drive-belt#R9uCJclSELsPQsbf.99

The OP on the other thread followed that advice

I managed to fit the new belt today, by taking of the water pump pulley (it's held on by four bolts) and Also slackening the adjustment nuts on the alternator it's still a tight fit but it did go on. The new belt is the same part number as the old one and exactly the same diameter, the older one has worn slightly thinner and the vanes (?) have worn down being the only difference.
Incidentally, the old belt came off, and goes back on without taking the pulley off so I will keep it as a spare in case it has to be changed at sea in an emergency, I wouldn't want to have to remove the pulley in an emergency situation.
Read more at http://www.ybw.com/forums/showthread.php?370604-Replacing-alternator-drive-belt#G5LjB6wQsFofGxK7.99

I did eventually manage to get the water coolant pulley off completely by undoing the four bolts, and only then could I get the new belt around all three pulleys. Once in place, I did the bolts on the pulley tight, and tensioned the alternator back up, and hey presto... all running fine.
It took a lot longer than I ever expected (lying over the engine to get access to the water pulley bolts, unable to see them without a mirror). Getting the pulley bolts off in the first place was a b*&gger of a job. Unfortunately we don't have easy access to the front of the engine, and only 100mm or so clearance. I can't imagine ever doing that at sea, so like another poster on the other thread suggested , I will keep the old worn one (which does slip over the pulleys easily) as an emergency spare. Makes me appreciate my old Beta engine which was easy-as-pie to change a belt, and also benefited from easy all round access in the old boat.

Here's a short video clip

 

[peteK]

You shoudnt have to remove the water pump pulley,I still say the belt is too small.

 

[aidancoughlan]

You shoudnt have to remove the water pump pulley,I still say the belt is too small.

I can understand your disbelief, I had the same presumption (which is why I started this thread). However, the evidence is against it...

• The belt was supplied by a Yanmar agent, with knowledge of the Engine & alternator models.
• Although it's a Mitsubishi belt, apparently Yanmar do supply belts made by Mitsibushi - and I've cross-checked the Mitsubishi belt number against other online sites supplying belts for that engine model, it's the same.
• At least one (I think two) posters in the other thread confirmed they were only able to fit new V-belts belts on this engine by removing the coolant water pump pulley,
• The belt, tight as it is still requires the alternator pushed out a long way on the adjustment arm to maintain tension - I suspect that a longer belt (long enough to slip over easily) may run out of adjustment space on the arm.
• Most significantly, the yanmar engine manual here says (on page 74) "If replacing the V-belt, loosen the V-pulley of the coolant pump to remove the V-belt".

I've attached the snippet from the online Yanmar 3JH5E owders manual below

https://www.yanmar.com/media/global...perationmanual/JH_series_OPM_0AJHM-M00201.pdf


Although I can't complain about the reliability (the engine has been very reliable for me so far), having come from a Beta marine engine with really easy serviceability, I'm disappointed in that aspect of it. I wouldn't like to be trying to replace a belt at sea , hence why I am keeping the old (really knackered) belt in case I ever need to replace it in a hurry - it just about slips on OK with just the alternator loosened on the arm as would normally be the case. I'm also a bit pissed off that I spent several hours over a couple of evenings scratching my head about how to bleed the engine, before discovering that the confusing instructions in the original printed manual that I have were simply wrong - eventually I accidentally came across a significant difference in the latest online version of the manual while researching at home. For anyone having that problem , some versions of the manual are wrong (including as it happens, the one I linked below) - the pipe to loosen (on page38 under "bleeding the engine") is "Figure 5(6)", and not at "Figure 5(4)" on the diagram as stated in that version!!.

I'm now convinced that (unfortunately) this is the "proper" way to change the belt on this engine. As well as the earlier ybw.com post, I also discovered a similar post on cruisersforum.com, but lost it again. The one thing I am still a little puzzled about is what the manual means by "loosen" the coolant pump pulley - as far as I can work out, you got to take the damn thing off as I did (without dropping the bolts in the bilge) - it's not just "loosening".

The exercise is not as easy as it sounds - The nuts are not bulky enough for the jam-with-a-screwdriver trick that car mechanics seem to use, and the pulley finish was too slippy to get solid purchase with a filter wrench. The first few nuts can be got by holding one of the other nuts with a spanner in the opposite direction, but the last bolt on a free-wheeling pulley was a bugger to get off. Because it's in such an awkward place (in my installation), I'm thinking of ordering new ones and having extra nuts welded on the end so that there's something decent to get a hold on. The heads on mine are now a little "worn" from the trauma ! I've also ordered a "pulley holder" tool online to cut down on the swearing next time. https://www.iedepot.ie/silverline-p...lAJmFiisA2DNn8zUuqdM8tFpSp9M9UKBoCPxwQAvD_BwE. You remove a couple of bolts (using the others to hold the pulley), then plop this in the holes to allow you hold it in place while the last two come out.


Hope this helps the next unfortunate new owner that finds themselves with one of these particular range of Yanmar engines with a belt to change.

 

[RichardS]

I can understand your disbelief, I had the same presumption (which is why I started this thread). However, the evidence is against it...

Hope this helps the next unfortunate new owner that finds themselves with one of these particular range of Yanmar engines with a belt to change.

As I said in post #5, it is the correct belt. I've changed both of mine. However, if you have reasonable access to the front of the engine, you don't need to remove any pulleys. I understand that your access is not great so pulley removal is necessary.

I have good access and can do both of mine in a few seconds using the "lever and turn" method I describe above.

Richard

 

[Plum]

I can understand your disbelief, I had the same presumption (which is why I started this thread). However, the evidence is against it...

• The belt was supplied by a Yanmar agent, with knowledge of the Engine & alternator models.
• Although it's a Mitsubishi belt, apparently Yanmar do supply belts made by Mitsibushi - and I've cross-checked the Mitsubishi belt number against other online sites supplying belts for that engine model, it's the same.
• At least one (I think two) posters in the other thread confirmed they were only able to fit new V-belts belts on this engine by removing the coolant water pump pulley,
• The belt, tight as it is still requires the alternator pushed out a long way on the adjustment arm to maintain tension - I suspect that a longer belt (long enough to slip over easily) may run out of adjustment space on the arm.
• Most significantly, the yanmar engine manual here says (on page 74) "If replacing the V-belt, loosen the V-pulley of the coolant pump to remove the V-belt".

I've attached the snippet from the online Yanmar 3JH5E owders manual below

https://www.yanmar.com/media/global...perationmanual/JH_series_OPM_0AJHM-M00201.pdf
View attachment 77982

Although I can't complain about the reliability (the engine has been very reliable for me so far), having come from a Beta marine engine with really easy serviceability, I'm disappointed in that aspect of it. I wouldn't like to be trying to replace a belt at sea , hence why I am keeping the old (really knackered) belt in case I ever need to replace it in a hurry - it just about slips on OK with just the alternator loosened on the arm as would normally be the case. I'm also a bit pissed off that I spent several hours over a couple of evenings scratching my head about how to bleed the engine, before discovering that the confusing instructions in the original printed manual that I have were simply wrong - eventually I accidentally came across a significant difference in the latest online version of the manual while researching at home. For anyone having that problem , some versions of the manual are wrong (including as it happens, the one I linked below) - the pipe to loosen (on page38 under "bleeding the engine") is "Figure 5(6)", and not at "Figure 5(4)" on the diagram as stated in that version!!.

I'm now convinced that (unfortunately) this is the "proper" way to change the belt on this engine. As well as the earlier ybw.com post, I also discovered a similar post on cruisersforum.com, but lost it again. The one thing I am still a little puzzled about is what the manual means by "loosen" the coolant pump pulley - as far as I can work out, you got to take the damn thing off as I did (without dropping the bolts in the bilge) - it's not just "loosening".

The exercise is not as easy as it sounds - The nuts are not bulky enough for the jam-with-a-screwdriver trick that car mechanics seem to use, and the pulley finish was too slippy to get solid purchase with a filter wrench. The first few nuts can be got by holding one of the other nuts with a spanner in the opposite direction, but the last bolt on a free-wheeling pulley was a bugger to get off. Because it's in such an awkward place (in my installation), I'm thinking of ordering new ones and having extra nuts welded on the end so that there's something decent to get a hold on. The heads on mine are now a little "worn" from the trauma ! I've also ordered a "pulley holder" tool online to cut down on the swearing next time. https://www.iedepot.ie/silverline-p...lAJmFiisA2DNn8zUuqdM8tFpSp9M9UKBoCPxwQAvD_BwE. You remove a couple of bolts (using the others to hold the pulley), then plop this in the holes to allow you hold it in place while the last two come out.
View attachment 77984

Hope this helps the next unfortunate new owner that finds themselves with one of these particular range of Yanmar engines with a belt to change.

If I had that problem I would just buy a longer belt from someone like "simply bearings" and not rely on the Yanmar specified part which is obviously too small then all future belt changes will be simple.

www.solocoastalsailing.co.uk

 

[UK-WOOZY]

on my 2GM you loosen the alternator to get the belt on

 

[ghostlymoron]

That's how most belts fit. I too would try a slightly longer belt. It would ease fitting and there's usually plenty of adjustment to allow it to be tensioned properly.

 

[evaneus]

I have the exact same engine/alternator combination and have had the same issue.
In my case I am able to get it on with some force and a screwdriver (without touching water pulley) but it invariably goes on twisted, so I turn the engine over for a couple of seconds which untwists it, and then I tension it.

I think there is adjustment room on the tensioner arm for a longer belt, and am going to try it out.
Below are some part numbers for Gates Fleetrunner belts:

I believe the Mitsibushi/Yanmar official part one is equivalent to the 9440HD from Gates.

The 9447HD is 12mm longer, and the 9451 is 27mm longer.

 

[rotrax]

Thanks for all the replies folks ...

It appears the belt is the right size ( double-checked the part number), and was supplied by a Yanmar dealer for this engine.

Turns out this problem was posted before on a different Yanmar engine , and the answer is in the manual


Another owner of a similar engine posted


The advice therein was




The OP on the other thread followed that advice


I did eventually manage to get the water coolant pulley off completely by undoing the four bolts, and only then could I get the new belt around all three pulleys. Once in place, I did the bolts on the pulley tight, and tensioned the alternator back up, and hey presto... all running fine.
It took a lot longer than I ever expected (lying over the engine to get access to the water pulley bolts, unable to see them without a mirror). Getting the pulley bolts off in the first place was a b*&gger of a job. Unfortunately we don't have easy access to the front of the engine, and only 100mm or so clearance. I can't imagine ever doing that at sea, so like another poster on the other thread suggested , I will keep the old worn one (which does slip over the pulleys easily) as an emergency spare. Makes me appreciate my old Beta engine which was easy-as-pie to change a belt, and also benefited from easy all round access in the old boat.

Here's a short video clip

That will do it, but imagine at sea in a storm. Always possible without taking a pulley off if the belt is correct, but needs strong hands.

Like tyre fitting the first bit into the pulley must go to the bottom of the groove in the pulley. If it does not, the belt WILL appear to be too short.
Achieve this, hold it there, turn the water pump or crank pulley and it will go. Push the bit you are holding into the bottom in the direction the belt wants to turn as you rotate one of the other pulleys. Dont get your finger squeezed!
Changed the speed on my lathe yesterday, even though the belt is 16 years old it is still very tight.
I used the above method and it worked a treat. Best to fit the belt around the largest pulleys first.

 

[pyrojames]

My watermaker is belt driven from the engine and is an exact fit. There is no adjustment on it. To get it off, I do it with the engine running, and slip it off with a carefully placed screw driver. To get it on , I can get a about a 1/4 lead on to the pulley, and then the give the engine a crank, and it fits itself. Not a process for the faint hearted!

 

[Caraway]

The belt is too short. There is obviously a lot of extra movement of the alternator to use to tighten a longer belt.

It is a Mitsubishi belt at about £7. That belt in the video is RECMF6430 which shows up variously as 13x1115mm and also as 11.18 x 1309mm (which will seat a bit deeper in the pulley). The spec seems to vary depending whose web-site you are .
I have just had all this with my car and found a belt with 10mm more length which fitted ideally. You have more play on the adjuster than I did, so anything between 1125 and 1135 should fit nicely (provided the belt you are trying to fit is actually 1115cm).
Motor factors used to have a handy belt measuring device to determine what size you already have.

 

[colind3782]

I have the same problem on my Sole Mini 34 and I have to take the alternator off to change the belt, which is the Sole specified length. I plan to order the next size up which is 2cm longer to make it easier to get on, Just a pity that I have three spare (short) belts.

 

[Gary Fox]

The belt is too short. Get a slightly longer one. Simples.

 

[evaneus]

Just an update in case anyone's interested. I purchased and installed a Gates Fleetrunner 9447HD.
It goes on a bit easier than the stock Yanmar belt. So far ( after 100 hours) looks fine.

 

[Arcady]

I think it’s a common Yanmar issue. I too bought the correct Yanmar replacement belts for a previous 4 JH series engine and I too had to resort to questionable screwdriver levering tactics. A black mark for a premium engine manufacturer.