Newbie Q - Overheating/Rubber smell

[knotproper]

Hey there, Newbie here. We bought an E31 awhile ago. We went to start it today and noticed a rubber smell with smoke. Also made a squealing sound for a bit ..

I shut down the engine (yanmar 3ym20) and noticed that the crankshaft pulley was blazing hot and it seems that the belt was making the smell.

Made sure that the seacock was opened before starting .. and waited to see water discharge before going below deck.

I have read a few things to check but wanted to get the opinions of some folks with experience

thank you!
Aaron

[Captn_Black]

Hi, you have a loose/worn/misaligned drive belt. It is slipping, and causing either your seawater or freshwater pump to not work properly. There is a chance that perhaps one of the pumps is jammed in some way, the result would be the same, and would damage the belt very quickly. So open them both up to check.

Edit - do not run your engine for more than a few seconds until it is fixed, and check your coolant levels, some has probably boiled away.
I have some experience with Yanmars, but my experience with this particular problem is with a BMC. But hopefully I can help

[knotproper]

ok im back. Checked the coolant levels, both the tank and the reservoir have fluid. With this I assumed that there may be a blockage..

i decided to pinch down on the supply line directly to the raw water sea cock and noticed a crunching sound... this made me think there was a ton of crap in the hose so I disconnect it from the filter and stuff did come out.. not a ton but...

this little half rounded metal bit. Tell me this isnt the inside the sea cock recepticle .. where the hose is clamped..

[a64pilot]

I think you first must determine what is seized, if the pulley was blazing hot and a burning rubber smell. Something belt driven seized, so crank it up and see what doesn’t spin is the cave man way.
The proper way is to remove the belt, it’s toast anyway and by hand see what the belt drives that doesn’t turn freely, the alternator and water pump should turn freely, if you have a belt driven water pump">raw water pump, it will be hard to turn, but it should turn.

[Captn_Black]

You really need to find where that piece came from. Although that might not be the root cause imo, and there may be another issue too, so check for seized pumps as a64pilot suggested as well.

[knotproper]

ok so what the guess is that the squealing noise is a belt rubbing a siezed component (pump, alternator) ? The noise dies down after a minute... I guess that could be because belt gets hot?

The hot pulley was the crank shaft. The serpentine belt seems ... intact? the tread looks ok (picture attached)

Also added a picture of the pump .. it has some corrosion.. it seems

Im not at the boat and day light is gone so will check all this out in the morning

[a64pilot]

Some corrosion is normal. It actually looks pretty good. However I don’t think it’s driven by the serpentine belt, I believe it has its own separate V belt.
I have not seen a serpentine slip that bad, it seems they break first, so I’d suspect the V belt, inspect it, if it’s been slipping that bad, it’s likely has dust on it and probably stinks if you smell it too.
I don’t know what the piece of metal is, but it does look to be a bushing or plain bearing.

[knotproper]

yep, it has a separate belt off of the crankshaft pulley, a smaller/skinner belt.

I did look for dust earlier but cant recall, at the time the engine was running I really didnt notice anything not spinning .... but .. it might have slipped past my eyes.

[Captn_Black]

Well, I think if that belt wasn't damaged before it is now, and the fit is not as good as it should be. In my case the problem was caused by an undersized home-made bracket for the alternator, which had bent slightly and caused the belt to become misaligned.
Still, better to find the problem before you replace the belt, unless you are sure it was the belt itself that was the problem.

[Cadence]

My SWAG is you have an alignment problem. I'd check first before worrying about seized pumps,etc. I can't see the belt that well but the pulley looks like it is a V-belt not a serpentine belt.

[PineyWoodsPete]

Originally Posted by Cadence

My SWAG is you have an alignment problem. I'd check first before worrying about seized pumps,etc. I can't see the belt that well but the pulley looks like it is a V-belt not a serpentine belt.

Can't see that even a severe alignment problem could lead to to the rapid heating of the crankshaft pulley the OP describes. Either the alternator or SW pump shaft must be seized IMHO.

Loose the alternator tensioning arm to slack the belt and see what can't be turned. And you def. need to remove the SW pump cover plate and see if the rubber impeller is intact, and change it while you're at it even if looks OK, and cleaning out any junk inside. And, of course, replace the supply line.

[Clivevon]

Hi. I would think the squealing noise that stops after a minute is caused by a loose belt slipping on the pulley as it brings the pulley up to speed. The noise stops after a minute because the pulley eventually catches up with the speed of the belt sufficiently to stop the squealing noise. That problem would not necessarily cause the engine to overheat, but you do definitely have a belt issue - whatever other issues you may also have. Also I would not rely on the belt you inherited with the boat necessarily being the correct size or type for your engine. Worth checking that out anyway.

[Clivevon]

By the way, if you have any doubts about the cooling water">engine cooling water sea cock. I suggest you make sure you have a correct size wooden tapered bung by the seacock before you do anything else. Then close the seacock, remove the water hose - which as was said earlier you should probably change anyway - & make sure no water enters the boat. Open & close the seacock a few times to make sure it is working correctly. If so, thats one thing less to worry about. Tie the bung to the seacock in case it is ever needed in future.

[Captn_Black]

Originally Posted by PineyWoodsPete

Can't see that even a severe alignment problem could lead to to the rapid heating of the crankshaft pulley the OP describes..

In my case the misalignment did cause both the crankshaft pulley and alternator pulley to become very hot.

[Boatyarddog]

Originally Posted by knotproper

ok so what the guess is that the squealing noise is a belt rubbing a siezed component (pump, alternator) ? The noise dies down after a minute... I guess that could be because belt gets hot?

The hot pulley was the crank shaft. The serpentine belt seems ... intact? the tread looks ok (picture attached)

Also added a picture of the pump .. it has some corrosion.. it seems

Im not at the boat and day light is gone so will check all this out in the morning

From what's visible in your photo, it's a V belt not a Serpentine.
It's probably loose enough to squeal when the engine starts, high alternator loading due to using power to start the engine.
Tighten the belt to an 1/2" deflection, when pushed on with a moderate pressure.
So, just don't over tighten it.
SV Cloud Duster