Squeal on yanmar 315 2003 engine on test ride what is it?

[slimjim]

Ran a Salmon Trip yesterday after I tighten up the forward belt that keeps coming loose on my and the boat ran great all day long, come in after a 50 mile ride go to the fuel dock and the Squeal comes back and I find the forward belt is loose again! and a lot of belt dust on the fuel tank buy my belt. Belt is almost new and looks ok?

Also I call Napa auto parts and Oriely to try and cross ref the part number, by Toyota, Mis and even yanmar and they all come up with nothing......they say I have to bring in the belt?

Anyone have any ideas on a good part number and what could be causing my squeal? Its only on the 1st belt 2nd belt close to the engine is fine. Thanks for any help.

[Russell]

Belts should not become loose that quickly. If your belts are getting eaten up fast you should check to make sure all the pulleys are in alignment. Look for a loose or missing bolt on an alternator or any other item the belt is turning. The pulley nearest the pile of belt dust would be the likely suspect. Also the surface in contact with the belt should be smooth.

[Albesaurus]

This is an old thread but now I am having the same issue with my 315 yanmar. It’s a 2002 28 TE engine box. I get the same squeal after being at anchor for a few hours then starting up to head home. Seems to just be then.... not when I pull out of the marina after being on shore power a few days. It goes like this: I start the engine and let her warm up. Then pull out of the marina. No squeal. Then run 30 minutes or so to a place that we anchor for the day. Two or three hours later I start her up and pull the anchor. I put her in forward. No squeal. Then bump her up just over 1000 Rpms and she starts squealing. It’s usually embarrassing because there are a dozen other boats in the area. So I come back down to just in gear. No squeal. Bump it up again to 1000 or 1200 squeal... Usually it only lasts for a few minutes and then no more noise. Never any squeal over 1200 Rpms. One time while backing into my slip I heard it briefly when I was forced to gun it a bit on a windy day.

When I bought the boat I noticed right away there was belt dust and the smell of rubber. I had the seller changed all the belts so my belts have less than 10 hours use. I did also try to tighten them up yesterday but the alternator bracket slot is at the extreme end of its length. The belts do seem to have more play than I think is normal but then again i’m a plumber not a mechanic. Thinking maybe it’s possible the belts are too long hence the lack of further tightening...

[dkirsop]

Sounds like your belt is slipping when the alternator is under a high amperage load during the initial bulk charging phase of your batteries. Could be your belt is loose, or undersized for the alternator. Some regulators have a belt saver mode which helps to eliminate this problem but these are high end external regulators. It also sounds like your belt is about 1/2 to 1 inch too long given that you are at the end of the adjustment range.

[Albesaurus]

“ Sounds like your belt is slipping when the alternator is under a high amperage load during the initial bulk charging phase of your batteries. Could be your belt is loose, or undersized for the alternator. Some regulators have a belt saver mode which helps to eliminate this problem but these are high end external regulators. It also sounds like your belt is about 1/2 to 1 inch too long given that you are at the end of the adjustment range.”

Ok so i took a few video’s and did some experiments to hone in on my squeal. I can post here if it’s helpful. What i’ve confirmed is the squeal is much louder when the batteries are down a bit. This time i stayed at the dock and started her up with shore power just disconnected. It took 5 or 6 start up and shut down to drain the battery enough to get the squeal to really sing. Before this its just slightly noticeable with the engine cover up. Not audible with cover closed. Also noticed that there does not seem to be any visible slippage of the belt on the pulley when it’s squealing. My video shows this. Only other clue is that in this experiment i found a leaking water pump. I have video of this too. Its coming from the spindle that drives the impeller. Its a steady stream of raw water into the bilge but only when running. Water stops when shut down.

I also checked that the old belts that were on the boat when i bought it are the correct belts as they are the same Mitsubishi 1395 that i see pictured in this post earlier. The replacements are a NAPA match that the broker ran out a bought and installed to save the sale. I have a photo of these belts as well. I’m sure they are not a perfect match

So. Does a belt squeal when there is not visible slippage?

[dkirsop]

Well, start with the obvious problem first. Repair the water pump. Sometimes a failed seal on a water pump shaft, or a worn pump shaft bearing will result in a squeal. This repair has to be done regardless of the belt so you will not be losing either time or money.

If the squeal persists after this repair try a shorter belt. Alternators are often swapped out during the life of an engine and there is no guarantee the pulley size was matched. To me, belt dust is a sure sign of slippage. A wet belt can also slip and squeal if the water from the leak is hitting it.

[Albesaurus]

Swapped out the belts today and indeed they were not the right belts. They were at least an 1” longer than the proper belts. Still working of the pump replacement. Took an entire day to get the old pump off. Three out of 6 bolts were rusted bad. One broke off but I was able to drill it out. I believe this pump to be original. Salt water spray on the block behind the pump did quite a bit of damage. Used a wire brush and rust converter and will paint before installing the new pump. Another thing the surveyer missed!

[Paddy]

Hey Albesaurus, please do yourself a favor and inspect the oil plug behind the injector pump, it is made of steel (not stainless) and if saltwater spray has been hitting it, the result will not be good if it rusts through. A few of us are founding members of the oil plug failure, an error from the factory that cost thousands to fix. My pics are below, Tree had a similar experience.

[Albesaurus]

Oh man.. i wish i would have seen your post before I wrapped up my install today. I will certainly look at it tomorrow and thanks very much for Alerting. See my photo of my new pump going in below.

[Paddy]

Take a look, its right behind the injector pump, inline with the raw water pump mounting bolts. I somehow caught the leak after docking, "only" lost 4 quarts of oil. Watch the oil pan rust too.

Looks like you are on the right path, good luck.