Noisy Yanmar

[riptide]

Hi all . have yanmar 3gm in a boat I just bought and it's very noisy. At first I thought I had a loose rocker arm but went through valves quickly and found no extreemly loose ones. Am now thinking piston slap. Question-would lack of thermostat and low operating temp [120 deg.] cause this?Any input appericiated.

[riptide]

Forgot to add that engine quiets down after about 1/2 hour.

[Tellie]

Curious, why do you run without a thermostat?

[riptide]

Boat was purchased that way -only have had boat 2 mo.

[gonesail]

my yanmar 3GM has a lot of valve clacking when it first starts up. i had them adjusted but this did not change anything. you should not run it without a thermostat.

[imagine2frolic]

I have twin Yanmar 30gm motors. One runs like a gasoline engine without any clacking, and the other runs, and sounds like a deisel. I have had several people look at the engines with no answers?.......i2f

[David M]

I may just be that its noisy because it is not running warm enough. I would put the thermostat in the engine not so much for the possible noise factor but because engines need a thermostat for other reasons.

Is the oil new enough? When oil gets old it loses some of its viscosity which can cause valve clatter.

[Solitude]

I have a 1GM10 they are known for being shakey and noisy. 3gm should be nice and stable but could be noisy.

You should not run without a thermostat. Buy one and put it in. Your wearing out your engine running it at an improper temperature. If it was taken out because of overheating (some people incorrectly do this) then find out why it overheats and fix it. There are alot of good diesel people on this site that can offer loads of suggestions, but start by setting the engine up the way it should be from Yanmar or you'll pull one string and 10 other problems will pop up.

[riptide]

Am planning to put t/stat in this weekend. I also thought it might be operating temp problem. There is a good chance it was taken out for no reason. Judging by all the other crazy things that were done to this boat I wouldn't be suprised by anything at this point.Thanks for your responses,Mark

[speciald@ocens.]

My 3GM was noisy as well. When it got to operating temp (about 170 degrees) it quieted down. Put the thermostat back in.

[Cheechako]

Both my 3GM30's had piston problems (circa '92) They ran but eventually started being hard to start. It took 3 mechanics to find out that the bottom land below the bottom ring on the piston of one cyl had cracked. They rebuilt the head completely in Antigua and it solved nothing. (almost ended up in a fist fight!) I doubted the third mechanic who wanted to take it out of the boat and overhaul it, but I was out of options... ended up loving that guy (well... my billfold didnt!) in the end.

[Chief Engineer]

Any smoke, sheen on the water?

When you bought the boat did you find any cans of ether aboard?

When was the oil changed (Rotella 15W-40)

Put the thermostat back in.

Did you adjust the valves?

[barnakiel]

There may be a problem with the engine. Or NOT - I have an older VP and my friend has Yanmars. I sometimes start them to do some maintenance and I am always shocked how noisy they are.

So, if you had a bukh/weterbeke/volvo/perkins before then it may just as well be that the new kind of clunking/level of noise disturbs you.

b.