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Strange noise, Volvo Penta 2002
I have a 1985 Volvo Penta 2002 18hp diesel engine in a 1974 Seafarer 31-1.
In August I was motoring when steam started pouring out of the engine compartment. Back at the dock we realized that the Pressure cap on the fresh water tank was bad and the coolant had nearly drained.
The next week we came back to the engine and discovered some newly bad seas on the sea water pump and in some of the piping in the coolant system. We also started hearing this horrible sounding noise the seems to emanate from the bottom of the engine. The noise can be heard in the youtube video and sounds like a repeating hissing. My mechanic also says it could be a bearing noise. The noise normally starts 15 - 30 seconds after the engine starts and doesn't seem to have a consistent pattern as it will sometime stop for up to a minute or more before it stars again.
At first we thought this was a bad bearing in the sea water pump since it seemed to have gone bad during the overheating incident was was now leaking. You can see that in the video. We replace the entire pump assembly but the noise persisted. I had my mechanic check out the vacuum system for leaks and remove the belt to see if the noise was coming from the alternator bearing, but those systems also checked out. I've also checked the exhaust elbow as that was a suggestion, but no leaks can be found there either.
The mechanic is stumped and thinks that the noise isn't related to anything that will have a catastrophic failure. I'm not sure what to think, any suggestions or advice would be greatly appreciated.
Note: It seems like I can't post the link to the YouTube video of the engine until I have 10 posts in this forum, so I'll try to post the link in the comments.
Updated note: Guess I can't post links in replies either. That's a bummer. Feel free to message me if you'd like to see the video of the engine running.
Last edited by mcat; 11-22-2012 at 01:30 PM.