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How much damage was done

B

blueflu

Member
How much damage could have bee

How much damage could have been done if my engine was not pumping oil strong enough. I heard a scraping noise for a few seconds so I shut down. It started right up and ran fine but at 3000 rpm's it sounded bad. It happened for a few seconds about 3 times over a 10 day period while testing and troubleshooting maybe a total of 10 seconds or less. There was no tapping and it runs great at lower RPM's. Could the wrong oil or filter do this. The other engine is fine. Both engines' oil changed at the same time. Also rund hot when this happens.
 
"Please provide more info. on

"Please provide more info. on the engine; year, 4, 6 or 8 cyl., model, engine hours, etc. and what you have been doing to it."
 
"1986 305 merc straight inboar

"1986 305 merc straight inboards. Engine hrs under 600. Both oil pressures mid 40's (book says 30-60 OK). Both temps run under 170 except as noted above in the starboard engine. I have been simply using it and never at full throttle or abused mostly cruising. Just replaced the raw water pump and changed the oil but used a compatable napa gold filter and put in straight 40 weight from 30 and live in N.J. Had no issues with this engine in the two years I owned it other than the raw water pump going in which the temp never went above 200 or thereabouts. Noise started out as a mild rumble and then morphed into what sounds like a starter engaging with the engine running only louder. I had a really loose belt to the alt and circulation pump, one of which I initially hoped had bad bearings and was the noise but alt and pump checked ok."
 
"Tony

It may very well be t

"Tony

It may very well be the starter if the bendix drive is buggerd and it is bouncing of the ring gear and catching every now and then.
When it does the noise put your hand on the starter and see if you can feel anything strange,

A scraping noise is not what I would call an internal noise, a dry and seizing uni joint on the drive shaft can give you a a sort of squeaking/squealing noise, so can a gimble bearing that is just about to drop a bundle, an alternator or water pump bearing can also give a squealing noise.

The only thing internal you might look at is the rocker gear, take the valve cover off and make sure you are getting oil to the valve gear.

I think you will find that the noise you are chasing is an external noise from something that is attached to the engine wether it be in your drive or your accessories.

Cheers
Peter C"
 
"Peter, I made the same conclu

"Peter, I made the same conclusion origionally. Could a bad water circulating pump feel good and tight but malfunction under higher RPM's. I had the alt bench tested, it's ok. The good oil pressure and high temp readings led me to believe it was the water pump but it felt perfect with no play at all. I hope it is just coincidental that I just changed the oil and filter and the raw water pump had a piece of impeller lodged in the trans cooler. How can I check the gimble bearing for wear and what part of the engine would malfunction/squeal at a high rpm and not at a lower one? This is driving me crazy. What about the trans, a Borg Warner Velvet Drive. Any way to check that?"
 
"Tony
Are you running your 30

"Tony
Are you running your 305's through the velvet drives through to legs or is it shaft drive setup, straight to the props from the velvet drive ?
If you check out some of your automotive tool or accessory places you should be able to buy a stethescope that has a metal probe out the front of it, you can touch the probe around the engine and listen for noises and it will make it easy for you to pinpoint where the noise is comming from.
A bearing in a water pump can make a noise even though it may feel OK, your velvet drive can also make a noise, dry oil seals can make a noise, there are many things that can make a noise.
My best advice is to find a stethescope and start probing around your engine and drive for where your noise is coming from.

Cheers
Peter C"
 
If they are straight inboards

If they are straight inboards you have no gimble bearings.
Sounds like you have a bad transimission bearing or too tight stuffing box.
Rod
 
"Peter and Rod, I'm runnin

"Peter and Rod, I'm running straight inboards and the seals are actually leaking more than desired and the shafts are very cool to the touch. I can't speak for the stuffing box but if that was getting hung up wouldn't I feel a sudden loss of thrust on the starboard side and pull to that side and can they tighten up themselves because I haven't touched them. The boat ran great on Friday even at the 3000 rpm mark all day. Engine idled at least 8 hours fishing without a hitch. On the way back the noise started and immediately the water temp rose. I monitered all the gauges that day including when it happened on the way in. Could a sudden lack of anti-freeze circulation spike the temp that quick. Once again a minute after killing the ignition and restarting the temp came right back to under 160. I have to believe it's a bad water pump. I can't see how anything in the drive gear could spike the temp so quickly. Do you guys agree."
 
Check for air trapped in close

Check for air trapped in closed cooling from low coolant level or a collapsed coolant hose.
 
"I think you are right, it pre

"I think you are right, it pretty much has to be cooling. If your raw water pump or circ pump are seizing, you will get a temp spike right away. That would be the first suspect.
Rod"
 
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