Lost RPMS

This is a 1973 reinnell with a 2.3L gm motor. The boat was running great all day until we were heading back to the dock. We were cruising along at about 4,500 rpms and then suddenly we felt the boat hesitate a little and the rpms dropped to about 3,500. We made it back to the dock but the boat died. We got the trailer in the water came back to the boat and it started up but with a very funny sound, almost like a belt rubbing or something. We could not pin point the location of the sound. Any ideas?

Re: Lost RPMS

While it is out of the water I would pull the drive & run the engine to begin to isolate where the sound is emanating from.......
Alterator, engine circulating pump, & power steering (ISO) all spinning freely?
What drive, BTW???......JK

Re: Lost RPMS

Well,.........There is NO 2.3l GM motors out there.......

I'd sooner think it's a Ford motor wearing OMC clothing........

If that's the Case,........ I Think it might have a belt driven Cam,......

Reguardless,............ I'd Check the Fuel Filter 1st.........

Re: Lost RPMS

Well the serial number plate says that it is a mercruiser with a merc drive so it must be a 3.0L correct? Here is the very bad news. I pulled the lower drain plug on the oudrive and water started pouring out. I replaced all the seals during the winter months but must have screwed one up. I flushed the drive with oil until I was getting nice clean oil, I looked at the top gears and they don't appear to have been damaged. I put new oil in and ran it on muffs for a while the oil looks fine still. The drive sounds the same as it has. I will be taking it in for a pressure check this week. What are my odds that I got away with out any damage. The last time I checked the gear oil was about a month ago and we have been on the water pretty frequently.

Re: Lost RPMS

What are my odds that I got away with out any damage.

Click to expand...

Pretty Slim.............

Re: Lost RPMS

So what should I do after the pressure check? Obviously fix the seal, but should I tear down the drive and inspect. I did not find any shavings in the oil, I sifted through it all and did not find a one. Could I have heated it up so much the my gears swelled? Man this sux! I have put my heart and soul into this beast. I guess it is about time to break down and get a new boat. I will say that buying a oldtimer like mine has really increased my overall knowledge of understanding how the "Boat" works. It has been a great learning experince.

Re: Lost RPMS

You keep mentioning gears, did you ever think the bearings might go bad and gall up from running in water?

Re: Lost RPMS

Well I keep mentioning gears because that is all that I can see for the time being, I can see one bearing and that is the bearing connected to the drive shaft going to the engine. I tool the drive off and rotated it and it is as normal as it was before, Thanks for the help I guess?

Re: Lost RPMS

While the drive is off crank and run the engine to see if the noise is present or not. If it is still present that would rull out the drive as the noise culprate. If it is no longer there the drive may be suspect which would suggest further inspection may be required.

Re: Lost RPMS

The prop shaft seal is the culprit. And also the timming some how got way out of whack. But these are now the least of my worries. I now have engine oil all over the ground. After tonights run to test everything out we came home and set the boat along side our house. Came back about two hours later and I noticed a huge wet spot in the road. I thought man I must have another leak in my drive. Nope ENGINE OIL! Dang it. I can see oil in between the head and the manifold. I was not able to see where it was coming from. I guess I will now take off the manifold and inspect that for cracks and worn gaskets. The engine did not get over 140 degrees but could still have caused damage. I got the serial number off the motor hopefully someone can help me out and identify this for me. I have the clymers book but for some reason my number falls into alot of catagories. The engine number is 3437004 and the outdrive is 3512779. I have been ordering stuff for the pre alpha and so far I have not hade any issues. Sorry for the long tale just a little frustrated right now.

Re: Lost RPMS

I forgot to mention that the noise went away after installing the shaft seal, I had the marina do this for me, they installed the seal and refilled her for me.

Re: Lost RPMS

Don't start disassembly until you determine where the oil came from. Clean the oil off the engine and refill the crankcase to proper level and look for the leak (may require running the engine). Then perform the proper repairs.

Re: Lost RPMS

Thanks for the advice. I will perform this when I get home today. Where are some place I should pay close attention to. The manifold? head? thanks