Slipping and Thud

My 35hp chrysler 354hc is acting up. <br />Symptoms:<br />works fine in reverse, but when in forward gear it thuds violently every few seconds at low and high speeds. If I throttle it up it will eventually fall completely out of gear and rev out of control and after a few seconds the rpms will come back down, but can't get it back in gear without adjusting shift shaft. After I adjust the shift shaft to get it back in gear, it does the same thing again. I took apart the lower unit and inspected the gears and clutch dog. They seem to look fine with no metal shavings in the oil, but I'm not sure what a bad gear would look like. I recently put on a brand new prop, but I thought I installed it correctly, and don't seem to think that's the problem, but not sure. I know FOR SURE that it is not an engine or fuel problem. I have no clue what else it could be. PLEASE HELP WITH ANY SUGGESTIONS!!

Re: Slipping and Thud

Hello John. This sounds like the forward gear and forward clutch is worn. First you should test the prop to see if it is spun. Take a permanant marker or finger nail polish and draw a line from the prop hub to the cone at the end of the prop shaft. After you have heard this noise check to see if the marks still line up that you drew on the prop. If not the prop is spun. If they line up it sounds like the forward gear and clutch will need to be refaced or replaced.<br /><br />The only way to check this out is to dissasmeble the lower unit. Where the clutch and the forward gear line up the edges should be square and not rounded. Look at your reverse gear and you will see they are square and have very little wear. This is because you hardly use reverse and these parts dont wear much. Some people just put the clutch on backwards however this is just a bandaid because the forward gear is already worn it wont take long for it to wear out the new clutch face. Check around with local machine shops. You might be able to find someone who will re face these for you for around 50 bucks.<br /><br />Also take the motor covers off between the lower unit and the power head. There is an adjustment nut about 1 1/4 inch long that has reverse threads on one side. There should also be a locking nut next to it. Verify this has threads on both sides of the nut and that the lock nut is tight. YOu may just be vibrating the nut so it goes out of adjustment. I doubt this is the case but you will have to go there to remove the lower unit. Also verify when motor is in neutral that prop spins freely in both directions with no clicking. If so it is adjusted correctly.

Re: Slipping and Thud

which gear is the forward gear? The one nearest the prop end of the shaft? I don't really notice a difference between the wear on the forward gear and the reverse gear. There was also no metal shavings in the oil when I disassembled the LU. There is a possibility that I may have a spun prop, but I don't think so, because it slip out of gear for extended periods of time. If the prop is spun, does that mean that the splines on the shaft are shot? I think maybe I just have a shift cable and throttle cable malfunction. Any ideas.

Re: Slipping and Thud

The forward gear is in the front. The reverse gear is nearest the prop. A spun prop is when the rubber separates between the hub and the prop. This will not affect the splines. Props dont have shear pins anymore and when the rubber separates you can not tell by trying to turn prop by hand. It happens when the motor is under higher rpm and a lot of torque is on the prop.

Re: Slipping and Thud

Well, I put the lower unit back together and reversed the clutch. Sealed and oiled her all up took her for a test run. After all that, I found that it was a rotted shift cable. The plastic around the cable had cracked away a little and the cable was buckling out the side. The previous owner had wrapped it tightly with electrical tape and it just now had begun to weaken. Slapped a little tape on and she's running like new!! Hallelujah!!