Why wont My Mercury Big Foot go from forward to reverse without stopping in neutral. It just clunked directly from forward to reverse without slowing down. I am afraid to drive it

Seems like your are describing a outboard motor. If so, the Boat section of Fixya may have more experts that you need. You would want to avoid turning any screws on the carburetor body. The externals on the linkage have some adjustments like throttle stops.

The linkage on boat shift mechanisms are tempermental. They usually combine 2 functions on 1 control lever. They are synchronized that when the transmission shifts from neutral to forward and neutral to reverse the idle speed is low. This keeps the gears from grinding and takes the shock out of the shifting process.

Another thing different than on a car engine is the effect of the propeller on engine rpm. You can change the "in gear"
rpm for both directions by changing prop size and/or pitch.
This also means you can over-rev the engine by having the wrong prop on the boat. There are engine rpm "stops" for the high end too, but some just rely on using the correct prop. As what you may be experiencing with a "stall" can be brought on by

A word of caution. The inboard/outboard engines can have the same problem as outboard engines. The shift levers are synchronized with a pivot system and adjusting the throttle can interfere with the shifting.

You may be able to view youtube videos by searching for these topics.

Who replaced these parts ? yourself or a repair shop ?

Any howling could be any bearing. I would go slow and quiet while holding the brake and pulsing the gas to listen for a bearing clunk. A driveshaft will also thump with play if you switch between forward and reverse while stopped. Don't forget that on a front or all wheel drive vehicle the drive axle is a driveshaft. I wouldn't drive it around like this either because if it breaks you're in big trouble.

check transmission oil,normally it should be red,smell it, it's not suppose to smell heated oil,have the clutch check.

Maybe the Shift interlock cable is your problem from shifting from drive to park but not sure about the reverse.

probaly a broken rear/lower planetary set or ring gear is broke

If this is the only problem you notice, it sounds like universal joint going bad in the drive line. Put the gear selector in Drive from neutral and then back to neutral and then select reverse. Listen for the clunk when changing from drive to neutral and neutral to reverse. A bad universal joint will make a clunking sound when the drive line reverses direction because of the slop in the joint due to the bad needle bearings.

Most likely you have a bad drive axle, each drive axle has 2 universal joints and when they get worn they make a big clunk sound. Especially turning or going from forward to reverse.


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sounds like a bad drive shaft on frt wheel

????? manual or auto tranny if its an auto check the tranny