Old 6 HP engine issues

I have this 6-hp engine from the 1950s that was inactive in my shed for about 10 years before I brought it out again. I had it tuned up when I brought it out of storage, and it's worked great for the past 2 or 3 years. Today, trying to start it for the first time this year, I got it going great, and cruised around the lake at top speed for a few minutes. Then it started slowing down eventually stopping. I thought it just needed some more gas. I got gas, and had a terrible time starting the engine. When I finally got it started, it revved up great, then when I tried to leave the dock, the boat wouldn't move faster than a slow crawl. Since it works great in neutral, but not in gear, I thought it might be a throttle problem. Can I fix this myself with no prior small engine repair experience, or do I have to take it in to get it fixed?

Re: Old 6 HP engine issues

i suggest not running it until you find out what is wrong. my guess is it ran hot. impeller failed. possibly blowing a head gasket. check your compression and spark.

Re: Old 6 HP engine issues

I agree with TD, it sounds like an overheat problem - was running well at WOT and then slowly diminishing in power until it quit.

Check the powerhead for signs of blistered or darkened paint and check the compression. You can also remove the head and/or exhaust covers to check for scoring in the cylinders. The 6hp has an inner and outer exhaust cover so there are a couple of gaskets that you will need, in addition to a new head gasket.

You should also verify whether your motor is a fifties/early sixties 5.5hp motor, or the later 6hp model. This is important because separating the shift linkage is done differently in each, and this task must be accomplished in order to rebuild the water pump.. In the older motors, the powehead must be pulled to disconnect the shift linkage, so that the gear case can be dropped. In the later motors, there is a link inside of the "lower unit," right at the junction of the exhaust housing and the gearcase. To separate the linkage, you must drop the gearcase slightly and then remove a screw in the link with a straight slot screwdriver or a small socket.

If an overheat does turn out to be the problem, don't forget to check or replace the thermostat, which is located in a small triangular housing at the top of the head.


PS: If your motor is a 6hp, it should look something like this 1965 Johnson. If yours is an ERude, the cover shape will be somewhat different and the paint will most likely be some variation of blue, but the rest of the motor will look pretty much the same.