1969 Mercury 200 20hp engine miss

[dstanek]

Picked up this motor on e-bay. Took it to the U.P. to try it out. Motor started right up, purred like a kitten. Took it out for a spin on a 14ft starcraft boat. It accelerated nice got up to top speed and ran good. Ran it for about a mile, slowed down to trolling speed, ran fine. Started to accelerate again and on it's way to full wot it missed a beat or to. After about a minute, started missing pretty bad even when bringing back down to idle. Checked plugs they were ok accept signs of not firing on the one. (Wet with gas) If I let the engine cool down it will run fine until it to warms up and then will start missing again. Engine is pumping water good. Waiting for a manual on this motor but would like to get some suggestions on possible problems. Any help would be appreciated. Also, is this a pretty good motor by mercury? I know it's old but it sure looks and ran good for a few minutes.... Thankyou,<br />Dan

 

[Chinewalker]

Re: 1969 Mercury 200 20hp engine miss

Hi DStanek,<br /> Sounds like you've got a bad coil or condenser in the ignition. They can act up a bit when the motor is warm, then seem to work properly when the motor has cooled down again. I would start with the condensers. Pull them out and have a small engine shop test them for you.<br /> I have a '68/'69 200 myself and love it. A couple of things to be wary of, though. The driveshaft is prone to rust pitting just below the waterpump cartridge and the seal that is located there will not seal properly. This will allow water into the unit. Keep an eye on the lower unit oil condition - if it gets watery or milky after only a couple of runs, consider checking the driveshaft out. A stainless steel Speedi-Sleeve can fix the problem.<br /> Also, if you're unsure of the last time the water pump impeller has been replaced, consider changing it. Not a big deal to do, and not very expensive, either. <br /> I strongly recommend getting a service manual for your motor if you plan on doing any of the work yourself....<br />- Scott

 

[dstanek]

Re: 1969 Mercury 200 20hp engine miss

Thanks Scott,<br />You were right about the lower end unit. The guy I bought it from says that it does leak water into the lower unit. What is a Speedie sleeve and where can I get one? I'm assuming that I can't just replace the seals but I will also have to put in a speedie sleeve. Can you email me at dstanek@summitpolymers.com. I would like to talk to you in more detail about this slick little mercury 200 since you have one just like it.<br />Thanks again for the help.<br />Dan