1971 merc 200 20hp

HELLLPPP!!!!<br />I have recently purchased a 1971 20hp merc 200 red band. After getting motor started I noticed that there was no water coming from tell tale hole. I stripped and checked impella (it was broken up)I renewed impella and retested. There was a slight improvement but it was mostly steam coming out. I also noticed that the exhaust gasses were being pushed through drive shaft housing into the water tub. I removed the lower unit and peered inside. At the top of the unit I could see the round hole for the drive shaft pick up, the water tube and a square shaped hole from which the exhaust gas and most of the water from the pump seemed to be re entering the drive shaft housing. Does anyone know if therer should be a cover over this hole? Ther seems to be a drilling on each side of the square hole but it is difficult (without stripping) to see if they are threaded. I hope someone out there can lend a hand to an outboard begginer.

Re: 1971 merc 200 20hp

I can't give you direct advice, I'm sure someone will. But, in the mean time, get yourself a shop manual. I have both the Seloc and "genuine Merc" shop manuals for my early 70s 9.8 hp. I believe both also include the 20 hp. Anyway, so far, both manuals are excellent for the work I've done - I really can't recommend the Merc over the Seloc, although "conventional wisdom" is that it is supposed to be better. I believe either will give you clear photos and diagrams of your lower unit and water system. The Seloc manual is almost always available in boat shops. The Merc, you generally have to order. Good luck.

Re: 1971 merc 200 20hp

Sounds like a piece of impeller blocking a water passage, Ck under the exh covers, if its not there it will be in the passage under the block cover. USE GREAT CARE IN TAKING THE BOLTS OUT THEY WILL BREAK EASILY soak them with pentrate for a while---Bob

Re: 1971 merc 200 20hp

Tricky<br /><br />If the impeller was broken up, odds are there are pieces lodged in the water jacket, tell tale hose, etc. Try backflushing it through the tell tale, maybe compressed air or water hose with a small nozzle. This might break any blockage loose and let the water circulate through the engine.<br /><br />Normally,most of the cooling water exits through the exhaust after circulating through the engine. It's exhausted down the leg and through the prop. So, yes there should be a hole for the exhaust and cooling water to exit down through the leg.