1973 Merc thunderbolt 200 cooling issue

[89polaris]

my merc will not pump water while immersed in water, only with a clam shell and garden hose, which is of course pressurized. im thinking bad impeller but im kinda new to the whole outboard thing and id like some advice from the people who actually know what there doing

 

[7920hpMercury]

Re: 1973 Merc thunderbolt 200 cooling issue

Suggest you get a factory service manual or Seloc and drop the lower unit and replace the water pump. Good idea to replace the water pump every couple of years on these motors. Great motors!!!

 

[green4themoney]

Re: 1973 Merc thunderbolt 200 cooling issue

agreed with above, best to change the water pump, the water pump on these engines have short veins, which helps for better pumping at lower RPM's but also tends to make them go bad a little quicker then a regular sized impeller (because when they are bent in the housing they seem to not get that extra spring after sitting for a year or two) no biggie tho, just replace it maybe once every 2 seasons depending on use and you should be in business

 

[89polaris]

Re: 1973 Merc thunderbolt 200 cooling issue

alright. will do. thanks guys

 

[green4themoney]

Re: 1973 Merc thunderbolt 200 cooling issue

you can go to your local merc dealer or order it online... part number #47-89982

www.oldmercs.com

these guys are the best if your ordering online, this is who i deal with