Logo
FULL SITE MENU

tips for rebuilding merc 20 hp

B

big-wils

New member
hi every 1 , i am looking for any tips on rebuilding my mercury 200 20 hp(1970-75) model

i have found my power head to be leaking water so am going to buy new head and rebuild,

i just wana know if there is anything i should be looking for or need to be carefull of.

cheers steve.
 
Is it a complete powerhead or are you going to use the crank and pistons from you're old head?If using the crank and stuff from your own I would suggest replacing the rod bearings,main bearing and top and bottom seals,well you shouldn't try and reuse the seals anyway,not forgetting the piston rings. Then read your manual before doing any assembly,then read it again just incase,measure twice,cut once.:)
You are in the UK,check out the CMBA,some of their members mightn't live too far from you and are always willing to help
 
cheers for that ,i am hopeing to go and buy a head with pistons already in but may have to use old ones if i cant get it with them in already.
OK 1 other thing ive striped this engine down pretty far took of all the head bolts but it seems to be on solid still am i missing something?
 
Refer to user name as far as these engines are concerned,so I don't know how many bolts there should be,but if you have them all out and she's not splitting you need to tap it with a rubber/deadblow hammer around the seam until she gives. When she opens a little, insert wooden wedges and tap them in gently to avoid damaging the case.I know you are replacing the powerhead but if it can be opened and no damage done then maybe a re-ring,a honing,new seals,bearings and gaskets will get you away.
Andrew who runs this site doesn't ship international but you can get parts from www.maxrules.com , http://store.eastcoastmarineservice.com/ , www.mercguy.com .Mercguy is Bob Grubb and is very helpful if you give him a bell,I have done so when I needed to pick someones brains.I live in Ireland and I get most of my parts from the 'States for my beautiful '69 Merc800:D. www.marinepartsdirect.ie have a lot of spurious parts as well and aren't too expensive. And I trawl ebay,both .com and .co.uk. Though if buying of .com watch the shipping,try and buy of someone who ships USPS.The US Postal Service hasn't lost anything on me yet.Good luck.If you give us the engine number the year can be found.
 
Last edited:
i got a second hand merc 20 head but there is a slight differance with some pipe work for the carb to fit but on the whole it is exactly the same,,

basically my head has two rubber pipes going between 3 places and just bolt in, the new (used) head has 2 of the exact same holes to bolt in to but it has a sort of pump maybe attached to the piping and the 3rd pipe hole is in a different place,

so obviously it is a differnt year ,but i am wondering if i could swap the pipe work from my old to this 1, but 1 hole is higher up and not in the same place ,

so i am in need of help right now

cheers steve
 
Back
Top