compresstion on my 1980 35 evinrude

[whopper jr]

hello all,<br /> I can not get my 35 rude to start at all, checked spark , has great spark. tested fuel pump, works. carb cleaned and rebuilt.. checked compresstion and got 25lbs on both. sounds a little low to me. couldnt find any compresstion facts in my service manual. any one got an idea?

 

[ob]

Re: compresstion on my 1980 35 evinrude

That's extremely low compression.Remove plugs and squirt two cycle oil in cyliders and distribute well.Conduct compression test again.If it rises and gradually falls back down it is indicative of probably heavily carboned stuck or worn rings.If it doesn't come up you may have a blown head gasket or piston damage.Acceptable reading is around 100 and even within 10%.Since both cylinders are reading equally low I'm guessing blown head gasket.Make sure your throttle flaps are wide open while conducting test.

 

[whopper jr]

Re: compresstion on my 1980 35 evinrude

thanks ob, i'll do the compresstion test over with the oil first then pull the head off the check the piston and cylinders if good ill replace the head gasget .

 

[whopper jr]

Re: compresstion on my 1980 35 evinrude

Ok I put 2cycle oil in, no change in compresstion. I pulled the head. found a bad head gasket. also found very minor scuffing of one bore. Im going to install a new head gasket and see what i get..thanks for your help ob. any more advice would be greatly appricated...

 

[ob]

Re: compresstion on my 1980 35 evinrude

Just be careful not to gouge into or otherwise damage the head cover or powerheads sealing surface in cleaning and prepare procedure and use crossover sequence in torquing bolts.Also, good to torque in increasing incriments of 1/3 ,2/3 ,and then final so that head irons out nicely.Keep us posted as to the compression reading when work is complete.

 

[G DANE]

Re: compresstion on my 1980 35 evinrude

Hi Whopper Jr<br /><br />You probably had a little water in the one cylinder as the headgasket started to go bad, which is the reason for scoring. Run it on doubble oil the first tank and carefully to smoothen out the scorings, maybe your compression will improve that way when you get it going.<br /><br />Remember to use a turque wrench

 

[whopper jr]

Re: compresstion on my 1980 35 evinrude

Hello, all<br /> I replaced the head gasket and water jacket gasket. and found my lost compression. both gave 95lbs. Im very thankfull for your help. now next problem I want to change the water pump impeller. on this motor (1980 rude 35hp) there is no acess plate on the lower unit to disconect the shift linkage. Please dont tell me I have to remove the power head... any ideas?? thank you... thank you OB for you help on previous problem...

 

[wilde1j]

Re: compresstion on my 1980 35 evinrude

Start by getting a shop manual and a parts list. It's not a difficult job with the books.

 

[whopper jr]

Re: compresstion on my 1980 35 evinrude

thanks for your response wildeone. I have the shop manuel for my motor, but. it doesn't show the lower unit that is one my outboard. It is an original shop manual from omc , but it shows the lower units for the older models not mine. if it had i would not be on this post asking for help. I feel these books go into enough detail. case in point my last post . no where could i find what the compression for my motor should have been. so here i am again.....

 

[snapperbait]

Re: compresstion on my 1980 35 evinrude

If your lower unit has rectangular plastic "screens" over the water intakes, remove the screens to access the shift rod that runs through the opening.. The shift rod is bolted together there..

 

[whopper jr]

Re: compresstion on my 1980 35 evinrude

thank you very much snapperbait. thats the clue I need. great. let you know how i make out. peace

 

[rickdb1boat]

Re: compresstion on my 1980 35 evinrude

Hi whopper jr <br />In case you need it, here's a good place to view blown-up pics of your lower unit and other engine parts: You need your model number to narrow it down....<br /><br />boaterssupply

 

[whopper jr]

Re: compresstion on my 1980 35 evinrude

hi guys, I'd like to take this time to thank everyone who helped me, an gave me advice. my motor now runs great, has great compression and pumps water like a fire truck. starts on the first or second pull. not bad for a $200.00 ebay motor. I hope the guy that sold it to me wasted alot of money buying that new motor he didnt need. lol, my warmest regards, and heartfelt thanks. cheers...