1987 Evinrude Runs great on muffs, wont start in water EDIT

I have a 1987 Evinrude 70hp, ran great 2 weeks ago, put the water to it yesterday to get it ready for a fishing trip today and it fired right up and ran and idled great for the 5 or so minutes I had it running in the driveway. Then when i got it in the water at the landing it would barely start, i could get it to crank but it sounded very weak then would die. Fianally got it running and got about 500 yards from the dock and when i got out of the no wake zone i gave it some throttle and it sputtered out, I couldnt get it to crank again so the paddle got put to good use. Once i got it home, i put the muffs back on and it started right up. I have not had a chance to check compression yet but i have heard that could be the issue. Water causing too much back pressure? I do my own work on my cars but I have nevered wandering into the world of marine engines, other than simple carb cleaning and plug changing. If head gasket is shot, its it something that I could do without alot of experience, If its piston or rings Im not even going to try. Any other ideas of what it could be before I start forking out big bucks to a mechanic?

EDIT- I just checked compression, cylinder 1- 80lbs, cylinder 2-90lbs, cylinder 3- 105lbs. Quite a variety, where should these numbers be? and what would cause this?

Re: 1987 Evinrude Runs great on muffs, wont start in water

Re: 1987 Evinrude Runs great on muffs, wont start in water

Well your on the right track. Do a compression check to make sure cylinder/s are not weak. Post back with psi results so we have a better idea where to direct you. Good luck and let us know.

Re: 1987 Evinrude Runs great on muffs, wont start in water

Re: 1987 Evinrude Runs great on muffs, wont start in water

Any signs of water on the plugs? There's to much difference in your compression readings.

Re: 1987 Evinrude Runs great on muffs, wont start in water

Re: 1987 Evinrude Runs great on muffs, wont start in water

I would be pulling the head and inspecting the cylinders, pistons, for scoring and cracks, also look closely at the head and head gasket to check for leaks.

Re: 1987 Evinrude Runs great on muffs, wont start in water

Re: 1987 Evinrude Runs great on muffs, wont start in water

Concures with sixmark^ I am thinking something going on between cylinders 1 & 2.

Re: 1987 Evinrude Runs great on muffs, wont start in water

Re: 1987 Evinrude Runs great on muffs, wont start in water

I am taking the head off now, or at least trying to. Got all the outer bolts out fine, 4 middle ones were seized up, used a 18inch breaker bar and got 3 then sheared the last on off, cant get the head to seperate from the block. tried prying but i dont want to crack it.

Re: 1987 Evinrude Runs great on muffs, wont start in water

Re: 1987 Evinrude Runs great on muffs, wont start in water

Get a stiff puddy knife and work it carefully.

Re: 1987 Evinrude Runs great on muffs, wont start in water

Re: 1987 Evinrude Runs great on muffs, wont start in water

You can use heat to try and loosen it as well, is this by chance a motor that was used in salwater?

Also soak it down with PB blaster or any other good penetrating oil, just be sure to clean it all off good before assembling the head again.

Re: 1987 Evinrude Runs great on muffs, wont start in water EDIT

Yes it has been used in salt water, by the previous owner. He gave me the ol "only once or twice" story. I quit trying to remove the head and just put the bolts back in. I torqued them in to about 50lbs. Just threw the compression tester back on and they are all 3 pumping around 118-120 psi. Does that number sound better? Could the head have just need to be torqued down more? Weird that was all it took to get almost 40 more psi back in cylinder 1.

Re: 1987 Evinrude Runs great on muffs, wont start in water EDIT

The problem now is that you have 1 bolt that you said you sheared off, if needs to be replaced, and if by tightening them all down again and getting compression, then you have a problem with a head gasket or the head which will become an issue now even more. You don't run them with a broken bolt.

Re: 1987 Evinrude Runs great on muffs, wont start in water EDIT

sportcraft88. Bad JuJu to run it like that. I recommend that you pull head and remove broken bolt. Chances are you can get a pair of vise-grips on it and remove it. Atleast you beable to see if the condition of all 3 cylinders. Clean head and all surfaces, install new head gasket using oil or antisieze on all threads pryor to install. Post back and let us know.

Re: 1987 Evinrude Runs great on muffs, wont start in water EDIT

Heat can be your friend on broken bolts.

Re: 1987 Evinrude Runs great on muffs, wont start in water EDIT

HOLY CRUD!!!! I just re-read what you posted earlier, you said you torqued them back down to 50lbs They are only supposed to be 18-20lbs max.

This is where we say, take the advice before doing more damage. Remove the bolts and the head and inspect things as instructed to do so earlier, taking a shortcut at this point will lead to nothing but problems.

Re: 1987 Evinrude Runs great on muffs, wont start in water EDIT

What should my compression be ideally?

Re: 1987 Evinrude Runs great on muffs, wont start in water EDIT

Missed the 50 lb torque, way to much.
The compression you have 118-120 would be ok. It will probably come up a little more when you get a new head gasket in it. Make sure the head is flat before you install it.

Re: 1987 Evinrude Runs great on muffs, wont start in water EDIT

Take the head off, remove the stuck bolt and "chase" the bolt holes to clean them up, take your head and make sure the surface is clean and flat (no warpage).

While the head is off clean the passages as best you can and gey any dirt and crud that has accumulated from saltwater use out of there, then reassemble the head starting with the head bolts in the center tigthen them in a circular motion to 9-10lbs working outwards toward the edge bolts, then do a re-torque starting again in the center working outwards at 18-20lbs.