1979 Evinrude 70973R 70 hp Outboard

[rodpaulrod]

The problem is when i took boat out today it ran real fast for just a few minutes and it did this
like 5x I explain some more engine while in full throttle the engine would idle sometimes and not go fast. Put it in full throttle It would go about 4 knots and it may stay at that speed for 5 or 10 minutes and depending on this engine once it decides to go real fast like 30 knots it would it keep doing this going fast and then only go slow. Now at end of my boat trip the boat only ran like 3 knots.
I got spark on all three cylinder when i checked it tonight when i got home. But the spark when i was checking before seem to not want spark on all cylinder like it should when i was checking before an think that it might be a problem there. Not just rule that out when i check it tonight and there was a spark on all 3 cylinder i am not ruling out that maybe one cylinder was not getting a spark today while in the water and not ruling out power pack is bad. Still I am Not sure what it is or what I should try to do to fix it. Could be a fuel pump.

 

[racerone]

I can not see , feel or hear your motor.----Up to you to post some information.---Post compression test values.----Does spark jump a gap of 3/8" ( 1 cm ) on a test device.-----Does manual fuel pump go hard when operating it ?

 

[rodpaulrod]

okay i notice a lot of what looks like gas and water mixed coming our where the spark plugs are more that normal i show you a picture tomorrow of it. I think for this it might be replace the head gasket and that is not a big thing i done this before it been a while but i know i can do that. I will add a picture here tomorrow it is dark here now. To show you what i seen and you can look at the picture and figure my idea and tell me if you think i am wasting my time. I would have never of thought of this but you got me thinking man thanks and any more idea to get this fixed let me know thanks because ideas get me thinking.

 

[rodpaulrod]

This is from engine running about 2 days ago and most has gone but you can see the black trail and residue. there was a lot of water below the spark plugs coming out surprised it ran at all.

 

[racerone]

Could be the exhaust covers leaking.-----A known issue with the 49 cube blocks,

 

[rodpaulrod]

Could be the exhaust covers leaking.-----A known issue with the 49 cube blocks,

tried to take off the water jacket and about 3 of them bolts threads stripped but bold came out and then the head cylinder bolts the water all leaking in there around into the treads and at lease 4 broke off an one i ground down close as i could without damaging any water cover seal where gasket would go got the bold ground down so like just a paper thickness. With all head bolts out and just a paper thickness on one bold dam head will not come off the bolt brock off like level on the head and are badly corraded in there so as say they like welded to the main head cover. head will come off even after tapping with a hammer all around it it like welded there. So no big deal need to try drill them out and to loose it enough to ger head off take a look. then i thinking maybe only chance is drill and put a helicoil in there for both some bolts for water jacket and the head. then maybe i will a have a good running engine. because what i remember when i did a compression check all cylinder came back with the exact same reading and that like no way can that be. But this can be hard to do no the less and if i mess up drilling or something game over i going but a good used engine from craiglist even if i got drive 400 miles to get it.

 

[racerone]

your location?

 

[rodpaulrod]

your location?

i in florida the fort pierce area and them bolts are like epoxy glued inside the cylinder head where they broke off thinking just ready to place this outboard in the back yard for now and find another one to spend time on.

 

[flyingscott]

So it's a salty motor? Time to get the drill.

 

[rodpaulrod]

So it's a salty motor? Time to get the drill.

 

[rodpaulrod]

Ok this still runs this head looked like was welded in there good please take look at this video today and do have any ideas on how get the head off.
i tried head and blaster and last thing i tried was to start it that did not work head still on there. Please take a look

video

 

[flyingscott]

Stop what you are doing. Spray those with penetrating oil.

 

[rodpaulrod]

Stop what you are doing. Spray those with penetrating oil.

i been spraying blaster penetrating PB letting soak over night and raising engine to sit in the holes but i done that 5 x i guess i just keep doing that Or if i can find something else better to spray in there i will try that to.
-------------------- added this -------------------------------------
i think i will try this

Sea Foam Deep Creep 12 Ounce Penetrating Lubricant - DC14 they got it https://www.oreillyauto.com/ sorry about the bold that is the way it came out when i copied the text . That is a great idea i should try doing that some more maybe for a week 3x a day put it on. Thank for the reply and i going pray in the mean time.​

 

[flyingscott]

Mix Acetone and ATF together and use that. Have you tried tapping on the head with a hammer and wooden dowel?

 

[F_R]

Junk it.

 

[rodpaulrod]

Mix Acetone and ATF together and use that. Have you tried tapping on the head with a hammer and wooden dowel?

ok thanks will try it

 

[rodpaulrod]

i tried tapping the head with a hammer all around the head and prying at same time with a large screw driver and all locations.
I like fix and try in all ways before i trash it so this boating discussion is very good give me ideas to fix

 

[flyingscott]

Well the head is destroyed already. So big hammer and a 2×4

 

[tphoyt]

Agreed a good solid chunk of hard wood and a big hammer. You should be able to find a used head with a little searching.
Keep at it man.
Best

 

[rodpaulrod]

The problem is when i took boat out today it ran real fast for just a few minutes and it did this
like 5x I explain some more engine while in full throttle the engine would idle sometimes and not go fast. Put it in full throttle It would go about 4 knots and it may stay at that speed for 5 or 10 minutes and depending on this engine once it decides to go real fast like 30 knots it would it keep doing this going fast and then only go slow. Now at end of my boat trip the boat only ran like 3 knots.
I got spark on all three cylinder when i checked it tonight when i got home. But the spark when i was checking before seem to not want spark on all cylinder like it should when i was checking before an think that it might be a problem there. Not just rule that out when i check it tonight and there was a spark on all 3 cylinder i am not ruling out that maybe one cylinder was not getting a spark today while in the water and not ruling out power pack is bad. Still I am Not sure what it is or what I should try to do to fix it. Could be a fuel pump.