1973 Evinrude 65hp What happened here?

[FFScott6]

OK...

I have been working on this motor for a couple weeks in the evening off/on. I found useful tests for ignition components. The rectifier is shorted. Timer base at lower end of limits. Stator & charge coils test very low (obviously leaking). I have low compression on the #2 cyl 60psi, 1 & 3 are 120 +,-. The thermostat was dead (boiling water test), poppets (2) stuck in slight corrosion, water cover good (no clogs) and gasket intact except for me removing gently, water side of cyl head looks good, removed head and gasket again old but no obvious breaks or cracks or signs of blow-by or rust on the meatal sealing ring either side. Now the but, not a lot of carbon on the piston tops or on the fire side of the head on #1 & #3 here's the but... check these pics of #2... (I can get more), what caused this "cleaning" & "pitting" of the comp chamber and piston top.

Oh, I did caliper the cyl bores in 1/4's and all 3 are 2.992 to 2.997in. cyl clean and smooth except #2 which has a barely perseptable scratch maybe 2 at the 2oclock position. I'm thinking lean carb in combination with overheating and I think it was F_R that said the water jacket on the exhaust could spray water if warped (that's overheating correct?).

I was told by a local fella that any movement of the pistons in any direction other than a slight wrist pin "wiggle" is not a good sign (I detect no crank bearing movement in or out at various stages of piston cycle and barely perceptable 'wiggle' against the rings.

I hope I can save this oldie!!! (maybe just replace #2 piston) and regasket the exhaust if its not to far gone or can manage to remove the bolts. (I'm guessing lots of heat on the bolt heads will help)

I found a post for installing a tell-tale in the top of the head. sounds like a great move.

Thank You!!!!!

 

[ONERCBOATER]

Re: 1973 Evinrude 65hp What happened here?

looks like lean burn condition, and or predetonation on #2..... in the pics the damage looks to have rounded edges... if they were sharp i would be thinking possibility of ring failure.... hard to tell in the picture. is there any scoring on the sides of the cylinder? I ask cause i would expect predetonation to have effected more of the dome.... and it doesn't appear to have. perhaps a few close ups of just the pitting and of the sides of the cylinder with the piston all the way down.... looking for scoring.

edit... also a good chance of a ring failure top ring.... thats why looking for scoring. A few years ago i had a VW bug 1600cc engine that did that... the cause was a welding berry got into the intake and bounced around in the cylinder....thinking pieces of ring could do that too and with porting instead of valves likely it could escape more easily ... just my thoughts. I had problems with my lean burn idea because I am guessing two carbs on 3 cylinders. still could be failing/failed reeds on that cylinder causing lack of lube causing ring failure... the cylinder wall should tell the story better though... without having to pull the piston. (myself I would have the piston out at this point most likely due to the compression) Looking for the scoring on the cylinder wall should give us a better idea of what happened without too much extra work. end edit

if anyone counters my thoughts they are prob right and listen to them instead

sean

 

[FFScott6]

Re: 1973 Evinrude 65hp What happened here?

Thanks Sean...

I've never split an o/b case. but i'm not afraid just apprehensive. I do have two manuals one is an original so I should be fine. I have plenty of room on my camera to take pics to be sure I get all the pasrts back together, hahaha not to mention several old tupperware containers to keep related parts in i.e. carb stuff with carb stuff... The iPhone pics aren't real good so I'll be taking a few better ones with a regular camera and posting them before I go to far.

With decent compression on #1, 3 I'm guessing I just need the #2. just tihinking about it... since it'll eventually be tore down that far I should just do all 3 and set a nice cross hatch... still in question though. We'll see what that #2 cyl looks like (crossing my fingers there is no gouges) wonder if I can hone out a slight scratch. I did a lawn mower engine once got several years out of it, well dad did , hehehe.

There is some kinda story with this motor, I just don't know it. The carbs have definately been done in the past, no Evinrude paint whatsoever... thermostat was never off I broke paint getting to it. That started me thinking maybe there was little of no care of the impeller/water pump. bad me I have not even drained the oil, however there are screwdriver marks on the plugs, and the LU bolts have eben on/off, whatever that means. My first concern was the powerhead. If it is trash then I would have a neat mailbox post! (and quit playing around with it).

What the heck I'm going for it... a few bucks and if it runs then I have a great older motor. I'm a sucker for the under dog, even if we get a short boating season, next year will get some ooos & aaawws at the beaches.

I'll post more soon... thanks and safe boating!

 

[FFScott6]

Re: 1973 Evinrude 65hp What happened here?

I just got some pics this evening of the middle cylinder. I took them with an 8mp camera but now I need to resize them to upload. I'm trying to retain as much detail as possible... stay tuned.