Rod Knock

[73Glasspar]

I developed a knock in my motor today. I have pulled many car and snowmobile motors apart and rebuilt them. Looks like I am about about to embark on my first journey of a Marine engine. What I have is a 1978 85hp Evinrude. Has anyone here tore into a V-4 ? Im thinking if I am going to tear this motor down....... It will get all new bearings, Wrist pins and new Piston rings. I will throw some new T-Stats in as well. Im sure this will be interesting. I would like to hear from some of you that have done this to your motor. Interested in hearing what is involved and what else I should replace.



Dave.

 

[Daviet]

Re: Rod Knock

Before you start get the OEM manual and look it over. It will ansewer a lot of questions and give you all the specs that you need.

 

[Dhadley]

Re: Rod Knock

Don't buy anything until you get it torn down and have a marine machine shop (not automotive) measure everything. If it's a rod bearing you may be looking for a crank.

 

[73Glasspar]

Re: Rod Knock

I hear ya. It just started today. Its not loud but its there. I dont hear it until I placed a load on it. I idled back and pulled her out of the water.

 

[Daviet]

Re: Rod Knock

A thought, before you start to tear it down, remove the cylinder heads and check for carbon buildup. It may save you some money and time.
With the heads off you can inspect the cylinders for damage.

 

[73Glasspar]

Re: Rod Knock

Honestly....... I think its going to be a see as you go type of tear down. Im not positive that it is a Rod. Could be a wrist pin too. What ever it is.... Im sure I will be breaking open the piggy bank I went on the net and started pulling all the exploded views I could find. Im pretty sure I will be purchasing the OEM manual.

 

[Daviet]

Re: Rod Knock

Good call on the OEM manual. If you have carbon build up on the cylinder, you woun't have to tear it down any further. If no carbon, go ahead and rip it apart.

 

[73Glasspar]

Re: Rod Knock

One thing I can say......... I am soooooo glad my mechanical skills are good! I am not afraid to get into it. The best part is the knowledge I will gain by doing it myself. Would be awesome if it was carbon build up. But...... Not the way my luck goes! lol! Oh well.... It is what it is. I will not let this motor beat me!

 

[Ganis]

Re: Rod Knock

If you do have to tear it down, get the factory manual. With previous experience rebuilding 4 strokes, the little V-4 2 stroke will seem to easy to rebuild. Just my .02

 

[73Glasspar]

Re: Rod Knock

If you do have to tear it down, get the factory manual. With previous experience rebuilding 4 strokes, the little V-4 2 stroke will seem to easy to rebuild. Just my .02

Just what I was looking to hear! "Easy"........ Love that word! Im sure I will stumble and get a little frustrated...... But a cool head will come into play. Just how it has to be.

Here is a motor that was a first. It was simple but, again a first. No problems with it in 2 years now.

Here is what my finished product looked like.

This entire machine was torn down and done from the ground up. Took me some time but well worth it! This was a first for me as well. So im pretty confident (With the help of some people like your selves) That I can do this

 

[Sixmark]

Re: Rod Knock

Nice 440, I had a 440 WT and a 634 WT and loved them both, but we'll save that convo for the winter season I guess.......lol.

Good luck with the rebuild!!!

 

[73Glasspar]

Re: Rod Knock

I would love to hear more! But yes...... Not ready for the snow! lol ! 634 w/t is worth a few $$$ today! Nice to see another Rupp head out in the Boating world!

 

[bob johnson]

Re: Rod Knock

I had a knock in my 90 hp, and when i tore it down , I found that the piston skirt was slapping...two sides were galled up, and the piston was undersize and out of round by .015"


everything else was nice...i was trying to do the check of the rod bearing by coming over top dead center and then trying to push the piston down...

didnt budge.. no slop at all..

you could try that with or with out the heads off, to get an idea..

but if you are going to tear it down anyway, it doesnt matter..

bob

 

[Faztbullet]

Re: Rod Knock

Check your lower unit as a tooth broken off pinion will cause this type of noise...noise will travel up driveshaft and sound like lower 2 cylinders or crankbearing has a problem...