1978 -115 - Johnson rebuild , Please Help!!

[KYHunter]

1978 -115 - Johnson rebuild , Please Help!!

When I started rebuilding my 115 etl johnson (1978) i had a very good friend , a retired outboard mech. I could call for advice well not to get into this too deeply he's no longer with us. I am down to the crankshaft / connecting rod installation. I have the connecting rod to crank bearings installed caps on. I havent torqued them yet but when I try to turn crank the pistons hit before it makes a full revolution. Will it fit when bolts are torqued or what have I done wrong. Its a new crankshaft and all the specs are in tolerance according to my manual, also the connecting rod caps (hand sanded) align like the manual says . <br /> Any info greatly appreciated ,I tried to get a dealership to finish being my buddy cant answer my ques. anymore but they are backed up for months and dont like to answer questions I cant really blame them for that just dont know who to ask.<br /> Thanks everyone for help,<br /> KYHunter

 

[mark.aa]

Re: 1978 -115 - Johnson rebuild , Please Help!!

Re: 1978 -115 - Johnson rebuild , Please Help!!

what are the piston hitting? are they the correct way round?have you checked the new pistons against the old ones to check they are the same.what have you replaced on engine and what has been done to it.

 

[KYHunter]

Re: 1978 -115 - Johnson rebuild , Please Help!!

Re: 1978 -115 - Johnson rebuild , Please Help!!

Anyone ???? I'll be glad to pay for advice , I am pulling my hair out trying to get just right as far as the connecting rod caps ligning up right they are perfect according to the manual . I ran a dental pick across the seams there fine. I know they'll move when I torque them but will the piston hit the bottom of the cylinder just because the bolts aren't torqued yet? The center main is positioned on the dowel pin and the crank is seated . When I rotate the crank by hand just before the crankpins on 2 cylinders come around the piston on one of the opposite pistons hits the bottom of the cylinder.<br /> Thanks any and everyone ,<br /> KY

 

[KYHunter]

Re: 1978 -115 - Johnson rebuild , Please Help!!

Re: 1978 -115 - Johnson rebuild , Please Help!!

I replaced the crankshaft, 1 piston , all bearings and had the cylinders honed . Also had the pistons checked and they are in tolerance according to machine shop also new rings . The new piston is a sierra and was given to machine shop so they could check it. I think I'm just missing a trick or two . I mean if I start to torque them will they fit and not hit . I just didn't want to torque the bolts more than once . I'm going to torque them in three stages will it start to correct the problem as I go or how will I know when to stop and when start all over again .

 

[lark2004]

Re: 1978 -115 - Johnson rebuild , Please Help!!

Re: 1978 -115 - Johnson rebuild , Please Help!!

You say that one of the pistons is hitting the bottom of the crank case. <br />Is it the new piston???<br /><br />If you can't spin the engine freely through-out the reassembly stages, then something is wrong. Do not tighten things up and hope for the best. You will break something.<br /><br />P.S. We help for free.

 

[OBJ]

Re: 1978 -115 - Johnson rebuild , Please Help!!

Re: 1978 -115 - Johnson rebuild , Please Help!!

If any of the cylinders have been bored out, check to see if the machinist went all the way down and didn't leave a ridge at the bottom. The piston must be able to go all the way down.

 

[McGR]

Re: 1978 -115 - Johnson rebuild , Please Help!!

Re: 1978 -115 - Johnson rebuild , Please Help!!

As markaa stated, if the pistons are turned 180 degrees from the correct position, you'll get big time interferance (been there done that...). I know this seems like a no brainer, but, did you possibly get those pistons in backwards?

 

[mark.aa]

Re: 1978 -115 - Johnson rebuild , Please Help!!

Re: 1978 -115 - Johnson rebuild , Please Help!!

have you matched all old parts against the new ones ?had the same problem with a polaris jetski engine pistons hit the cylinder head when engine turned over,had new rods and they were 5mm too long centre to centre.if your are new and too short they will bottom out on bottom of block.<br />check the pistons go all the way up and down bores with the crankshaft out.are you replacing the conrod end cap bolts as most engines have strech bolts that can only be used once,and if reused become brittle and can snap destroying engine.

 

[KYHunter]

Re: 1978 -115 - Johnson rebuild , Please Help!!

Re: 1978 -115 - Johnson rebuild , Please Help!!

Thanks everyone for your responses, I took a break and figured out my problem . I was following my repair manual . It said to temporarily install heads after installing pistons and to leave crankhead bolts loose . I took off heads and snugged up crankhead bolts after uninstalling the rod caps and bearings and did it all over one at a time . It turned out great . I did get new rod bolts as well as most of the others. Thats one reason I tried to get ya'lls help I didn't want to have to torque rod bolts more than once. Looks like I can test it monday I can't wait am going to put new water pump kit in tommorrow. One question I only replaced one piston and all the rings had it honed and new crank and all the bearings . What kind of break in should I follow under these circumstances.<br /> Again your replies were greatly appreciated!!!!!!!!!!!<br /> KYHunter

 

[mark.aa]

Re: 1978 -115 - Johnson rebuild , Please Help!!

Re: 1978 -115 - Johnson rebuild , Please Help!!

treat it as a new engine, to be on the safe side,double oil it 50:1 in fuel plus injection oil.for first 3 tanks of fuel,no more than 1/2 throttle for first couple of hours.then 3/4 throttle for no more than a few seconds in the next 1 to 2 hours.then 4/4 throttle for few no more than 1 minute every 10 minutes.check the manual it should tell you