1986 Johnson 70 Hp VRO Rebuild

[maineboat]

Wow!! I am so impressed with all the information on iboats, that I just have to start a thread so others can follow and perhaps benefit from the progress on my rebuild.

A little history:

I purchased a 1986 Starcraft SS-160 Series SL, bow rider for $500 back in October. The motor was in boxes.... I was told that the engine had a blown piston, damaged head, but the crank was OK. The exterior of the boat is immaculate, but at least some of the interior will need to be fixed. The floor has a large spongy spot in it.


He said that I should be able to bore out one cylinder, replace the head and be good to go. Well, after review and math, I've decided that a complete rebuild is more economical and less risky than just doing the one piston. I also found that the top bearing was very "gummy" and turned with some difficulty. The crank does appear to be OK, no scoring, scratching or discoloration. I will mike it later. Only about $300 difference and I will have a "new" motor. I also discovered 4 broken bolts as I looked everything over.

The PO did do a good job with disassembly; everything is marked and grouped in Zip-Lock bags. He also gave me a OMC parts book specific to my Motor, and a Clymer repair manual. Not as good as the OMC book, but it will do. I am not a novice.

 

[maineboat]

Re: 1986 Johnson 70 Hp VRO Rebuild

So here is the first step of many.

Tonight I got the last of the 4 broken bolts out of the aluminum parts. One in the Block, one in the Lower Engine Cover, and two in the Rear Housing Cover.



I read on a ton of blogs about how to do it, and I can only tell you what worked best for me. The first two I worked on the most, and they proved to be the hardest. I soaked them for about 2 weeks with Liquid Wrench; nothing, not even a twitch. (one was sticking out about 3/16", enough to get a pair on Vice Grips on) Then I soaked with PB Blaster for a week; still nothing. So I then resorted to a method I wasn't real keen on trying. I welded nuts on them with my wire feed welder. I could wiggle them back and forth some, but every time I tried to crowd them, the nuts would twist off, leaving me with the same mess I started with. I searched in vain for my propane torch, but couldn't find it, figuring maybe a little heat on the aluminum first would be more successful, since the aluminum absorbs heat and expands faster than the steel. Then I discovered the other 2 broken bolts. Well, they came right out with the welded nut method, so I went back to the first 2. Still no luck. (yes, I even tried the paraffin wax, but that didn't work either) Well, late last night I finally found my torch, so after welding on 2 more nuts after work tonight, cooling the whole mess, and reheating just the aluminum, I could gain a little more, but they still broke off. Well, I happened to have a small "dropper" bottle of ATF by the work area, and just out of curiosity, I put a couple of drops on the broken bolt as I heated the aluminum, and to my surprise, the first one backed right out!! Well, about then my very patient wife called me for dinner, but when I came back down after eating, the last one backed right out too!!



Now all my parts, as far as I know are ready for re-assembly. As soon as I get my rebuild kit, I am going to send the block to the machine shop for boring.

~ More later ~

 

[maineboat]

Re: 1986 Johnson 70 Hp VRO Rebuild

Oh, I almost forgot to post a picture of my engine (or what there is of it right now) on the stand I built the other day form a bunch of scrap 2x's I had kicking around. As you can see, it's nothing special, but it should work fine. Most of the work will be done on a bench to the powerhead itself.



Yeah, I know the shop is a mess, and it will have to be cleaned some before I can do too much......

~ More later ~

 

[boobie]

Re: 1986 Johnson 70 Hp VRO Rebuild

Try mixing the ATF with Acetone 50/50 once and see what it does.

 

[maineboat]

Re: 1986 Johnson 70 Hp VRO Rebuild

My rebuild kit showed up yesterday, and I have installed the new waterpump kit.

I was ready to put the lower unit back on the midsection, but I can't find the exhaust seal gasket. No matter; I'll pick one up later. I would like to get it put on so I can change the gear oil in the lower unit.

I have talked to a friend at work who has fixed a couple of propellers, so I removed mine to take it to him tomorrow. I found this behind the thrust washer:



This is why you don't throw fishline over the side. I inspected the seal, and it dosen't look compromised; we'll see what the old grease looks like when it comes out.

I will also be dropping the block and new pistons off at the machine shop for boring.



Hopefully it won't take too long!! I'm not too good at waiting.

~ More later ~

 

[maineboat]

Re: 1986 Johnson 70 Hp VRO Rebuild

Today, I'm pretty discouraged...I removed the lower crankshaft bearing, and then the top and two center ones. To my dismay, there is significant discoloration on the crank, progressively as you go up! The bottom center main looks good, and the lower and center rod journals look good, but the upper center journal is slightly discolored, like it's been overheated. Also, the upper rod journal is discolored, perhaps a little more than the upper center. The one I'm really worried about though, is the upper main journal. It is really discolored, and there is a definite groove where the seal rides.



Guess I'll have to send that to the machine shop too, and have that mike'd and polished, or Heaven forbid, ground undersize, (the sound of $$$'s flying away...) or worse yet, replaced. I have more in it now than I had hoped for.....
Maybe I'm over reacting, and a good polishing will straighten it right out. We'll see.

On a good note however, I dropped the cylinder block off to send it to the machine shop for boring and honing. The shop told me I could have it back as early as Thursday or Friday. At least I can install the Pistons this weekend....

~ More later ~

 

[pviekman]

Re: 1986 Johnson 70 Hp VRO Rebuild

Just clean them with crocus cloth and put it back together - Be sure to premix rather than run the VRO. The top groove is just seal wear - that's no problem. It is a 25 year old outboard - put it back together and RUN IT!! BTW - there's no undersize rods available for that outboard. Make sure you check your lower unit seal, as well, fishing line can cut into the seal. Good job!

 

[maineboat]

Re: 1986 Johnson 70 Hp VRO Rebuild

OK, so yes, maybe I did over-react; but one thing I have never believed in 'skimping' on is things that are expected to last. For instance, hand tools. Our Dad taught us to buy the best you can afford, take good care of them, and they will last you a lifetime. I guess that's why I was a bit discouraged yesterday. I really want to rebuild this motor so I know it has been done right.

That being said, I stopped at the auto parts store on the way home tonight, and bought some 600 grit, and some 1000 grit, wet/dry sand paper. Well, I have to say, I am thouroughly amazed!!! I read a bunch of posts on how to polish a crankshaft yourself, and here's the method I used; an adaptation of all I read.



I cut a strip of the wet/dry just smaller than the width of the rod journals, wrapped it firmly (not too tight or it won't spin) around the cleaned journal, and taped it with some masking tape. Then I sparyed it with a goodly amount of WD-40. I then took a boot lace, and wrapped 3 to 4 turns around the paper, and gently pulled the lace back and forth, thus spinning the paper on the journal. The 'spooling' effect if you would, moved the contact area back and forth on the journal.



I did this for 15 to 20 strokes and then passed the ends so the lace came under the journal, and did 15 or so more. When I removed the paper the first time, I just about fell over!! The journal was clean and shiny!!!



I did all the rest of them, cutting a piece for the main bearing journals a little wider. I then went back and did them all over with the 1000 grit. I don't mean to brag, but I think it looks as good as from a machine shop!!! Tomorrow I'll see if I can borrow a micrometer, and check for trueness, and I'll be good to go!!!



~ more later ~

 

[maineboat]

Re: 1986 Johnson 70 Hp VRO Rebuild

Oh, one other quick note, I was told by a reputable mechanic, that the groove left by the old seal is nothing to worry about. The new seal will settle in and be fine. Also, after going back and looking at the pictures I realize that I probably want to polish the two 'seal?' areas on each side of the middle rod journal. They look like they have a little "wear" in them too.

Also, can anyone tell me why my pictures are not avaliable to the general public? I don't care if someone without an iboats account can see them or not.

~ more later ~

 

[Haffiman]

Re: 1986 Johnson 70 Hp VRO Rebuild

600 grit paper on your crank journals? Why not just take the grinder!!!
Just clean it of and check for damages, not grind off material. It may look nice, but you may have removed more material than you wanted and reduced the diameter. The 'shoe lace' trick may work, but you should have soaked the lace in fine grit Carborundum (valve paste) and not used the 600 - 1000 grit paper. Another solution might have been to just buff it with some SST polishing paste.

 

[James R]

Re: 1986 Johnson 70 Hp VRO Rebuild

You need some roughness in the journal finish for the rollers to ride on and not skip. The roughness also retains the lubrication.
Cross hatch pattern finishing is the best, however we don't have the machinery to do that, so use 320 grit wet and dry folded to form a strip a little narrower than the journal and wrap around the journal. Hold the W&D ends one in each hand and pull back and forth. A light application will suffice and be sure to do it evenly around the journal . You will get something like a cross hatch and a good journal. Mercedes made tests many years ago using high polished journals and the motors seized adding credibility to what Chrysler developed many years before.
Cross hatch pattern finishing.

 

[timg19]

Re: 1986 Johnson 70 Hp VRO Rebuild

James, really looking forward to seeing your progress!

I have a 70 Hp 1980 Johnson I'm taking apart to paint right now. I just got the lower unit off and I'm working on getting the exhaust housing off. My only concern is how the engine is sitting. I read in the service manual to keep it "up" so when you disconnect the exhaust housing you don't have a sudden release of parts. Any advise on how you took apart your engine (did you do it on or off the boat) would really help me out.

 

[maineboat]

Re: 1986 Johnson 70 Hp VRO Rebuild

James, really looking forward to seeing your progress!

I have a 70 Hp 1980 Johnson I'm taking apart to paint right now. I just got the lower unit off and I'm working on getting the exhaust housing off. My only concern is how the engine is sitting. I read in the service manual to keep it "up" so when you disconnect the exhaust housing you don't have a sudden release of parts. Any advise on how you took apart your engine (did you do it on or off the boat) would really help me out.

timg19
I received the motor in boxes, so I guess I really can't answer your question, and I'm not really sure what parts would suddenly release. I did take the lower unit off the mid-section, and then the mid-section and motor mount off the boat. Perhaps someone else can answer your question. Thanks for your interest!

 

[maineboat]

Re: 1986 Johnson 70 Hp VRO Rebuild

OK, I haven't posted in a while, but I have been "puttering" on the motor. Since the last post, I have miked the crank, and it was within specs. I also assembled the pistons & rings, and installed them in the block. I got the block back last Wednesday, and have been so busy with that and other things, that I haven't had a chance to sit down and type a note.

After the crank was installed, and the rods carefully torqued, I went to clean up the crankcase cover, and this is what I found:

not too impressive. I found other places where the PO forced a screwdriver in to seperate parts!! After a little careful filing, and sanding with 200 grit on a piece of Mirror (1/4" thick) glass, and finishing with 400, it was good to go.

 

[maineboat]

Re: 1986 Johnson 70 Hp VRO Rebuild

The next thing I accomplished was to thoroughly wash the crankcase cover in hot water and dawn dish detergent. I then rinsed it in very hot water, and blew dried it with compressed air. (I also used this method on the crankcase) After spreading a thin coating of Loc-tite 518 anaerobic, I torqued it all down.


It's amazing to me how close the crank counterweights run to the cover!


Next was the exhaust manifold cover. Then, to complete the "sub-assembly," the head. I also cleaned this up on the glass & sand paper, just enough to clean all the gasket residue off, and "shine" it up. Then a good washing and drying, and it was installed too.


The head before hot water bath


Head installed and torqued

 

[jeffersondodson561]

Re: 1986 Johnson 70 Hp VRO Rebuild

600 grit paper on your crank journals? Why not just take the grinder!!!

:facepalm:

 

[maineboat]

Re: 1986 Johnson 70 Hp VRO Rebuild


After installing the new seal in the lower head, it too was installed.


Then, to make the rest of the work easier, I installed the mostly assembled motor onto the midsection. This allows me to work on it at a better height, rather than bending over all the time?

I have run into a slight snag. I am missing a few relatively minor parts, but the one that has me the most frustrated is one of the timer base hold down clips & screw. A friend of mine works at a local marina, and apparently they have an abundance of parts motors, but I only run into him occasionally. Next time I see him, I will see about getting the missing parts, so I can progress much further.

In the mean time, I will work on the reed plates and carburetors. Both need a good cleaning, especially the reeds & plates. I disassembled them last night (of course I forgot to take pictures; sorry!!) and I?m glad I did. I had thought about just cleaning them good with carburetor cleaner and sticking them back on the motor, but upon further inspection, found quite a bit of crud wedged deep into the voids in the blocks. So, they too got the hot water/detergent scrubbing and compressed air drying.

That?s all for now, I?ll try to do better in the future?.

~ more later ~

 

[maineboat]

Re: 1986 Johnson 70 Hp VRO Rebuild

http://www.hotrodders.com/forum/how-properly-polish-crankshaft-journals-yourself-178604.html

 

[maineboat]

Re: 1986 Johnson 70 Hp VRO Rebuild

:facepalm:

http://www.hotrodders.com/forum/how-...lf-178604.html

Read the 4th post down;

and I quote: "You can put oil on the emery cloth or do it dry, start with 400 and go up from there. I like to go to 1000. Its alot of work but you will like it when you finish. It takes practice to get it right, like just making sure the emery will snuggly fit into the journal and get it to make a couple turns but you’ll get it"

Yes, I know this is only one's opinion, and you can't trust everything you read on the internet, but I have done extensive reading, and talking with trusted mechanics, and all pretty much said the same: you're not going to remove even a significant amount of material with 400 wet & dry, even if you worked it for 5 minutes. It just isn't going to do it. I doubt my 30 seconds had any effect on the diameter at all; it miked out fine.....

 

[pviekman]

Re: 1986 Johnson 70 Hp VRO Rebuild

It sounds like Haffiman knows more than anyone else.