1957 Johnson Javelin 35HP Compression

[BayouBengal]

I have a vintage Johnson Javelin that I hope to restore. I know that compression should be nearly equal in both cylinders, but, I was also curious as to an approximate range for normal compression. My motor has 60 psi on one cylinder and only 40 on the other. While I knew from just pulling the rope that one of the cylinders was bad, the other feels pretty tight, and I was expecting to get a higher reading than 60. Does 60 psi sound about right for a good cylinder or should I see a higher reading?

 

[1946Zephyr]

Re: 1957 Johnson Javelin 35HP Compression

How long has this motor been sitting?

If it's been sitting for a long time, then it's likely the rings are sticky. In a situation like this, I usually set the motor on it's backside and pour some fuel in the carb and cycle it through slowly. Since this motor has a silencer mounted on the carb, I would just spray some fuel mix all around in the cylinder and get it worked in around the rings. You'll probably feel things loosen up as you do this. Then once you get it running, do a decarb.

 

[BayouBengal]

Re: 1957 Johnson Javelin 35HP Compression

How long has this motor been sitting?

I acquired the motor from the owner's grandson who said the last time he could remember seeing the motor on a boat was in the 1970's.

I would just spray some fuel mix all around in the cylinder and get it worked in around the rings.

I figure the rings are sticking, but had not really thought about your idea; so thanks, because that beats just tearing into the block right away and changing out the rings. What if I sprayed WD-40 (instead of fuel mix) in through the sparkplug hole, do you think that would do it or should I pull the head off?

Then once you get it running, do a decarb.

By decarb, I presume you mean removing all the carbon buildup on the pistons. I'm confused by your comment, "once you get it running". Is there a way to do this by running some type of solution through the engine (instead of removing the head and scraping)?

Lastly, back to my original question. What would you expect the compression should read?

 

[tashasdaddy]

Re: 1957 Johnson Javelin 35HP Compression

1st tilt the motor all the way up. remove spark plugs, put marvel mystery oil in the cylinders, let it sit for a day. having a rag handy lower the motor, and pull thru several times to blow out excess oil. now take your compression reading. 60 psi on a rope start motor is not bad.
good reading here >>> http://forums.iboats.com/showthread.php?t=299680

 

[1946Zephyr]

Re: 1957 Johnson Javelin 35HP Compression

60 psi is actually kinda low. I got 100psi on my old 18, that was stuck earlier in the day. but then again, I do have a pretty hefty pull. I would do the Marvel Mystery oil trick first then spray the hell out of it with WD-40. If this motor hasn't ran since the 70's, then it should be almost like new inside. Things always seem to get better after running for an hour or two....at least that's been my usual experience. The ignition system will most likely need to be replaced as well as a carb rebuild, but I believe the powerhead should be good for many years to come. The main thing is getting everything inside all lubed up and spinning nice and free. My usual method is dumping a bunch of fuel mix into the carb, till it runs out the spark plug holes. By this time, the bearings and rings are all nice and wet with fuel mix and freed up nicely.

 

[F_R]

Re: 1957 Johnson Javelin 35HP Compression

With only 40 and 60 psi, I think there is more wrong with it than mere stuck rings. But it won't hurt to try the "cures" mentioned.

Do you have the compression relief disabled? You will get low readings if you don't. But 40 and 60 is still too low. And if the compression relief IS disabled and you are only getting those numbers, that motor is sicko.

 

[BayouBengal]

Re: 1957 Johnson Javelin 35HP Compression

Okay, Mystery Oil is in the cylinders. I'll let you know how it comes out. Thanks for all of your input and advice.

 

[1946Zephyr]

Re: 1957 Johnson Javelin 35HP Compression

Well, all I can say is, there has never been a "worn out" outboard that I have seen. I think it'll be just fine. A lot of things are stuck and need loosening up. These are great motors and come to life easily, unless there is a rod hangin' out the side of the block.

My final note is: Don't tear into it.

Not untill you at least get it running.

 

["G"]

Re: 1957 Johnson Javelin 35HP Compression

At the very least I'd yank off the intake covers and look inside. Scars or scrapes are bad signs. Stuck rings are fairly easy to fix with out a tear down. It's the next best thing to a compression test.... Remove the power head and check the gasket. That's a good place to start for freeing stuck rings at least.

Next, what is the lower end like? Water in the oil??? Will it hold pressure or a vacuum??? Shafts if bad will be spendy. Hard to get speedy sleeves to work on those old straight shafts.

These old 35 HP engines were "heavy drinkers" too so I hope it has sentimental value to you if it needs a lot of work. They were easy to work on and generally speaking cheap parts are still available. Those engines had upper crank seal issues too. Lots of dried up seals should be expected and you should check availability on that right away.

Hmmm, I don't know on this one... it's an antique and that's worth something for sure. BTW, is that a two hose tank set up?

 

[BayouBengal]

Re: 1957 Johnson Javelin 35HP Compression

Do you have the compression relief disabled?

No. Not until you mentioned it did I do a search on this forum for compression relief and discovered that's what the rod going from the pull crank to the cylinder heads is for. I'm not at the house at the moment (where the motor is), but this evening will take a look and see how I can override this. Also, it's an electric start motor (RJE-19), but the starter is broke. I have a starter on my parts motor I bought along with this one. While I'm not sure if that starter works either, maybe I'll hook it up give it a try to give my shoulder and arm a break.

Well, all I can say is, there has never been a "worn out" outboard that I have seen.

That's encouraging.

My final note is: Don't tear into it.

Yes. I hope to avoid this and with the excellent advice I've been getting here, hopefully I won't have to. I'm certainly concerned that if I break open the block, I'll never get it put back together right.

Thanks again for all the help and advice.

 

[1946Zephyr]

Re: 1957 Johnson Javelin 35HP Compression

You'll also want to check and make sure that you have about a .020 gap on those little compression relief arms. If one of those are gapped to close and holding one of those compression relief valves open, then you'll get false readings on your compression. I honestly can't believe that motor will need a tear down, if it is low hours. Like TD said, put some Marvel Mystery oil in the cylinders and let it sit for a while to loosen those rings up. Then, when you're ready to try it, flush the cylinders all out with fresh fuel mix in a spray bottle. Removing the intake bypass will give you a good visual of the pistons and rings. Often times these can be romoved without damaging the gaskets. Just apply a light coat of gasket sealor on the gaskets, when you put them back on.

And yes, this motor should likely have the twin line tank set up.

 

[BayouBengal]

Re: 1957 Johnson Javelin 35HP Compression

Thank you, thank you, thank you. Top cylinder is 100 psi, bottom is 80 psi pulling with the rope. Yes, I know they should be closer to even, but the readings are high enough that I'm going to take Zepher's advice and get it running and do the de-carb procedure from the TopSecret File with the SeaFoam. Hopefully, after that, the lower piston pressure will come up to match the upper.

And yes, this motor should likely have the twin line tank set up.

Yes, but I'm changing it over to a fuel pump. The parts motor was already converted so I'll scavenge the pump from it.

Do you have the compression relief disabled

After doing the compression check, I reconnected the compression relief valve link arm and did it again. FYI, the compression relief makes a difference of about 20 psi on each cylinder.

 

[tmcalavy]

Re: 1957 Johnson Javelin 35HP Compression

Until you get the starter on there, pull the recoil starter on top and wrap a rope around the flywheel using the flywheel notch...more leverage and you won't crater your arm or shoulder

 

[jbjennings]

Re: 1957 Johnson Javelin 35HP Compression

If you're getting 80 on one and 100 on the other then something is wrong. It could be stuck rings or comp. relief valves or whatever. Personally, before spending money on coils and other such items to get it running, I'd look under the bypass covers and take a look at the pistons and cylinders as best I could. Those motors typically have around 110 to 135psi of compression if they're in decent shape. If the compression is not up to snuff, it won't idle well at all. If you look at the pistons and see them all gouged and scuffed and such, it's not worth fixing. You might also get your pistons close to top dead center and push on them through the spark plug holes to look for slack in the wrist pins/bushings. If there's a bunch of slack, it's probably not worth fixing. 20psi difference is a lot, and usually indicates a major problem. I'd try and do a little more digging on that motor before spending a dime on it. And the powerhead is just half the battle---- you need a working lower unit, too! Some of these old motors can be stressful moneypits if you're not careful. The only old motor I've ever bought that had 20 or more psi of compression difference had a totally wallowed out wrist pin and bushings. It ran---but was totally useless.
JMO,
JBJ

 

[BayouBengal]

Re: 1957 Johnson Javelin 35HP Compression

Thanks JB for the input, even if it is a little bubble-bursting. Here's the story with the motor and boat. I built a Glen-L Squirt and finished it with mahogany decking to look like a classic boat from the 50's (click to see boat), and so I want a classic motor to go with the boat. I bought a 1956 15HP Johnson, but the boat needs more power. It's only an 11 foot boat, but with all the decking, framing, steering, battery, stereo, chrome, etc., it's not a light boat. I began looking for a vintage 25HP, but had a difficult time finding one with electric start. Then I ran across this Javelin on Craigslist that I bought for $100. It has a perfect cowling with no dings or dints and all the chrome trim and I figured worst case, I could sell the cowling and trim and get my $100 back, so I bought it even though I was suspect of the motor. But I'm pretty committed to having this cowling going on my boat sitting atop something even if it's another RDE or RJE that I paint white to look like the Javelin. Both you and Zephyr stated to pull off the bypass covers and I plan to. I actually plan to pull off everything that won't be too much trouble to put back together, clean, and repaint it. Also, I have a RDE parts motor and my plan is to disassemble it first to increase my knowledge before disassembling the Javelin, particularly the lower end which I have absolutely no knowledge of at present. I changed out the ignition and rebuilt the carb on my 15HP, so, I'm pretty familiar with that and also have the old ignition parts I pulled from it (the 35HP uses the same coils, condensers, points); so, I can use these to try and get the Javelin running. While I don't want to throw away time or money, I'd really like to restore this motor. But if it don't work out, I'll have learned a lot from trying and whatever parts I buy can be used in the RDE or RJE I buy to replace it.

By the way, yes, I'm a little concerned with the 35HP being too much motor, not because of the power but because of the weight, but with my battery and fuel tank moved to the front I think it will be okay. You can see from the pictures the boat presently sits pretty low in front with the 15HP Johnson on back. Additionally, while I haven't experienced any splash over the transom when slowing down, I set the boat up with a continuous drain motorwell in event I did.

This forum is a terrific resource and I appreciate greatly the knowledge and experience you all are sharing.

 

[Willyclay]

Re: 1957 Johnson Javelin 35HP Compression

I'm certainly concerned that if I break open the block, I'll never get it put back together right.

You should not to be afraid of doing a teardown/reassembly on that model motor. My first outboard overhaul was a RDS-21, which is essentially the same as yours. It was seized when I got it and the PO said, "it just quit in the middle of the lake". Armed with a non-factory manual, I disassembled it and found bad crank bearings which had scuffed the crankshaft. Put all the parts&pieces on a sheet of plywood in the basement. Polished out the scuffs on the crank, replaced the bearings, honed the cylinders, replaced the piston rings, used all new gaskets and it started and ran on the first crank after reassembly. Used it for ten years. These are great old motors that will not just die; you have to kill them. Good luck!

 

[steelespike]

Re: 1957 Johnson Javelin 35HP Compression

A beautiful little boat.
The 15 is 75lbs the Javelin is 136 About 61 lbs more.Not that far from double the 15.
The 15 on a light reasonably fast boat is rated at 25 mph.The 35 is rated at 33.
Your boat is light and fast but being so small struggles as you add weright.(61lbs)
With careful setup and the right prop I would think you should get close to the 25 mph with one aboard.Another thought is the 22 cube 25 hp which weighs about 85lbs with manual start and short shaft.Last year available is 76 may have appeared in
70.Capable of speeds over 30.Not as cool looking as the 57 Javelin few are.
The 57 18 hp is rated at 27 and is the same basic block as the 76 25 hp.
We had a 15 footer that resembled your boat and our 18 would occasionally push it at an indicated 27.

 

[BayouBengal]

Re: 1957 Johnson Javelin 35HP Compression

You should not to be afraid of doing a teardown/reassembly on that model motor.

The saying is, "If you're scared, then say you're scared". Well I'd be scared that I'd spend a lot of time and money and never get it back together right, but if I have to, I'll give it a try anyway. Hopefully, it won't come to that.

A beautiful little boat.

Thank you. Weight of my 15HP with electric starter, starter solenoid, electric choke solenoid, and assoicated cabling is closer to 90 pounds. Still I agree, the difference in weight between the Javelin and the 15HP is substantial. Going with an 18HP is plan B. Going with a motor from the 60's is plan C. Changing over to a Mercury is plan D. I've considered playing with the prop pitch, but that cost money too, so I'd prefer just to spend my coins on a bigger engine. Going with a motor from the 70's is not an option, I'd buy a new motor instead of doing that which would be plan E. Going with a manual start is also not an option, I can pull it but my wife can't.

 

[steelespike]

Re: 1957 Johnson Javelin 35HP Compression

The saying is, "If you're scared, then say you're scared". Well I'd be scared that I'd spend a lot of time and money and never get it back together right, but if I have to, I'll give it a try anyway. Hopefully, it won't come to that.


Thank you. Weight of my 15HP with electric starter, starter solenoid, electric choke solenoid, and assoicated cabling is closer to 90 pounds. Still I agree, the difference in weight between the Javelin and the 15HP is substantial. Going with an 18HP is plan B. Going with a motor from the 60's is plan C. Changing over to a Mercury is plan D. I've considered playing with the prop pitch, but that cost money too, so I'd prefer just to spend my coins on a bigger engine. Going with a motor from the 70's is not an option, I'd buy a new motor instead of doing that which would be plan E. Going with a manual start is also not an option, I can pull it but my wife can't.

You can also work on your setup.Those older motors with the 2 piece gearcase can't be raised as much as a modern motor but if you raise it to a point just before venting becomes a problem you could gain a couple of mph.Also be sure it pumps water.
just add sticks to the top of the transom be sure the clamps retain a good grip.
With a modern gearcase they shoot for the antivent(cavitation)plate up to an inch or so
above the bottom of the boat.Not likely to get there with the 2 piece gearcase.

 

[Mas]

Re: 1957 Johnson Javelin 35HP Compression

Beautiful boat! The Javelin will have a lot more torque...is the transom rated at all?

Mas