1958 Johnson Seahorse 10 HP QD - 19

Wayne.McC · May 11, 2012

I posted a thread a few days ago and received allot of good information about ignition timing, coils, plugs, wires, points, just allot of good need to know links and I thank you all. I was pretty convinced at that point that I should replace all or most of the system. It starts and runs, it starts and runs with one plug pulled out, it started and ran today in gear with the plugs not tightened in the sockets ( left that way by me the day before ) But today I wanted to do a compression test and I wanted the motor to warm up first as I read in a link some where. Top cylinder reads just above 0 psi, the bottom reads 30 psi. I think I need a link on rebuild parts and cost involved. I think that the compression test really sums it up. Ok, maybe not, I know I'm going to pull the head cover and try to determine why the loss of compression I hope it's a blown gasket.

Chinewalker · May 11, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

If it ran, then the compression is likely not as low as you described. A blown head gasket, particularly with the blown area between both cylinders, would explain the drop. Won't know for sure until you pull the head - easy enough and shouldn't take more than a few minutes - assuming no bolts break!

Wayne.McC · May 11, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

That is something I can recover from but I do have a limited budget and trying to stay in a range. I have saved some by not replacing an electrical ignition that obviously works but now am looking at a more expensive project. In the end I want this motor to run as good as new so what ever I have to do I will do.
Thanks for your quick response.

HighTrim · May 11, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

Pull the head first so we know what we are dealing with.

IF by bad luck the powerhead is toast, the cheapest/easiest repair would be to buy a powerhead and new base gasket rather than rebuilding. Post a wanted ad on aomci.org in the webvertize, should be able to get a powerhead from a parts motor for a fair price. I can guarantee cheaper than rebuilding yours.

Wayne.McC · May 12, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

Pulled the head today, didn't see any real signs of blown gasket. The cylinder walls have lines I can see but can't feel so I think that is good. Tops of the pistons are blackish but no sign of crack or holes.

Not real good pictures. How about worn out rings?

Mas · May 12, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

I'm wondering about your compression gauge...not gonna run with numbers as low as you described...but you said it did, so the numbers must be higher...bad gauge? Poor seal on the compression gauge? How may times did you rapidly pull the motor over during the test? Were both spark plugs removed (and grounded?)?

Mas

HighTrim · May 12, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

Also pull the bypass covers and see if the rings are still spongy and bounce when you press on them with a screwdriver.

Wayne.McC · May 12, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

The gauge was never used right out of the package, I tested the motor warm hand turned the crank with the plugs out. Turned it over six times releasing the pressure each reading.

Wayne.McC · May 12, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

I opened the top cover and could see the rings, I didn't press on them, they are not broken. How much spring should they have when I press on them?

HighTrim · May 12, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

They should bounce a bit. If they dont bounce at all they are stuck with carbon.

bbstacker1 · May 12, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

I have to agree with Mas, 0 and 30, I don't think the engine would even run with that. I think your tester is bad or your method of testing is wrong. Did you say your were turning the crank by hand? If you are only hand turning the crank and not using the starter cord that is most likely why your readings are so low.

Wayne.McC · May 13, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

Well that could be the case, should it matter how fast the crank is turned? I don't know. I made a flywheel puller that has a handle for holding in place while pulling it also serves to turn the crank. Ok I missed the part about turn over 5-6 times till the gauge reads no higher. So now the head is off and I have inspected the cylinder walls and they look like I think they should. Pistons have no apparent holes or cracks. I can now inspect the rings through the ports from side covers. I just pushed on the rings in the top are they are springy.

I can't get to the lower one as easily. What now? buy torque wrench and a new gasket and test it again? The top is the one that I thought was the worst.

bbstacker1 · May 13, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

Wayne, the correct answer is yes, you need a new head gasket and torque wrench then do the test again. If you have not removed the old head gasket, I think you could snug up the head bolts, not very tight if you do not have a torque wrench, and try the test again using the recoil starter, give it 5-6 good quick pulls, see what you get for a reading then do the other cylinder. I am betting you are going to see a considerably higher number than before. And yes crank turning speed does make a difference in the reading you will get. In the end and as I said to start you will need a new head gasket and torque wrench to do and complete the job properly.

HighTrim · May 13, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

Yeah I did not see the part about the hand turning. You will never get proper readings like that.

Pull both plugs out. Ground the leads to the block. Install the compression gauge in a cylinder. Pull the recoil a good 7 to 8 times quickly. Check the reading on the gauge. Release pressure, remove and then install in second cylinder. Pull the recoil a good 7 to 8 times quickly and check the gauge again. Let us know what you find.

Wayne.McC · May 13, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

I hope you guys are grading on a curve, just put it back together, retook compression as you said. 70 lbs per.

Thats good or better? now I'm back to square 1. I do now at least know that the rings are in good shape cylinders and all so far looks good.

jbjennings · May 13, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

As I mentioned in the first post on your other thread, your problem the whole time has most likely been bad spark on one cylinder. At least you know you have a good powerhead to work with. Be sure you have an air gap tester for spark testing, or you'll be chasing rabbits for a while. There can be tons of reasons for bad spark on one cylinder. It could be a bad plug wire, a bad coil that appears to be good without testing it, a bad condenser, dirty or improperly gapped points, arcing from the wires to the block, etc. etc. You may also have a dirty or improperly adjusted high speed jet in your carb. There's a super good detailed method for setting your carb once it's cleaned in the "top secret files" thread at the top of this forum written by Joe Reeves, an expert technician....
Good luck,
JBJ

Wayne.McC · May 13, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

New head gasket, torque wrench for now. got to go to bed.

kfa4303 · May 13, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

Hi Wayne. Great motor you got there. My personal favorite paint scheme of all the vintage OMC motors. I used to have a '61 QD-22 myself. Glad there are no piston issues. 70 psi per cylinder should work and may go up a bit after you do a decarb on the motor. Here are some handy links that can walk you through a tune up from top to bottom. Holler if you get stuck.

http://www.marineengine.com/parts/v...ntage-evinrude-johnson/377513/37751300001.htm

http://www.sschapterpsa.com/ramblings/johnson_QD.htm

http://www.outboard-boat-motor-repa...on 3 HP 1952-1967 Ignition System Tune-up.htm

http://forums.iboats.com/showthread.php?t=167352

Wayne.McC · May 14, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

Hi guys, I bought the gaskets, Head and side cover also ignition tune up coils points condensers. Have to borrow a torque wrench Sears wanted $ 79. 99 Not this guy! What is the torque on the head bolts I thought I saw 40 flbs somewhere can't recall where? I'm going to start assembly on Thursday. The weather here is shaping up and I want to enjoy that water soon.

bbstacker1 · May 14, 2012

Re: 1958 Johnson Seahorse 10 HP QD - 19

Wayne, I don't have the numbers right in front of me, but I am pretty sure the torque is 8-10 ft lbs, hopefully one of the other guys will correct that if I am wrong, but I do know it is not 40 (way too much).

1958 Johnson Seahorse 10 HP QD - 19

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