69 Johnson 9.5 low compression.. Will it start?

[brtc]

Just inherited a 9.5 johnson. I rebuilt the lower unit, cleaned up the old head gasket (new one on order now), changed spark plugs, and cleaned the carb. I tried to start it and got nothing. So i went to auto zone and got a compression gauge and it's pulling 50 psi in one cylinder and 60 psi in the other. I know it should be around 80 to 90. . I have pulled and pulled on this thing and get nothing. Is it possible to start it that low? What do I need to replace? I assume the culprit is the piston rings, just hoping there could be something else. It was holding pressure in both cylinders, it was just low. Thanks for the advice..

Also, this could sound dumb, but when i was replacing the impeller, I noticed that the drive shaft rotates counter clockwise, so i placed the impeller so it would rotate counter clockwise. Makes sense. on http://www.**********/parts/search/BRP/JOHNSON/1969/9R69S/GEARCASE GROUP/parts.html, (place boats dot net in place of stars) it shoes a breakdown and the impeller looks like it rotates clockwise? is this just a poor drawing, or am i missing something?

 

[kfa4303]

Re: 69 Johnson 9.5 low compression.. Will it start?

This link should help. Make sure you're testing the compression with the head gasket properly installed. The driveshaft should only ever spin clockwise as well.

http://www.leeroysramblings.com/OMC_9.5.htm

http://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1969&hp=9.5&model=9R69S

 

[boobie]

Re: 69 Johnson 9.5 low compression.. Will it start?

Depends on which end of the d/s you're looking at.

 

[HighTrim]

Re: 69 Johnson 9.5 low compression.. Will it start?

As Boobie stated, if you are looking up the driveshaft from the bottom it is CCW, but in actuality the driveshafts orientation is described looking down at the motor from above, so it would turn CW. True, when you install the impeller it turn it CCW in the impeller housing looking at the housing turned upside down in your palm.

Regarding compression, first try another gauge. If it is accurate, you will never run/start properly with that low compression.

Dress the head by taping a piece of 0 or 00 emory cloth on a flat surface such as a piece of plate glass or a lapping block.

Now using light even pressure, run the head in a figure 8 motion on the emory cloth until you have an even dull luster throughout. You will be able to tell farily easily if there are high/low spots by the uneven polishing.

 

[the machinist]

Re: 69 Johnson 9.5 low compression.. Will it start?

If the motor has sat for some time, that compression may be normal, low but did you pull both plugs when testing & have it in neutral & pull like you were mad at it? Any resistance will bring out low readings. How many pulls did you do per reading?

There are a multitude of things that could make it not want to fire off. Did you check for spark at the plugs? How about fuel delivery?

 

[boobie]

Re: 69 Johnson 9.5 low compression.. Will it start?

I just looked at the pic you posted and saw that you had one plug in when testing compression. Both plugs have to be out.

 

[brtc]

Re: 69 Johnson 9.5 low compression.. Will it start?

Thank you for all of the useful information! I did have one plug in. I'll re check compression tomorrow and reply. I had spark at the plugs, and they were brand new. On that note... I got it to start!!! I definitely have some throttle linkage issues to work, but it runs! I had to rebuild my fuel pump. which I made the mistake of completely disassembling. Thank you for letting me know about the drive shaft rotation. I was confused when I was building the gear case because i could only get it to move counter clockwise looking down at it. I ordered a new impeller to replace the old one, and I will install it the correct way before i run the motor again. Thanks again for everybodys' insite.

 

[kfa4303]

Re: 69 Johnson 9.5 low compression.. Will it start?

Depends on which end of the d/s you're looking at.

........when viewed from above, in normal operating position.

 

[brtc]

Re: 69 Johnson 9.5 low compression.. Will it start?

If the motor has sat for some time, that compression may be normal, low but did you pull both plugs when testing & have it in neutral & pull like you were mad at it? Any resistance will bring out low readings. How many pulls did you do per reading?

There are a multitude of things that could make it not want to fire off. Did you check for spark at the plugs? How about fuel delivery?

Thanks for the info Machinist.. I had one plug in. I will check again when i get the chance. However, I got it to run! It was the fuel pump.