1972 6hp johnson

[seas]

went and bought compression tester from autozone the one that threads in the sparkplug hole screwed it in pulled starter rope 8 times it read 45 on number one and 35 on cylinder 2 is that ok did i hook up the tester right. should she b set on full when testing.

 

[Rick.]

Re: 1972 6hp johnson

No that isn't good compression. Are you sure you had a good seal on the tester/plug hole? Were the cylinders lubricated recently or were they bone dry after years of storage. More info would help here. Best of luck. Rick.

 

[jbjennings]

Re: 1972 6hp johnson

Welcome to iboats!
Most of the 6 hp johnsons I have tested that ran good had about 80psi of compression. Lots of those cheapo compression testers give inaccurate readings. The most important thing about your reading is that you've got a 10psi difference in cylinders, which is not good.
I'd pull the cylinder head and take a look see. The cylinder head gasket could be blown and may be obvious when removed, or you may see grooves and scratches in the pistons and cylinder walls. If the head gasket is blown, make sure the head is flat by laying it on a pane of glass and looking for gaps. IF warped, put a piece of 400 grit sandpaper on the pane of glass, and rub the head on the paper in a figure 8 motion until it is flat. If you've got bad grooves and scratches.......... that's another story.
Good luck,
JBJ

 

[seas]

Re: 1972 6hp johnson

when i got this motor it was siezed it took me about a week of soaking but i got it free, i was futzing with the cover lock on backside when i noticed one no two head bolts r not there i did replace all gaskets and used gasket sealer. do u think the two missing bolts have alot to do with it n torque them to the right specs. when i put it back together i used a regular 3/8 socket which i found out is not correct.so my question is no torque wrench two missing head bolts could that help

 

[jbjennings]

Re: 1972 6hp johnson

You need to get a torque wrench, and NEW head bolts, along with a new head gasket, and torque the bolts to the right measurement, along with the right pattern of tightening. There is not supposed to be gasket sealer on most head gaskets. Honestly, you might consider taking the whole block apart and doing an inspection before putting money into the motor. If there's rust on the crank journals or wrist pin bearings it will crater quickly. A good used OMC manual for your motor would be a good investment. You can get one pretty cheap---ebay can be a good source.
JBJ

 

[1946Zephyr]

Re: 1972 6hp johnson

when i got this motor it was siezed it took me about a week of soaking but i got it free, i was futzing with the cover lock on backside when i noticed one no two head bolts r not there i did replace all gaskets and used gasket sealer. do u think the two missing bolts have alot to do with it n torque them to the right specs. when i put it back together i used a regular 3/8 socket which i found out is not correct.so my question is no torque wrench two missing head bolts could that help

Two head bolts are missing?? Yea, I would pull the head and correct this. Good chance the head gasket is blown, the rings are sticking and possibly, this motor needs a decarb. I think if you soak the pistons down good with a mix of 50% Acetone and 50% ATF and soak the pistons for a few days, the rings will losen up and then do a decarb, once you get it running.

 

[Rick.]

Re: 1972 6hp johnson

when i got this motor it was siezed it took me about a week of soaking but i got it free, i was futzing with the cover lock on backside when i noticed one no two head bolts r not there i did replace all gaskets and used gasket sealer. do u think the two missing bolts have alot to do with it n torque them to the right specs. when i put it back together i used a regular 3/8 socket which i found out is not correct.so my question is no torque wrench two missing head bolts could that help

Why and the world would you not have told us this in your original post? Seems like important information to me. Rick.

 

[seas]

Re: 1972 6hp johnson

it cant b a blown head gasket can it i just replaced it and i didnt try to start it yet. ibought the compression tester from auto zone its bascially 4 cars can i use this on a marine outboard. also with this low compression will it start.

 

[seas]

Re: 1972 6hp johnson

i need to check piston rings how do i do that and if bad how do i get them out any kind of video

 

[tx1961whaler]

Re: 1972 6hp johnson

Did you replace the broken head boats? The auto zone tester is fine. It may not start if the compression is that low.

 

[seas]

Re: 1972 6hp johnson

i will thanx can i test compression even though the motor has not ran in sometime. wat is the head gasket? they say it may b blown is it the one covering the pistons were the plugs go in?

 

[jbjennings]

Re: 1972 6hp johnson

You're in dire need of a service manual.
JBJ

 

[tx1961whaler]

Re: 1972 6hp johnson

i will thanx can i test compression even though the motor has not ran in sometime. wat is the head gasket? they say it may b blown is it the one covering the pistons were the plugs go in?

Yes.

 

[seas]

Re: 1972 6hp johnson

i rented one from the library but they dont explain much

 

[seas]

Re: 1972 6hp johnson

cant get the exhaust screws out to remove exhaust cover any ideas

 

[tx1961whaler]

Re: 1972 6hp johnson

cant get the exhaust screws out to remove exhaust cover any ideas

Impact driver

 

[seas]

Re: 1972 6hp johnson

that worked thanx but cant get at lower 3 any suggestions

 

[seas]

Re: 1972 6hp johnson

is there a way i can c the rings at wat condition there in. do i have access through the exhaust cover?

 

[seas]

Re: 1972 6hp johnson

1972 6hp johnson how do i get to the rings 4 an inspection, cause i have low compression

 

[AlTn]

Re: 1972 6hp johnson

marineengine.com has diagrams of your motor...as jbjennings stated in post #12, you could really use a factory manual now..use the search feature on this forum <magnifying glass icon next to it> and read about 6 hp.'s and engine rebuilding in general then decide if you have the knowledge, skill,funds, and desire to do this. As in most things mechanical, getting it apart is relatively simple. YouTube has some videos on folks rebuilding various powerheads.