start 1986 johny 140 with no lower unit

[rickybobby123]

hi i have a johnson 1986 140 with no lower unit .i would like to no if i can start it four 5seconds without any isues ..i have the heads off and have some play in all four pistons and would like to hear if there are any unwanted noises before i purcase a lower unit..i just bougt it and am not sure off the power head life ?????thanx compression has 110 on all 4 cyl

 

[oldcatamount]

Re: start 1986 johny 140 with no lower unit

Starting a motor (with no lower unit) so that you can hear potential problems, will absolutely not work. The engine exhaust will be deafening, and if you run it like that for more than 5 - 10 seconds, you could seriously damage the powerhead. Plus, the motor won't run correctly without the exhaust back pressure created when it's in the water. My advice, do not do it.

 

[rickybobby123]

Re: start 1986 johny 140 with no lower unit

thank you i new about the deafening exhaust but not the back pressure..what are my options before spending on a lower unit .i still have the heads off..any suggestions would help

 

[daselbee]

Re: start 1986 johny 140 with no lower unit

How do you start it with the heads off?

But, I understand the concern re piston play.

The pistons in these engines are surprisingly loose. The have a whole lot of play compared to a 4 stroke engine. I thought it was a defect when I first saw it, but when seeing more and more engines, and even new rebuilds, the pistons seem loose.

If you want to run the motor with no lower unit AFTER you get the heads on, you can attach a hose directly to the water tube and start it right up, no problem.

 

[rickybobby123]

Re: start 1986 johny 140 with no lower unit

thank you i just thought it would help to no the heads where off .since we where in the conversation.lol i will put the heads back on with old gaskets first and run some water in thanks again guys for all the great help?

 

[daselbee]

Re: start 1986 johny 140 with no lower unit

err....the old gaskets?

You might not get a good seal and leak some water into the cyls. Probably not, but it is possible.
Then if you let it sit for even a few hours, rust!.

Here is something you can do while the heads are off. Rotate the engine clockwise, bring each piston up to TDC, and continue a bit more until the piston starts down in the cylinder. Stop, and try to push the piston further down in the cyl by hand. It should not move at all.
If it moves down, it shows play in the rod bearing or piston pin. It will be obvious. Do all of the cyls.

You already had good compression, cyls are good, put the heads on with new gaskets, torque properly, and leave them alone.

I made up a hose to use to hook to the water tube, clear 5/8" vinyl, with a female hose fitting on one end, and a hose clamp in the other for clamping to the water tube.

You can run it as long as you want with that water supply. You will not be able to hear any rattles or knocks tho.