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Compression Check Issue 1998 200 hp

westrong

New member
My dad was doing a compression check on a pair of 1998 200hp Johnson Ocean Pros. The first engine went fine during the check...removed all the plugs, turn the engine over...no issues.

Now the second engine was a different story. After removing all the plugs and inserting the compression gauge the motor would crank over once then quit. The engine would continue not to turn over more than once without any less than 5 plugs installed. 5 or 6...no problem. 4 plugs or less installed the engine would crank once then quit. Hit the key again, same issue.

What am I missing here...besides a brain.

Both engines run fine otherwise.
 
Re: Compression Check Issue

this is due to the gear reduction starter....very common,..put a cpl of plugs in the oposite bank u r checking,and test,,,,.........make sure u have a hot batt,this in fact,..applies to all the newer gear reduction eng's.
 
Re: Compression Check Issue

so you are saying that with the plugs on the motor will crank, but w/o them it will not???

Yes with 5 or more plugs in the engine will crank. Take out any two plugs and the engine cranks once and that's it.

I can't seem to get the "Multi-Quote" thing to work on this forum so I'll follow this with another reply to the statement by jwbmarine.
 
Re: Compression Check Issue

this is due to the gear reduction starter....very common,..put a cpl of plugs in the oposite bank u r checking,and test,,,,.........make sure u have a hot batt,this in fact,..applies to all the newer gear reduction eng's.


The battery appears to be fine. I checked the voltage, load tested and all connection are clean and tight.

Now, you mentioned the gear reduction starter...The opposite motor doesn't appear to have any issue cranking with all plugs removed. That is what struck me as being odd.

I'm going to the boat today and try your method of putting plugs in the opposite bank and see what happens.

Thanks to all!
 
Re: Compression Check Issue

The earlier V6 looper models had that identical problem but some change was incorporated that corrected the problem. I encountered the problem constantly back in 1986/1987. All plugs removed..... as soon as compression was met via the compression gauge, the electric starter bendix gear would disengage from the flywheel. The only cure was to have the other five spark plugs installed. My question to the reps on this problem was answered with something like... That's the nature of the beast.

Bottom line...... Do what's necessary in order to take the compression readings and don't try to figure it out.

What's the model number of that engine..... and does the number on the core plug of the powerhead coincide with it?
 
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