mercruiser 165 compression test questions

[youknowmeasbud]

recently bought a 1971 fiberform 22ft cuddy, i now understand the acronym b.o.a.t, so for now i wanted to do a compression test on it and make sure im not trying to saddle a dead hoarse. my pressures are as follows, front to rear.. 130,130,165,130,130,125.
i read in the manual that 140 is the correct pressure, and that a variance of 20lbs is 'ok' .. what i dont understand is how i have a pressure spike in the one cylinder @ 165.. could i fix this with love, or will it cost money.. har har.

 

[alldodge]

Re: mercruiser 165 compression test questions

recently bought a 1971 fiberform 22ft cuddy, i now understand the acronym b.o.a.t, so for now i wanted to do a compression test on it and make sure im not trying to saddle a dead hoarse. my pressures are as follows, front to rear.. 130,130,165,130,130,125.
i read in the manual that 140 is the correct pressure, and that a variance of 20lbs is 'ok' .. what i dont understand is how i have a pressure spike in the one cylinder @ 165.. could i fix this with love, or will it cost money.. har har.

Your readings calls questions but not to much for major concern. As you probably know compression numbers can vary due to temp, moisture/oil in cylinders, valve seating and cam lift. If I had the engine and it was running ok I wouldn't be to concerned.

The 165 to 125 is a bit of difference but how was the compression test done? Were all the plugs pulled or just one at a time? Was the engine cold or warm? How does the engine idle and run now?

 

[youknowmeasbud]

Re: mercruiser 165 compression test questions

i removed all the plugs, and did a compression test at cold/ not previously ran. i have it running right now at idle and it sounds fine, purrs. also.. i did another compression test with a fully charged battery (not that it should make a diff) but i got 140 out of the last one instead of 125.. kinda weird.. but im sure it had a little more oil in it this time around
** a new question** maybe even a new thread.. but when i go into reverse it grinds pretty heavy (out of water) but finally engages when i lean into it.. but (in water) it wont go into gear.. can i just adjust the linkage a couple turns and solve this?

 

[alldodge]

Re: mercruiser 165 compression test questions

i removed all the plugs, and did a compression test at cold/ not previously ran. i have it running right now at idle and it sounds fine, purrs. also.. i did another compression test with a fully charged battery (not that it should make a diff) but i got 140 out of the last one instead of 125.. kinda weird.. but im sure it had a little more oil in it this time around
** a new question** maybe even a new thread.. but when i go into reverse it grinds pretty heavy (out of water) but finally engages when i lean into it.. but (in water) it wont go into gear.. can i just adjust the linkage a couple turns and solve this?

With the 140 afterwards I wouldn't touch the engine except maybe after running it for a few hours and check the hydraulic valve adjustment. Even that I might take a pass but that would be about it.

As for the grinding and no engagement, this more then likely is the lower shift cable needs to be replaced. The cables wear quite a bit over time and is the number one thing that gets replaced when shift trouble is found. You could start with checking adjustment and if no help then replace.

 

[youknowmeasbud]

Re: mercruiser 165 compression test questions

so, i did a dry test (with a hose only) and it engaged fine into forward, and a bit of clunking into reverse with no total engagment , so i turned the adjustment pin 2 turns clockwise, and it engaged better.. so i took it to the marina boat launch and put it in just deep enough to test, and it sounded terrible again.. so i turned it 2 more times and it seemed to engage , so i gave it one more turn and finally got it into reverse.. but then it had trouble coming out of reverse i would have to bump it into forward then back to neutral for total neutral. and visa versa in forward.. so the 'lower shift cable' this is the short one that goes into the bellows/outdrive.. right.. ok well what actually happens when these things start going out? seems like mine is working fine.. but im sure its old and could use a replacement.. i suppose i have to take the out drive off to do this too... huh, got some work ahead of me..

 

[alldodge]

Re: mercruiser 165 compression test questions

Yep, to replace the shift cable the drive comes off. Turning the barrel nut isn't all that is involved in the proper adjustment of the shift cable. The link below is from achris and he has all the bases covered on how to remove the drive, adjust the shift cable, replace impeller and other things to look at. Have a look and let us know if anything needs clarification.

http://forums.iboats.com/mercruiser-i-o-inboard-engines-outdrives/couple-new-videos-590378.html

 

[youknowmeasbud]

Re: mercruiser 165 compression test questions

jeez, so i followed the video to a T, and it worked, with some adjusting i managed to engage forward and reverse with little to no noise.. a couple times.. then i couldnt get into reverse again, at all. just heavy grinding.. and now the remote/throttle cable seems really stiff... i pretty much know i have to replace the lower cable, right? the fact that it engaged once and worked at all rpm's makes me feel better.. i thought it might have been the gears themselves , but why would it work once and then not at all again a min. later.. huh.. well like i said i got to to some work on this beast.. anything else i should replace when i got it apart.. my bellows are good, but new ones would be better right, and ill have to wait to inspect the bearings.. what about u-joints, what should i look for on them? thanks for the input..

 

[Bondo]

Re: mercruiser 165 compression test questions

jeez, so i followed the video to a T, and it worked, with some adjusting i managed to engage forward and reverse with little to no noise.. a couple times.. then i couldnt get into reverse again, at all. just heavy grinding.. and now the remote/throttle cable seems really stiff... i pretty much know i have to replace the lower cable, right? the fact that it engaged once and worked at all rpm's makes me feel better.. i thought it might have been the gears themselves , but why would it work once and then not at all again a min. later.. huh.. well like i said i got to to some work on this beast.. anything else i should replace when i got it apart.. my bellows are good, but new ones would be better right, and ill have to wait to inspect the bearings.. what about u-joints, what should i look for on them? thanks for the input..

Ayuh,.... As the inner cable wears a groove in the outer casin', the travel is affected, the hit or miss could be many things,...

Did ya disconnect the cable at the shift switch, 'n try shiftin' the drive by hand,..??

Odds are, ya need a new 1, it's common after 6/ 8 years for 'em to go bad,...

U-joints are like any other bearin',... smooth, free, no play,....