Compression Question????
 

I have a 1997 Johnson Oceanrunner
Compression as follows
looking at rear of block
left side
120
120
85

right side
120
120
90

Per mechanic possible rebuild of engine or sell as blown motor???
Motor runs fine...just never had compression test done before :(
Any other suggestions decarb etc. etc.
I am aware that there is no mechanic in a can but just trying to come up with ideas etc?
Thanks in advance
-Fred H

Re: Compression Question????
 

You can try a De-carb process, but those #'s are pretty far off. General rule is: the range should NOT be more that 10 psi or max max of 10% differnce. That would be a 12psi max. You are 35 psi, surprised the engine runs well w/ those #'s.

Did you check the compression when the engine was warmed up?? Also was fuel/oil running through it at the time of the test?(Kill switch in safe mode) All the plugs out at when you cranked it over?? All of the above can affect the #'s as I have read in many articles on the subject.

I just went through this exercise myself in the past month. Fortunately my max range was 9 psi.

Re: Compression Question????
 

oops...not 120 but 110..typed it wrong
so let me redo!!
left
110
110
85
right
110
110
90
still looks like off more than 10 percent
Any more suggestions..rebuild....etc???
thanks again
-FRED

Re: Compression Question????
 

You need to know what the specification is. Some of those motors had two opposing cylinders lower

Re: Compression Question????
 

Those bottom two are toast. Pull the heads and take a look at the damage. Scoring is probably minimal at 80psi . . . but do not run that motor anymore . . . don't even turn it over (unless you do it by hand slowly with lots of oil). I bet you have two stuck rings and some nice aluminum paint inside the bottom two with light scoring. If you stop now you can probably get away fixing the motor with a hone and two new pistons. Don't even bother decarbing at this point. Pull the heads and look. If you just have stuck rings and no cylinder wall damage . . . then consider yourself extremely lucky. The nice thing about that motor is that you can pull both pistons out without cracking the block open.

Re: Compression Question????
 

Motor was cold when compression done
all spark plugs removed and remote starter used at motor


Tim... wish you were closer.....

I will check specs just in case..I really dont feel like dumping money in that I dont have!!!!

Re: Compression Question????
 

Fred - 1st thing I would do is buy a compression tester yourself and double check the mechanics claims on the bottom two. If they test low . . . pull the heads.

if the scoring isn't bad, you can do a 2 hole fix on that motor w/o a total rebuild. It'll take about 1 day and you'll need 2 new head gaskets, 2 new pistons and rings, bearings (may be able to reuse), intake gasket, a ball hone that will fit that motor, lots of oil, wd-40, locktite, gel seal, and carb rebuild kits. It's a bit of a hack fix, but it'll work if you keep everything clean clean clean. The alternative is to sell it. Parts will probably run $300 - $400, so you have to make the call and decide if you feel mechanically inclined.

Re: Compression Question????
 

You should pop a head....and have a look. Tim walked me thru this exact repair. Yes you can pull the reed block unbolt the rod and push the piston out. After doing that you can "de glaze" with a hone. I did this to one cyl that had a stuck ring (my fault) on my 225. Compression went from 80 back up to 120 where the rest were. Parts for the piston, rings, rod bearings etc was just over 200ish I think. Its a pretty basic motor. I dont think I would move it into the "parts motor" catagory without looking inside 1st.

Re: Compression Question????
 

Mine's 105 - 108 and 98 on the bottom port. When I rebuilt a couple years ago, they were 110 except that bottom one at 105.

Re: Compression Question????
 

John - Do you have that picture of the piston with the stuck ring, so fred can see what 80psi looks like in that motor?

Re: Compression Question????
 

Yea...Unfortunately :o

80 psi: note verticle grooves:

http://i155.photobucket.com/albums/s...c/pic004-2.jpg

Pull piston: note stuck ring :mad: and more vert damage
http://i155.photobucket.com/albums/s...c/pic023-2.jpg

120 psi: Cy; deglazed with hone 90% of vert grooves gone, cross hatch re-established, comp back up to 120, motor is happy again. Thes pix were about 3/4 thru...it looked a bit better when cleaned. I put in a new cly and ring kit. Rod and needle bearings too.

http://i155.photobucket.com/albums/s...c/pic019-2.jpg

http://i155.photobucket.com/albums/s...ncc/pic015.jpg

It dosnt make me feel good that I had to perform surgery but like Tim has said these motors are tough and basic and it didnt seem to mind the work. My motor was a nice clean motor that I aquired for cheap money before I gooned it up. I hope to get a few seaons from it still.

Re: Compression Question????(TIM HELP!!!!)
 

John and Tim thanks for the valuable advise and pics to go along with it.

Tim...question for you...before I continue with this motor..with my minor mechanical abilities when it comes to outboards

I spoke with my mechanic who came out and again verified compression last night and it came out same.
He said he would buy my motor as is for $1000 and put it towards purchase for a 2001 200 hp Merc carbed motor that he is going to rebuild plus install all new guages and harness, cables and cotrol box for total of $4000 minus $1000 for my motor..so basically a rebulit motor with 1 yr warranty for $3000. He rebulds motors for race boats etc and did some nice work on my carbs on my 1993 merc 135hp on the back of my Seafari. That was the best boat/motor I ever owned!!!! Also said weight would be 80 lbs lighter with Merc!!!

What should I do...?????oohhhh....
He also found out that stator has been dripping black goo and he said it will probably start to arc..and will eventually need to be replaced and reepoxied???!! and we are abe to tilt up motor by hand..so t/t needs attention.Guess my initial purchase of the Johnson for $1800..taught me a valuable lesson...bring a mechanic!!!
tim..let me know your ideas..do I fart around with this Johnson...I just want a reliable motor that I can put on another Seacraft in future!!!!
Thanks
-Fred H

Re: Compression Question????(TIM HELP!!!!)
 

Fred - Pull the heads and look first before you jump into anything or better yet pull the head with the mechanic. You know what you are looking for . . . The bolts are cake to remove (15 minutes total) and even if you do the deal with the mechanic . . . he has to yank the heads off. Make your decision then. That motor parted out is worth around $1000, so what can you get for $4000.

If that 2001 Merc 2.5L 200 has o ring (flat looking heads) style heads . . . stay away. If not, it doesn't sounds like a bad deal to me, especially if he'll rig it and provide gauges, remove oil injection, and offer some sort of warranty/support. If he's rebuilding it . . . ask him exactly what he's doing to "rebuild" that motor.
************************************************** ****
Hope this helps!

Re: Compression Question????
 

Now the class has my attention. :(
When I talked to Art @BRP tech he said that these motors left the factory at spec between 90 and 130 comp. I thought that to be strange. He said that as long as they were even that was proper spec for release.Said they matched the piston/ ring combos. My motor is 87-92 and turns 5200 light Bimini up. Should I be concerned? Anyone local have a scope?

Decarbed 30 hrs ago w/ Engine tuner thru the Schrader and then pony tank Seafoam 3 cycles. `til the forest fire smoke stopped. 930 hrs now."Pros" all say don`t worry, but I am. Always.
Thx,
GFS

Re: Compression Question????(TIM HELP!!!!)
 

Thaks Tim..spoke with him 2 minutes ago on phone..not using o ring heads on rebuild..says he stays away from them...doing total teardown and rebuild back up to specs, including carbs..eliminating oil injection..and using block off plate??-- and said will look like came from factory..no extra wires etc for oil injection. He is going to pressure test lower unit and if any problems will also go through that as well. Also gauges hooked up and quicksilver binnacle control mount.(said he will not charge for rigging)
He is also going to pull head off for me on johnson and give me his opinion before this whole deal takes place. will repost next monday...gotta go to MS for thanksgiving..hate going out there..havent seen father in over 2 years and he always looks older every time I see him :(...and he tells me I look fatter!!!!
I will start new thread regarding this due to only 2 thread at a time on this topic....just remember this is on a Mako ...hopefully not for long!!!
Tim....GUESS $4000 could buy me "BIG RED"

Sandy....still have your gps :)...your outriggers look tempting.
http://i271.photobucket.com/albums/j...01/Mako203.jpg

Re: Compression Question????(TIM HELP!!!!)
 

Hey Fred - He sounds like a stand up guy. I'd do 4K delivered with a gallon of flag blue awlcraft 2000 just to make space in my yard.

Re: Compression Question????
 

Sandy,
Like Fred...my motor was all 120's. I had a lean condition that casued the ring to hang up. After it hung it didnt take long to glaze the walls of the cyl. Tim did coach me up for the repair work which was not bad at all.

Fred...you can have that head off that motor in 20 mins. The lower cowl splits open and you have complete access. This is one thing I have come to like about this motor. Its very easy to work on...but I'd rather be running it [img]/forum/images/graemlins/tongue.gif[/img]

Re: Compression Question????
 

Sandy - your guy is right. I've seen two 1994 200 and a 1995 225 that had 100 - 105 psi in all 6 and perfect cylinder walls. The point were I'd be concerned if you had a motor with 120 psi like hermit's 2000 225 and had one cylinder drop to 80psi from 120. I mess around with merc's so I can't tell you exactly what OMC models were higher compression. If all yours are the same and the motor runs well . . . I wouldn't give this another thought.

Re: Compression Question????
 

Thanks Tim and John. I`ve got the ex 150 low comp version.
There were 5 or 6 versions. the 175 has bigger carbs and I`d imagine more comp. I`m curious now. Bet Corey`s got a scope. Motor runs nicely , even at idle, which from what I`ve read is not really common. Knock Knock.
GFS

Re: Compression Question????
 

Our 60 degree, or properly named "Eagle Series" motors are lower compression. The one in the pictures appears to be a 90 degree cross flow which can have upwards of 140. The 60 deg 175 has different carbs and porting, not sure on compression numbers. The 60's also use o-rings for head gaskets. If you pull the heads, make sure to apply sealer to the bolts and a thin ring of sealer around the water ports making sure to keep it out of them.

Re: Compression Question????
 

Good idle on this style motor is attributed to all 6 butterflies being completely closed and a slightly rich idle air adjustment. I shoot for 600 rpm in gear.

Re: Compression Question????
 

Red...my 225 is a 90 degree V6 Looper :D

Re: Compression Question????
 

Have you heard about going one or two jet sizes up in the #2 cyl on the 90 deg loopers. Heard that`s the thing to do from Monty Racing.

Re: Compression Question????
 

Sorry Hermit, I should have paid closer attention to all the photos. Sandy's and mine are the 60's. Your slightly domed pistons certainly are looper.

Re: Compression Question????
 

OK..I'm all ears here...whats this all about?

Re: Compression Question????
 

They said that the #2 is a cause of failure due to lean out. Something about the design of the motor. Said that they recommend this mod when rebuilding them.Monty Racing 954-328-4445
GFS