Evinrude Fleetwin 7.5 compression test

[duckland23]

Hi I trying to test the compression on my evinrude fleetwin 7,5 hp motor . Im not getting a reading from the gage i got from autozone . Im wondering is the gage special for testing compression on outboard motors . I thought the one you use for automotive should work for the reading . I turned the pull start like 4 or 5 times and no reading . It it I have no compresion . The gage will goto 30and then back to 0 .should I get a read of some pressure of some kind . I am also getting a oil in the water thats black in color . is that noromal for running your engine in a tank or garbage can . My nieghbor told me I should not get any oil like that in the water at all . If I place my finger by the hole I get some pressure but not alot of it . that maybe why Im have a hard time starting the motor . But from that I gat see in the holes the cyclinders dont look torn up from bad rings . Im not for sure . But is it normial for oil in the water them your runnin it in a garbage can . It not the lower unit The oil is fine . I checked that . If I have bad ring can I rebuild it and will it cost me alot of money to do . If I can do it for under 100.00 then Ill do it .

 

[HighTrim]

Re: Evinrude Fleetwin 7.5 compression test

Oil in the water while barrel testing is quite normal for a 2 stroke.

There is something wrong with your test, you are not getting a reading at all on either cylinder?

 

[duckland23]

Re: Evinrude Fleetwin 7.5 compression test

No reading it jumping to 30 on the gage them back down to 0 . its not holding the pressure on the gage . it a automotive gage from autozone and its new loaner tool from them too . The gage should hold the pressure for the reading right thats what I remember for testing cyclinders in a car . I know also to do a wet test too with oil and compare the reading so pressure diferents .

So the black color oil is fine to have in the water while barrel testing . I had her running but she's giving me alot of trouble . I hate to keep posting but Im in need of some help . I hope I did'nt buy a bum motor or lemon . Oh the gage is not special for marine engines to so a compression test , the automotive one will work right .

 

[duckland23]

Re: Evinrude Fleetwin 7.5 compression test

so its ok to have oil black in color while Im testing the moter in the barrel , Im not gettina reading from the gage and it a new loaner tool from them too . It jumps to 30 ten back down to 0 . It wont hold a reading at all . It a special marine engine comression tester or is the one in the auto parts store fine to do a compression test . I Must have compression from the cyclinders My father said he felt the air blowing out of the spark plug hole and it will hold my finger as well and blow it out but nothing major by that matter . i never seen a gage that would not hold a reading even if it 30 psi of pressure . I have to have more that that it would not run on that pressure am I right . But that may as well be my problem . Let me know that I can do and what type of reading should i get from that engine . Oh it a 1957 evinrude 7.5 hp model 7522 .

 

[Beek14]

Re: Evinrude Fleetwin 7.5 compression test

Don't worry about the oil in the barrel, that is going to happen, no way around it. Are the spark plug threads in good shape? Is the tester tightened in the plug holes tight enough? If you don't have it in tight enough it can lose it's pressure. If there was a crack in the powerhead or cylinders it could also cause a loss of pressure.

 

[duckland23]

Re: Evinrude Fleetwin 7.5 compression test

how would I know if theres a crack inthe power head . Theres a lot of oil in the water when running her . Can I see that if ther was one . Im wondering if the compression tester im bad Its new out if the box but thats the second one we got from autozone . The first one the gage would not work and the second one would only go to 30 and back to 0 asap without it holding the pressure on it . I can try it on are lawnmower it new from sears and runs . that way I will know if its the gage .

 

[Beek14]

Re: Evinrude Fleetwin 7.5 compression test

That works. You should be able to hook that up to any gas engine you have that supports the same size spark plug. Have a 4 wheeler or snowmobile or lawn mower at home you can try it out on? Or even the truck..

 

[duckland23]

Re: Evinrude Fleetwin 7.5 compression test

Im going to try that in the morning or afternoon if it dont work its going back to autozone . Thank god it there loaner tool but it was new open in front of me too and was the second one from them too . Well thats what you get when its made in china . there products are no good they should bring making thing like that back to the usa again . I hope the engine has good compression if not that why it hard to start or hard starting . But I had her running she geting fuel and after she ran for a liitle while she would start back up again with one pull . It may as well be the point not set right or I have a problem with fuel im over looking . But I think if I get 75 to 100 psi she should run fine . The plugs where normal color when I pulled them out a little black but fine for two cycle engine .

 

[Beek14]

Re: Evinrude Fleetwin 7.5 compression test

But I think if I get 75 to 100 psi she should run fine . The plugs where normal color when I pulled them out a little black but fine for two cycle engine .

Yes, as long as compression is even (between 0 to 10 psi difference) those numbers should be just fine.

 

[duckland23]

Re: Evinrude Fleetwin 7.5 compression test

Should I be getting a reading even with bad rings no matter what . I did'nt try a new compression gage yet But I'll let you know whats going on . Whats the max and min numbers Im looking for in compression on this engine . I never had a gage do this before its a first for me . I was wondering if bad reed valves would cause a bad compresion reading and make it run like crap . When I ran it in the barrel on saturday evening it was hard to start and sounded like she was running on one cylinder . The other day I ran her and i was adjusting her and she started to run real smoth in gear . somethings up with this engine . I rebuilt the carb and changed the plugs the wires are new looking the coils look like someone before me changed them The points look like there in good shape not burned up and I adjusted them to 020 gap . So where do I go from here what do I do .

 

[jbjennings]

Re: Evinrude Fleetwin 7.5 compression test

Bad reeds would keep it from pushing fuel into the cylinders, but not give a bad compression reading as far as I know. If it ever ran good recently, then compression is likely not your problem. Use an air gap tester and check your spark.
JBJ

 

[duckland23]

Re: Evinrude Fleetwin 7.5 compression test

I pulled the powerhead anyway .

 

[duckland23]

Re: Evinrude Fleetwin 7.5 compression test

I posted picture of the engine In one of my thread for you to see . The fact of the matter is I got 30 and maybe 35 on cylinder two , cylinder two was a little higher than number one . Just the head gasket would cause bad compression ans not the ring as well .

 

[Beek14]

Re: Evinrude Fleetwin 7.5 compression test

Was it holding at 30 and 35 or was it falling like earlier as you were saying it was before? That's too low. Could be a number of factors if that actually is the compression. Bad rings, cylinder head, shot pistons etc.

 

[duckland23]

Re: Evinrude Fleetwin 7.5 compression test

Well it wont matter at this point , I have the hole powerhead disassembled . Im replacing the rings and complete gaskets of this engine . She should be brand new after im done with her . Im waiting on evinrude to get the parts in I ordered from them . Maybe next week I should see them come in from evinrude . I also waiting on a honer from sears to hone the cylinders . My niegbor told me to use light sand paper on the cylinder walls , not to use the hone for the cylinders . Yes my compression is too low for her to run proper , Im getting 35 to 40 psi in each cylinders . I did the test the right way and when I took the engine apart I see worn out rings . My rings are too lose for them to hold a good compression for the engine . Some of the guys on here told me that the old engines use to run on low compression , but I cant see how she would run on the cimpression Im getting , there's no way it can .