Pressure

[Boonie]

What’s the procedure for pressure testing seals in the lower end?

[fleetwin]

Well, it usually involves using the Steven’s pressure tester, which few have and is pricey. What type of outboard is this? Am assuming it is some sort of classic OMC, so will start with gear lube inspection. I am assuming there is water present which is why you are asking. The next step is to make sure the leak was not caused by a missing drain plug seal, or perhaps two seals on one screw and none of the other. Oftentimes these seals stay behind in the housing when the screw is removed, other times the seal comes out with the screw. It is hard to see the seals left behind in the housing, especially covered in gear lube.
So, assuming the drain plug seals are not to blame, we move on to the pressure test. Install the lower drain screw and seal, then screw the pressure tester into the top vent hole. Make sure the pressure tester has some sort of seal on its threaded adapter. It is best to use the top/vent hole for the pressure tester to keep residual gear lube/water from running back through the line and into the tester. The seals are tested using relatively low pressure, 5-7PSI. Over pressurizing the unit can over come the seals ability to seal, and might actually damage them. At this point it is helpful to submerge the gearcase in a bucket of clean water so leakage issues can be easily pinpointed. It is best to rotate the shafts, and move the shift rod up and down while testing as well. You can use a higher pressure setting to check orings and gaskets, 12-15PSI.
Just a side note when checking OMC 5.5-7.5, 10hp gearcases. Do not remove the water pump screws, then perform the pressure test. The water pump screws hold the upper bushing seal housing in place as well. Pressurizing the gearcase with no water pump screws will probably just push the bushing/seal housing up and off its gasket. I realize it is tough to pinpoint leaks up there with the water pump in place. You could remove the impeller housing/impeller, then secure the upper bushing seal housing in place with shorter 10-24 screws to hold it in place while testing.

[Boonie]

It’s a 1956 fleetwin. 7.5 hp. Georgeous shape. Had a little milky look in the gear case oil. Not sure if it warrants a tear down? That’s why I’m thinking of a pressure test.

• This reply was modified 4 years, 4 months ago by Mumbles.

[Boonie]

90 psi on both cylinders. Not one dent in the cowl. Just faded paint. And taped to the handle is two shear pins. Looks original as the tape is falling apart.

[Boonie]

Oh forgot to mention I paid $150.00 CDN for it. I usually restore them but I think this one needs to stay original. It came with the matching evinrude pressure tank as well.

[fleetwin]

I would definitely leave it original…A little wax and she will look almost like new…
If the lube is only “milky”, you could surely just change it more frequently…But, if raw water is present, you may want to pressure test and reseal. This engine has that pesky driveshaft shock absorber that I’m sure will be adversely affected by raw water… It is always best to pinpoint the actual leakage issues before just ripping the gearcase apart and “resealing”. I almost ignored my own advice the other day on a 58 10hp…Pulled the gearcase off after noticing milky gear lube, and saw the milky mess all over the pesky shift rod bushing/oring seal…Made sense, those orings are often to blame for leakage issues. Decided to pressure test it anyway, only to notice that the actual leak seemed to be coming from the driveshaft seal under the water pump…Pulled it apart, but didn’t see much wrong with the driveshaft seal…Finally had a real close look at the driveshaft, it had pitted right in the area where the driveshaft seal rides…All the new seals and orings wouldn’t have fixed this issue, needs a new driveshaft….Doing the pressure test prior to disassembly, forced me to look closer at the actual leakage issue and spot the damaged driveshaft…Probably would have missed this had I not pressure tested first….But, sure would have noticed it while doing the pressure test after resealing without driveshaft replacement…

[outbdnut2]

I’ve seen homemade pressure testers and am thinking about making one some day when I have time. You need an adjustable air pressure regulator that you can easily adjust over a range htat includes good resolution from near zero to around 10 pounds (psi). Those made for CO2 gas for beer keg tap setups will work, and have the pressure gauge on it. You need to make up the connector to screw into the motor’s gear oil vent hole and also attach a fitting to connect the input to an air compressor. Here is an example of a regulator that should work on Amazon: https://www.amazon.com/PERA-Regulator-Pressure-CGA-320-Brewing/dp/B082XQZSZK/ref=sr_1_4_sspa?crid=1DDF54M6IL37E&dchild=1&keywords=co2+pressure+regulator+for+beer&qid=1626099637&sprefix=CO2+pressure+regulator%2Caps%2C228&sr=8-4-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzQ0MyTVBaVFlLVTJSJmVuY3J5cHRlZElkPUEwODg4MDUzM0pDQUdSTEJLWVBJVyZlbmNyeXB0ZWRBZElkPUEwNTYxMzkxMzdaVldOU0w0TlJWTiZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

Dave

[Boonie]

Amazon says regulator not available at this time. I think what I will do is replace the oil and use it. Check oil condition frequently. I really think this motor has low hours. Look on the spark plug holes and it looks shiny new. One problem I have is the fuel lines are disintegrating. My first time dealing with a pressure tank (2 lines). Is there specific fuel lines for replacement?

[outbdnut2]

Amazon has a lot of those regulators, priced all over the place. I agree you should just try it and check to see if it is leaking or you are getting water in the oil. Consider a pressure tester if you plan on restoring/repairing a lot of motors. Here are all the co2 regulators on Amazon: https://www.amazon.com/s?k=beer+tap+co2+regulator&crid=2OISNOZWT1QTJ&sprefix=%27co2+regulators+beer+tap%2Caps%2C419&ref=nb_sb_ss_ts-doa-p_1_23
Dave

[Boonie]

Thanks Dave. Any advice on fuel lines?

[Author]

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