Mercruiser procedure for pressure testing

[loun]

I am looking for the Mercruiser recommended procedure for pressure testing my Bravo II drive. I have the Merc manuals but have not found the procedure. I have read a lot of opinions on how much pressure and for how long but I wanted to read what the manufacturer has to say. Has anyone come across this information?

Thanks

 

[Don S]

Re: Mercruiser procedure for pressure testing

You won't find it in any service manuals, however, you will find it in Merc's basic training manual and a few of the service training manuals.
I'l just post what the manual says, you don't need a line drawing of the gauge showing pressure on it, or showing a gauge hooked up to the drive.

Here is word for word from the 98 training manual.

1. Drain gear lube and install lower drain plug.

2. Remove vent plug and install pressure tet gauge. Tighten securley

3. Presureize housing to 7=10 psi and observe gauge for 5 minutes.

4. Rotate drive shaft, prop shaft and move shift rod while housing i pressurized to check for leaks.

5 Pressurize housing to 15-16 psi and observe gauge for 10 to 15 minutes.

6. Rotate drive shaft, prop shaft and move shift rod while housing i pressurized to check for leaks.

7. If pressure drop is noted, immerse housing in water (or use liquid soap and water mixture).

8. Repressurize to specification and check for air bubbles.

9. Replace leaking seals as necessary. Retest housing.

NOTE: Vacuum tests are not recommended due to the design of the labrinth seal (will not hold vacuum.)

10. Remove tester from housing, fill with lubridcant and install vent/drain plugs.

PS, the labrinth seal they are referring to is the input shaft seal on the ujoint yoke. It's designed to keep the oil in, no need to worry about water coming in, since the bellows is supposed to do that.

 

[loun]

Re: Mercruiser procedure for pressure testing

That is exactly what I was looking for thanks!

Lou

 

[Simoniz]

Re: Mercruiser procedure for pressure testing

I need to test my Alpha 1 Gen 2 drive and was wondering if its necessary to pinch off the oil line to the reservoir? The procedure doesn't mention doing so and I know theres a check valve in there but will that hold the pressure in?

 

[Dshow]

Re: Mercruiser procedure for pressure testing

I believe the check valve is in there to prevent the oil in the reservoir from leaking out when you remove your outdrive, so when your outdrive is on the boat, it is always open. It makes sense you need to pinch it off when pressure testing on the boat or plug the oil passage on the outdrive if trying to pressure test with the outdrive off the boat.

 

[Don S]

Re: Mercruiser procedure for pressure testing

The procedure doesn't mention doing so and I know theres a check valve in there but will that hold the pressure in?

That is because you need to remove the drive to properly do the tests. The input shaft seal is a common problem for leaks, as well as the vertical shaft seal carrier under the water pump and the shift mechanism bushing. You really can't see in there to check them with the drive on the boat.

 

[Dshow]

Re: Mercruiser procedure for pressure testing

So, what the best way to plug the oil passage to the reservoir if you pull the outdrive off?

 

[Fun Times]

Re: Mercruiser procedure for pressure testing

So, what the best way to plug the oil passage to the reservoir if you pull the outdrive off?

There is no need to plug the oil passage on the sterndrive or the bell housing end, Basically it does it on it's own when you pull the drive off.

 

[Simoniz]

Re: Mercruiser procedure for pressure testing

That's very clever of it. When I had mine apart last, I could see no way that the oilway in the upper housing (not bellhousing) would seal itself.