'87 Mercruiser Sterndrive Pressure/Vacuum Test

[g_speran]

Hello ALCON,
I have researched this awesome site and successfully built a home made pressure test device using a bicycle pump. I read to test the pressure at a max of 15psi, which I did. It held, successfully, for 3 hours, prior to me dissconnecting it.
I have gone to AutoZone and rented Item #27010, OEM Vaccuum Pump to start the vaccuum test. However I do not know at what vacuum reading I should be testing at and for how long it should hold. I hope I am making scence? so if the pressure test was done at PSI, I am going to say the vacuum is VSI. Therefore at what VSI reading should I vacuum to and how long should it hold.

Also, for clarity, there is absolutly no lower unit oil in the lowere unit. It is completly drained

Finally, is there a manual on-line someone can point me to for the lower unit, such as where ist shows to do the pressure and vacuum test?

TIA,
Gary

 

[ktbarrentine]

Re: '87 Mercruiser Sterndrive Pressure/Vacuum Test

Hello ALCON,
I have researched this awesome site and successfully built a home made pressure test device using a bicycle pump. I read to test the pressure at a max of 15psi, which I did. It held, successfully, for 3 hours, prior to me dissconnecting it.
I have gone to AutoZone and rented Item #27010, OEM Vaccuum Pump to start the vaccuum test. However I do not know at what vacuum reading I should be testing at and for how long it should hold. I hope I am making scence? so if the pressure test was done at PSI, I am going to say the vacuum is VSI. Therefore at what VSI reading should I vacuum to and how long should it hold.

Also, for clarity, there is absolutly no lower unit oil in the lowere unit. It is completly drained

Finally, is there a manual on-line someone can point me to for the lower unit, such as where ist shows to do the pressure and vacuum test?

TIA,
Gary

First off, Here is a link to your manual!

http://www.4shared.com/office/L17_ufPa/06__Drives_R-A1_83-90.html?

Next, you will find differing opinions on performing a vacuum test on your seals. Some people swear by it, some people relate that Mercruiser mechanics say not to vacuum test (no need). I have performed the vacuum test with good success, and I like it because in my opinion, I want to see if my seals are not letting water in, as well as not letting oil out. So I guess it is user preference... But, I will add, you must be careful not to pull too much vacuum on the drive, or you will cause problems with your seals. When I did my vacuum test, I pulled only 5 inches Hg (BTW, vacuum is measured in inches of mercury, or "Hg".. Your vacuum gauge should be calibrated in those units.) I have read on the forum that 7 inches is about the absolute max you want to pull... Then you do a drop test (I help my vacuum at 5 inches for about three hours and called it good).

I test via the bottom (oil drain) port. (You can actually use either the top or bottom port for a complete assembly test). Make sure your test rig is absolutely tight. I test my setup before I hook it up. Then hook it up with new gaskets. Some people (and I have done this) test the drive halves separately before reassembly, then again after putting the halves together. If you test separately, you need to put a plug into the quad seal area (the oil passage where the drives join). I used a simple piece of clear packaging tape. Works great for pressure and vacuum, but surfaces need to be squeaky clean. Oh, and I not only do a time-drop test when at 15 psi, but I also use a soap solution just to be sure the seals are tight...
HTH! KTB. Let us know how it goes for you!.

 

[g_speran]

Re: '87 Mercruiser Sterndrive Pressure/Vacuum Test

Ktbarrentine,
Thanks for the helpful information. At the time you replied, I immediatly connected the vacuum tool to the lower drain plug an initiated a 6 Hg vacuum. This held over night till 9am this morning when I released the vacuum. Like you, I am calling this good.

Thanks for your assistance
Gary

 

[Reel Poor]

Re: '87 Mercruiser Sterndrive Pressure/Vacuum Test

Ktbarrentine,
Thanks for the helpful information. At the time you replied, I immediatly connected the vacuum tool to the lower drain plug an initiated a 6 Hg vacuum. This held over night till 9am this morning when I released the vacuum. Like you, I am calling this good.

Thanks for your assistance
Gary

You should also pressure test it to 14-15 psi. If it holds pressure then you can call it good.

 

[ktbarrentine]

Re: '87 Mercruiser Sterndrive Pressure/Vacuum Test

You should also pressure test it to 14-15 psi. If it holds pressure then you can call it good.

He had indicated that he successfully did that in his first post... Sounds like he's got a tight drive... KB

 

[Reel Poor]

Re: '87 Mercruiser Sterndrive Pressure/Vacuum Test

He had indicated that he successfully did that in his first post... Sounds like he's got a tight drive... KB

oops!!! I started reading the second paragraph, totally skipped the first one. :facepalm: On that note, call it good and go boating.