1996 Mercury 175 lower unit pressure test.

[formulatpi00]

While pressure testing my 1996 Merc 175 lower unit I saw air bubbles coming from the water pump pressure fitting the one that goes to the dash that tells water pump pressure was wondering what the problem could be or if this is normal just did a complete reseal on lower unit all help appreciated thank you!

Torre

 

[carholme]

Re: 1996 Mercury 175 lower unit pressure test.

What is your engine s/n?

When you say "water pump pressure fitting", do you mean the one on top of the engine block or might you be referring to item 2 in this link?

Mercury, Mercruiser, Force, etc. - GEAR HSG (DRIVE SHAFT)(STD. ROTATION) (S/N-0G438000 & UP) - 135/150/175/200 XR6 MAGNUM III 105-140 JET

Gerry

 

[formulatpi00]

Re: 1996 Mercury 175 lower unit pressure test.

What is your engine s/n?

When you say "water pump pressure fitting", do you mean the one on top of the engine block or might you be referring to item 2 in this link?

Mercury, Mercruiser, Force, etc. - GEAR HSG (DRIVE SHAFT)(STD. ROTATION) (S/N-0G438000 & UP) - 135/150/175/200 XR6 MAGNUM III 105-140 JET

Gerry

Yes Item 2 on mine its just a plastic fitting with a hose attached, s/n 0G406061, when i pressure tested it bubbles came from there not sure why that would be no bubbles coming from anywhere else.

thanx

 

[carholme]

Re: 1996 Mercury 175 lower unit pressure test.

That item 2 should be for the speedometer. You can verify that by looking again at this link:

Mercury, Mercruiser, Force, etc. - GEAR HSG (DRIVE SHAFT)(STD ROTATION) (S/N-0G437999, BELOW) - 150/175/200 (EFI)

If you see item 1, where the line is pointing from the number 1, you should see the water inlet hole for the speedometer inlet. You should be able to blow air throught that hole and out through the top connector on tube, item 2.

Can you verify that it is the speedometer system?

Do you have the manual for the engine?


Gerry

 

[formulatpi00]

Re: 1996 Mercury 175 lower unit pressure test.

That item 2 should be for the speedometer. You can verify that by looking again at this link:

Mercury, Mercruiser, Force, etc. - GEAR HSG (DRIVE SHAFT)(STD ROTATION) (S/N-0G437999, BELOW) - 150/175/200 (EFI)

If you see item 1, where the line is pointing from the number 1, you should see the water inlet hole for the speedometer inlet. You should be able to blow air throught that hole and out through the top connector on tube, item 2.

Can you verify that it is the speedometer system?

Do you have the manual for the engine?


Gerry

Ok I assumed that was for the water pump pressure, yes I have the manual right here, from what i remember there is a hole there. I will test that with pressure if it blows out there then I would assume I'm leak free? Would there be any way bubbles would come from there while pressure testing?

 

[carholme]

Re: 1996 Mercury 175 lower unit pressure test.

That's what I don't understand as I thought the water passage for the speedo was and should be independent. Where are you inputting the air pressure for your test?

Gerry

 

[formulatpi00]

Re: 1996 Mercury 175 lower unit pressure test.

That's what I don't understand as I thought the water passage for the speedo was and should be independent. Where are you inputting the air pressure for your test?

Gerry

I pressure tested it from the vent hole submerged in water. maybe it was just bubbles from the initial dunking of the unit? I hit it with 10 psi and did see a stream of bubble coming from around that fitting it did eventually stop but had the tube capped off with a bolt and seemed to be slightly leaking from there. I would see no way that would be tied into the gear case. thats why i thought it was water pump related but no bubbles came from there at all when i tested it.

 

[carholme]

Re: 1996 Mercury 175 lower unit pressure test.

The manual you have does not seem to show clearly the speedometer passageway from the inlet up to the top of the LU. I will see if I can find another picture.

Gerry

 

[formulatpi00]

Re: 1996 Mercury 175 lower unit pressure test.

sounds good only way i can see it leaking there is if the #23 shift shaft bushing is somehow connected. I will have to double check it.


Torre

 

[formulatpi00]

Re: 1996 Mercury 175 lower unit pressure test.

Ok I put air to it and it comes out the small hole in lower front center on lower unit so I figure thats for the speedo nothing coming out the side holes that i could tell. I went ahead and pressure tested it with soapy water and no bubbles at all so I'm not sure what was going on with the bubbles maybe fitting was a little loose I pulled it out sealed it up. I'm thinking it was just air bleeding out when it was submerged. I'd like to know ur input I appreciate the help!

 

[carholme]

Re: 1996 Mercury 175 lower unit pressure test.

Well if the plastic fitting was loose, it may have just been trapped air in the speedo passageway and as you had the top end of the speedo tube plugged, the only way for the air to escape was around the loose fitting. If it passes the pressure test now I wouldn't worry about it as there is just no connection between the oil in the housing and the speedo passageways.

Gerry

 

[formulatpi00]

Re: 1996 Mercury 175 lower unit pressure test.

Yup that makes sense thanx again for your help!

Torre