2007 Mercury Optimax Pro XS Leaking Water Between Driveshaft Housing and Lower Unit

[bobby.leejr]

2007 Mercury Optimax Pro XS Serial #1B458912

Water is leaking where the gear housing and driveshaft housing meet. Also seems to be leaking from the lower mount and cover. I had a local mechanic install a new water pump kit, but it didn't fix the problem. Here is a short video of the problem.

https://www.youtube.com/@bobbylee5351/shorts

Can anyone help me identify the culprit? I just ordered a service manual.

Thank you all for the help.

[JOE54]

the return water in the mount area is normal , you have a leak on the powerhead also , torque all fasteners on gearcase , inspect inside cowling for leak

[bobby.leejr]

No leak inside the cowling. I removed the lower cover and nothing. It’s all coming from where the lower unit is bolted on.

[Savage]

What is the water pressure at idle speed?

[JOE54]

No leak inside the cowling. I removed the lower cover and nothing. It’s all coming from where the lower unit is bolted on.

was the water running from cowling cause it was tilted up ????

[EuropeanAM]

^^^^ Need to determine answer to Posts #4 and #5. Very important- while the water coming from the lower mount area is normal, water coming from the lower cowling like that is not normal.

[bobby.leejr]

I let the engine warm up for a few minutes on the muffs. The temperature was 118-120 at idle. The water pressure was 3.6-3.8 psi. The engine was idling from 560-590 RPMs. I have included more video of the water issue here:

https://www.youtube.com/shorts/qvMJApYzaiI

https://www.youtube.com/shorts/gMDRy-jCtFI

Also, I took the top cowl off and discovered fuel leaking from the hoses that run from fuel rail to fuel rail on the starboard side. I previously discovered this leak last weekend and changed the two O-rings on the front hose where it meets the rail. The leak quit, but now it is right back. Video of the fuel leak can be viewed here:

https://www.youtube.com/shorts/qCPrXosws7E

https://www.youtube.com/shorts/zzTvaJwpv-0

I appreciate the help everyone. I am beginning to get really frustrated with this engine. Every time I look at it something is wrong.

[apdriver]

Prolly should put tape over the low water pickups when running on those muffs. Just remember to remove it when finished.

[JOE54]

that fuel leak is gonna sting a little , needs hose replacement ,or crimp is leaking or fitting is cracked

[DewRonInc]

To me all looks normal except rail leak, Gotta be fixed

[Savage]

Is the lower unit one of those Chinese lower units, or is it genuine Mercury Marine?

[bobby.leejr]

Beats me Savage. How do you tell the difference?

[EuropeanAM]

It's a Verado-Style gearcase...

Replace that fuel cross hose BEFORE using the engine again. Leaking fuel poses a risk of FIRE or EXPLOSION.

[bobby.leejr]

Fuel cross hose has been replaced with a brand new one from European Marine. That has fixed the problem so far on the muffs. I did rev the engine to about 1000 rpms with no fuel leak visible.

I am still trying to figure out the water leaking. IT can be seen coming from the top of the driveshaft housing, I think. Here are a couple videos of it without the lower cowl.

https://www.youtube.com/shorts/lDQK9SCgydc

https://www.youtube.com/shorts/fGryPPga0IM

https://www.youtube.com/shorts/e1YvFeSBYD0

[JOE54]

uh oh time for powerhead removal, gota leak into the mtr mount area , that leak will have abunch of pressure at 5750 rpm

[Savage]

^^^^^This^^^^^

[bobby.leejr]

Any idea what seals or gaskets need to be changed?

[JOE54]

tuner seal on bottom of tuner , water tube seal , both powerhead gaskets use only OEM HPERF gaskets . shift shaft bushing few clamps few tie straps should about do it , you gonna love those base gaskets ,,,,,,, good luck now