four winns 214
Senior Chief Petty Officer
- Joined
- Oct 25, 2008
- Messages
- 757
I had to replace the hydraulic manifold on my Mercruiser MR outdrive. The MR is functionally the same as an Alpha 1. There's not a lot of information in Merc Service Manual 6 about accomplishing this task, so I thought I post a few "nice to know" things about this job.
First, where is this thing? The hydraulic manifold is fastened to the bottom of the gimbal housing. It's purpose in life is to take hydraulic pressure from the trim pump in the boat and route it to the outdrive trim cylinders via the four external hydraulic lines you see on the every MR/Alpha 1.
To gain access to the hydraulic manifold on many Alpha 1 drives, you will have to remove a block anode that is bolted to the bottom of the hydraulic manifold with two stainless bolts. My MR drive did not have this block anode. I added it when completing this job. More about that later.
The Merc manual describes using plugs and caps when disconnecting the hydraulic lines to the manifold, but it does not specify the sizes required. If you choose to use them, you will need four 3/8-24 thread caps and plugs and two 7/16-24 thread caps and plugs. These caps and plugs may not be easily found. I purchased mine at the local Parker store that carries all things hydraulic. I found I did not need the 7/16-24 plugs. And really, I didn't HAVE to have the other caps and plugs. Very little oil came out upon disconnecting the hydraulic lines. If you have all your parts ready for immediate reinstallation, I think you can get by without them.
I used trailering clips on the trim cylinders to support the outdrive while the hydraulics were disconnected. Having the drive in the full out/trailering position provided access needed to remove the manifold. I suppose the absolute correct way to provide access is to pull the outdrive off.
When disconnecting the four external hydraulic lines, be sure to mark them so that you put them back in their original position.
After disconnecting the four external hydraulic lines, remove the two nuts that fasten the manifold to the bottom of the gimbal housing. After removing the nuts, I used a stiff, sharp putty knife and a ball peen hammer to break the gasket seal between the manifold and the bottom of the gimbal housing.
When the manifold is free, work it down the studs as far as you can. It won't come down very far because there are two hydraulic lines coming from the boat to the manifold. Use a 7/16 wrench to disconnect them. Once those lines are disconnected, the manifold can be pulled off.
It took about 20 minutes of scraping and work with a Scotchbrite pad to remove remnants of the old gasket and some light corrosion to prepare the gimbal housing surface for the new gasket and manifold.
Installation of the new manifold is the reverse of removal. The Merc manual said that small amounts of air will self bleed from the trim system. I found that to be true. I did not have to bleed it.
I had to replace my manifold because in the process of trying to install the block anode described at the beginning of this post, I broke one of the stainless bolts that held a plate to the bottom of the manifold. That plate is removed to install the block anode and the same bolt holes are used to attach the block anode. I tried drilling the bolt and using an "easy out" and many other techniques to remove it, but that bolt was just plain seized. I had to buy a new manifold.
One caveat to this whole post: I am NOT a professional mechanic. I am a completely average to below average driveway mechanic. This may not be the best way to complete this job, but it's the way I did it.
First, where is this thing? The hydraulic manifold is fastened to the bottom of the gimbal housing. It's purpose in life is to take hydraulic pressure from the trim pump in the boat and route it to the outdrive trim cylinders via the four external hydraulic lines you see on the every MR/Alpha 1.
To gain access to the hydraulic manifold on many Alpha 1 drives, you will have to remove a block anode that is bolted to the bottom of the hydraulic manifold with two stainless bolts. My MR drive did not have this block anode. I added it when completing this job. More about that later.
The Merc manual describes using plugs and caps when disconnecting the hydraulic lines to the manifold, but it does not specify the sizes required. If you choose to use them, you will need four 3/8-24 thread caps and plugs and two 7/16-24 thread caps and plugs. These caps and plugs may not be easily found. I purchased mine at the local Parker store that carries all things hydraulic. I found I did not need the 7/16-24 plugs. And really, I didn't HAVE to have the other caps and plugs. Very little oil came out upon disconnecting the hydraulic lines. If you have all your parts ready for immediate reinstallation, I think you can get by without them.
I used trailering clips on the trim cylinders to support the outdrive while the hydraulics were disconnected. Having the drive in the full out/trailering position provided access needed to remove the manifold. I suppose the absolute correct way to provide access is to pull the outdrive off.
When disconnecting the four external hydraulic lines, be sure to mark them so that you put them back in their original position.
After disconnecting the four external hydraulic lines, remove the two nuts that fasten the manifold to the bottom of the gimbal housing. After removing the nuts, I used a stiff, sharp putty knife and a ball peen hammer to break the gasket seal between the manifold and the bottom of the gimbal housing.
When the manifold is free, work it down the studs as far as you can. It won't come down very far because there are two hydraulic lines coming from the boat to the manifold. Use a 7/16 wrench to disconnect them. Once those lines are disconnected, the manifold can be pulled off.
It took about 20 minutes of scraping and work with a Scotchbrite pad to remove remnants of the old gasket and some light corrosion to prepare the gimbal housing surface for the new gasket and manifold.
Installation of the new manifold is the reverse of removal. The Merc manual said that small amounts of air will self bleed from the trim system. I found that to be true. I did not have to bleed it.
I had to replace my manifold because in the process of trying to install the block anode described at the beginning of this post, I broke one of the stainless bolts that held a plate to the bottom of the manifold. That plate is removed to install the block anode and the same bolt holes are used to attach the block anode. I tried drilling the bolt and using an "easy out" and many other techniques to remove it, but that bolt was just plain seized. I had to buy a new manifold.
One caveat to this whole post: I am NOT a professional mechanic. I am a completely average to below average driveway mechanic. This may not be the best way to complete this job, but it's the way I did it.