I have a 2005 baja275 with a 496ho / bravo x drive (closed cooling). A year and a half ago boat spent 6 months in shop due to overheating condition. It was eventually determined to be a blockage due to corroded inserts at the transom assembly water hose- $2500 repair to pull drive and motor, replace transom ass'y. Merc warranty covered repairs. Apparantly this is a common problem. I am developing the same problem again and would like to bypass the drive plumbing by installing an adjustable transom water pickup. Is this a reasonable approach, or am I asking for trouble? It seems this can cause issues with excessive water pressure. Any advice would be appreciated!

The transom mount pickup will solve the problem you are having, but so will better maintenance(don't take this the wrong way.....I'm trying to help). Lake Pontchartrain can get saltier than most think. You have to flush the engine and drive religiously. You should also use a product like Salt Away or similar. It is a fairly common problem when all of the salt is not removed. I have run across this problem many, many times and it was all do to lack of proper maintenance. Most were boats that stayed in a hoist and were not flushed correctly.
To answer your question, the transom mount pickup will work just fine. However, you should have a sea strainer if you use an extermal pickup. Since they pull water closer to the surface than the drive, they are more susceptable to picking up trash, sticks, weeds, etc. Hope this helps.
Eddie

Do you slow down with transom pickups? Looking at them myself.

The one I installed is a small Stainless Marine pickup (1/2"). I think upon trimming it for flow/pressure I ended up gaining 2 or 3 MPH, its been a couple years so I cant remember exactly how much is slowed the boat down, but it did scrub off speed. This one only feeds my intercooler.

Yes it will cost you some speed. How much depends on how deep it needs to be to supply enough water. That will depend on the boat. Step bottom boats tend to need the pickup a little deeper since the water flow coming off the back of the boat has been so disrupted. But, it is also going through aerated water, so it will not have as much drag as compared to putting it in the same place on a conventional bottom boat. Figure on average 1-2 mph with it at the optimum height.
Eddie

They over-charged you , that can be done with only removing the drive, helmet and bellows assembly. I've done it before.

Thanks for the info. I am leaning towards the Hardin marine 410-BK-1084 adjustable transom pick up.
When the install is done is it ok to block off the water hose from the drive, or will this result in drive overheating? Can I install a tee and pull water through both the transom pickup and the drive?
Also, in related links, I have read that excessive water pressure may be a problem at high speeds and that a "dump valve" should be installed ahead of the seawater pump. Is this accurate?
Thanks

You can block off the water thru the drive into the transom. You then tap into the side of the upper unit, to hit the water source, and use this for a drive shower.

Chris

Teague has a great adjustable transom water pick-up. Installation is straight forward. Many may have to plug and relocate their existing bilge drain fitting holes. Much less drag as compared to my thru hull water pick-ups.

Chris, GREAT point. Many do not understand that if you decide to block off the water thru the transom, water flow thru the drive no longer exists. Water must somehow exit the drive. The explaination given above is needed for proper cooling of the drive and a great source of water for your drive cap shower.