Bought a used 2005 Mercruiser 5.7 Horizon MPI engine - things to inspect/replace before I drop it in?

[Devil_Inside]

Bought a used 2005 Mercruiser 5.7 Horizon MPI engine - things to inspect/replace before I drop it in?

I purchased a used 2005 Mercruiser 5.7 Horizon MPI engine setup for a Bravo drive, serial number 0W3285##. The engine has 1050 hours on it, verified with VesselView. I got the engine at a fair price considering it's age and hours, and I am hoping to get another 1000hrs out of it.

As you can imagine I don't have a good maintenance history for this motor, so I am trying to put together a laundry list for all the things that I should inspect and/or replace prior to dropping it in my bilge. I am not new to engines or boats, however this engine has a lot of things that are new to me - dry joint exhaust system, full closed cooling, MPI fuel injection, strange fuel supply module, etc - just to name a few.

This is my to-do list so far:

Oil+filter
Coolant flush
Fuel module filter/water separator
Sea water impeller
Spark plugs
Starter (needs a new one)
Slave starter solenoid
IAC muffler (found that guy completely by accident)


In the "maybe" column I have the following items:

Exhaust elbows + gaskets
Drive belt
Thermostat


I am pretty sure both the manifolds and the elbows are most likely original. The manifolds are on the closed cooling circuit, however the elbows obviously aren't. I drained the block yesterday and I took one elbow off and I saw a lot of corrosion and big rust chips on the part where the rubber boot goes, but all the mating surfaces, and inside looked good. I also found a lot of sediment in the elbow water passage where it meets the manifold - this is probably normal since I have a block-off gasket and water would just sit there. Anyway - how often should these be replaced and what is the proper way to inspect them? I am not familiar with the "new" dry joint design, nor FCW.


Anything else I am forgetting?

 

[wingless]

The salt water cooled exhaust parts last three to four years, w/ annual disassembly for inspection and replacement when required the appropriate interval. There must be sufficient SOLID WALL thickness between the exhaust passage and the raw water passage and there cannot be excessive internal corrosion.

On mine, I was discarding those expensive parts every three to four years until I redesigned the exhaust system from no flush possible and from impossible to drain, to now fresh water flush, then soapy water flush, then Salt Away flush, then drain bone dry after each usage.

The parts were disassembled after three years of usage and still look brand new inside.


A plumbed-in oil pan sump drain hose could be a handy addition while the engine is out of the boat.

 

[Devil_Inside]

I will look into the plumbed oil pan drain sump - good idea. I also want to plumb the raw water side in such a way that I can flush the raw water side after each trip.

I am familiar with the regular manifold/riser lifespan and inspection, but I wasn't sure if the same applies to the dry joint design... I priced out two elbows and two gaskets at ~$900

 

[tpenfield]

You have already replaced more stuff than I would have. I'd pull and inspect the elbows, but only buy new ones if they really needed it. New gaskets of course . . .

How about any paint touch-up, rust treatment?

Compression and cylinder leak test? Have you run the engine as a 'bench test'?

 

[Devil_Inside]

You have already replaced more stuff than I would have. I'd pull and inspect the elbows, but only buy new ones if they really needed it. New gaskets of course . . .

How about any paint touch-up, rust treatment?

Compression and cylinder leak test? Have you run the engine as a 'bench test'?

I am just trying to be as thorough as possible, besides it is so easy to work on it outside the boat, it's really easy to get carried away I was getting ready to order new elbows yesterday, but I choked when I saw the price... I am really tempted to pull the elbows off for a quick inspection and run at as-is (with new gaskets) until the end of the season at least. I want to make sure it's a good motor before I sink a lot of money in it.

I will absolutely touch it up with paint and spray the ever living $#%@$% out of it with CorrosionX or similar before I install it.

Bench testing and compression tests are OK, haven't done a leak test because I don't own the tool. I really ought to buy one.

 

[QBhoy]

Above all else the diz cap should be changed. No 1 reason for these to break down. I’ve beem through 5 in 5 years now.