Cooling system

[tonka329]

Hey folks. I picked up a boat on trade this week and it looks like it hasn;t been registered since 2003. I took the water pump hose off and the pump was full of rust. I then decided to remove the water pump to check for rust in the ports. The left side showed a little bit of rust around the opening but, nothing too bad. The right side port was clear. How can I tell if the engine cooling system is rusty? Also, how can it be fixed?

-Not sure if the internal water jackets are protected from rust from the factory? Is a marine 5.7 different than the 5.7 in my 1996 4x4 truck? Sorry for all the questions but, I want to check this out before I move forward in getting this engine a new water pump and fuel pump...

Thanks again,
Tonka

 

[Bt Doctur]

rust would indicate a raw water cooled motor a block sitting dry for 12 years ,I`d be wondering if the manifolds and risers are in the same condition

 

[tonka329]

How would I investigate further? Not sure what the risers are and where they are located? The engine tag on the bell housing shows a number D716624.

 

[alldodge]

How would I investigate further? Not sure what the risers are and where they are located? The engine tag on the bell housing shows a number D716624.

Risers, or exhaust elbows are the part which is connected to the exhaust manifold. A boat that has sit that long I would put the old pump back on for initial start up. Pull the plugs and put some oil in there and rotate the engine to coat cylinders.

Your serial number listed is for the outdrive which is an alpha 1. The drive has an impeller in it which supplies water to the engine. This is the part which needs to be changed before you fire it up the first time. The drive needs to be split in half to get at it.

Guess you could try and start the motor without replacing it to see if the engine is damaged. Doing this could cause pieces of the impeller to go other places if it comes apart during test. They can be cleaned out if it happens but with 12 years your rolling the dice

 

[tonka329]

I understand. The engine runs on starting fluid for about 2-3 seconds. I wasnt going to push it any farther. Should i take the whole drive unit off?

 

[tonka329]

I also found some brass fittings in the cupholder. Not sure where they go?

 

[Scott Danforth]

the brass fittings are most likely the block and manifold drains. one each side of the block, about midway, just above the oil pan.

the manifold plugs will be bottom of the manifold.

running the motor on ether without water to the raw water pump FUBAR'd the raw water pump. where you may have just needed an impeller, most likely you will now need a complete water pump assembly and the plastic tube

STOP running the motor on ether.

start by pulling the drive, splitting it and putting in a new water pump kit
properly pull the plugs like Alldodge stated and get some oil in the cylinders.
change the engine oil and filter.
replace the distributor cap and rotor (and points if you still have points).
go thru the entire fuel system from the tank to the carb. your carb needs rebuilding, the fuel pump may be ok, however any fuel in your tank has long turned to varnish. this needs to be taken care of first
after you clean the carb, if you want to try to run the motor, you can do so on a separate fuel tank. with the outdrive off, put a garden hose either in the inlet hole in the transom shield, or plumb it directly to the thermostat housing. crank the motor a few times with the plugs out, this will both pump fuel thru the fuel pump to carb (then you can check for leaks). after 20 seconds of cranking, you should have good oil pressure. put the plugs back in. turn on your water supply fully. now attempt to start the motor

 

[tonka329]

Thanks for the info Scott. I ran the engine on starting fluid to see if it even ran before I purchased it. It is not a habit. Anyhow, I am having difficulty locating the parts you are talking about. I am new to the MerCruiser world.

 

[alldodge]

Here is a link to your outdrive, all the pump parts are in the lower section of the drive
http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=818183+91

The impeller is item 27, housing is item 22, then you have gaskets and plates, see link below
http://www.mercruiserparts.com/Show...=Gear+Housing,+Driveshaft+-+Standard+Rotation

If you remove the 6 nuts holding the drive, and 2 off the ends of the hydraulic rams, the drive can be removed off the rear of the gimbal housing. Put gear shift in the full forward position before you attempt to remove it. This puts the shift foot straight forward.

 

[tonka329]

Sounds good. I'll take the trim rams loose, remove the prop then the 6 bolts that hold the lower part and split it there. The impeller is on the main shaft with a keyway right? I'll get some parts ordered up this weekend. Does anyone know how to rebuild these carbs? Maybe a quick way to clean it out? Are there any schematics like this for the engine and components also?

 

[Rick Stephens]

There is no quick way to clean it, not after 12 years of sitting. Need full kitting and cleaning.

The Mercruiser manuals usually have pretty good details on rebuilding and adjusting the carb. You might start there. Not sure what year motor you have, but you can find online versions of the manuals here:
http://boatinfo.no/lib/library.html

Rick

 

[tonka329]

Im having a hard time finding the specs on my engine... The number on the bellhousing tag is D716624

 

[Rick Stephens]

Do you know what year?

 

[tonka329]

Do you know what year?

Boat is a '78

 

[alldodge]

Im having a hard time finding the specs on my engine... The number on the bellhousing tag is D716624

The serial number comes up as a 1992 at the Merc site 350
WOT 4400 to 4800 rpm
8 degrees BTDC
Plug gap .035
Plugs AC-MR43T NGK-BR6FS
140 degree thermostat

 

[tonka329]

Dang dude! Thanks AllDodge! Now, all I need to find is someone locally to rebuild my Quadrajet...

 

[Rick Stephens]

I got the same answer - however, if that is the actual motor serial number it would be 0D716624 for the 92 350 Mag. The search for just D716624 leads to that 0D716624 serial number for the '92.

tonka329 stated the boat is a '78, the transom serial number seems to indicate maybe a '92 motor serial number. Seems unlikely. Possible, of course, if someone repowered.

tonka329, you might post a couple pictures, engine and outdrive. Can get expensive not being sure before you buy parts and make adjustments.

Rick

 

[tonka329]

The D716624 is the tag on the engine near the starter. Boat title says a 1978