Testing used engine

Joined
Aug 18, 2011
Messages
3
I've looked through the forums and haven't found this asked yet. If it has please provide link and don't insult me ;)

We're going to look at a boat on Sunday that has a MerCruiser 3.0L LX engine in a 1992 Glasstream boat.

What should I be checking on the motor to make sure it's in good shape?
Probably a dumb question, but is it possible to run the engine while out of the water?

This will be our first boat and I'd like to avoid surprises as much as possible.

Thanks in advance for any suggestions.

James
 

mpdive

Chief Petty Officer
Joined
Apr 23, 2011
Messages
567
Re: Testing used engine

I've looked through the forums and haven't found this asked yet. If it has please provide link and don't insult me ;)

We're going to look at a boat on Sunday that has a MerCruiser 3.0L LX engine in a 1992 Glasstream boat.

What should I be checking on the motor to make sure it's in good shape?
Probably a dumb question, but is it possible to run the engine while out of the water?

This will be our first boat and I'd like to avoid surprises as much as possible.

Thanks in advance for any suggestions.

James

Hi James and congratulations on purchasing a boat. I purchased mine used and it too has the 3.0 engine and I love the performance and fuel economy. Call the seller before you go and ask if he has a set of "muffs" there. These go on the outdrive and attach to a garden hose to enable you to run the engine. There are many things to look for and questions to ask. I will name some and there are some great members on this board with solid advice to help you out.

Ask about the owners winterization process. Has it been winterized every year?
Pull the dipstick before starting and make sure the oil is clear. No milkiness allowed.
Start the engine and look for visible leaks on both sides of the engine block, intake manifold, etc. Watch for rust stains and if present follow the stain upward to see if it had a leak source.
Look for any patches to the block. Some people have had a crack in the block and use metal bonding agents to fix it. Stay away from that.
Put the boat in and out of forward and reverse. It should slide into gear solidly with no large clunks and the outdrive should be relatively quiet.
Watch the temp gauge. It should hover around 160 degrees.
Inspect the hull thoroughly for gouges, road rash, cracks etc...You'll have some wear and tear for a 1992.
After running for at least 15 minutes inspect for leaks again. Shut off and pull the dipstick. Again no milkiness allowed.
Lastly inspect the bellows which is the rubber accordian looking part inbedded in the outdrive. It should feel flexible and not hard and rotted like old rubber exposed to the elements. Look closely between the pleats for cuts. Failed bellows is the fastest way to sink a boat.

There is much more and if you lived near Augusta GA. I would go with you. Another option is to look for a marine surveyor to inspect it for you. Sometimes it's a couple hundred bucks well invested. Let me know if I can help.
Mike
 

sdowney717

Petty Officer 1st Class
Joined
Jul 16, 2011
Messages
225
Re: Testing used engine

if it is in the water under load that is good way to see what is up with it.
When running watch out for a lot of steaming out the exhaust, could mean anything from cracks to rust to major repair to a whole new engine.

A little steam is ok, but not a lot and one side could look normal and the other steams a lot.
watch the color of the exhaust for blue smoke and check the oil appearance.
see if the engine has the expected normal power.
check that the motor is smooth running.
 

mnypitboat

Lieutenant Junior Grade
Joined
May 31, 2010
Messages
1,091
Re: Testing used engine

First thing is a test drive. Running it on muffs is not the way to test for major problems. When my 5.7 went, it ran beautiful on muffs, revved up fine, went into gear and was perfect. You put it in the water and it clattered and banged like crazy. So definately drive it. Do a compression test on the engine. While test driving it look for an oil sheen around the stern/outdrive area. Could mean a leak. WHen you pull it out of the water, pull the plug and look for water coming out. A little is OK, but a lot is bad. Look for oil mixed in with that water. Boy there are so many things to remember. Winterizing is a much larger concern in the north where it freezes, so if you are up there, ask what they did for winterizing. It wont hurt to ask in the south too, but it isnt as critical. I usually do not winterize other than keeping the tank full to help eliminate some of the condensation. Of course I use my boat almost all year long. In the beginning of the season and depending on the usage that year, at the end too I change all fluids, and water seperator, and visually inspect the cap, rotor, wires and plugs. If they do not do that stuff at least yearly, run.

Honestly, it might be best to find an inspecter/surveyer to take a look. Might cost you a bit of money, but might save you a lot of money. Or take it to a dealer that sells those boats and have their shop take a look.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Testing used engine

DO NOT buy a boat without an on the water test.
The big reason, is problems can be covered up with paint and new oils.
A test run will tell you more about the boat than anything else.
Before the test run, check the engine oil level and color (make a note) do the same with the drive. The 92 should have a dipstick in the top. Just be sure you take some new gaskets with your for the dipstick. (NEVER reuse a gasket on the drain, vent, or dipstick plugs. You do not want to see milky oil at all.
Then do a test run, at idle when the engine is warming up, listen to the engine. Any odd noises, growling, knocking, clicking, etc.
Turn the steering, any grinding or knocking noises or changes in the sounds back there?
Where is the temp gauge when warmed up, make a note, oil pressure, make a note.
Take it for a run, allow the owner to drive. Have him get on plane normally, and trim the boat out and you keep an eye on the gauges, especially the temp. With a raw water cooled engine, it should never exceed 170? or 175?.
Go to WOT rpm and trimmed out. What is the rpm. Should not be below specs for that engine.
(specs are 4200-4600 for a 3.0L and 4400-4800 for the 3.0LX models)
If it is low, that means they have been lugging the engine, which is very hard on an engine. If over 4 or 500 rpm below specs. There are problems, and and may take a while to figure out why, and probably NOT the prop when that far below specs.
Also look at the temp gauge after running at WOT for 20 to 30 seconds. Then back off to cruise speed and watch the gauges.
This whole time you should have been listening for any weird noises.
Head on back and park the boat.
Shut off engine. and after getting boat secured. Do another oil check. Look at the level and the color. Is it milky and over full? If so, you probably have a cracked block. Many times cracked blocks don't show up on muffs, just not enough water from the hose to make it leak.
Once on the trailer, check the gear lube again. Milky means water. Another new gasket.
Boat back on trailer, pull drain plug. Did the boat take on water while running? if so................ WHY ???

You should now have some idea the shape of the engine and drive.

One note. I don't know about other sellers, but I would never allow a buyer to do a compression test or any work on the engine or drive. I don't want someone I don't even know taking things apart on my boat.
If you want a compression test and a drive pull to check the ujoints, bellow, etc. then you need a certified shop to do the job, and YOU pay for it. Not the seller, it's your inspection.
 

mpdive

Chief Petty Officer
Joined
Apr 23, 2011
Messages
567
Re: Testing used engine

DO NOT buy a boat without an on the water test.
The big reason, is problems can be covered up with paint and new oils.
A test run will tell you more about the boat than anything else.
Before the test run, check the engine oil level and color (make a note) do the same with the drive. The 92 should have a dipstick in the top. Just be sure you take some new gaskets with your for the dipstick. (NEVER reuse a gasket on the drain, vent, or dipstick plugs. You do not want to see milky oil at all.
Then do a test run, at idle when the engine is warming up, listen to the engine. Any odd noises, growling, knocking, clicking, etc.
Turn the steering, any grinding or knocking noises or changes in the sounds back there?
Where is the temp gauge when warmed up, make a note, oil pressure, make a note.
Take it for a run, allow the owner to drive. Have him get on plane normally, and trim the boat out and you keep an eye on the gauges, especially the temp. With a raw water cooled engine, it should never exceed 170? or 175?.
Go to WOT rpm and trimmed out. What is the rpm. Should not be below specs for that engine.
(specs are 4200-4600 for a 3.0L and 4400-4800 for the 3.0LX models)
If it is low, that means they have been lugging the engine, which is very hard on an engine. If over 4 or 500 rpm below specs. There are problems, and and may take a while to figure out why, and probably NOT the prop when that far below specs.
Also look at the temp gauge after running at WOT for 20 to 30 seconds. Then back off to cruise speed and watch the gauges.
This whole time you should have been listening for any weird noises.
Head on back and park the boat.
Shut off engine. and after getting boat secured. Do another oil check. Look at the level and the color. Is it milky and over full? If so, you probably have a cracked block. Many times cracked blocks don't show up on muffs, just not enough water from the hose to make it leak.
Once on the trailer, check the gear lube again. Milky means water. Another new gasket.
Boat back on trailer, pull drain plug. Did the boat take on water while running? if so................ WHY ???

You should now have some idea the shape of the engine and drive.

One note. I don't know about other sellers, but I would never allow a buyer to do a compression test or any work on the engine or drive. I don't want someone I don't even know taking things apart on my boat.
If you want a compression test and a drive pull to check the ujoints, bellow, etc. then you need a certified shop to do the job, an YOU pay for it. Not the seller, it's your inspection.


Lot's of good points Don. I wasn't able to water test mine but being a GM tech for twenty five years I relied on instincts of boat condition, seller willingness to answer questions etc. I lucked out on mine but I did spend an hour and a half going over everything. Again good advice.......
 

relocyo

Chief Petty Officer
Joined
Apr 14, 2010
Messages
446
Re: Testing used engine

Always a good idea to ask WHY hes selling it, if hes tellin the truth he will give a quick response, if he stutters and stammers he may be lying... Look him square in the face and see if he can look you in the eyes with ALL of the answers, people who tell the truth can keep eye contact, liers often look down, around and tend to scratch the face when telling a lie... Lol I guess thats the poker player in me!
 

mpdive

Chief Petty Officer
Joined
Apr 23, 2011
Messages
567
Re: Testing used engine

Is that why politicians always do that?
 
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