Questions about mercruisers

I am going to look at a 1987 g

I am going to look at a 1987 glassstream with a 4.3 liter merc. I am wanting to know what to look for in way of potential problems with these engines and drives and are there any tests I can do to check the the mechanical state of the drive. up until know I have only delt with OMC's and now need a crash course in merc's thanks Michael

"I have the same year engine.

"I have the same year engine. The 4.3L is a marinized GM engine that has been around a long time. They are very rugged and dependable.

Never buy a boat w/o having it surveyed by a professional. The compression needs to be checked on the (warm) engine both dry and wet (tsp. of oil in the cylinder). If the compression goes up on the wet test the rings are worn. The numbers between cylinders should be uniform and not vary by more the 15%. Example: 150 - 152 - 151 - 149 - 150 - 150
If there are one or more cylinders out in left field then there is a valve/head problem. Example: 150 - 151 - 80 - 90 - 150 - 152

Hull integrity is very important. Check the inner transom below the waterline especially down low under the OD for rot. Also check the engine mounts, stringers and floor. Walk all over the floor feeling for soft spots particularly around the ski locker area. If it has back-to-back seating lift the skirts and look for rotted frames.

IF YOU FIND ANY ROT OR POOR COMPRESSION; RUN!!!"

I have found out alittle more

I have found out alittle more about the boat. it has an alpha one drive and a thunderbolt ignition system. Is that ign. system points or electronic and what do I need to check for in the drive besides milky oil?

"look at the bellows on the dr

"look at the bellows on the drive also, especially the drive bellows. turn the drive to the left and look at the right side of the bellows and vice versa, looking for cracks. ask when the water impeller was last changed. ask if gimbal bearing or u-joints were ever replaced"

Salt water or fresh water usag

Salt water or fresh water usage??? Age of exhaust manifolds???

in my opinion all is very corr

in my opinion all is very correct. but look at the overall care of the boat. if it looks good then you can expect good care all around. if its sorta rough then the care of the engine was sorta rough and so on. other than that what guy and the rest said to inpect is a must!!

"There are usually three reaso

"There are usually three reasons to sell a boat
1) I want a bigger boat
2) I can't afford to run/maintain this boat.
3) I can't afford to fix this boat.

Usually you can't believe the owner as to why.
Sometimes even if it's #3 it can be a good deal, BUT caution is in order."

It's electronic ignition.

It's electronic ignition. Ask if the optic sensor under the rotor is rusted or been replaced - $50; it will fail. Ask if the ThunderBolt amplifier module has been replaced - $500; located on the port exhaust manifold.

Pull the oil drain screw on the OD and stick your finger in the hole while you look at the screw magnet for metal shavings and chunks. Run if you find them.

"I don't own a 4.3L but af

"I don't own a 4.3L but after reading a lot about them on this board the one thing that stands out is freeze cracking. Depending on where you live, if it's a cold environment and the boat wasn't drained completely for wniterization you could almost count on a cracked block with these things. Search the archives there are plenty of stories about it.

What I alwys do when I take a boat for a test spin:

ALWAYS take the boat out for a trial run. You would never buy a car with out taking it for a test ride why would you buy a boat without one. Forget the excuses of the owner, if he wants to sell you the boat and you're serious about buying it then he shouldn't have a problem, unless he's hiding something.

Make sure it starts easily and runs smoothly. See how easily it get's on a plane. Run it around for a bit. Keep an eye on the gauges like temp and oil pressure if they are steady and somewhat normal.Come back to the dock shut the motor off. After a few seconds check the oil, if it's clear oil (honey color to carmel) then you probably don't have a cracked block or bad head gasket. Check the compression while the motor is still warm but not too hot to touch. If the readings are all withing 10% of each other you probably have a pretty decent motor.

Check the floors for soft spots, tap around the transom for soft spots with the plastic end of a screw driver. Any changes from sharp banging to a thud will probably be some dry rot. Check the over all cleanliness of the engine, is there a lot of oil, rust, corrosion, water in the bilge?

Check the water surface behind the boat for oily sheen, could be leaking from several places like hyd rams, oil cooler, inside the motor, etc. These are all problems that YOU will have to fix.

Thgis is just what I do when I go to look at a boat and so far I've had pretty good luck. My first boat I bought on a whim and still regret it to this day, all I did was work on it. Although I learned a lot but I would rather be out enjoying the water any day!

Stay away from fixers. You can have a boat given to you for free but in the end cost you way more than the thing will ever be worth. And in the end you could've just bought a decent boat to begin with and enjoyed it instead of cursing it. Just my $0.02"