302 Merc New Buyer Checklist

[mbuffone]

Hello,

Hopefully I can find some good tips here. I'm looking at a '79 John Allmand w/ a 302 merc outdrive w/ 300 hours on it. It's been sitting for about a year. That boat is in excellent shape and was well taken care of. I'm new to all of this and I have a mechanic so I will not be 'working' on it as of yet. Just wanted a checklist for going through the engine and to see what are some of the main issues w/ this type of engine. I've been reading up on it and overheating seems to be an issue. Water pump, plugs, thermostat, clogged water intake, etc. Please if anyone could be so kind as to give me a rundown of simple maintainance and what to look out for. Thanks.

Matt

[powerabout]

fresh or salt water use?
Exhaust elbow/risers are a maintenance item so need replacing every few years when used in salt water.
The cylinder heads eat out in the exhaust ports when used in salt water.
You would want to know the gears in the stern drive are in good condition so that involves removing the top cap of the sterndrive and removing the bearing carrier in the lower unit.
Did it get annual services for last 30 years?
Drive bellows will need replacing at that age as well so remove the drive to check they havn't already failed.
The market value of that model sterndrive at that age is close to zero so factor that in when you buy it.

[mbuffone]

Hey, thanks for the reply. It will be used for salt water and he always took it out of water after use. It has new gimbel bearing and bellows he said. Thanks for the tips. If there anything else you can think of please let me know. Thanks.

Matt

[mbuffone]

And one more thing. The guy was a mechanic also and took good care of it. So I believe it was serviced recently.

[FMS]

If it was used in salt water, look closely for corrosion that's been painted over. Better that it was out of the water, but still salt corrodes. Look at how many salt water boats have newer trailers because the old ones rusted out. As far as the engine, remove a few of the freeze plugs and see how much rust is sitting there. There will always be some, but if the threads are rusted away it will give you an idea how bad it is.

[CDK]

Like powerabout wrote in post #2 the Merc 302 has no market value, so you buy the boat and get the stern drive for free.

Messages about engine hours and meticulous service in the past are very hard to verify, but there are a few things you can check.
If a new gimbal bearing was installed, there has been water intrusion, so the upper bellows was not replaced in time or there has been damage of some kind. If there has been water intrusion there may also have been gear shift problems. Has the shift cable been replaced?
Does the drive have a conductivity kit installed? It didn't exist in '97 but Mercruiser made an aftermarket kit when the drive proved to suffer from rapid corrosion in seawater.
Does the skeg still have the original triangular shape or has it been cut off? That would indicate collisions from the past.
The exhaust manifolds have drain plugs near the lowest points. Does water come out if you remove one? Or do you have to dig through a layer of sludge before the first drops appear?

[mbuffone]

Hello,

Thanks for replying to my ad a couple of weeks ago. I ended up buying the boat w/ two of my friends and we have been out a couple of times. We did a complete tune-up, plugs, distributor cap, oil, wires, etc. You mentioned that if the bellows were not replaced at the right time then there could have been water intrusion. The previous owner stated that he did replace the gimbal and bellows. You also mentioned that there could be gear shifting problems and that is what we recently ran into. The boat starts up relatively quick and idles pretty good but as soon as we try to put it in drive or reverse it stalls out. I'm not sure if it's the whole shifter unit that needs to be replaced or if it is just the cables. Once we get it in gear it drives like a champ. If we replace the shifter, is there anything else that needs to be replaced in the sterndrive or it is a basic fix? How exactly would water entry into the sterndrive effect the shifting also? It may also just be the cables. Once again I thank you for your time and any information that you could provide would be greatly appreciated.

[PAR]

Nope, it's stalling likely because the linkage needs adjustment or you have one or more bad lock out or cut out switches (which also could be out of adjustment too). This isn't an easy thing for the novice to diagnose. The best advise you can get is two fold. First buy a manual for the engine drive combination, then take the boat to a qualified boat mechanic, as this sort of thing is common, but a regular automotive mechanic isn't going to catch it easily. You need a boat guy.

[CDK]

Originally Posted by mbuffone

How exactly would water entry into the sterndrive effect the shifting also?

The shifting mechanism has a few parts in the drive that are supposed to stay dry, like a slider in a small chamber, a shaft in a bushing and the end of the shift cable. After water intrusion these parts have more friction, causing the cut-out switch to stay closed too long.
Have the lower housing removed, the parts cleaned and greased and a new shift cable with bellows installed. Then the shift mechanism must be adjusted and the troubles will be over.

[mbuffone]

Thanks for the replies fellow boaters. Greatly appreciated.

[powerabout]

Other than adjustment the most likely part of the shift system causing that is the vertical shaft in the bell housing that goes through the exhaust
Put your drive in forward and remove it and you will see how it works. This is the area CDK is talking about which is not meant to get wet but the lower end of that shaft is in the exhaust and can get sticky even though it is a ss shaft in a bronze bush. Originaly they had too small a clearance which was changed on later models. Just remove the shaft ( easier said than done) and re drill the lower bush to 3/8


You can also then feel the shift cable ( after you disconect it from the engine) to see if that it is at fault ( very common on the ford that if there was a mild overheat the routing of the cable held it at the bottom of the exhaust Y and they would melt).
The cut out switch should not operate going into gear only coming out