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Stern Drive Repair

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the-menace

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Hey, I am fairly new to this site but if someone out there could share with me the items I need to replace when repairing my lower unit, I would greatly appreciate it very much. I own an "84 Mercruiser 470R engine with a Mercruiser outdrive. Last few times out the engine got hotter than usual. Last time out it got TOO hot. One thing I did notice is the exhaust bellows is shot and a couple of friends, (Not experts) tell me to replace everything in the lower unit. I guess I just am asking what all should be replaced when I repair it? And can I buy kits with all the necessary parts? Thanks, "the-menace" Dennis
 
Get a manual first, then check the impeller in the drive, might as well change the whole water pump, then check the t-stat, then if you still have a overheat the heat exchanger, still overheating pull the riser.

Or you can do yourself a favor and use that motor for a anchor, cause your troubles are just starting, see one little overheat you might have water in the oil. Did you check the oil ? Look like a milkshake, if yes then the head gasket went and what else who knows.

Good luck !
 
Replace all the bellows and water inlet hose. Drop the OD lower unit and replace the impeller including new upper and lower housings. You may need the water pocket seal in the bottom of the upper OD.
Last time out it got TOO hot.
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The hot engine may have damaged the head gasket or more. Open the heat exchanger endcap and make sure the tubes are not blocked.
 
with the age of this you must do some inspecting.. having a shop manual for instructions remove the exhaust elbow if its all rusted inside replace. replace the thermostat you must use the correct thermostat as this is a 2 stage specific for this engine coolant system.remove the end caps on the heat exchanger and flush out any debris.

if the drive impeller water pump has not been replaced in a few years this must be replaced..


with the boat out of the water and with the muff on to supply water to the engine the flow out the prop should be a large flow of water ..if its small these issues are all part of this...overheating ..

since I own a MCM470 I have had to do all this ...some say these engines are a poor design but 30 plus years later many still operate..
 
My experience with the imfamous 470 and OVERHEAT condition is NOT GOOD!

They do not like it hot.

As long as the rubber tube that connects the elbow and rams horn (at the exhaust of engine) did not melt or start to then you may be OK.

Definatly change the oil and filter and drain and replace all the antifreeze with new 50/50 mix........

Also a good tune up with fresh plugs and points and rotor and condenser....

Use a good quality oil such as mercs 25w 40w or a good synthetic such as mobile 1 15 -50 or even NAPA 20-50 synthetic, It is valvoline in a different bottle.

If you have starting issues or idle issues you may have stretched the timing chain...........TBD.
 
Here is a list of what you need for the lower unit:

http://www.marineengine.com/newparts/part_details.php?pnum=SIE18-3319&ptype=&Engine=&Model=

Double check your numbers as the pump base for the MR is a slightly different diameter from the Alpha1. I believe you have an Alpha1 Gen1 for 1984. My 1982 happened to be a MR.

Once you've checked and replaced your impeller pump check to see if that fixes your problem. It's not difficult if you have the manual. Fix it now so you don't cause serious damage to the rest of the motor.

j_cat: "the flow out the prop should be a large flow of water "

Not so much. The most flow will come out the starboard side of the outdrive at the transom assembly. The prop lets some exhaust water out but not a huge amount.
 
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chiefalen said:
Get a manual first, then check the impeller in the drive, might as well change the whole water pump, then check the t-stat, then if you still have a overheat the heat exchanger, still overheating pull the riser.

Or you can do yourself a favor and use that motor for a anchor, cause your troubles are just starting, see one little overheat you might have water in the oil. Did you check the oil ? Look like a milkshake, if yes then the head gasket went and what else who knows.

Good luck !
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I appreciate all the replies and help for my problem. Hopefully I can get something done next week. Thanks again. Dennis
 
Thanks for the web site for the parts. My son will be home from Korea Saturday and we will begin the repair as soon as I receive the parts I have on order today. Thanks for your help as I appreciate all the advise I received on this chat room. I am sure I will stop back one day. Dennis
 
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