1978 merc 200hp v6

ducerman

Cadet
Joined
Sep 5, 2011
Messages
14
Well im a newbie on this forum and to the world of outboards.. Ive been around boats all my life but only IO's. The other day i bought my very first boat. Its a 1978 checkmate enchanter 19'. The boat has a 200 hp mercury v6. The boat had been sitting for over 7 years so i did what i thought should be maintnaced before i took it out. I cleaned the carbs, changed the impeller, changed all of the fuel lines, fuel filter and a good visual inspection of the wiring and so on.. When i started the motor the first time outside the water with bunny ears, i noticed there was no water comming out of the cooling hose (not sure of the tech name). Since i had checked the water pick up for blocks and changed the impeller, the only other thing to my knowledge was the thermostats. Next i took the thermostats out and boiled them in water. Sure enough they opened and looked very clean. At that point i figured running the boat at idle doesnt warm the motor up enough to open them, my guess?? The next day i took the boat out to a local lake. As fast as i could turn the key, (with out choke) the motor started. I did a few half mile loops near the boat ramp and it died. Got extremely hot!! So hot a rubber hose had burnt on the cyl head. After cooling down, i was only able to get spark from 2 coils. My guess the heat was too much for them. Well thats the boat im in, literallly.. I am willing to put more money into it but im limited to around 500 bucks. I need opionions from the pros!! I really hope that the block is unharmed and all i have to do is wiring and cooling. I had one chance to buy a boat and really hope i didnt screw it up. Any help would be fantastic!! Thanks to everyone for their replys.
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: 1978 merc 200hp v6

First, check these links and get a copy of the service manual for your motor.

http://1manual.com/Mercury manuals/Service_Manual_Index.html

http://forums.iboats.com/showthread.php?t=309079&p=2072211#post2072211

Next, download the Ignition Troubleshooting Guide from the Support page of CDIElectronics.com This will guide you thru testing and diagnosing your ignition problem.

Then, drop the lower unit and recheck the water pump, make SURE the impeller key is in place. Leave the lower unit off, rig a garden hose to the water transfer tube and start the motor, check water flow to the stats. Maybe also disassemble and clean the poppet valve to make sure it is not sticking, restricting cooling at high speeds.

Lastly, install a water pressure gauge to key an eye on cooling pressure.
 

ducerman

Cadet
Joined
Sep 5, 2011
Messages
14
Re: 1978 merc 200hp v6

Thanks captain for replying.. It turns out the motor only has between 35 and 60 psi compression. Maybe i can save up enough money before next summer to rebuild it. Either that or sell it for parts. Thank you for your time with helping me troubleshoot some problems, i guess next time i will know what to look for when buying an old boat.

Thanks!
The Tavis family
 
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