No Spark! 1973 Merc 85hp

[freebyrd24]

Hello, I have a 1973 Mercury 85 hp outboard and it doesnt appear to have spark. Turns over great but has no spark. Now reading through the book I took out the switchbox to have tested. Is there a way that I can test the switchbox myself? It seems that just by browsing a little that switchboxes are a common problem. Is this true? Thanks

 

[ricksrster]

Re: No Spark! 1973 Merc 85hp

http://www.homestead.com/dolphinmarineservice/Ign4.html

 

[emckelvy]

Re: No Spark! 1973 Merc 85hp

The trigger is a more common problem than the switchbox. Here's a good ign troubleshooting thread to check out:

http://forums.iboats.com/showthread.php?t=181795&highlight=MERCURY+BATTERY-POWERED+CDI+TEST

 

[Motor Boater Bill]

Re: No Spark! 1973 Merc 85hp

Check out the post by Laddies in this thread--it is the best I have seen for troubleshooting this ignition system:

http://forums.iboats.com/showthread.php?t=213892&highlight=850+spark

 

[freebyrd24]

Re: No Spark! 1973 Merc 85hp

Wow thanks everyone for the great links! I'm extremely glad I found this site. I'll report back with my findings, thanks again though~!

 

[freebyrd24]

Re: No Spark! 1973 Merc 85hp

Well I was discussing with a friend what to do and decided to take the cap off the distributor, and found quite a scene. The rotor blew apart. I believe i was told that the rotor cannot be detached from the shaft, and that I need a whole new distributor assembly. Is this true? If so, where can I find one, I need a push in the right direction here, Thanks a lot

Also, will any other year or different hp motors have the same type of distributor? Also in need of a timing belt.

 

[ricksrster]

Re: No Spark! 1973 Merc 85hp

Scroll down when you get to this page;
w ww.oldmercs.com/ignsys.html

 

[freebyrd24]

Re: No Spark! 1973 Merc 85hp

thank you for the link ricksrster! i found the timing belt, but the rotor/shaft assembly seems to be outdated. Can I buy the rotor/shaft assembly instead of a whole new distributor? Thanks again

 

[Chris1956]

Re: No Spark! 1973 Merc 85hp

Free, You should be able to buy a new rotor and shaft ($200) for that motor. The distributors, rotors and caps were the same for all the distributor motors, except for some of the linkage, which is easily transplantable. You should run the "Clams Canino switchbox test" to assure the switchbox is good and the trigger is good. No sense in buying a new rotor, if the trigger is bad.

 

[freebyrd24]

Re: No Spark! 1973 Merc 85hp

I was seraching for part #'s and came across 393-4371 and 393-4370, do they both work? What is the part # i need, just to be sure?

 

[freebyrd24]

Re: No Spark! 1973 Merc 85hp

destruction attached

 

[Chris1956]

Re: No Spark! 1973 Merc 85hp

393-4371 was the original part number for your motor. 393-4312 will also fit.

 

[freebyrd24]

Re: No Spark! 1973 Merc 85hp

Excellent, thank you very much. what is the 393-4370 part # that i saw?

 

[freebyrd24]

Re: No Spark! 1973 Merc 85hp

Any idea how to separate the rotor/shaft assembly from the distributor? There appears to be some sort of piece on the bottom that holds it in, im not sure how to get it out. It looks like a large fishing weight. I'm not sure how clear my description is. Any ideas? Thank you

 

[ricksrster]

Re: No Spark! 1973 Merc 85hp

This might help. 1973 and 1975 were similar:

 

[freebyrd24]

Re: No Spark! 1973 Merc 85hp

fantastic information ricksrster! The only problem so far was on disassembly. The ball bearing, #10 on the sheet, broke and I'll need a replacement. I need the part ASAP, I'd love to get it together before the weekend, so I can put the motor completely together over the weekend. Any idea where I can find the bearing?? Thanks again!

 

[Chris1956]

Re: No Spark! 1973 Merc 85hp

Free, The bearings appear to be still available. First call should be to a Merc Parts dealer. You may get lucky and he has one or can get one quickly. Second call should be to Dougrussell.com or CrowleyMarine.com. Crowley will ship in 3-5 days.

 

[freebyrd24]

Re: No Spark! 1973 Merc 85hp

Wow thats an expensive little bearing, 45 bucks on that site

 

[ricksrster]

Re: No Spark! 1973 Merc 85hp

Try here:
"http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=63271"
"http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=%2063271&ivar=images/MERMAR/63271/6.png&inbr=461&bnbr=40&bdesc=DISTRIBUTOR+HOUSING+AND+ROTOR"

 

[emckelvy]

Re: No Spark! 1973 Merc 85hp

Wow thats an expensive little bearing, 45 bucks on that site

Years ago when my 1350's distributor grenaded, I picked up brgs from my local auto parts store. Just show them the numbers stamped into the bearing race and they should be able to come up with an equivalalent in SKF, BCA, etc. Didn't cost anywheres near that much, either.

If you have a local "bearing house" such as Kaman Bearing, they can fix you right up too.

Cheers.........ed