Mercury Mark 6

[sbrown21]

I just bought 2 mark 6 Mercury’s that were locked up for 45.00 $ brought them home and freed the cyl’s. but noticed one was welded behind the prop. I than looked at the other one and it was cracked in the same place on the lower housing behind the prop. Is this a common problem ? Will I be able to get into the gear housing on the lower unit that has the cap welded ? The one motor is nice all the parts except for the weld. I think it will run after I check coils , the other is all there except the crack around the lower assy. broken starter spring and broken starter cable. Can these be fixed and are they worth fixing ?

[dave-bernard]

yes that is a problem. not a big deal call me 1 914 310 7086.
good motors but hard to do a fuel pump.

[billw]

Boy, if cracked Mark 6 gear cases are not a big deal, I sure would like to know your secret…..

Long live American manufacturing!

[20mercman]

I would love to have a die to cut the threads into the housing after welding. Then it really would be "no big deal", as I could weld them with full penetration without worry. Hard to weld it that does not distort the threads, and then it is not getting the penetration you want for maximum strength.

Steve

[RICHARD A. WHITE]

Do you know the diameter and thread pitch? You can get that info from the water pump cover….

http://www.richardsoutboardtools.com
classicomctools@gmail.com

[green-thumbs]

A GOOD machinist could carefully indicate case so as to recut thread…very close work to
get everything aligned within original specs. It can be done but given the number of Mark 6
made probably far less expensive to find a good used replacement even though such damage
may be a weal point of the design. If you are the machinist probably just an interesting
job on lathe or mill. BYB thread cutting both internal and external is usually done with a
60 degree single point tool. Tap and dies in larger sizes tend to be cost prohibitive
if infrequently used. Given the irregular shape of gear cases the first step to getting the
alignment right might be building a holding device.
Opinion not Fact
Louis
I dabble in machining. I know a great welder and a great machinist but given the time
and cost involved a good used replacement would make more sense. There several
ways to determine the thread diameter and pitch…helps to have a basic understand thread
standards, cutting threads requires paying close attention to what you are doing…THE
problem is obtaining an accurate set up so threading aligns with case and the existing
thread in case. It can be done and there are more than a few in hobby that can do that
level of work.

[dockbuster1]

Tipically the housing cracks just behind the cover if you shorten the seal carrier the cover will catch the remaining threads works fine except you have a bit more space behind the prop ,assuming the bearings haven’t been ruined by the water in the gearcase

[sbrown21]

Thanks I think I will try to shorten the seal carrier since there are some good threads left on the housing.

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