Mercury KE/KG 7 spark plug threads

[Waunnaboat]

Hello. I bought what is either a KE7 with a KG7 nameplate, or a KG7 with a KE7 gas tank at Tomahawk.  I inspected the condition of various mechanical aspects of the motor, but in one cylinder, I did not have much compression and air was leaking out via the spark plug.  Upon further inspection, I noticed that there was some sort of wire that made up the composition of the threads for the spark plug.  In the lower cylinder, the same type of wire thread was used but in good condition, and still had good compression, but in the upper cylinder, this wire was out of place and damaged.  I have tried a little bit to fiddle around with getting it into place better, but did not want to mess with it too much before getting more input.  Is this something that can be effectively fixed, and if so, how would I go about getting the wire into position without damaging the motor?  The(sort of) threads that seem to guide this wire are mostly intact but a bit damaged in some areas.  I was thinking that if all else fails, I would just buy a new motor, but I do not want to do so until I have exhausted all of my energy that can be applied without machining tools I do not possess.

"Outboards seem to multiply exponentially..........I find that for every finished project, there are two more waiting to be completed."

[bkrsdoz]

It sounds like the original threads were damaged, and a previous owner installed Helicoils. You might be able to remove the broken Helicoil, and replace it. Otherwise you would be looking for a good replacement cylinder head.

1 user thanked author for this post.

Waunnaboat

[Waunnaboat]

I think I would prefer to go with the new cylinder head route if it would cost less than replacing the helicoil.  Otherwise, I would get the materials for replacing the helicoil.  Do you know of anywhere I could find the cylinder(s) for a decent price?

"Outboards seem to multiply exponentially..........I find that for every finished project, there are two more waiting to be completed."

[dave-bernard]

That motor has no head, it is a dead-end cyl. repair the threads

1 user thanked author for this post.

Waunnaboat

[Waunnaboat]

I was meaning to say to replace the whole cylinder, but I suppose there was no clear communication of that on my part.  I think I will repair the threads anyway. Does anybody have a recommend kit to buy for this?  otherwise, I will just select the best-looking kit off of Amazon based off of reviews (of the sort that you can tell they were not paid to review) and price. Also, considering that it had already had a helicoil installed, and that had broken off to some extent, do you think that I will need to get an even larger helicoil to install the helicoil for the spark plug inside of?

"Outboards seem to multiply exponentially..........I find that for every finished project, there are two more waiting to be completed."

[Tubs]

Watch this video to get an understanding of some of the different options for thread repair and how well some work compared to others.  Link – https://youtu.be/jknMrFOGMOQ?si=RBEI3nyjKQvjk1BU 

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

1 user thanked author for this post.

Waunnaboat

[bkrsdoz]

You might want to take it to a machine shop if you have one nearby. They could do a professional job repairing the threads. I forgot that those have a removable water jacket, and not a removable head.

 

[Waunnaboat]

I would take it to a machine shop, but in my area labor is extremely expensive, and I would easily end up paying twice what I paid for the motor, which was 40.  I got a relatively inexpensive kit to repair the threads that had good reviews, and I will see how it goes.  If it doesn’t work, I will just buy another motor.  If I can’t get the threads right, buying a new motor would still likely be cheaper than getting it machined in my area.

"Outboards seem to multiply exponentially..........I find that for every finished project, there are two more waiting to be completed."

[green-thumbs]

A KG7 powerhead should have a Tillotson AJ 32 carburetor
while KE7 should have Tillotson
AJ23 or AJ19.
First order of business is to identify what you have and see if replacement cylinder block or repair is route to go,
A KG7 has 8 petal reed block,
Those who REALLY know their Green Tank Mercs can tell what
is what at a glance. With the older Mercs it is more common to find mixed parts motors than as they left the factory,
Damaged threads are not unknown in aluminum, so there
are thread repair products and
techniques. Some fasteners are
best left alone as they are
notorious for damaged thread
if removed… exhaust cover screws in thie KE7 to KG4 series while some screws always snap off flush.
Good Luck

It is not clear if you have only the powerhead or a more or less complete outboard,
Your experience level with h Green Tank Mercs seems to be at low end of learning curve,
Mr, Kiekhaefer did things differently to put it mildly,
The path to knowledge is steep
and winding.
I have a KE7 powerhead on bench in process of assembly
will pose and post photos

[Waunnaboat]

It has a Tilleston AJ 29, so it is probably a KE7, which I had thought it to be based on the propeller as well.  I am going to try to repair it first and can replace the cylinder block if that doesn’t work.

"Outboards seem to multiply exponentially..........I find that for every finished project, there are two more waiting to be completed."

[Author]

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