'86 115 rusting plugs

redjmp

Chief Petty Officer
Joined
Mar 16, 2005
Messages
536
I clean my plugs after every outing and I have noticed that all of my plugs except the lowest, #6 have nice clean porcelains but rusty electrodes. (surface gap).

Now I understand that usually, the bottom seal lets go and causes water intrusion in #6 but obviously this is not the case with mine.

Where could all this water be comming from?
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: '86 115 rusting plugs

Exhaust cover plate gasket leaking water back into exhaust ports
 

redjmp

Chief Petty Officer
Joined
Mar 16, 2005
Messages
536
Re: '86 115 rusting plugs

Help me understand.
I thought that the exhaust areas were under pressure and if anything if they leaked it would be to let gas into the cooling passage... No?
Do they suck water in somehow?
Or is it my water pump that is forcing the water in?
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: '86 115 rusting plugs

The exhaust cover contains another plate such that cooling water flows between the inner plate and the outer cover, assisting in cooling exhaust. A pinhole corroded thru the inner plate or a faililng inner gasket and cooling water can spray into the exhaust stream at the exhaust port(s) and enter the cylinder(s).

If the end of the spark plug inside the cyl has signs of rust, then disassemble the exhaust side taking great care not to break the bolts off, the have a nasty habit of seizing. Inspect the gaskets and plate very carefully, looking for signs of a leak. Replace the gaskets after checking all surfaces for straightness.
 

canoemang

Petty Officer 1st Class
Joined
Apr 9, 2011
Messages
350
Re: '86 115 rusting plugs

I just did one on a 84-115.. make sure you use alot of PB Blaster and heat.. alot of heat. I didnt break a single bolt, but it took me 4 or 5 hours to get it off.

Take your time and try rocking them a little bit out and in.. then hit it with PB..

since your doing the inner you might as well spend a couple bux and do the outer also.
 
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