What is wrong with this motor?

[rcb130]

Hello All,
Motor is question is a 1996 Johnson 6 Hp two stroke, model J6REDS.
Here is the problem: Overheat after running for approx 3-5 Min.
What I have done so far:
Replaced water pump with new evinrude pump kit including housing, etc. A complete kit.
New vernatherm..
new powerpack
compression is 85 and 90 lb hot.
spark plugs do not appear steam cleaned
I see not vapor coming from spark plug hole when motor is hot
water flow from telltale is good when first starting motor but slowly decreases to spurts and finally steam.
If I remove lower unit I can get a constant stream of water out of telltale using a garden hose hooked to water tube.
I can get a reverse flow the same way.
If I remove the vernatherm I can not get any water from the telltale with the lower unit connected and running. This I do not understand.

What am I not seeing/doing?
Thanks
rcb130

 

[DECK SWABBER 58]

Post more info to get help here. Is this motor new to you? If not did it overheat before you did the water pump overhaul?

 

[oldboat1]

Might check to see that the t.stat is assembled correctly: http://ww2.iboats.com/Cylinder-Crankcase/dm/cart_id.717008700--session_id.902523051--view_id.1533674 Also check the housing to make sure the bypass is clear.

Use a piece of weed whacker line and run it into the tell tale outlet -- may simply be a blockage (favorite for insects).

 

[flyingscott]

Is this a salt water motor?

 

[rcb130]

Not a saltwater motor. Bought motor used and it overheated on first startup. telltale is clear. Was not aware of a bypass in the vernatherm housing. Will check it out to be sure it is clear.
Thanks
rcb130

 

[tomhath]

The head gasket is cheap and very easy to replace. Most motors I've pulled the head off have the water passages clogged with dirt. Might this motor have been used in muddy lakes or rivers?

 

[rcb130]

Hello all,
Pulled cylinder head off this a.m. Blown head gasket. One side of each piston is bright and shiny, steam cleaned.
Thanks to all who responded.
Rcb130