Johnson running hot on 1&3 cyl. only

[DJAY2003]

I have a '65 90hp Johnson v-4 that is running hot on the #1&3 cyl. only. I just installed a new impeller and it appears to be functioning properly[peeing and water from exhaust]. Have a lamp on the console to warn if hot, not sure if it is functioning. Did the 3-5 second touch-test after running in a garbage can for 10 minutes. #2&4 no problem, 1&3 painfully hot. Shut her down started right up. Tried again in 10 min--no problem. Good compression in all cyls. New plugs set at 030, new coil,rotor,fresh properly mixed fuel. Dist. cap is in good condition...but 1&3 contacts have grooves. Don't know if this is a factor. $65 for a new cap <br /><br /> Again this beast is the v-4 with electronic shift, w/Distributer Battery breaker point ignition and 4 carbs[leaking small amounts of fuel]. Any help would be appreciated. Thanks.<br /><br />[should be running rich to all cyl--set just prior to stall.Did that to rule out running too lean. Engine runs and sounds great for now.]

 

[Solittle]

Re: Johnson running hot on 1&3 cyl. only

Doubt that the distributor cap has anything to do with heat problem. How long has it been since you have changes out the thermostats?<br /><br />If this is a salt water motor another place to look is the water passages. The salt crud builds up over time. If you suspect this pull the heads and inspect. Clean out crud and blow thoroughly with high compressed air from air compressor. This crud can also block the cooling passages behind the exhaust cover but this can be a bear as the bolts that hold the cover on have a tendency to break.<br /><br />It is also helpful to have a shop manual for your motor as they contain a diagram of the coolant flow.

 

[DJAY2003]

Re: Johnson running hot on 1&3 cyl. only

Solittle thanks for the quick reply. Didn't think the cap was the culprit either, just wanted to give all the info. that I know on the engine. Have a Clymer manual. Does not specify if there is more than one t-stat. It seemed to me there would be only one and if it went bad it would overheat the whole engine. Could there be two? Have had the engine only a month. Know the previous owner only had it in fresh water. Would flushing the engine possibly clear out the passages? New to this stuff. Thanks.

 

[DJAY2003]

Re: Johnson running hot on 1&3 cyl. only

Just read the post on "reply to fix" and couldn't agree more. So here goes.<br /> <br /><br /> Engine only had one t-stat. Replaced all parts associated, t-stat, springs and valves and also removed cover and cleaned passage ways. Fixed. Total costs to include gaskets under $50.