Fri Mar 15, 2013 2:19 pm
Found the problem with "lucky" my 48 Cub yesterday. When I could not find a problem with the fuel system I started to ck the electrical side of things. Traced the problem to the points by using a ohm meter to see if they were working. Found that the points were not closing and pulled the Mag to ck/adj the points and she fired up on the first turn. Let her run for a little while and found the head getting to hot for my liking so added coolant and found her to be about 1/2 gallon low. as I added the coolant slowly I noticed white smoke start to puff out the stack every once and a while. I think I'll have to pull the head and ck/replace the head gasket when the weather permits. The question I have is what kind of sealer do you use when you button her up. I didn't use a sealer when I rebuilt the motor and it ran fine last year with no smoke. Any thoughts/suggestions would be greatly appreciated.
Fri Mar 15, 2013 2:37 pm
You may have cracked the head, if it was very hot, when you added coolant. As far as gasket sealant I use the gold spray stuff, on head gaskets. Ed
Fri Mar 15, 2013 3:27 pm
Same as Ed, Copper Coat. The spray version is real easy to apply.
Fri Mar 15, 2013 6:53 pm
Did you re-torque the head bolts after you ran it a bit?
Fri Mar 15, 2013 8:50 pm
re-torquing the bolts cant hurt, but I have never had that to help. If you end up taking the head off use the copper coat and spray both sides of gasket and let it get tacky , not dry before replacing head. use a sealer on the head bolts, I use Indian head gasket shellac.
I hope you did not crack the head.
Sun Mar 17, 2013 5:56 am
I have my fingers crossed that the head is OK. I did re-torque the bolts. When I was running her last summer it seemed to use a lot of coolant. Nothing in the oil just "low" every time I went to use the Cub and I had to add coolant. I had the block boiled out when I rebuilt the motor but not the head. Last fall I ran a cleaner through the system and installed new antifreeze. Weather looks like it will be cold for the next couple of weeks and the trail to the heated shop is snowed in. Maybe I'll just pick at it a little at a time and see what is going on. The smoke out of the stack did not smell sweet as it usually does when you are "burning" coolant and I have my fingers crossed. Thanks for all the info and wish me luck.
Sun Mar 17, 2013 6:52 am
Normally you do not fill the cub radiator all the way up to the filler neck. Liquid expansion will occur as the engine heats up and the only place this can take place is at the top of the radiator. Since there is no external expansion collector tank attached to the overflow tube, any liquid beyond a level just above the top of the core will be pushed out through the overflow tube by expansion. Look down through the filler neck and use a flashlight to check for the proper level.
Since you suspect a head leak, you should fill the radiator all the way up to the neck, run the engine and watch for air bubbles coming up in the water, which indicates a compression leak. A compression test will also help confirm whether you have a compression leak.
Sun Mar 17, 2013 2:25 pm
I forgot to check for the bubbles when it was running. Sun is out so maybe I'll go start her up and see what happens before I start tearing her down. Thanks for reminding me. Getting old sure leaves me backtracking more and more. Thanks for the tip.
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