Suffolk Super Punch Crankcase Pressure
Hi,
I am a new member and would appreciate some advice.
I have had a 17inch Super Punch for many years (30) and bought one for spares about 4 years ago which was better than my original so restored it. The 75cc engine did not have much wear on the bore and is still running OK, but am getting oil pumped from the dipstick when driven hard and would like some advice as to what to check/do. I have checked information available and have done some initial checking/observations:
1. Oil SAE 30 filled to the minimum level
2. No smoke from exhaust and runs OK
3. Dipstick firm in oil cap
4. Can feel "puffs" with dipstick removed at a distance of about 10cm
I will be checking on the crankcase diaphragm later this week as the slot in it is fairly clean.
Other than valve guide wear, what else could be causing the problem and if it is wear does that mean it cannot be repaired!?
I want to keep it as long as possible can but am over 70 and while letting go under an apple tree I did not catch it as normal the other side and now have a neatly cut flower ben!!
Thanks for your time
PS I have been getting spares from Jon Cruse over the years.
Forums
Hi,
Hi,
I just found I had some time and checked the valve:
Generally clean inside the the case except for oil!
Washer not in good condition but intact
I found one of the two small spigots centralizing the bottom casing to the breather hole has broken off
Everything cleaned and put back, running and revving up in the garage and it seems to have improved, but it might be my imagination! Will give it a proper test later.
It may be the diaphragm case moved sideways from the breather hole and so was not effective, if so I will need a new lower case as I cannot see how to make such a small spigot!!
Regards
Hi, I also had the same issue
Hi, I also had the same issue recently with one of the small legs broken on my alloy breather housing - Jon managed to supply me with a replacement so hopefully you can get hold of one too! Good to know it's located properly.
It will be worth removing the
It will be worth removing the valve chest cover and inspecting the little breather valve. It may just be gummed up but more likely will be showing signs of wear, both in the alloy body and the paxolin valve disc. The sealing surface of the body gets rounded off and the disc has a corresponding worn ring around its circumference. Sometimes just turning the disc over to present an unworn surface to the body will make a difference. Also the composition washer between the body and the valve chest can disintegrate . I’m sure that Jon Cruse can come up with the necessary bits.
Love the story re the apple tree. A late customer of mine got distracted and his 17” Punch ended up in a “ bottomless” pond at the end of his lawn. We managed to retrieve the mower with a grappling iron on a rope but the grass box was never fished out.