Hello,
I have now had a A4 with a new to me 1970 Coronado 30 for about 1 year. The A4 has been easy to start and received a new carb in 2011. Recently it felt sluggish. I checked compression with the engine warm and here are the results:
Dry
#1 120
#2 120
#3 100
#4 70
I rechecked #3 and #4 after adding MMO to the spark plug opening:
#3 100 (no change)
#4 100 (increased)
My question has to do with the next step. If the specs for the engine put compression at 100, why would I get 120 on the first 2 cylinders? Also, with the compression rising in #4 with MMO, does this implicate rings or could this be a valve that is partially stuck? My understanding is if the valve was completely stuck the compression would be 0.
From what I read the #4 exhaust valve often gets stuck. People seem to use MMO and an allen wrench to work it free, but I am not sure this my problem.
Do I need to be thinking a bad head gasket? There is no water in the cylinder or oil.
Thanks for any direction you can point me.
Jeremy
I have now had a A4 with a new to me 1970 Coronado 30 for about 1 year. The A4 has been easy to start and received a new carb in 2011. Recently it felt sluggish. I checked compression with the engine warm and here are the results:
Dry
#1 120
#2 120
#3 100
#4 70
I rechecked #3 and #4 after adding MMO to the spark plug opening:
#3 100 (no change)
#4 100 (increased)
My question has to do with the next step. If the specs for the engine put compression at 100, why would I get 120 on the first 2 cylinders? Also, with the compression rising in #4 with MMO, does this implicate rings or could this be a valve that is partially stuck? My understanding is if the valve was completely stuck the compression would be 0.
From what I read the #4 exhaust valve often gets stuck. People seem to use MMO and an allen wrench to work it free, but I am not sure this my problem.
Do I need to be thinking a bad head gasket? There is no water in the cylinder or oil.
Thanks for any direction you can point me.
Jeremy
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