The saga continues.
Got the car running after a cylinder head refurbishment, which included new exhaust valves, guides and seats…inlets were well within tolerance and only needed tidy up of the seat and re-lapping. Before removing the head I made a note that cylinder 3 was down a bit on compression as was cylinder 6 (front), both at 130, cylinder 1 was 135, and each of the others were 140…engine is 8:1 compression ratio. Then did a wet test and no material change. So with that + some coolant leakage and cylinder 3 also had some oil fowling on the spark plug decided to remove the cylinder head.
The water leakage had caused Cylinder 6 & 4 to be perfectly clean…no carbon build up on the pistons. The head gasket was a brand that ceased production in the late 60’s (Cogsal - if I remember correctly) …so likely had been on the car since 1964. Despite the rusted out parts of the gasket the head did not require any aluminum welding. No scoring of the bores and no ridge on the cylinders 2 through to 5, could not check cylinders 1 or 6.
I had only driven the car less than 100 miles since purchase, and before the head repair. Other than coolant usage a bit of oil no other major issues. I did notice one day just before the repair a lot of blue smoke after startup following a run of about 50 miles. Put this down to oil leaking past the valve guides.
Since the start up and driving since the head repair, at first I noticed blue smoke after driving about 2km on very light acceleration. Then on a few other occasions, however now only at higher revs under acceleration. For example, yesterday drove about 50 miles and only happened once when in 4th gear I overtook another car and accelerated from 3000 to about 3500 revs…did not use the overdrive during the run, preferring to keep the revs up a bit. performed perfectly, outside temp about 30c, temp gauge sat just below 70, only moved about the thickness of the needle when going up a couple of long sheepish hills. Oil pressure at 40 and dropped to about 15 at 500 RPM idle.
The car seems to be using a bit of oil maybe 1/2 liter in about 100 miles traveled…plug 3 has some oil deposits as does plug 6, but not fowled completely. Checked all plug wires from inside the dizzy cap to the end and all at near zero (using copper core wire).
I am wondering if the oil ring(s) in 3 & 6 might be gummed up, as the blue smoke situation has become less since driving a bit. Before my ownership the car did about 300 miles in 3 years, before that about 200 in 1 year, and immediately prior was in a private collection (not driven for about 5 years). The car is low milage, 69,000 and according to the paperwork back to 1994 has not had any major work, excluding the cylinder head recently .
Finally, my question: If it is a gummed up oil ring is this likely to fix itself with usage, or will a complete tear down be required. Is there any proprietary engine flush type products (snake oil!), that could be used as a possible clean out?
Apologies for the long, long version…thought it best to give as much background as I could.
Any thoughts very much appreciated.