Smokey LH exhaust on 53

[Quentin Hall]

I have a 53 conv that was stored on and off for many years. Apparently 10 years ago the engine was a decent runner. I am trying to get it up and running again as a lowcost driver. Nevertheless after  it reaches operating temp a mild oil smoking appears at the LH exhaust. (not clouds but a light but constant flow)  I have disconnected  and blocked the vacuum line from the fuel pump to manifold in case it was sucking oil.
I will check compression again tomorrow ( once my loaned out comp tester is returned) but it was about  110 to 120 all round when I tested 6 months ago.  But if it is an oil ring comp won't really be affected?
I have driven up and down the street a few times and also put a decarboniser down the carb. It appears to be the end pot that is the trouble. Plug was a bit oily when pulled yest and there is a bit of a miss. Could it just be gummed up from sitting with oil poured down there during storage? How do I diagnose broken (or unbroken oil ring without a tear down?)
Thanks in advance. Q

[The Tassie Devil(le)]

G'day Quentin,

Could be a badly worn valve guide or a broken valve seal, and also gummed-up oil control ring, but the compression reading is on the low side, as a normal pressure should be around 150 plus.

Oil Rings don't break like compression rings, as they are steel scrapers and a wafer separator between them.

Bruce.

[Quentin Hall]

Thanks Bruce, I redid the compression test over the weekend and it showed zero comp. So I topped the cylinder with oil and still no comp. So I assume I have a bent push rod or a stuck valve. Though no clatter so I assume stuck valve. I'll take the rocker off as soon as I can turn the car round in my shed. What is the latest advice on hardened valve seats? Just unsure if I want to spend another $1000 on the heads just now. Q   

[LeRoy DeVol]

I had a similar problem with my 47 Cad. and i bought a fuel system cleaner and drove the car about 100 miles, and every 2 miles i would accelerate in passing gear from 50 to 75 mph. After that the car ran perfect. I believe that after being stored so much, you have a stuck valve . I used Lucas Gas additive and because it worked so well i use it every 3,000 miles. The product also is could for cleaning your rings.

Lee DeVol

[The Tassie Devil(le)]

G'day Quentin,

Boy, Zero compression on both counts, and no clatter of the valve train would lead me to suspect a hole in the piston.

But, in this case, I would be investing in one of those new-fangled video systems that are now available with a 9mm camera on the end of a line that you can put down the spark plug hole and see what is going on inside the engine.   Never thought Endoscopes would become so cheap.

But, initially, take off the rocker cover, and see if the valve is actually stuck open, and the pushrod and rocker arm are loose.

Hardened Valve Seats won't cost that much down here.   I have heard that the material used in the construction of the later Cadillac Heads is tough enough not to require hardened seats.   I am not sure about the earlier heads.

Bruce.

[Quentin Hall]

Well good news. I removed the rocker today and quickly found the culprits, a stuck valve and bent pushrod. Valve freed after 3 short raps  with a timber block. The pushrod was a bit harder to remove, however a jimmy bar and a pair of vice-grips and a bit of pushing and pulling and out it came. I had a spare pushrod, installed it and started it up and the smoking was still there for a few minutes but then subsided to nothing. Miss is gone. Hooray.
Next issue though is the lifter is very noisy. Only ran for about 10 minutes so far. Probably just gummed up and needing a bit of a run . . . I hope. Oil is the same that has been in there for 25 years so that will be addressed next. Is a quart of kero in the old oil the wrong thing to do to break up the sludge that no doubt is built up in the engine ? Inside rocker wasn't too bad for years of sitting but certainly wasn't clean.   Q