valve stem seals - How to?

[Sailor Bob]

Hi

I've been showing some white smoke at start up and recently a freind told me that she's blowing white (smoke) when I shift. After a conversation with a mechanical freind and described the history of the car he immediately said the Valve stem seals were shot. The key words were extended layup (10 years), appearently without oil the little buggers dryrot permitting oil to travel the stem to the combustion chamber (blah blah blah) = white smoke.

He suggested the I replace them by making a fitting from a spark plug and blow air into the cylinder to keep the valves closed:ermm: . Sounds good - if it works. In the meantime while I'm waiting on parts - is there anyone out there that can verify, deny or offer additional info befor I take this on.

Thanking you in advance

SB

[datsunrides]

Usually white smoke indicates water in the combustion process. Blue smoke would indicate oil consumption, usually.

Mark

[RogerZ]

Yes the air trick will work unless your air hose blows out. Another method more time consuming is to feed cotton clothesline in thru the spark plug hole while the piston is part way down. Then rotate to tdc (by hand). If you put enough clothesline in there the valves won't fall down into the rabbit hole. Use cotton cause anything left in there will just burn off. Nylon etc probably not so good. obviously after the valve seal exchange you pull the rope out. You can do two cylinders at a time because they go up in pairs.

[RogerZ]

Oh yeah forgot to ask. What is your oil consumption? if not burning oil (say quart in 800 mile)then datsunride has a good point on head gasket leking. Another indicator of valve seals is oil consumption high around town stop/go but out on hte highway goes away.

[beandip]

If your oil consumption is not high , was previously stated . I wouldn't bother with the seals. If this is a high mileage engine in need of a overhaul or valve job , do the seals when the other work is done. Both the air and cotton rope will work. What you said about the lack of oil on the valve stems is true. This is the reason it is recommended to put oil in the cylinders and pour oil over the valve train , on a engine that has set for a long period of time. There are always 2 valves open when the engine is not running . What is the compression like ? If this engine was one that had set for a year or so , could you turn it over with a socket with out difficulty and the plugs out ? If you had difficulty turning it over because there may have been some rust in a couple of cylinders , then watch the oil consumption closely . But do a leak down test or compression test in any event. If your valve seals are leaking . If you remove the intake manifold you will see build up on the exhaust valve stems . My old L-24 had almost golf ball sized deposits and the seals were not that bad . But she was tired. Gary

[Sailor Bob]

Hi RZ / BD

I've lost about 2 - 3 litres over the summer, approximately 3000 miles. I do combination driving - I'm 10 miles from the city and I travel there at least once a day (if there's no rain) in the Z.

The car had a significant layup - records show an oil change in 95 then no records to 2005, I was led to believe that was garage time. The milage provided by the vendor was 70k and judging by condition I have no reason to doubt this.

Compression test - not yet, but tomorrow looks good to me.

SB

[Sailor Bob]

Just did the compression test: 150 on all cylinders give or take a lb or two. I have no loss of coolant since purchased.

[TomoHawk]

I'm getting some vacuum from the valve cover. Is that related to the valve seals? I need to get a compresion gauge & see what the compression is like.