Little bit of Blue.Grey smoke after oil change on startup

[ustang73]

Wondering if anyone has advice regarding this smoke and sorry for the long post but want to give all the info I can think of.

I bought this 1973 mustang convertible a year ago, 302 with a 4BBL edelbrock carb, edelbrock perform intake, dual exhaust. Car idles great, has plenty of pep, has 95K on the original engine. It has a pcv valve to the carb on the passenger side and just a breather on the drivers side.

I had the oil changed by a local shop when I got it last year, they put in 5 qts 10w 30 Quaker State and new filter. Occasionally I noticed a little blue/grey exhaust smoke on the driver side exhaust only and I think after it sat a while. It was very infrequent.

I did my own oil change yesterday with 5 qts of pennzoil 10w 30 for high mileage cars and a new filter. 4 QTS came out of the car and it ran 400 miles between that last change. After the new oil I noticed the driver side exhaust blowing the blue smoke at idle, not much but enough to notice. Also noticed a tapping noise which I heard before from time to time. Took it out for a ride today and once it's on the road no smoke. It ran great and the tapping seemed to go away after it warmed up. Started it up again and no smoke.

My research online indicates this could be a classic "valve seal" issue. I wanted to check with the 7173 forum for any advice? Such as adding an additive? Fixing the seals or doing additional trouble shooting. I'm a novice when it comes to engines but I was going to pull the plugs and see if they are oiled up. Maybe it's just a matter of letting this new oil do it's job but any advice would be appreciated. I love this car and would like to keep her for a long time.

Thanks .

 

[barnett468]

you can plug the pcv valve and pcv hole then remove the oil fill cap then shield the hole so the fan doesn't blow on it then rev the engine a few times and look for a little smoke.

if it smokes, the tings are worn.

.

 

[Don C]

How old is the pcv valve? It could be gummed up and free up while warm. Could also be worn valve guides and oil seeping down the valve stems when parked for a while.

+1 on the worn rings and method (blow-by) for checking them.

 

[ustang73]

How old is the pcv valve? It could be gummed up and free up while warm. Could also be worn valve guides and oil seeping down the valve stems when parked for a while.

+1 on the worn rings and method (blow-by) for checking them.

The PCV valve is about 6 months old. When I got the car it had 2 breathers and a mechanic recommended a PCV valve which he added.

 

[Don C]

The mechanic was correct, crankcases must have positive ventilation to draw the vapors and moisture out of the crankcase. Before the pcv systems road draft tubes pulled them out into the atmosphere. PCVs draw them through the engine to be burned.

 

[piper62j]

I lost an engine using Quaker State oil years ago.. Quaker state had additives that did not mix with other oils.. After pulling the oil pan, we saw a goldish slime on the bottom. I was in the Air Force at the time and sent a sample to the oil diagnostic center on base and they came back with the additive issue along with some metal filings.. I never went back to Quaker State and use only Mobil oil now..

MHO

 

[c9zx]

Checking the plugs is a good idea but, from what you have said they are probably ok. From the description it does sound like valve seals to me. Modern oils do not have enough anti wear additives to be kind to flat tappets and cams. I suggest using an oil formulated for older cars with flat tappet cams. Using an engine flush product at the next oil change may help with the lifter noise and clean out the ring lands for better sealing. Let us know what you find out. Chuck

 

[Bill73Ragtop]

95K on the engine...worn and age-hardened valve guide seals are probably the biggest culprit. Doubtful that additives will cure the problem, but they might lessen some of the oil seepage into the cylinders. If you can live with the little bit of exhaust smoke, drive it until you're ready to pull the heads for a rebuild and/or the rest of the engine while you are at it.

 

[73pony]

95K on the engine...worn and age-hardened valve guide seals are probably the biggest culprit. Doubtful that additives will cure the problem, but they might lessen some of the oil seepage into the cylinders. If you can live with the little bit of exhaust smoke, drive it until you're ready to pull the heads for a rebuild and/or the rest of the engine while you are at it.

+1 on that. I have the same issue, When it sits for a while I get a little bit of smoke then it goes away. The heads have never been off my car so I will address it this coming winter.

 

[ustang73]

95K on the engine...worn and age-hardened valve guide seals are probably the biggest culprit. Doubtful that additives will cure the problem, but they might lessen some of the oil seepage into the cylinders. If you can live with the little bit of exhaust smoke, drive it until you're ready to pull the heads for a rebuild and/or the rest of the engine while you are at it.

I was out of town for a few days and started the car tonight and no smoke. Took her out for a drive, restarted and no smoke. Maybe the new oil just needed to settle in, it was rate as "high mileage" .

Thanks folks for the replies on this always appreciate it !! I will keep an eye on it but hopefully this is the end. I also filled up the tank and looks like I'm getting about 10.5 miles/gallon with a 'non ethanol' gasoline that a garage around here sells.