Smokin'

[case12]

As normal, I crank my 'Stangs in storage once a month in the winter and let them run for 30mins. This time my GT/CS starts smoking blue smoke (oil) on one side (passenger side). It was doing this just a barely perceivable amount in the summer - but now it is really puffing. It puffs blue smoke on idle and when I rev it to higher RPMs, even after it is warm.

Any ideas what I should do to check this out?

Some background. 289, Edlebrock 4 barrel and intake - otherwise stock. Heads and valves redone (with hardened seals) about 1.5 years ago. Compression check out fine when I adjusted the valves then. (as a note, I did have some trouble setting the valves on this side to keep the rocker/push rod noise down - but no smoking then). Maybe 200 miles on the new heads. Here are pictures of the plugs - they look pretty good to me...

Thanks for any ideas to check next. Casey

 

[Mosesatm]

Casey, what were the compression readings, and how many miles are on the rings?

The 2nd plug from the left looks wet (oil covered), does that cylinder have the lowest compression?

 

[Midnight Special]

Casey,
... how many miles are on the rings?

...That was my thought. Also, how many miles since the heads were done?
I would maybe look at too much compression on old rings, or possibe "nicked" valve seal or bent pushrod(s)...

 

[miller511]

Casey,

It's either piston rings or valve seals.

I agree with Arlie in getting the compression checked again. If they are all good consistent readings (150 psi or so) you might have an issue with one of the heads.

Good luck, Jeff

 

[GTCSMustang]

Did you try putting in new plugs and seeing if the problem goes away?

 

[case12]

Thanks for the support!!

The questions were asked faster than I could answer them. So, here is the answer to Arlie's question. The psi in each cylinder is:

1 - 145
2 - 150
3 - 150
4 - 145

5 - 150
6 - 145
7 - 145
8 - 140

The 1-4 side is the side that is smoking. To Arlie's other question, the second plug from the left is number 2. So, it appears that I have good pressure on all the cylinders?

To Arlie's third question - I dont know how many miles are on the rings. That was before I had the car. Receipts I have back to 1996 dont show any engine work.

The heads were redone about 1.5 years ago - maybe 300 miles. No problems at then. I saw some blue smoke before putting her away for the winter this year. But now the problem is very noticable.

I have not tried changing out the plugs. The way they appear to be burning, they seem to look ok. Do you think that would make a difference?

I put in good push rods when we redid the heads, so I dont think it is a push rod. I hope it is not a valve seal (on redone heads?), and I sure hope it is not a ring (wouldnt that show in the pressure test??)

So, now I need some more ideas please....And thanks for your help. Casey

 

[Mosesatm]

Here are a few random thoughts.

There is a way to tell if only 1 cylinder is smoking. Disconnect a plug wire and see if the smoke stops.

Since it happened so suddenly my 1st thought was a blown up valve seal. Those umbrella seals tend to get brittle and sometimes simply explode all over the inside of the valve cover. An easy way to tell is to pull off the cover and look to see if each seal is in place. Also look for little pieces of seal on top of the head.

140 to 150 on the compression is ok but not stellar and with the car sitting you may have lost the ring-to-cylinder wall seat causing the blow-by.

I agree with Jeff in that you probably need to run another compression test to see if there have been any changes. That way you can at least narrow it down to a particular cylinder.

 

[Midnight Special]

Casey, did you to a "leak down" test in conjunction w/ compression test? Otherwise; do check the pushrod as you may have over-torqued (and bent) it when you were trying to quiet the lifter noise, only other culprit would seem to be valve seals. ???? Frustrating, I know. 'Hope for the best.

Arlie says: "... with the car sitting you may have lost the ring-to-cylinder wall seat causing the blow-by."

Great point! After testing, take it for a good drive & see if it re-seats. My white 302 car did that, after driving up & down the highway, she cleared up.

 

[case12]

Arlie, sorry I didnt make it clear. Those compression tests were done today.

By "leak down test" I think you mean, putting oil in the cylinder and testing the compression again? Even so, arent the current pressures adequate?

I will also try the other two ideas - taking spark plug wires off each cylinder in the bank to narrow it down. And the other thing I will do is drive her (fortunately we have had good weather here and lots of rain to wash the snow and salt off the roads).

Keep the ideas coming! Casey

 

[miller511]

Casey,

NO!!!! Do not put any measurable amount of liquid in the cylinders!!! Air compresses. Liquids do not. Bad things will happen if you turn the motor over...if you were to put the spark plug back in.

You want to use an air compressor with a setup of a gauge that goes up to 150 PSI or so. On each cylinder see if it "holds" pressure for a specified amount of time. You want to do this when the cylinder is at top dead center (so that the valves are closed).

-Jeff

 

[Midnight Special]

Arlie, sorry I didnt make it clear. Those compression tests were done today.

By "leak down test" I think you mean, putting oil in the cylinder and testing the compression again? Even so, arent the current pressures adequate?

I will also try the other two ideas - taking spark plug wires off each cylinder in the bank to narrow it down. And the other thing I will do is drive her (fortunately we have had good weather here and lots of rain to wash the snow and salt off the roads).

Keep the ideas coming! Casey

No, rather use a "threaded" comp. gauge and see how long it holds compression once you see what it initially is.

Re: driving to seat rings - try to go uphill or accellerate repeatedly in high gear a few times & make the engine "work"... My car failed an innitial "leak down", (on a relatively new engine) so the mechanic I spoke to said drive it as described. It smoked only at idle for awhile, then cleared up completely after a few more normal trips...

 

[miller511]

Sorry Casey,

I was thinking if the engine is not in the car and you couldn't turn it over.

Here's the gizmo I'm talking about-

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=94190

-Jeff

 

[Midnight Special]

Casey,

NO!!!! Do not put any measurable amount of liquid in the cylinders!!! Air compresses. Liquids do not. Bad things will happen if you turn the motor over...if you were to put the spark plug back in.

You want to use an air compressor with a setup of a gauge that goes up to 150 PSI or so. On each cylinder see if it "holds" pressure for a specified amount of time. You want to do this when the cylinder is at top dead center (so that the valves are closed).

-Jeff

WHOOSH!... Thanks Jeff, looks like we sent at the same time! Liquids in the cylinder will bend/ ruin/ break piston rods/ bearings!

 

[case12]

There is a way to tell if only 1 cylinder is smoking. Disconnect a plug wire and see if the smoke stops.
.

I did this excercise this morning. I removed each plug wire on the side smoking and it did not stop. Interesting.

I havent done the drive test yet. Looks like rain.

I dont think it was 'sudden' problem as I did see some smaller amount of smoking in the summer.

Casey

 

[case12]

Casey,
NO!!!! Do not put any measurable amount of liquid in the cylinders!!!

I did not mean to scare everyone. In my past days I was taught to try a drop or two of oil through the spark plug hole, and then test the compression with a gauge again. Either way, I don't need to do this in this case since the pressure seems ok....Casey

 

[case12]

No, rather use a "threaded" comp. gauge and see how long it holds compression once you see what it initially is.

Re: driving to seat rings - try to go uphill or accellerate repeatedly in high gear a few times & make the engine "work".QUOTE]

Please be patient with my ignorance. I have a compression gauge that threads in. It holds the pressure until I push the button to release it. I think you are telling me I need a different tool (like the one Jeff sent a link to). Do I need to buy this tool?

What do you mean about seating the rings? I only had the heads redone.

Thanks! Casey

 

[imported_tree]

Smoken

Casey.Sounds like i had the same problem with my GT/CS.The previous owner had the heads done at 80,000 miles and worked fine until i bought it of course, (not a bad thing).My friend is a classic car nut and when i told him what was happening with the blue and black smoke at start up , he suggested that i try one can of combustion chamber cleaner and see what happens.The blue smoke can be caused by weak oil rings(bottom end) or bad valve seals which will cause oil to get into combustion chamber and cause smoke.This can of cleaner that i used as per directions caused the GT/CS to smoke white and blue and a lot of black. due to the carb being to big for the motor and causing a whole lot of problems(fixed the oil problem) .And by the way 140 150 lbs in the cylinders is quite acceptable for a car that is almost 40-years.Again if the heads were done and the bottom end was not you could have a Blowby situation on the valve seals.Sorry i cant seem to put works to paper today. terry.....................................

 

[case12]

Terry, It sounds like you are suggesting NOT to use the combustion chamber cleaner - right? (so, what is the situation on your car now - still smoking?)

For the other ideas - I did get it out and drive it (a rare occurance of good weather in Chicago in December), and it improved some. Keep in mind that I am anal and that any smoke, however small, gets to me. So, many of you might say "What smoke?", but I can see it.

Question I havent asked - Would valve settings have any impact? In other words, can oil get in through my intake valve because I havent set it right? Maybe a dumb question - and maybe mute point given the compression is decent?

Casey

 

[Mosesatm]

Terry, It sounds like you are suggesting NOT to use the combustion chamber cleaner - right? (so, what is the situation on your car now - still smoking?)

For the other ideas - I did get it out and drive it (a rare occurance of good weather in Chicago in December), and it improved some. Keep in mind that I am anal and that any smoke, however small, gets to me. So, many of you might say "What smoke?", but I can see it.

Question I havent asked - Would valve settings have any impact? In other words, can oil get in through my intake valve because I havent set it right? Maybe a dumb question - and maybe mute point given the compression is decent?

Casey

Probably a mute point given the compression is decent.

If it smokes a lot at start up then smokes less when you drive it the problem is usually valve seals or guides.

I've always been told that rebuilding only the heads is risky because the increased pressure created by the good heads can create blowby past the rings. That could just be urban legend so someone more experienced with engine rebuilding should probably address that issue.

Casey, since you start your engine once a month or so in the winter you may want to consider installing a pre-oiler. When the engine is started after sitting for a long time the dry rings scrape against the dry cylinder walls, with no oil to act as a lubricant. Because of the ring and cylinder wear created by such starting of the engine some people think it's better to not start the engine until spring.

Have you replaced the PCV valve?

One of the rings on the piston is the oil ring. One of its jobs is to scrape most of the oil off the cylinder wall as the piston descends. If that ring isn't doing its job the engine will smoke, but again, it will usually smoke more then the engine is cold.

 

[Midnight Special]

No, rather use a "threaded" comp. gauge and see how long it holds compression once you see what it initially is.

Re: driving to seat rings - try to go uphill or accellerate repeatedly in high gear a few times & make the engine "work".QUOTE]

Please be patient with my ignorance. I have a compression gauge that threads in. It holds the pressure until I push the button to release it. I think you are telling me I need a different tool (like the one Jeff sent a link to). Do I need to buy this tool?

What do you mean about seating the rings? I only had the heads redone.

Thanks! Casey

Casey, my experience synonymous with yours has to do with what Arlie said. My white car sat a long time before I bought it. It would smoke on the passenger side at idle only where I had the compression checked and a leak - down (yes, use the item Jeff recommended) where it failed on two cyls. on that side. I was told to change oil, change PCV valve, and drive it as I described to hopefully re-seat the (dry) oil rings... It seemed to work beautifully - but I have a comparitively new engine. I too have always believed (and heard a few horror stories) that you should not do the heads/ valves only on a high mileage engine.

You said you noticed some improvement after driving, and that your compression is good - that's a good thing. At this point, just keep driving and don't worry about it until you have to. My old '66 smoked intermittently and on start up for many years. I gave up stressing it... All these older V8s can emit smoke for alot of reasons. If it ultimately gets catastrophic - what can you do 'til then given what you already know here? 'Just another $0.02...

Good luck my friend