Engine smoking...and I don't know why

[tbirdtbird]

we'll all be guessing until we get some readings

[Rocketdog1]

Art - Just running the engine here at the house - didn't go anywhere.

I'll get a compression test done (won't be til next weekend), and update with that information.

[Patrick L.]

Originally Posted by glenn in camino

Years ago, a good friend complained about his engine smoking, but it turned out that a previous owner had replaced the vacuum fitting in his intake manifold with a grease fitting and he had been pumping grease into it whenever he greased the chassis.

Now we'll have to add grease to the MMO and SeaFoam debate.

[Art Newland]

Originally Posted by Rocketdog1

Art - Just running the engine here at the house - didn't go anywhere.

I'll get a compression test done (won't be til next weekend), and update with that information.

I think I'd get it out and drive it a bit, probably can't really get it very hot just sitting there running. Since it was OK before the exhaust system install, seems to me to be pretty unlikely that anything major in the engine "all of a sudden" broke. Compression testing won't be able to check for bad oil rings... will it? I had a thought that maybe oil it collecting in the valve chamber and under high vacuum conditions (like idle) it's drawing some oil through the valve guides? Heck I don't even know if a flat-head can do that! Don't you just hate "arm-chair" quarterbacks? I've heard some rumors if you put straight MMO in every orifice (on the car, not anywhere else) and grease the intake manifold, probably that mystic red stuff, that it will fix everything!

[VFRhugh]

In high school I installed a dual exhaust on my 56 Chevy 265. All new pipes and glass packs were used. On my first drive it smoked like crazy for a couple of miles.
Hugh

[tbirdtbird]

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to answer the person wondering how a compression test affects oil rings,
if the test shows low readings dry, and the numbers don't increase wet, then the valves are leaking. If the numbers get better wet, then the rings are worn. If the compression rings are worn, it is a sure bet the oil rings are worn, too.

I am gonna bet one cylinder gets better when wet......probably #4

A leakdown test would not hurt either

[Flathead]

I would go for a good drive, that is the only sure way to get things cleaned out.

[dave11]

Curious....my 30 has developed the very same affliction. I know it's been a while, but what did you find out ?

Dave Eddie

[George Miller]

Originally Posted by tbirdtbird

to answer the person wondering how a compression test affects oil rings,
if the test shows low readings dry, and the numbers don't increase wet, then the valves are leaking. If the numbers get better wet, then the rings are worn. If the compression rings are worn, it is a sure bet the oil rings are worn, too.

I am gonna bet one cylinder gets better when wet......probably #4

A leakdown test would not hurt either

Are we sure it was put together right. After working on some of the A,s I found out some guys can do anything wrong. Maybe it has a scraper ring on the number two groove up side down. Then it would scrape the oil up instead of down.

[Mitch//pa]

Originally Posted by George Miller

Are we sure it was put together right. After working on some of the A,s I found out some guys can do anything wrong. Maybe it has a scraper ring on the number two groove up side down. Then it would scrape the oil up instead of down.

Unbelievable some of the shit ya see...you gotta work on these cars with blinders or you'll never finish fixin all the botch work, it keeps snowballing ..

[Synchro909]

Without any test results, we're shooting in the dark but here's my wild guess at this early stage.
Do you have one or three piece oil rings? The one piece ones are as useful as fly screens on a submarine.
If you have the 3 piece ones, the scrapers have an up and a down side. Install them up side down and they won't work so well yet I've never seen this mentioned with any of the sets I have installed over the years.
Is there any chance something has found its way into a cylinder and scored the bore?

[Lawrie]

Also ,maybe the guides are loose in the block,mine were.
Lawrie

[Rocketdog1]

Hey all-

Wanted to chime in and thank everyone for their thoughts and suggestions.

I've been out of town for work, so I haven't had the opportunity to perform a compression test or a leak-down test - though I now have both of those little goodies sitting on the bench.

If I get lucky, perhaps tomorrow or at some point this weekend I can get some testing done and post the results.

Thanks again!

Bob

[inex01]

Originally Posted by Rocketdog1

Have not run any MMO as of yet. I've only had the rig for just under a month, and only filled the tank once during that time (non-ethanol btw).

Was seriously considering running some MMO or Seafoam - have had good results in the past with other rigs.

Try MMO in crankcase and put some in a spray bottle and with the car running spray into carb, with car running. You could have a sticky oil ring. What the heck this can not do any damage and it worked for me on my Friends Packard Eight that was not run for ten years, in that case we put a full bottle in the crankcase and drove the car for ten + or - miles and it worked.

[Rocketdog1]

OK - finally a bit of additional info:

Ran downtown today to grab a burger and pick-up a few things at the store, and she didn't seem to exhibit the smoking that I had observed before. Perhaps it was just some gunk in the works from the new exhaust system that I needed to burn out.

Upon returning home, I did a compression test and came up with the following:

60, 60, 58, 60 (warm engine, dry, throttle wide open, sea level, 8-10 revolutions)

Not great (I think), but at least consistent. I was going to perform a leak-down test as well, but I'm in need of one air hose fitting for my compressor, so that'll have to wait for another day.

I do have another question, kind of in the same vein. When I rev the engine up, think revving in second to get to third, there's a notable knock that develops. It only occurs at higher RPM's - but you can "feel" it as well as hear it, and adjusting the spark advance doesn't seem to make a difference. My first thought was perhaps I needed to check the clearance on the main bearings, especially since I have no history on this engine. Hell, maybe I should just take the damn thing out and go for the full rebuild. At least then I would know what I'm dealing with.

As always, your thoughts and input is greatly appreciated.

Bob

[tbirdtbird]

those are very respectable compression readings; leave it alone.

If the motor is an unknown to you, and you have a knock as you describe, I would drop the pan and inspect/adjust the bearings. Not all that hard to do, mostly time-consuming

[Tom Wesenberg]

Yep, and check the center main first because that's the one that usually goes first. My 29 Tudor sounded great at the swap meet, but after I bought it and drove it past 15 MPH, a deep knock started and it could also be felt and heard. My center babbit was completely gone.

If you need to do a rebuild, be sure to add counterweights to the crank.

[Synchro909]

Originally Posted by Tom Wesenberg

Yep, and check the center main first because that's the one that usually goes first. My 29 Tudor sounded great at the swap meet, but after I bought it and drove it past 15 MPH, a deep knock started and it could also be felt and heard. My center babbit was completely gone.

If you need to do a rebuild, be sure to add counterweights to the crank.

Ditto the counterweights and if the budget runs to it, put in inserts then, so long as you don't flog it, it'll outlast you ( a brave statement I know coz I don't know your age.)

[heneste]

Is your knock a low thud noise or is it more like metal on metal pinging sound? I'm just wondering if you are having an intermittent sticking valve. It could affect compression and give you some blowby from the cylinder. It would probably cause the exhaust to miss intermittently as well.