Fleet Meadow

Exhaust smoke and oil consumption

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So now that the weather is getting cooler I think it’s time to fix the smoking issue my ‘51 Meadowbrook has. Has 48k miles. I got it 4 years ago with 43k on it. It hadn’t been on the road since 1973. It uses about a quart every 100-150 miles, depending upon if I go about 40mph. I can use a quart if I go 55-65 for about 15 minutes. At those speeds I get a faint smoke out of the tail pipe. During deceleration I get it too. I was going to replace the seals but i can’t find any and don’t see them in the book. Does this engine not have seals? I have been told it’s the oil ring on the pistons. I have been told it’s the valve guides. Is there a way to definitively know prior to taking off the head? My dry compression test was around 95 across the board. I didn’t do a wet compression test, mainly because I’m new to a lot of this and didn’t know I was supposed to do it. 

Edited by Fleet Meadow (see edit history)

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Are you sure you are not leaking any oil, with that kind of consumption you should be seeing a real fog behind your car.  I would suspect that your oil rings aren't doing their job and therefore the compression rings are overloaded which would account for your good compression.

Another possibility would be worn valve guides.  A vacuum test would confirm this.

You really need a wet and dry compression test, preferably a leak down test.  Having a vacuum gauge hooked up when the engine is running would give you a lot of information,

What does your coolant  and what does the oil in the engine look like.  What weight of oil are you consuming,

When I started driving my Grandfathers Pontiac (99,000 miles) it was burning quite a lot of oil.  He had started using heavier oil to stop this and obviously it was not working.  A mechanic in the dealership where I worked said to go to a lighter oil as it would not overload the rings.  Over a couple of oil changes I went from 40wt to 30wt to 20wt and the consumption lessened. But within five years (50,000 miles) I had to replace all the valves with oversize ones and ream the guides.  I should have opened the engine in the beginning and fixed it right.

Long distance diagnosing and advice is easier with more  data.

 

Edited by Tinindian (see edit history)
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Concur that's way way too much oil depletion for burning in comb chambers or exhaust without having real billows of oil smoke out behind you...

Assuming you're not leaking it out (no puddles in the driveway?? look at the underside behind the motor; don't be surprised if you find your oil liberally coating everything)..

As recommended above, sounds like a prime candidate for opening up...

If you replace rings, at least carefully check the bearings; if they have any slack at all putting in new rings=more downward force on bearings, and if slack they'll get very slack very quickly...,

Forgot these are (in)famous for disgorging the first quart of oil...before disemboweling, if no visible substantial leak(s), try running one quart low to see if reduces consumption...

Edited by Bud Tierney
Senility (see edit history)
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If an engine has worn rings it will smoke when you accelerate, if it is valve guides  it smokes when you lift off the gas pedal. When in good shape they could still burn a quart of oil in 500 miles and that was normal. How many miles on the car? How is your oil pressure?

 

Tinindian has a good point, heavy oil won't cure a worn engine. But if the car was sitting and the rings got gummed up light oil and a few long drives, like over 100 miles, might free them up.

 

I also agree that you are likely leaking a lot of oil. If the engine is a greasy mess you want to clean it then  go for a drive and inspect for fresh leaks. But you may be able to see where it is leaking by where it is greasy.

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It has 48k on it. I got it 4 years ago at 43k. Last time it had been on the road was 1973. The rear of the engine does have a lot of oil on it. Actually it’s more on the transmission after the draft tube. Because it’s covered in oil i get small puddles under the car. Small as in 1.5-2” puddles overnight. They show up in full size after about 2-3 hours of sitting. I have been using 15W-40 in it. When I have 10W-30 and SAE 30 in it it lost the same amount of oil. On normal driving it does not smoke. After 50mph I see random puffs of smoke. At 65 it is a good amount of smoke coming out. Then it puffs at deceleration. 

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I'm thinking if you burn a lot of oil the plugs will be fouled, or at least have a lot of carbon on them. Try putting a catch can over the breather / draft tube and see what shows up.

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With under 50000 miles and good oil pressure it should not be smoking like that. I suspect that while in storage the rings got stuck and the seals dried out. A few long drives might straighten it out, especially if you add some lubricant to the gas and oil, like Seafoam.

 

Otherwise you will have to tear it down for a ring and valve job and new crankshaft seals.

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So I did some research today and found out it smokes at acceleration as well so I’m leaning towards the rings. I know I was asked but forgot to answer, my oil pressure is correct for the speed, essentially it’s 35 at 35, etc. I did some highway driving and some rapid accelerations. Overall it was a fun day of driving. 

Edited by Fleet Meadow (see edit history)

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You can't rule out stuck rings just yet though.

I would add a can of oil detergent additive and put a few hundred hard miles on it.

Just loafing around won't fix anything.

The worst that can happen is it starts burning MORE oil at which time it's a nearly sure thing the rings have had it.......or worse.

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I wasn’t ruling out the rings. In fact I am believing that is what the issue is. When it comes to ring size, how do I determine the right ones? I don’t believe the engine has ever been rebuilt. I’m pretty new to rebuilding an engine so ordering parts is where I lack experience. 

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You will order rings after taking off the head and measuring the bore.

 

Give it a bit longer. Go for a couple of 100 mile drives, with lots of hills along the way.

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Can you be sure that the engine had only done 43,000 miles when you got it?  From the symptoms you describe I would suggest it has done a lot more and it is time to rebuild.

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37 minutes ago, Fleet Meadow said:

I’ve gone 5k miles on back roads and highways. That’s not enough?

Arrr. Yes, that is enough! So since you bought it, the consumption has not decreased?

 

Have a look at @hchris's suggestion to check for blow-by. If there is blow-by with that much oil consumption, you should see a bit of smoke and under the car would be a mess behind the bottom of the breather tube.

Edited by Spinneyhill (see edit history)

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I would really suggest you clean and degrease the bottom of the engine well. I would then check for leaks after driving it a bit. From your description, I think you may be leaking more than you are burning. Also, what color is the smoke? Is it blue or is it black? I once thought I had some oil burning in an engine and it turned out that it was leaking oil, but was running rich giving the car black smoke under acceleration. With the oil leaking stopped and the carburetor fixed, the car does not use any oil and it does not smoke anymore. 

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Stop and go, short trips won't free up the rings. Years ago when I worked in a garage we had a customer who bought a beautiful 1971 GMC six cylinder half ton. It was about 15 years old and had been off the road and in storage for 10 years. It ran beautifully but burned oil. After 2 years he had us tear the engine down, it was in perfect shape except the rings were frozen in the pistons. You could see circles of rust on the cylinders where the rings rusted to the cylinders while it was in storage. We  installed new rings and it was good as new. I believe we had the head done while it was off, so a ring and valve job.

 

The customer was a carpenter who used the truck locally, never for long trips. If he had taken it out on the hiway for a few 100 or 200 mile drives the rings might have come free. I know of other cases where this happened.

 

One was a local collector who bought a Morris Minor convertible in California and drove it back to Canada. When he started out it burned a quart of oil in 100 miles. By the time he got home it did not burn any oil at all.

Edited by Rusty_OToole (see edit history)
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Breather tubes can get plugged up too and make the smoking worse. The reading on the odometer may not be accurate, most likely more than it says. Given that the engine sat for a long time it is most likely stuck rings and not so much worn guides. Sometimes by removing one quart of oil from the sump and replacing with a quart of transmission fluid and run engine , may be for a fifty miles helps to dislodge the rings. Also idle engine at about 1000 R.P.M while feeding transmission oil through the carburetor works. The spark plugs will give a good indication of the condition of the engine. If all fails tear the engine apart and do a complete rebuild. Do not forget to look for a reputable rebuilder.    

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On 9/24/2018 at 1:07 AM, Spinneyhill said:

Arrr. Yes, that is enough! So since you bought it, the consumption has not decreased?

 

Have a look at @hchris's suggestion to check for blow-by. If there is blow-by with that much oil consumption, you should see a bit of smoke and under the car would be a mess behind the bottom of the breather tube.

The oil consumption has started this year. Before that it was fine, a quart once in a while. There is a lot of mess behind the bottom of the breather tube. And I get smoke out of that tube, both tubes actually. 

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Today and tomorrow will be raining pretty hard so I can’t play with it too much but I’m going to take it out on the highway a little and see if it gets better. I do tend to drive back roads instead of the highway because I don’t like the higher rpm of the engine working the 3 speed transmission.

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Did the oil consumption increase fairly suddenly?

 

It sounds like it will not get better. You have a lot of blow-by indicating ring problem(s), maybe even a piston problem.

Edited by Spinneyhill (see edit history)

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I think you *should* have a single action fuel pump and electric wipers, but if you have a double-action pump (fuel + vacuum for wipers), a bad diaphragm in the vacuum side of the pump can cause huge oil consumption.

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Maybe the best answer is a ring and valve job. To do this you will need to take off the head and oil pan, remove the pistons and rods, take out the valves and check them for wear, grind in the valves and knurl or replace valve guides as necessary.

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Six additions to the original post asking for advice.  It's hard enough to help someone and impossible without the whole story.  Who knows how many more facts may come along.

As I am into the last quarter of my first century I'm too busy to bother with this thread anymore. Fleet Meadow I do wish you good luck.

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