Projects 1956 Cadillac engine smoking

You might arm yourself with a valve cover gasket. I once bought a truck that had a 327. and it smoked and had a miss. Turned out it had a pushrod off on the intake valve. If the cyl cant fill with air & fuel mix from the intake valve. It would create a high vacuum and suck oil from the crankcase but still not fill the cyl enuf to create any compression when cranking with the starter. It will not cost much to check.

 

A leak down test will tell ya where the problem is without taking anything apart. I just looked on amazon, you can buy a leak tester for $31... if it’s a piston issue the motor is coming out but if it’s valvetrain / head related you can fix it in a weekend . That’s the direction I would go.


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I’ll check the condition of the gasket, unfortunately I don’t think that’s the culprit as I replaced the valve cover gaskets a little over a year ago.


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That might be what I try next, if I can figure out what it is I’ll be able to reside what to do with the engine and the car.


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I wouldn't bother to do any more testing. You already know that one cylinder is a dead player and pumping intake air into the crankcase due to a cracked/burnt piston or broken piston rings, or both. Plus, you have at least two more cylinders that tested poorly and the only remedy is to take it apart and replace the defective parts and do the necessary machine work.

You didn't mention how many miles this beauty has on the clock, but keep in mind that engines made back in that time frame were not the high mileage wonders that we have in this day and age. Most of those cars, unless they received meticulous maintenance, were candidates for the Lou's Garage Ring & Valve Special by the time they achieved the 75K-85K + mileage range.

I think you either need to save your money for some serious overhaul work or send the car down the road.

 

Do you have an air compressor? You need one to use a leak down,

 

Yes Kid, when I would stop at a stop light people would roll down their windows and say man your cars on fire. LOL. Bruce.

 

This would not be transmission fluid getting into the intake manifold as the old hydramatic transmissions did not have a vacuum modulator.

 

In my post, in reference to that, I said "I don't know ..........but if so......" only suggesting something else to check out that might be a factor or not. I had not seen one of those in probably ten years and could not recall for sure whether they did or didn't.

 

I understand I just wanted to let those that didn’t know this

 

The question what conforms to exhaust smoke and increased blowby?

 

I would pull the valve cover and look for a broken rocker or push rod out of place. That would explain zero compression on the one cylinder, the one with 60 look at that one closely too. But I think a rebuild is in your future. Those are huge cars to work on, not easy and expensive to have it done by a shop, if you can find one to work on it.

 

I pulled the valve cover off yesterday there was alot of baked down oil but nothing looked out of place. I think you are right that the engine will probably have to be replaced.

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How many miles are on the engine and has it ever been rebuilt, I was going to say something about the valve guides when you mention it cleard up after driving it a while but from the look of the plug it appears you may have a ring problem.

The engine just might need to be rebuilt. HRP

 

Check out a guy named Jonathan W on U Tube. He reciently repaired a engine that had bad compression and was smoking. He did a in frme overhaul it was a Packard 352 engine. in a Studebaker hawk body. Two cyls had damaged pistons and broken rings. However the details will be pretty much the same.

 

The speedo cable has been broken since I've owned it so I really dont know how many miles it actually has but it shows 79,000 and I dont think it was ever rebuilt.
Before it started smoking really bad it would just smoke a little when it started and then clear up but now it's just lots of smoke all the time.

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Thanks I'll check it out.

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Kid, didn't you have another parts caddy or am I confusuing you with some one else.Thanks Bruce.

 

That may be the way to go, have the heads done over at the same time, take your time with the disassembly. Mark and bag EVERYTHING, take tons of pictures. There should be lots of room to drop the pan. Providing the cylinder walls are in reasonable condition (no gouges) you can get away with a hone job. The kicker will be how good the crank looks. If it is good looking, just clean it up as you go and put in new bearings. The shells should be marked if they are undersize.

 

In the 50,s and 60,s it was commonly accepted thinking that a oil burning engine could be torn down the heads (cooked) and a valve job done. A in frame hone and ring job with new rod bearings could be performed one time. When it started using oil again it was time for a complete rebore & rebuild or junk the car. Most where junked. The funny thing. I don't remember seeing anyone mike or measure the bores or crank ect. They gave them a visual inspection. and when they pulled the heads if there was a lot of ring ridge and the pistons could be moved a considerable amount in the bore. They had the pistons knurled and in extreme cases bought .020 oversize piston rings and cut them down to fit. And for the most part those ring and valve job overhauls where successful.

 

The '56 in my sig came out of junk yard. Burned oil like crazy. Replaced the missing valve guide seals still smoked.
Long story short, there is a vacuum pump in the oil pan for the wiper motor. The oil was being pumped up through the hose to the intake manifild. Capped off the hose and no more smoke.

 

Smoke sucks. But the real concern is the "0" compression on one hole.

 

There is really only one thing that explains picture #2 in the first post. That is alot of blowby at idle.