Smoking/Sooty Issue

[49 Dodge Dude]

I've been trying to narrow down the cause of my 49's oil burning. I did a compression test today, and got readings of 110, 105, 105, 120, 120, & 115. It begins to blow light but steady bluish smoke about 3-4 minutes after being started. Engine idle is good and oil pressure stays at around 40psi.

The plugs do get a dry, sooty covering after awhile, and if it's run for some time there will be a little sooty deposit on the floor by the exhaust pipe. I have not yet checked the idle mixture screws to see if they are set correctly - the choke appears to be operating OK.

My main concern, though, is the oil burning. What else should I be checking to identify the culprit?

[greg g]

leaky valve guides. Does it go away after drivig a bit?? Have you ever noticed blue smoke after making a hard left turn???

Could be as simple as sludged up return holes in the valve gallery. If the oil is puddling in there from not returning to the sump quickly it may be getting sucked up through slightly worn guides.

If you take a close look at the pic I stole from Capt Freds thread you can see the castings in the valve area, there are drain holes in the bottom of the casting that are met to return oil back to the pan if they crud up and the oil hangs there instead of draining it can get sucked past the guides during the intake stroke, then it get burned and shows tail pipe smoke. the symptom usually goes away when the engine heats up and the guides expand a bit sealing better.

[49 Dodge Dude]

Valve guides was one of the things I was suspecting. I haven't had the head off yet, but I'm gonna do that this weekend so I'll be able to check for any sludge buildup. If the return holes are gunked up, what's the best way to clean them out? And if the guides are worn, is that something that can be done with the block in the car or does it have to come out?

[greg g]

The valve galley is under the exhaust manifold behind the sheetmetal covers. In the old days they used to knurl vlave guides. that process employes a tool that raises some of the metal in the guide by displacing some by depressing it, usually forming knobs or ridges. The ridges restore part of the clearence tolerence. Its a temporary fix, but the way we use these cars temporary can be quite a while. Bronze lends itself to the process though it ductile property.

[Jim Saraceno]

I don't think it can be done with the engine in the car. I tried that once and got nowhere.

I eventually waited until the rebuild and replaced the guides while the block was empty.

[49 Dodge Dude]

I found the following blurb on another automotive website:

Oil consumption depends primarily on two things: the valve guides and rings. If the valve guides are worn, or if there's too much clearance between the valve stems and guides, or if the valve guide seals are worn, cracked, missing, broken or improperly installed, the engine will suck oil down the guides and into the cylinders. The engine may still have good compression, but will use a lot of oil. If the oil burning is due to worn or broken rings, or wear in the cylinders, the engine will have low compression. </

Is it safe to assume that, since my compression readings appear to be quite good, that the most likely cause would be valve guides, and can knurling the guides be done without removing the engine?

[Don Coatney]

I found the following blurb on another automotive website:

Oil consumption depends primarily on two things: the valve guides and rings. If the valve guides are worn, or if there's too much clearance between the valve stems and guides, or if the valve guide seals are worn, cracked, missing, broken or improperly installed, the engine will suck oil down the guides and into the cylinders. The engine may still have good compression, but will use a lot of oil. If the oil burning is due to worn or broken rings, or wear in the cylinders, the engine will have low compression. </

Is it safe to assume that, since my compression readings appear to be quite good, that the most likely cause would be valve guides, and can knurling the guides be done without removing the engine?

I am not sure how a flathead 6 engine can suck oil down the guides and into the cylinders. This sounds more like an overhead valve application.

[greg g]

If the galleys are not draining and it fills up with oil, under vacuum, oil could be sucked up a worn guide. Not likely but could happen in a higly sludged up engine. Or if there is a lot of blow by pressurizing the sump, same thing with vapor.

[49 Dodge Dude]

You're probably right, Don. Wouldn't the basic premise be the same, though - that if it were worn guides, compression would still be good, and if it were rings, compression would be poor?

Sorry for so many questions, but I'm about as well-versed on these engines as a tree stump

[49 Dodge Dude]

Greg - I took off the one of the valve gallery covers and snapped this shot. It looks like there is major sludge buildup in there. Would it be wise to run some Marvel Mystery Oil through the engine to help clean some of that out?

[Dodgeb4ya]

How about your oil control rings and cylinder wear?

[1941Rick]

Yuck....the rest of the engine will be just like that or worse.....might be looking for a major tear down......then run synthetic oil.....15/50 mobile 1

[Tom Skinner]

49 Dodge Dude,

If that is a picture of your engine, where pray tell is the heat riser Flap?

I see no weight, spring or otherwise to tell me if your Heat Flap is operational etc.???? Is it frozen open/closed or even operational?

Tom

Edited May 23, 2011 by Tom Skinner
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[Tom Skinner]

Could this then be part of the problem?

[49 Dodge Dude]

I took the spring off because the darned thing is stuck solid. Vice grips, penetrating oil & elbow grease, and I still can't get it to budge >

[Tom Skinner]

If what Shel Bizzy said, "its open" then you run like your "cold" all the time.

That is to say the Flap never closes letting exhaust straight to the tail pipe.

Therefore causing exesive carbon build up and light exhaust smoking?

I'm going to guess that is un-burnt fuel/carbon smoke not oil smoke.

I would look into cleaning up those reseviores in the Valve Chambers and Freeing up that Flap and addressing the Weight Spring issue.

It looks to me like your going to have to remove the Manifolds.

I did that last month on my engine and it was a Bear of a job.

Tom

[Tom Skinner]

By the way, if you can free it up with liquid wrench applications and a vice grip plier you would save yourself a REAL wresttling match.

[Joe Flanagan]

Antique Auto Parts Cellar sells rebuild kits for the heat riser. It's not hard to do but you'll have to pull the manifold, I believe.

[49 Dodge Dude]

This will take some self-restraint on my part to keep from swearing, but I tried to remove the manifold a few weeks back (a part of the manifold gasket was missing and leaking exhaust.) I tried like hell to get that thing off (broke two bolts in the process) but it wouldn't budge. I think I figured out why - the 'gasket' I was trying to replace looks a helluva lot like a weld, not a gasket.

Has anyone ever seen a manifold welded to the block?? It sure doesn't look like a gasket to me.

[ptwothree]

Greg - I took off the one of the valve gallery covers and snapped this shot. It looks like there is major sludge buildup in there. Would it be wise to run some Marvel Mystery Oil through the engine to help clean some of that out?

Once you start to fool around with trying to clean up that goo, you will never get it all unless you take the motor completely apart to get it all.

If you don't, the bits and pieces you miss will end up wearing out pistons, rings, bearings etc. Save yourself some heart ache, labor and cash and either fix it right or leave it alone.

You also might want to check the thermostat; might be stuck open. If not then someone hasn't been changing the oil on the old girl....

Good Luck

[Don Coatney]

This will take some self-restraint on my part to keep from swearing, but I tried to remove the manifold a few weeks back (a part of the manifold gasket was missing and leaking exhaust.) I tried like hell to get that thing off (broke two bolts in the process) but it wouldn't budge. I think I figured out why - the 'gasket' I was trying to replace looks a helluva lot like a weld, not a gasket.

Has anyone ever seen a manifold welded to the block?? It sure doesn't look like a gasket to me.

Very doubtful that the manifold is welded to the block. Did you remove all 13 fasteners?

[Dan Hiebert]

Back to the original Q - I have the same "problem", you can always tell where I've been with the Dodge by the cloud of blue smoke . Neighbors don't seem to mind since it keeps the skeeters at bay, but annoying none-the-less. (Not REALLY that bad, but makes for a better tale.) Good compression, etc. Besides the renowned members of this forum, (this issue comes up on occasion), I've checked with several mechanics in at least three states, a couple of whom date back to working on these cars when their mileage was getting to the cusp of "worn". The unanimous first diagnosis has been worn valve guides as the primary culprit, and according to the Mopar-centric ones, a common malady. Other issues such as plugged valve galleries and sludge contribute and make it worse. The guides don't even have to be excessively worn to draw oil up. Matter of fact - just stands to reason that the better your compression is, the better the engine will be at drawing oil into the cylinder during the intake stroke through worn guides. My engine's innards are very clean, but when I did a partial rebuild (honed cylinders, new rings and bearings) I didn't replace the guides and the car smoked more than before.

[Don Coatney]

Back to the original Q - I have the same "problem", you can always tell where I've been with the Dodge by the cloud of blue smoke . Neighbors don't seem to mind since it keeps the skeeters at bay, but annoying none-the-less. (Not REALLY that bad, but makes for a better tale.) Good compression, etc. Besides the renowned members of this forum, (this issue comes up on occasion), I've checked with several mechanics in at least three states, a couple of whom date back to working on these cars when their mileage was getting to the cusp of "worn". The unanimous first diagnosis has been worn valve guides as the primary culprit, and according to the Mopar-centric ones, a common malady. Other issues such as plugged valve galleries and sludge contribute and make it worse. The guides don't even have to be excessively worn to draw oil up. Matter of fact - just stands to reason that the better your compression is, the better the engine will be at drawing oil into the cylinder during the intake stroke through worn guides. My engine's innards are very clean, but when I did a partial rebuild (honed cylinders, new rings and bearings) I didn't replace the guides and the car smoked more than before.

How "good" can the compression be if the valve guides are worn?

[49 Dodge Dude]

Very doubtful that the manifold is welded to the block. Did you remove all 13 fasteners?

I'm thinking now that I missed one under the manifold after taking the inner wheel cover off and getting a better look at it.

[Tom Skinner]

49 Dodge Dude,

Even with all stud nuts off that baby is stuck on there good.

My motor was relatively rust free and I used flat bars, wedges of wood, and a hammer, for 2-3 hours with no results. Finally marinating the whole manifold with several cans of liquid wrench overnight, then using wedges and a handle from a sledge hammer I climbed into the motor compartment sitting on the motor I stuck the handle of the sledge into the intake maniflod hole where the carb used to be and shook that whole manifold loose up to and including breaking several studs along the way to pry that rascal off. It werent no party. I felt like I was going to have a heart attack. Then slowly I removed all the studs and replaced them after I chased the holes with a tap.

Use Silicone thread sealer when re-nstalling studs to keep any leaks from developing from the water jacket.

Tom Skinner

Huntersville, NC

Edited May 24, 2011 by Tom Skinner
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