Help with cranky breather?

[Dwight Romberger]

Hi all,

Smoke pour out of my crankcase breather (1930 model 47). Inside is a just a screen. Otherwise it is an open hole to the crankcase. Is this how it is supposed to be or is there something missing?

Coughing in PA

[Guest Straight eight]

Some breathers used a steel wool, Chore Boy type of mesh.:confused:

[Guest Roger_Roy]

you shouldnt be getting much/any smoke out if the engine is good, perhaps a compression test? (leakdown test would be better)

Roger

[Bob Engle]

Piston rings worn or broken; hole in piston; valve guides shot; cylinder bores worn.

Are you losing water? Blue smoke is oil, white smoke is water.

Any smoke out the tailpipe?

Bob

[Dwight Romberger]

Bob,

I can't really tell if it's blue or white, but it doesn't have the characteristic smell of antifreeze being burned. Not that much coming out of the tailpipe. Just seems to be a steady flow out of the breather cap and a crack in the exhaust riser valve. Increases as you rev the engine. I put in a heavier weight oil. 40 wt. It had 20-40. Smokes less, but I think it's still alot more than it should be. Should I be getting ANY smoke out ot the breather?

Dwight

Dwight

[Bob Engle]

Did this problem come on all of a sudden or has it been a problem for a while? The more wear on an engine, the more smoke you will see out the tailpipe and/or breather. I suspect you have worn rings and cylinder bores and the compression and power strokes are blowing exhaust into the crankcase and then out the breather. Worn valve guides ussually blow smoke out the exhaust pipe. The faster you run the engine, the more blowby will occur ans be seen out the breather.

A compression check and cylinder leakdown test will ID individual cylinder problems or low compression on all cylinders will ID engine wear as the problem.

A caution on running heavy weight oils, 40 or 50 weight can starve the valve train of proper lubrication. I know of a recent 1935 Buick that had stuck valves from using 50 weight oil.

Hope this helps.

Bob

[Dwight Romberger]

Bob,

I don't know if it came on all of a sudden, I just purchased the car last month.(We are still in the getting acquainted stage) The head was redone, so I think you are correct about the rings. I'll have a leak down test done. Before I tear it apart.

Otherwise, it seems to run well, except it takes at least 60 seconds for the gas to get to the carb.

Thanks for the help. I really appreciate it.

Dwight

[Bob Engle]

It's not to bad a job to overbore and instal new pistons. It's the bearings that are a bigger issue. Many engines I have torn down have acceptable bearings even if the engine shows severe wear. Rebabbiting is expensive. 50 series pistons have to come out the bottom as the rod end is bigger than the bore.

On the gas side, Most of these old cars have fuel system corrosion problems. Rusty gas tanks and fuel lines. Also, the fuel pumps are not the strongest. I would suggest flushing the gas tank and blowing out the fuel lines. Many people instal an electric fuel pump which they use for starting and then shut it off after the engine is running. Remember, if the car sits for a while, the gas will evaporate out of the carb and it takes some cranking to get the carb filled again. This is where an electric pump helps. Somewhere, I've got an article on installing an electric pump with a bypas check valve so the regular fuel pump can be run in parallel with the electric one. I'll look for it.

Bob

[Dwight Romberger]

Bob,

It's a 40 series if that makes any difference. I think the pistons still have to come out the bottom.

Is it going to be obvious if the babbit bearings are bad? How can I tell?

I've heard about the accessory elec pump. I think I'll do that. There also may be a leak that is allowing the fuel pump to suck air somewhere. The previous owner rebuilt the pump with no improvement.

Dwight

[Guest captbrian38]

hi Dwight captbrian38 here. Had a lot of the same symptoms as you with my '38 special, 248 engine that I just had rebuilt at CAMS in New Bern, NC. Not only did mine smoke like you say yours is I was also pushing oil out the dipstick hole and had no power to go along with everythting else. Couldn't get more tyhan 900 rpms. Whe when we pulled the engine apart the lands on 5 pistons were burnt away from a detonation problem somewhere in the past. Further inspection showed very little wear on the crank and rod journals so we were able to reuse those after just a polishing. Put 30 over pistons and rings, and cam bearings in cleaned and boiled everthing rebuilt the head using all the old parts that were in great condition also and now it runs like top. It was showing 37,000 on the odometer and judjing from the condition of the engine's bearings that was acurate mileage. The car sat for about 30 years before I purchased so the detonation problems had happened long ago. But take heart, unless there is something really amiss it should be fixable and worthwhile doing.

Brian '38 special

'41 Plymouth P11 TPC

Arapahoe, NC

[Dwight Romberger]

Thanks, captbrian

[Bob Engle]

To check bearings, you have to drop the pan and pull a cap off of a connecting rod. Be careful not to lose any shims on the rod capscrews. If the bearing is smooth, no deep gouges and the crank shaft is not scored, the bearings will be Okay. You can adjust the bearing gap with plastigage and changing shims to get to spec on the proper clearance.

Let me know what you find on the smoking.

Bob

[Dwight Romberger]

Thanks Bob.

Dwight

[Fred Rawling]

First, the breather only has the screen inside.

I remember from why back, they always said that if you did the valves on a straight 6 without doing the rings, you would burn oil. A compression test as previously suggested will tell you a lot.

A vacuum gauge is also very helpful diagnosing the problems

I would drive it a while with some marvel mistory oil in the gas. If the rings are just stuck from sludge, they may free up.

I think you should buy a shop manuel to get the information on how to turn the crank shaft to allow the pistons to come out before you start taking anyting apart.

You do not have to pull the head to pull the pistons however you may not be able to get your hand up far enough in the cylinder to see if there is a ridge at the top of the cylinder.

If you are going to do the rings, you must besure that any ridge at the top of the cylinders if removed which means removing the head.

I would check the rod bearings and the clearance with plastigauge. You can remove shims if necessary to get the .002 clearance. It would be a good idea to pull the pan. The previous owner may not have cleaned the sediment out of the pan and when you buy a car that starts to have problems right away, you need to check everything.

Be careful if you remove and reinstall the fuel pump. The ears that the bolts go through can break easily.