Engine Blow By or Not

[Cape Codder]

I have had what appears to be Blow By from my engine for some time now. I originally that I was loosing water because the drain was always wet. Of course further investigation showed that in fact it was oil DRIPPING down the return pipe to the drain. Is there anything that can be done about this short of taking the oil servicing cap off and installing one that has the extended flexible pipe?

With just a little over 12,000 miles on motor, should this be happening? Does anyone else have this problem?

I would also like to hear from some of the engine re-builders that are often on this site!

[nick c]

Heres what we need to know, did you take this block to a machine shop and have it bored out and buy new over sized pistons and rings or did someone say it was rebuilt when you bought it?
Now removed all 4 spark plugs, open throttle and check the compression and report back to us.
carry on

[ryanheacox]

Sounds like a lot of oil but then it is a pretty common complaint for oil to spray out of the breather. Do you know if you’re burning oil? If you have bad blow by odds would be you’d also be burning quite a bit of oil.

My old engine had the disliked “steel wool in the cap” fix and I never had an issue. The engine rebuilder removed it and now I do get a mist of oil aft of the filler tube, not a big deal to me.

[Cape Codder]

Want to thank you both for your responses!

First, I had the motor rebuilt 12,502 ago maybe 5 years ago at a noted machine shop with either 60 or 80 over pistons. Just this past March I had a valve issue which has been rectified with NEW valves and cut seats. In March I also checked the compression at 60-62 lbs. in all cylinders.

As far as the oil I don't usually add oil during my 800-1000 mile oil changes. And no I don't have steel wool in the oil filler cap.

As best I can tell is the mist comes out the oil filler cap onto the water return hose and then drips down to the water petcock and drips off that onto my engine pans where I wipe it down every time I check the oil before a ride.

Last comment: the car runs very well especially since I did the valve work!

[ryanheacox]

I'm guessing with those compression numbers you have a stock head? If so, I really wouldn't worry too much about it especially since you say the engine runs well. There are a few different ways to address it if you want to, the breather tube, the steel wool, or a sock over the filler.


Oh, how tight does the filler tube fit in the block? Mine is a little loose and I get a little oil coming out from around the base sometimes. Also, check the baffles in the tube, they were revised a few times over the production run.

[Johnny Nitro]

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Like ryanheacox, I reluctantly placed a stainless steel scrub pad in the oil filler tube. Solved my admittedly minor mist problem.

[chrs1961815]

I like to use the last design of the filler tube as I think it performs the best. Ford realized that blow by was an issue and tried to correct it by changing the way the baffles are oriented in the tube but they never quite got it right. The interesting thing is that some engines have this problem really bad, others maybe a little, and some are completely blow by free. Probably due to the way oiling was experimented with in the block castings. Some designs better than others.

[daveymc29]

Perhaps some variation in misting could be attributed to the orientation of the baffles? I would guess if one is really concerned that you could mark the tube and rotate it some until you discover what orientation gives the best results. I had used a copper scrub pad to eliminate my misting, then folks seemed set against that so I took it out. Don't notice much difference, so maybe it mysteriously cured itself?

[Kurt in NJ]

I experimented some with my smiths compresser--- I overfilled the oil to just above the "F", it proceeded to spew drops and drool --- for about 3 hours, then it mostly stopped, and the oil level was just below the "F"

[Bob Bidonde]

The 1st thing you should do is to test the compression in each cylinder. Everything is conjecture until you get some facts about the engine's internal condition.

[Railcarmover]

The previous owner of an engine I have added an additional crankcase vent in the valve cover at the rear top.It reduces crankcase pressure at another spot and helps relieve any crankcase pressure in the valve gallery,potentially reducing rear main leakage.It seems to work well.

[nick c]

Heres an idea, I just cranked up my rebuilt engine with .040 pistons and rings, I held my hand over the filler tube for 30 seconds, there was No pressure build up, just the fluttering of the pistons. I must confess that I installed a pvc valve high on the valve cover because I saw it in a magazine maybe? I believe a minute amount of oil can only help the valves and upper piston and rings.
Here's my question, what difference could it make if you over filled the crankcase, all excess oil runs off the dipper tray, and the crankcase oil level is well below the dipper tray, and they made 2 dip sticks, the F mark is 1/2" higher than others.
carry on

[1931 flamingo]

Your rear main is going to leak due to the over fill. JMO
Paul in CT

[Cape Codder]

Bob Bidonde My readings are still the same: #1 - 62lbs., #2 - 60lbs, #3 - 60lbs. #4 - 60lbs. Now what?

[ryanheacox]

I can’t speak for Bob but even readings that are the same as last time would indicate to me that your engine is in good shape.

[chrs1961815]

Those compression readings are very normal. Your motor is fine. It is probably just your oiling system combined with the filler pipe.

[Charlie Stephens]

Originally Posted by chrs1961815

I like to use the last design of the filler tube as I think it performs the best. Ford realized that blow by was an issue and tried to correct it by changing the way the baffles are oriented in the tube but they never quite got it right. The interesting thing is that some engines have this problem really bad, others maybe a little, and some are completely blow by free. Probably due to the way oiling was experimented with in the block castings. Some designs better than others.

I agree with you. The last design made for the 1932-34 4 cylinder engines was the best.

Charlie Stephens

[talwrench]

I have a good running engine that used to mist oil out the fill tube until and old timer told me to put one of my old socks over it. Problem solved. I change it with oil changes.

[Dirtrack49]

I just purchased a 30 Town Sedan that had 2 miles on it. I have now put a little over 140 miles on it trying to break in the engine. I noticed that my return pipe also gets oil on it. One of the first things I saw was the oil filler pipe was loose, so I shimmed it up with some metal tape.
I still get a little blow by from the top of the filler tube. I am thinking this is somewhat common place and I really am not that concerned.
Your compression readings are good, so I would just continue to drive and maintain your A.
Tom L.

[Cape Codder]

Thanks to all for your suggestions and comments!!!

[Kurt in NJ]

It's the cars built in self preservation feature

[100IH]

When dealing with blow-by the object needs to b to lessen the loss into the crankcase and not to provide more escapes i.e. pcv. The filler tub should be enough. A cylinder leakage test will identify how much and where the leakage is occurring. The break-in period is the time , usually about 300 miles, that the cylinder cross hatch and the rings have to wear in for the best seal. Ring gap is the other factor that can put a monkey in the works and it is 2 fold. Too tight and too wide. Those who start off a new motor with Synthetic oil are defeating the wear in process in my opinion. Sometimes things have to come apart to Re-do the walls a little rougher or the rings a little softer. As a last resort, before tearing town, might try running oil lower on the stick for a comparison. Holding a piece of paper over the fill tube with the cap removed is a way to compare your car to another. Question; If you have excessive leakage won't that give you pressure to the mains? You built a hot rod and didn't know it.

[john in illinois]

Originally Posted by Charlie Stephens

I agree with you. The last design made for the 1932-34 4 cylinder engines was the best.

Charlie Stephens

I use a 32 fill tube and never have any oil coming out.

John

[Conaway2]

I think your motor is just fine. I’ve had Model A’s since I was 15 (decades ago) and 2 professionally rebuilt engines always blew oil mist out of the stock breather cap given enough time. I’ve used a breather cap with flexible metal hose for many years, and the problem with mist and oil odors is nonexistent.

[Tom Wesenberg]

Originally Posted by Conaway2

I think your motor is just fine. I’ve had Model A’s since I was 15 (decades ago) and 2 professionally rebuilt engines always blew oil mist out of the stock breather cap given enough time. I’ve used a breather cap with flexible metal hose for many years, and the problem with mist and oil odors is nonexistent.

X2
As soon as I removed the flex pipe, then the left side of the engine got a light coating of oil mist.