Blow by from oil fill tube

[Hoodooman]

Alright,
so my 52 8ba gets a decent amount of blow by out of the oil fill tube. I know the engine is worn. However, after a complete tune up, having Charlie redo my carb, and getting my plug gap correct, the car actually runs and starts really well for what it is - a worn 73 year old flathead.

The blow by is making its way into the cabin of the car. I understand anything other than a 5-10k rebuild is a "bandaid." I'm not willing to put that kind of money into the car. I've heard some other guys with model A's etc, talk about a cap for the oil fill tube that can redirect the blow by under the car. Or, I've also had comments that installing a pcv could help. I want to enjoy driving the car and potentially be able to do so without having all of the windows down.

I don't think the road draft tube is plugged because it does drip some oil out of there.

Is there anything I can do to alleviate this?

Thanks!

Edit: I wanted to add that I took a CO detector with me on the last drive and it was in the safe zone. I was getting curious because I became light headed one of the last times I went out on a drive!

[tubman]

I wouldn't be so sure the road draft tube is clear; the oil filler cap is the inlet for the road draft system, so something is not right. It's not that hard to remove it to check it, so that's where I'd start. Be prepared also to remove the intake manifold and make sure the internal plumbing is OK. Who knows what's been done in there in the last 73 years.

A little smoke out of the cap on shutdown is not unusual, but it shouldn't be getting in the cabin while underway. Sounds like a fun weekend project.

[signsup]

I know nothing about engines or if there is a draft tube or PCV system already in place on your engine. But, some military vehicles vintage I have worked on have a system as simple as a short rubber hose coming from a short connection on the oil fill tube near the cap to a similar connection at the top of the valve cover. Some have a PVC valve connected from this same oil filler neck to an access to the air filter tube to allow the gases to get burned through the carb. And, I thought the very early engines just had a tube that came out of the block and deposited their wares on the road surface. Can't elieve your 53 doesn't have something already in place. JMO

[Drbrown]

Don't think any fumes should be getting into the car's cabin. Is the heating system tight to fire wall and the rear hood gasket in good condition ?

[signsup]

Is there a cowl vent on the 53?

[tubman]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by signsup

Is there a cowl vent on the 53?

Nope. Another solution would be to install a true PCV system. Although it is simple enough to do yourself, I believe that someone offers a complete kit for 8BA's. Although the problem (if there is one) will still be there, engine vacuum is better at sucking in the fumes than the draft created by just running down the road.

The "aerodynamics" of the road draft system come into play as well. If the end of the tube is bent or damaged in some way, the system may not vent as designed. A few years ago, I decided the long (12") oil fill tube on my '51 looked like a little too much. I replaced it with a chromed, shortened (6") unit. It looked better to me, but I started getting oil on my engine. All I can think of is that I had somehow disrupted the air flow through the system when I installed the shortened tube. Re-installing a stock oil filler tube corrected the situation.

[Hoodooman]

Thanks. I'll have to start checking the vent/heat system to see if it's sealed up well. I'm sure it ain't!

[Seth Swoboda]

I ran a 221 V8 that had low compression once. It smoked out of the breather cap all the time. When going down the highway, you could smell the crankcase fumes. I solved it with a rebuilt engine though. However, you are trying to avoid that.

Maybe do a compression check also. That will let you know the condition of the rings. Sometimes you can find good V8's that are being removed for SBC's for sale at reasonable prices.

How often are you adding oil to the engine?

[tubman]

Originally Posted by Seth Swoboda

I ran a 221 V8 that had low compression once. It smoked out of the breather cap all the time. When going down the highway, you could smell the crankcase fumes. I solved it with a rebuilt engine though. However, you are trying to avoid that.

Maybe do a compression check also. That will let you know the condition of the rings. Sometimes you can find good V8's that are being removed for SBC's for sale at reasonable prices.

How often are you adding oil to the engine?

I am sure you are aware that the engine ventilation system on the 8BA series of engines are completely different from the earlier flatheads, so you have to be careful when making comparisons. The "draft" actually flows in the complete opposite direction. Your other points are well taken.

[Seth Swoboda]

Originally Posted by tubman

I am sure you are aware that the engine ventilation system on the 8BA series of engines are completely different from the earlier flatheads. The "draft" actually flows in the complete opposite direction. Your other points are well taken.

Yes, I understand the road draft tube. It could be blocked. Maybe the engine is very worn out and the blowby is prolific enough that the fumes from the road draft are coming into the cab at low speeds and from the breather cap? I'm curious what a compression test will show.

Maybe the valve chamber is loaded up with sludge and not venting well?

I never liked that set up on the 8ba engine. The only one I've had I tried the PCV valve idea. But again, it was on a freshly rebuilt engine.

[Hoodooman]

As I mentioned, the engine is worn. Cold compression checks anywhere from 90psi to 60. I had a stuck valve in that 60 psi cylinder that seems to have gotten better after running with MMO. Sometimes it would be 0psi when the valve was stuck. She's worn. I've only driven it maybe 100 miles total. It burned about a 1/2 quart already. If she continues to run, she'll get maybe 1,000 miles a year. Not worth a rebuild. Runs much better after complete tune up and that valve loosening up. Haven't rechecked compression, doesn't really matter at this point.

[Seth Swoboda]

Hoodooman, How long did this engine sit since you have started it again? It sounds like you recently woke it up from long storage?

[Hoodooman]

Originally Posted by Seth Swoboda

Hoodooman, How long did this engine sit since you have started it again? It sounds like you recently woke it up from long storage?

Correct. The guy wasn't positive how long it sat, but years. Maybe 10?

[hueyhoolihan]

Originally Posted by Hoodooman

Correct. The guy wasn't positive how long it sat, but years. Maybe 10?

i'd put some miles on it and see if it improves. sitting does little good.

[Seth Swoboda]

Originally Posted by hueyhoolihan

i'd put some miles on it and see if it improves. sitting does little good.

Yes, the rings might start to seal better. Drive the heck out of it for a while. Maybe try some MMO in the crank case and gas, it might be snake oil but I've used it from time to time.

[cas3]

"drive the heck out of it" is perfect advise. I would also check to be sure there is no gas in the oil, old fuel pumps can leak a bit and still work for a while. Maybe even an oil change

[Hoodooman]

Thanks folks! I'll keep driving her and see what happens. I did put a new fuel pump, gas tank, oil change, tires and dual master cylinder on her. Also a complete tune up.

[aussie merc]

a leakdown test may well show whats wrong however a good 15w40 truck oil with frequent changes may well clean out enough of the build up. Try running some good quality mineral 2 stroke oil in the fuel [ 250 mls to a tank] this will help the valves free up as todays fuels are more alcohol than oil

[pistonbroke]

When I first started driving my 41 pickup with an 8ba it had so much blow by the fill tube smoked more than the exaust. It was obviously a junk yard transplant that was done by someone with very limited funds and knowlage. I drove it quite a bit for two years and folks would ask if I had a fire under the hood.You had to keep the windows down all the time or the cab would fill with smoke. It was bad. I tried to do the modern venting from the fill tube to the air cleaner , this just caused the engine to stumble and die. Then came my best hair brain fix ever. The tail pipe came out in front of the right rear tire so I took some spa tubing and canibalized a parts house breather cap and ran it out in front of the left rear tire. Sort of dual exaust right? It worked perfect fover a year when the trans went out. Tim

[Hoodooman]

Originally Posted by pistonbroke

When I first started driving my 41 pickup with an 8ba it had so much blow by the fill tube smoked more than the exaust. It was obviously a junk yard transplant that was done by someone with very limited funds and knowlage. I drove it quite a bit for two years and folks would ask if I had a fire under the hood.You had to keep the windows down all the time or the cab would fill with smoke. It was bad. I tried to do the modern venting from the fill tube to the air cleaner , this just caused the engine to stumble and die. Then came my best hair brain fix ever. The tail pipe came out in front of the right rear tire so I took some spa tubing and canibalized a parts house breather cap and ran it out in front of the left rear tire. Sort of dual exaust right? It worked perfect fover a year when the trans went out. Tim

Love it!! Hey, you drove it for another year like that! The thought crossed my mind already actually. I think any means to keep the car on the road, safely, is a good idea.