Question for those w/o PCV system - fumes

[DanEC]

My ERA has a nice, not too rowdy Keith Craft engine with very few miles and no signs of any issues. I don't have PCV but I have a breather oil fill cap and a manifold breather at the back of the manifold. Nothing on the valve covers.

I get the usual stench of a couple drops of gas dripping out of my rear carb shooter on to hot throttle plates after about 10 minutes heat soak after shut off. I've done about all I can for that with carb heat shields and insulator gaskets.

But, I've noticed when warmed up and pulling up to a stop light or when pulling into my driveway and stopping, I get a real acrid exhaust odor that waffles over the top of the door for a bit. I'm guessing it's when my radiator fan has kicked on. Seems odd as there is no sign of issue with the motor and then it dawned on me - is this crankcase fumes I'm smelling that are circulating out of the engine breathers and getting blown underneath and out the louvers when the fan kicks in. This is while I'm driving so it's definitely not gas boiling off anywhere which has a different odor. Anyone else with a non-PCV car noticed something like this? Sound like what's happening? I've been around awhile and have several 60s era cars but they all have PCV.

[1795]

Dan,

Have you tried running the car when warm in the garage (with the garage door open) and the hood open to see if you can smell the same fumes coming out of the engine compartment? I do not have the PCV hooked up on mine, but my breathers go to a catch can with vent holes. Does the smell appear to come more from the engine compartment, or is it from the exhaust possibly? Is there anything that could have come loose and is touching the exhaust or engine and is melting?

Seems like you have had this car for a long time and this is the first time that I have seen you mention it. It sounds like something new, as opposed to something chronic. Being that winter has just subsided somewhat, is it possible that there is a mouse nest that is warming up?

Jim

[patrickt]

I have nothing like that. Either it's fumes coming out of your engine, or your percolating out of your boosters, but why don't you just put in a nice PCV? There's only upsides to one in a street driven car -- use the Wagner adjustable PCV along with a Moroso oil/air separator and you'll see an improvement on idle and off-idle gentle driving. Here's a pic of mine:

[hotrodyankee]

Run a PVC, you need to get all that unwanted condensation and fumes out of the engine. There's a lot of condensation built up on initial start, especially on a cold engine.

[DanEC]

Pretty certain it's coming from the engine compartment. My exhaust run all the way out to the back and the odor is not quite like exhaust. Standing back by my exhaust with the car running I don't smell anything like this particular acrid odor (best I can describe it - not overpowering but definitely something noticeable at times.

Not sure what I would have to do for PVC. My carbs do have a fitting (not sure of size) but since my primary carb is up front I would have to study the access to it.



Things are pretty tight.

[1795]

Dan,

I forgot that you have the under car exhaust. It does look tight there with the carbs. If you cannot find a way to plumb a line to the carb, and you want to minimize that smell and allow for proper breathing, you might want to consider running a vent line from each valve cover to a catch can on the fire wall like the old race cars had. Just make sure that the catch can can breathe. With my catch can I do not recall smelling any vapors under the hood.

It seems like I have seen some vehicles run the PVC to the intake manifold as well, but I could be wrong.

Jim

[jhv48]

First of all, those heat shields won’t do much to insulate your carbs from engine heat. If you have the hood clearance, try a 1/2” phenolic spacer under each carb. Should help quite a bit with the percolation problem. Also, open the hood after a long ride and leave it open if you can. All that heat can really build up after a run if you leave the hood closed.

Also, I believe the larger of the two capped nipples on the base of your carb will accommodate a pcv hose from one of the valve covers if you choose to install a pcv valve.

Now, as for the acrid smell, do your eyes burn too?

[Ron61]

Mine came from the factory with the PVC going to the intake manifold and it has never given me any trouble. But back in 1969 they didn't have all of the good stuff they do now.

Ron

[DanEC]

Originally Posted by jhv48

First of all, those heat shields won’t do much to insulate your carbs from engine heat. If you have the hood clearance, try a 1/2” phenolic spacer under each carb. Should help quite a bit with the percolation problem. Also, open the hood after a long ride and leave it open if you can. All that heat can really build up after a run if you leave the hood closed.

Also, I believe the larger of the two capped nipples on the base of your carb will accommodate a pcv hose from one of the valve covers if you choose to install a pcv valve.

Now, as for the acrid smell, do your eyes burn too?

Jim - the heat shields were mostly for keeping radiant heat from the intake off of the accelerator pump covers and it's a system that works with a series of alternate aluminum gaskets/gasket material gaskets. I ran a stack of as many of them as I could and still maintain clearance to my hood - I have a smooth hood so a 1/2 inch (or even 3/8 in) insulator gasket is out of the question. Worked pretty well actually. I still boil a couple of drops of fuel out of the rear accelerator pump discharge after some heat soak but it's now a fraction of what it was.

I do open the hood as soon as I pull into the garage. I usually shut the engine off first and although I sometimes pick up the odor slowly pulling into the garage and the fan comes on, I don't really smell it when I open the hood - but the engine is off.

No fittings on my 63 intake except for the breather port at the rear where I have a custom Survivor Motorsports breather installed. I think people have taken a blank off plate for that and installed a PVC valve in it. I would have to change to different valve covers to plumb anything there.

I wouldn't say the odor is concentrated enough to bother my eyes. The odor is not really a major issue as it's very intermittent (no one likes sitting at stop lights anyway). I've just been curious as to what it was as my engine does not appear to be an oil consumer or smoker. I can't smell it back at the tail pipes. It was more a curiosity than anything as I don't remember having a similar odor in any other old car. I think it just must be crankcase fumes. My motor doesn't have many miles and probably does have a bit of ring leakage like most engines set up for performance with modern low tension rings and loose clearances. I probably need to pull the front breather/oil cap off after a drive and take a sniff inside - suspect it will smell the same.

Thanks

[DanEC]

Originally Posted by Ron61

Mine came from the factory with the PVC going to the intake manifold and it has never given me any trouble. But back in 1969 they didn't have all of the good stuff they do now.

Ron

Hey Ron - yeah my 427/425 vette has PCV and my 67 GTX also. My first car I owned - 64 Ply Sport Fury even did. But my ERA engine is basically very close to a 63 427/425 and I think they ran a road draft tube or something off of the back of the intake. PCV has always seemed to work well for me. Except for when a PCV valve on the Sport Fury did go bad and I complained about oil consumption. Plymouth rebuilt the engine without checking it. When I complained it still used oil they decided to check it and said - Uhhh, the valve was stuck and we changed it. No more oil use.

[EM-0785]

Hi Dan,

I assume if the breathers on your newer engine are starting to get more oil/vapor soaked they would likely exude quite a greater odor when air/vapor passes through them, which maybe is now more noticeable. If so, I assume pulling and sniffing a breather may tell.

Then if so, I imagine you could replace the breathers to give yourself a breather while you consider the other solutions for longer term.

I’m glad you said it’s an 'acrid exhaust' odor and not just an acrid odor, hopefully so. Are you sure it isn’t the acrid odor a wire or something else in the engine bay burning or melting? Also you sure it’s not a header connection leak (although you did say it doesn’t smell like the pipe exhaust and I suppose that would).

Before I added my PCV system, I’d replaced the breathers a couple times as they would get very dark/oily/smelly fairly quickly, with a very strong, pungent oil/fuel odor after they got bad whenever I opened the hood.

Best of luck with it! Brent

[Gaz64]

Originally Posted by hotrodyankee

Run a PVC, you need to get all that unwanted condensation and fumes out of the engine. There's a lot of condensation built up on initial start, especially on a cold engine.

Correct.

There are ways of having a sealed PCV system that can still allow the engine to be ventilated to the air filter base under load.

I have a sealed pcv on one of my cars, Moroso air/oil separator meant for crankcase racing vacuum pumps, maintenance free, self draining to valve cover, large 12an to base of air filter, no oil in pcv line or breather hose to air filter. No fumes, no maintenance, no legal issues, no worries.

Gary

[Gaz64]

Originally Posted by DanEC

Pretty certain it's coming from the engine compartment. My exhaust run all the way out to the back and the odor is not quite like exhaust. Standing back by my exhaust with the car running I don't smell anything like this particular acrid odor (best I can describe it - not overpowering but definitely something noticeable at times.

Not sure what I would have to do for PVC. My carbs do have a fitting (not sure of size) but since my primary carb is up front I would have to study the access to it.



Things are pretty tight.

To run a PCV system, you need to access the back of the front carburetor, primary barrels of the front carb, where the choke is, not the rear carb.

[DanEC]

Correct - and that is where there is a lot of throttle linkage - very crowded. I

looked and hooking up a PCV line to the carb just isn't likely. There is a finger's width between the end of it and the cross shaft for the throttle linkage. Even if I managed to get a PCV hose on it, it would be rubbing on the linkage and probably fouling my throttle. Not something I'm willing to risk. Only other real option is to drill the manifold (not sure a good idea on a 63 427 manifold or plumb into the S&H air filter base - and I don't think it's big enough to give me clearance from the carb.

Interestingly enough - my breathers are staying clean and not getting gooped up at all. The inside of my oil filler one looks spotless. I'm not even getting any oil spits or other mess outside of them. Engine is staying very clean. Running copper exhaust gaskets that I took great pains to be sure they sealed up tight. Everything else is away from the exhaust and most of it insulated or shielded.

I'm just going to call it crankcase fumes and stop wondering about it. More an issue of curiosity than anything.

[patrickt]

Originally Posted by Gaz64

... Moroso air/oil separator meant for crankcase racing vacuum pumps, maintenance free, self draining ...

My separator is also self draining, but I'm the self.

[xb-60]

Dan, is it possible that there's a small oil leak somewhere that's not obvious, and the delinquent hot oil is the cause of the smell?

Cheers,
Glen

[Ron61]

Dan,

You could try getting a set of those valve covers with a breather hole in them and then use the breather caps and see if that helps. Also as XB-60 said, you may have a very small oil leak that burns away before you can see where it is. I used some stuff in my oil once that a black light made visible and found that I had a very small leak from one of the valve covers but it was not enough for me to see as the heat burned it away before I could find it. The black light showed where it was and I changed the gasket and that stopped all of the smell and leak.

Ron

[DanEC]

Doesn't exactly smell like hot oil - someone else suggested the term pungent. That might be a good term. I get a bit of weeping of oil on the gasket at the bottom of my valve covers in a couple of spots but I usually dab it with a paper towel after a drive and haven't noticed it every being more than enough to give me a slight stain on the towel. Hasn't been enough to run or drip.