36 replies to this topic

[Gatti]

Hi,

 

My 186 has a catch can installed and has always been a bit of a heavy breather where it has some vapour that comes out of the catch can filter at idle to the point that you can sometimes see it when sitting at the traffic lights.

 

The catch can has two hoses attached to it from the rocker cover but I have been thinking of adding a third hose to it and running it back to the intake manifold.

 

 

The usual PCV that goes on the top of the rocker cover won't work with my setup so I was wondering if one of these inline type PCV's would do the job?

 

Edited by Gatti, 29 March 2023 - 02:12 PM.

[Gatti]

Here's a video of my old catch can setup where you can see the vapour

 

https://youtu.be/3LrLiUO0BV4

 

It uses no oil between changes

Edited by Gatti, 29 March 2023 - 02:12 PM.

[yel327]

Are you thinking of a simple T where the brake booster goes? Or drill and tap another port to #1 cylinder intake?

[I'm a Red Motor fiend]

Do not tap in to the booster line. Run it to a different point on the intake manifold.
That's not really a proper sealed system that you have proposed but it may work somewhat.
It should have a fresh air in point so run a vented filler cap.

PCV valves don't like big cams.

[Gatti]

Are you thinking of a simple T where the brake booster goes? Or drill and tap another port to #1 cylinder intake?

 

There's two there that are currently running the brake booster so I was thinking I'd change it back to one for the booster and the other one for the PCV line.

Do not tap in to the booster line. Run it to a different point on the intake manifold.
That's not really a proper sealed system that you have proposed but it may work somewhat.
It should have a fresh air in point so run a vented filler cap.

PCV valves don't like big cams.

 

I was thinking it will be sucking in fresh air via the filter on the catch can?

[claysummers]

You need to vent one end of the rocker cover to atmosphere, and suck the other end to achieve positive crankcase ventilation. Suck to manifold vacuum, via catch can if you need one. So catch can needs to be sealed from atmosphere.

In effect, swap oil filler lid for a vented one, use a stock pcv at rear of cover per existing line, then run other line to manifold vacuum.

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[I'm a Red Motor fiend]

I was thinking it will be sucking in fresh air via the filter on the catch can?

Thought I read u would add a third line from the can to the intake with a valve? In which case it would suck the vapour out the can that the two other lines are putting in there.

I just watched your vid and yeah that's a crap ton of vapour.

What about deleting the lines from the rocker cover to can. Use the can to vent the sump?

Use the AN fitting at the back of the rocker cover to put an inline pcv valve to the middle intake runner (delete the second booster pickup)

You can buy AN fittings with hose barbs to use. Put a blank cap on the middle AN fitting.

Then fit a vented filler cap.

[Gatti]

Thanks fellas

 

It seems the way I was planning isn't the right way to go.

 

Maybe the vapour is due to a bigger issue like rings or valve seals?

 

Might be time for a freshen up

[I'm a Red Motor fiend]

100% rings mate. Perhaps do a dry then wet compression test to get an idea how bad.

Edited by I'm a Red Motor fiend, 29 March 2023 - 06:54 PM.

[RallyRed]

Does it puff like that when its running on the road,( not idling at the lights) or when it's been fully warmed up?
i.e is that water vapour, oil mist? or something else.
Are all the cylinders running good/ same compression?.
Seems like a lot of venting going on...thinking maybe the plumbing to the inlet is 2nd in line to what is the main issue?
No expert.

[rodomo]

Looks more like water vapour to me?

Oil smoke lingers longer.

[Bruiser]

Good spotting R-O-B and C-O-L
Is it oily around the catch can?
If it’s just condensation you’re laughing

[jd lj]

Connecting the pcv to Webers is one of the problems that I wanted to solve years ago when I made my triple Weber air box. Now the pcv goes through a catch can (which has no breather) and then into the the air box backing plate. The air box also allowed me to keep the ram tubes but have good quality air filtration. Unfortunately those screen filters on the ram tubes don't filter air to a very fine level and also disrupt the function of the ram tubes from my experience.

My I also suggest moving the front carb spindle lever to the other side of the carb as it's currently unsupported where it is and could be susceptible to flex in the linkage rod.

I noticed that you have the cold start mechanisms hooked up, not many people do. Does it work well?

[S pack]

Good spotting R-O-B and C-O-L
Is it oily around the catch can?
If it’s just condensation you’re laughing

Hi Bruce, the thing I'm wondering is if the vapour is condensation then should there be that much water vapour in the crankcase? Or is it a sign that there may be a small cooling system leak inside the engine?

[Gatti]

100% rings mate. Perhaps do a dry then wet compression test to get an idea how bad.

 

I did a comp test on it a while ago and got around

 

150

140

140

140

140

150

Good spotting R-O-B and C-O-L
Is it oily around the catch can?
If it’s just condensation you’re laughing

 

It's not oily around the catch can

[Gatti]

Hi Bruce, the thing I'm wondering is if the vapour is condensation then should there be that much water vapour in the crankcase? Or is it a sign that there may be a small cooling system leak inside the engine?

 

I've been thinking it could be this as well but I've driven the car long distances (Sydney to Albury and back)

and don't have to top up the water.

 

If water was getting into the crankcase would that make the oil look milky?

 

It's always just black when I do an oil change

[RallyRed]

yeah, I was thinking just moisture from long stints in the shed?....that's why I wondered it it still did it in the shed , after returning from a good drive i.e. the moisture should have boiled off by then.

 

From my experience, it is not uncommon to find the slops in the catch can to be a bit milky/watery.  Maybe just due to the hot oil and alloy can slowly returning to ambient after you park it up. i.e. draws in moisture as it cools...next start, you then need to burn this moisture off.

Edited by RallyRed, 30 March 2023 - 08:41 AM.

[Bruiser]

Hi Bruce, the thing I'm wondering is if the vapour is condensation then should there be that much water vapour in the crankcase? Or is it a sign that there may be a small cooling system leak inside the engine?

The “you’re laughing” comment did come across like I know what I’m on about,
was a bit more glib than guru.
Seems you have thought it through better than me
Just thought if it’s not oil fuming that much, it’s a big relief
If it’s not oily around the can, it must be water vapour(?)

Gatti, does your can need to be emptied from time to time?
(I assume there is no drainpipe back to the sump)
Maybe condensation is building up in cool humid conditions
faster than the heat from running the engine can evaporate it off as normal?

Beautiful car, by the way, sounds great, too

[rexy]

Just fit a PCV system and get rid of the catch can.

 

You will be amazed as all your vapour problems and oil leaks disappear.

[Gatti]

Does anyone know if the vacuum threads on my redline manifold are 1/4 inch NPT?

 

My plan is now to order adaptors so I can connect one of my -12AN hoses to a vacuum port on the manifold.

 

I'll then add an inline PCV valve and fit a filter at the back of the rocker cover (pic below)

 

Then if needed I'll remove the filter off the catch can and close it off to make it a sealed system.

 

[Gatti]

I should have all the parts to change this on the weekend.

 

When I add the inline PCV and re-route the hose for vacuum would it cause an issue if I keep the filter on the catch can?

 

Would it make those cylinders run lean because they'd be getting fed air that hadn't gone through the carb?

[dron]

https://mustangfancl...upr-products/   Shows how a PCV system works. The catch can should not be vented. Filtered air goes into the engine, Air and any fumes are drawen into the inlet manifold through the PCV to avoid build up of flamibles in the crank case and to reduce the risk of a crank case exploshion. Simple system and good thing to have right.

[claysummers]

As above, however you are right to be concerned that idle mixture may vary between ports, unless you tap all three.


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[Gatti]

Thanks

I’ll remove the filter from the catch can and make it a sealed system and see how it goes.

If it’s not right I might ditch the catch can and change the rocker cover to something more like standard and make it a stock style PCV system

Thanks for the advice


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[warrenm]

You'll probably have to balance the carbs as you are adding another source of air behind the throttle butterfly's.