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What to do with breather pipe as my new air filters have no connection for one?

Bob Hughes

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You could run a pipe from the T on top of the rocker cover into a can fitted to the bulkhead to catch the oil - racer style. I have fitted a pair of rams (trumpets) to mine and fitted the rear one with an ally pipe to take the rubber from the T, by the look of it you can not do that.

:cheers:

Bob
 
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Hi all,
I have just installed two new PiperX air filters (https://www.ahspares.co.uk/austin-h...Engine-Bay/PERFORMANCE-AIR-FILTER-HD6HS6.aspx) on my BT7. They have no connection for the breather pipe from the T-connector on the rocker cover. What should I do with the breather pipe assuming I want to keep the pipe open?
Thanks
Phil

Install a PCV valve. That's what I did when I installed K&N filters, and haven't regretted it (it may reduce oil drippage).

You're welcome
Bob
 

haasad

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Here's mine the alloy bottle now has a vent filter on it and the pipercross filters have gone in favour of a DWR one piece job.

 
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Phil--

The idea was to recirculate any oil mist, gasses, etc. back through the engine via the slight intake vacuum. As others suggest you could use a catch bottle or simply do away with the tee entirely and plug the hole.

FWIW I have a cast AL valve cover which does not have any provision for ventilation and I have not experienced any issues. There is a downpipe on the left side of the block that provides for venting crankcase pressure, if only to the atmosphere.
 

John Turney

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Phil--

The idea was to recirculate any oil mist, gasses, etc. back through the engine via the slight intake vacuum. As others suggest you could use a catch bottle or simply do away with the tee entirely and plug the hole.

FWIW I have a cast AL valve cover which does not have any provision for ventilation and I have not experienced any issues. There is a downpipe on the left side of the block that provides for venting crankcase pressure, if only to the atmosphere.

If one plugs the hole on a 6-cyl engine, there is nowhere for the pressure to vent (except for the oil filler cap and past the crank seals), unlike the draft tube on a 4-cyl.
 

DerekJ

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Agree with John. You can't just plug the hole as there will be a pressure build up and oil will be pushed back out of the filler cap amongst other undesirable things. The connection from the 'T' to the carbs was a simple environmental solution so that oil mist and other pollutants were not expelled to the atmosphere. It is actually better if this dirty air is not fed back into the engine via the filters. The choices are:

- Fit a filter to the 'T'
- Fit a catch tank, with a filter on the catch tank breather
- Fit a longer hose and vacate to atmosphere. (Not for the environmentalists!):wink-new:
 

vette

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Here's One filter arrangement which hasn't shown any sign of oil saturation in many years. I change the filter every spring.

You can convert the 6 cylinder engine to a downdraft tube arrangement if you wanted. Just take the tubing off the Tee and the valvecover and remove it from the sidecover then put a tube down from the side cover to the bottom edge of the bell housing. Don't know why you would want to do that since it is alot of trouble and just putting the filter at the top like the pic is good to go.
 

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My apologies--I mistakenly assumed that 6's had downtubes.
There I go showing my ignorance again.
 

steveg

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I'm with Bob S.

Have been running a PCV for a couple of years and pretty sure it results in less leakage thru rear crank seal.
You can insert a barb fitting into the vacuum port adjacent to the rear carb with a PCV inline from the T.
 
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... Have been running a PCV for a couple of years and pretty sure it results in less leakage thru rear crank seal.
You can insert a barb fitting into the vacuum port adjacent to the rear carb with a PCV inline from the T.

BTW, pulled the BJ8's engine the other day. Expected to see some gunk on the intake ports/valves on the rear cyls due to the PCV porting into them, but they looked no different than the front 3 (clean, no 'carbon' buildup). Not sure exactly when I put the valve in, but probably 10 or so years ago so ~50K miles. After installing the valve my oil loss--dripped, not burned--was cut in half, from 1qt/1,000 miles to 1qt/2,000 miles (mostly hwy driving, which generally results in less leakage as I believe the 'reverse scroll' oil 'seal' is more effective at higher speeds). I do run the rear carb a little richer, to compensate for the intake 'leak.'
 

vette

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I know that the PCV valve can work very well. I have read of installations that caused some trouble, either more pressure in the crankcase or oil fouling of the spark plugs. Probably on badly worn engines.
I was quite surprised to find after fitting the K&N filter to the tee on the valve cover that my rear main seal stopped leaking completely. Shocked but happy. I can only attribute this to what I believe is excessive crankcase pressure from the factory set up. We have discussed this in the past. The venting of the crankcase to the rear carb air cleaner does nothing more than provide a vent and a poor one at that. There is no "recirculation" There is only one opening and it must act as a two way street. Putting in a PCV valve without doing anything else will draw a suction on the crankcase, but where is the air coming into the crankcase at. I believe it is drawn from any minor opening such as a weak gasket, the oil dipstick tube (most likely) and the rear main. In the case of suction on the crankcase, air is pulled in thru the rear main instead of oil leaking out of it. The older cars that have the downdraft tube are venting the crankcase thru the tube which is usually bigger that the tee fitting at the valvecover on the later cars. I must be noted that a road draft tube only works when the car is in forward motion and in a relatively high rate of forward motion. Thus they leaked alot. I inadvertantly stumbled upon the fact that a small 2" filter at the tee will not only vent the crankcase better than the original set up but will very nearly if not completely stop the leaks. Here are my illustrations of possible solutions if a PCV valve proves to be problematic.
 

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DerekJ

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Guys, I think we are mixing up two issues here. The installation of a PCV valve doesn't really have anything to do with how you vent the crankcase which was the original question. I personally do not think the PCV on a Healey is a good idea. It is not the same set up as a PCV valve in a modern car and as Vette says it will result in air being sucked into the crankcase through places that are not meant to do that. And all this just to prevent a few drops of oil leaking out.
 
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I didn't install a PCV valve to 'prevent a few drops of oil leaking out.' I installed the valve because it was the best--if not the only--way to vent the crankcase when I installed K&N filters, which have no facility to accept the hose from the crankcase (which WAS the original question). The reduction in oil drippage was a serendipitous side effect.

The kit I got from BCS had a washer for sealing the dipstick tube, and instructions for sealing the oil filler cap (I used a small sheet metal screw). At idle, you can feel a vacuum at the oil filler port; I don't think you'd have that if there was significant 'air being sucked into the crankcase.'
 

John Turney

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Like Bob, I installed a PCV because the Denis Welch ITG filter didn't have a connection for a hose from the valve cover T. Like Bob, I had no drips from the engine. Unlike Bob, I later found that the tops of the intake valves on Cylinders #5 and #6 had significant deposits. So I modified the ITG backplate to add a connection for the hose between the two carbs. Now, I have significant engine oil leakage onto the new concrete driveway.

I've been trying to figure out a way to reinstall the PCV to have some vacuum on the crankcase, no deposits on the intake valves, and flow filtered air into the crankcase. My thoughts are an oil catch tank between the valve cover T and the PCV, and modify the front side cover to add a port for a small K&N filter to allow air in, probably with a restrictor plate.
 
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I just pulled my engine for a rebuild. We haven't torn the head down yet, but there aren't significant deposits visible from the ports (I didn't expect this myself). Dunno about the valves, will be hearing from the rebuilder shortly.

Cyl Head.jpg
 

DerekJ

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John,

Can you elaborate on when you say 'I installed a PCV because the Denis Welch ITG filter didn't have a connection for a hose from the valve cover T.'

What exactly was your set up?

thanks
 

vette

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John, just put a filter on the Tee and see what happens to the oil drips. How hard can that be? People think you need a hose stuck in an air filter or into a PCV valve to draw anything from the crankcase. the hose was just stuck into the air filter as a means of filtering any air that did move thru the hose. The velocity moving down the carburator is not pulling anything thru the hose from the tee. The air cleaner is just a filtered vent opening. take a look at any crankcase venting arrangement on an American engine after the years that the downdraft tube was discontinued. There was a suction point either from a side cover in an in-line engine or at a valve cover in the V8 arrangement which drew its suction from some point in intake stream below the throttle blades. The inlet point was always a hose stuck into the air filter. It was in the air filter just to filter any air that moved " INTO" the hose. the Healey arrangement is an ineffective compromise.
 
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John, just put a filter on the Tee and see what happens to the oil drips. How hard can that be? People think you need a hose stuck in an air filter or into a PCV valve to draw anything from the crankcase. the hose was just stuck into the air filter as a means of filtering any air that did move thru the hose. The velocity moving down the carburator is not pulling anything thru the hose from the tee. The air cleaner is just a filtered vent opening. take a look at any crankcase venting arrangement on an American engine after the years that the downdraft tube was discontinued. There was a suction point either from a side cover in an in-line engine or at a valve cover in the V8 arrangement which drew its suction from some point in intake stream below the throttle blades. The inlet point was always a hose stuck into the air filter. It was in the air filter just to filter any air that moved " INTO" the hose. the Healey arrangement is an ineffective compromise.

Not sure what you mean here; do you mean the hose was stuck in the air filter to filter the gases from the crankcase exiting to the atmosphere (because that's that all an air filter on the 'T' will do, and why a catch can is a better solution)? The vent in the stock (Cooper?) rear filter of a Big Healey is flattened and opens as a 'slot' right next to the mouth of the carburettor; I believe there is significant suction at this point due to the venturi effect, as evidenced by the fact my rear carb's throat and throttle plates were always more gunked-up than the front's.

On every stock PCV valve arrangement I've seen the gases from the crankcase are vented by the PCV valve directly into the intake manifold, either inside the air filter or directly through a separate port. The intake air to supply the PCV circuit was always filtered from inside the air filter or by a separate--usually valve cover-mounted--filter. Unfiltered crankcase gases ported directly to the intake manifold have always been a bit of a problem; my Ranger's throttle would get sticky every 20K miles or so due to the accumulation of gunk from the PCV valve. Newer engines with direct injection can be even more problematic, as you don't get the benefit of the 'miracle' cleaners--Techron, V-Power, etc.--at least partially cleaning the intake ports and the backside of the intake valves (this is why some Toyota DI engines have an additional port injector to help keep the intake valves from gunking up).
 
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