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Vapor Hose Oil  Rating:  Rating
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 Posted: 02-12-2008 02:36 am
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flatlanderep
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I have owned my 73 JH for almost 2 years and just noticed that when the car is driven for about 20 min. and then stopped, there is a small pool of oil coming from a vapor hose that is the rear of the engine. The prior owner ran this hose about 1/2 in. diameter from the back of the engine and then about half way under the body. Up until recently, the oil coming out of this hose was a few drops but now it is a small pool. I know that this is supposed to be vapors only and in my previous JH, this hose was connected to the back of one of the K&N filters. I keep the engine oil half way between min and max. Oil pressure is good and the car runs well. Please explain what is happening and if there is anything that can be done, besides a new engine!

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 Posted: 02-12-2008 03:33 am
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Jim Ketcham
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The crankcase ventilation hose connects to the back bottom of the airbox.  The oil vapors condense there and then flow back down the same hose back to the crankcase.  Vapor light ends, such as fuel vapors, are sucked into the carbs and burned.  It is important the hose is connected to the back bottom so the condensate can flow back out.

Many JH's are now missing the air box.  Unfortunately, hooking the hose to the back of the aftermarket air cleaner does not allow the oil vapors to condense and flow back.  Usually, they condense and drip out the air cleaner.  Some owners have fabricated a small reservoir (from a can) and attach the hose to a fitting in the bottom to accomplish what the missing airbox used to do.  The reservoir should also be vented to the air cleaner from a fitting near the top so that the "light end" vapors can be sucked into the carbs.

I believe you can find pictures of this makeshift setup in the JHP Photo Gallery.

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 Posted: 02-13-2008 02:06 am
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Jensen Healey
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Are you running 20-50?

Before my rebuild I had to use a steel can which was cut in half and a screen with breather media inserted. It was positioned so any oil would drain back down into the engine. It did keep gunk out of the K&Ns.

Kurt

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 Posted: 02-13-2008 03:06 am
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flatlanderep
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Yes, I am using 20W-50 oil. Does anyone out there have an oil separator? Delta Motorsports?

Steve

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 Posted: 02-13-2008 05:30 pm
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Joel
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I'm running Dells w/ no filters.  So, I have an extension on the hose that directs the vapor away from the engine back by the tranny - under the car.  If oil is condensing and dripping - I'll just add more oil. :-)


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 Posted: 02-18-2008 07:40 pm
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Judson Manning
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Steve,

The short answer to your question is you probably have worn piston rings and are getting a fair amount of blow-by of combustion gasses into the crankcase.  While annoying, consider this 'normal' for the age of the car.

As previously stated, do not pipe this vent directly to the back of your carb or else the oil will gunk-up the carbs and pretty much everything else.  The last customer of mine who did this had his piston rings literally fall to pieces.  The environmentally friendly thing to do is install a catch-can.

Check my older posts regarding my procedure for purging the crankcase.  You want to give your rings every chance to seal with nice clean oil free of any sludge. 

The only 'fix' is to machine the liners and install new rings & pistons.  If the car is running well otherwise, I wouldn't make that leap just yet.

Judson

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 Posted: 02-22-2008 05:46 am
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Frank Schwartz
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Judson:
Just came across this thread.  I am renovating an early 73 for a friend and it has that oil cannister business...and K&N filters with a single hose going to the front one from the oil can mounted on the firewall.  You mentioned pictures or a diagram somewhere in the depths of the archives.  Can you direct me to that?
Thank you,
Frank Schwartz

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 Posted: 02-22-2008 04:57 pm
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Judson Manning
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Frank,

Along with Bruce Madden I really do like the Early catch can.  I am attaching a photo showing how I modified my windshield wiper canister to act as one, along with a photo of the MkII engine I put in Hugh Furr's early 73 where we kept the catch can.  Recently, I did an engine for Kate O'leary where we did basically the same thing.

Judson

 
http://jhppg.com/gallery/album08/Hugh_EngineBay

http://jhppg.com/gallery/album08/910_907_hybrid1

Last edited on 02-22-2008 05:06 pm by Judson Manning

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 Posted: 02-22-2008 06:11 pm
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Frank Schwartz
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Interesting indeed, Judson.  I went through the whole list of your pictures.  Glad to hear Kate Oleary is still around...did not know she needed a rebuild..and Hugh is still out there too..traded cloth tops with him, my black for his tan some years ago...
On this car, the origiinal catch can is in place...but I seem to remember your comment that the vapor from the catch can should not be routed to the carb filters without another catch can as well.  Maybe I misunderstood???  Or did you put the old washer bottle in series with the line from the carbs to the original catch can?  And how is the washer bottle now drained?   Finally where did you place the "new" washer bottle?
FYI the bottle and clamp are missing from this car. PO must have thrown it away.
Thanks and best regards,
Frank

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 Posted: 02-25-2008 02:50 pm
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Judson Manning
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Frank,

Kate's original MkI engine died 4 years ago after injesting a loose carburetor nut that was supposed to be holding on the air box.  It got pulled into either #2 or #3 and got pinched between the head and piston right next to the liner.  There is a nice hex 'stamp' on her head and liner literally cracked in two.  The worst part is she had loaned the car to another club member for an autocross event when it happened!

As far as catch-can strategy goes, the important thing is to have something - anything to catch the heavier oils and keep them from gunking up the carbs.  The 907 is not a "fix it and forget it" kind of engine, and no matter what one does, the important thing is to keep constant vigil on little things like this.

Where people get into trouble is when they overfill the sump.  Of course the intent is to minimize slosh and oil starvation, but this tends to cause other problems.  Oil starts to pool in the head, the crank foams up the excess oil, and when the vapors do get a chance to excape, they take as much oil as they can with them!

My converted Windshield washer reservoir does not have a drain and it probably gets about 1/4" of sludge dumped out of it every 3-6 months.  Of course that engine is a Nikasil 910 block with brand new pistons and rings.  An older engine with older rings will naturally 'puke' more oil and will need more constant attention.

Even Kate's new MkII rebuild with the MkI catch can does collect a little oil in the factory air-box.  Is the MkI catch can too small or can we conclude that pretty much every 907 variant was a bit prototypical and needs to be 'baby-sat' more than most engines?

Judson

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