49 replies to this topic

[TerrA LX]

By the sounds of it you have way too much crank case pressure.
If you do not have to comply to ADR27a  etc for rego I would be going for one or two catch cans vented to the atmosphere.

Onus is on you to rectify crankcase pressure, if installed correctly, you will find the rear seal will stop leaking once the engine is vented.

[TerrA LX]

Sorry, not making sense, can you show some photos of the system you have for venting now?
Every motor needs to vent the crank case pressure somewhere.

[rexy]

Just add a PCV. It should cure your woes unless you have major blow by.
If not cured by PCV then its leak down test time.

[TerrA LX]

Current setup which is really nothing...have holes for original PCV setup and was originally going to put mini filters over these holes

Can't really tell from what you are saying, is the engine open vented atm or is the venting sealed?
Either way, fit the OEM style PCV or catch cans, you need to vent the engine but it has to be filtered.

[mick_in_oz]

VN Group A Twin Throttle manifold had the PCV in the valley, between the valley and the PCV, attached to the underside of the manifold, it also had a sheet metal box with holes and something akin to a pot scourer inside to catch and condense oil onto to help separate oil from air before entering the manifold.

Edited by mick_in_oz, 02 November 2015 - 12:30 PM.

[RallyRed]

yeah, from the pic it looks like you just have 2 holes vented to atmosphere. Thus Bombers concern.

The gases just get pushed out by crankcase pressure......by adding a hose to the inlet, you are sort of ""vacuuming"" the gases out, better way to go.

You could just try a test setup where the 2 tappet covers are joined by a hose, and then a T piece runs off to a ( sealed) hole/fitting on the underside of the air cleaner. i.e. get the inlet vacuum to do the work of scavenging the gases for you.

Use garden hose if you need to, just to see if it improves things....then make it pretty later.

[mick_in_oz]

The open holes in the covers will let out crank case pressure, and nothing can get in while its running, not the same I know, but similar to an old Holden 6 with the walking stick down the side of the engine, no one ever grumbled they sucked in dirt and f^%$ed an engine.

 

Mine has about 7" of hose hanging off a gutted PCV valve to the outside world, (haven't gotten around to building a filtered catch can with return to the sump), never had a problem, but I do use a Totalseal gapless ring set that has VERY low leakdown % and hardly any blowby, but the engine gets turned hard, gear change at 7450 and finish line at 8000 at the local 1/8 mile strip.

 

If its breathing and its not managed it"ll leak everywhere, pushing the dip stick out sounds a bit average, even more so when we see that the covers are open to the atmosphere. Might be time for a leakdown test.

 

Is it a new build? Maybe it needs a good work out to get the rings to bite and settle down?

[IMORAL]

Have you considered a vac pump?

 

Similar issue discussed here

http://www.gmh-toran...stick-oil-leak/

Edited by IMORAL, 03 November 2015 - 10:09 AM.

[mick_in_oz]

A comment about the use of a PCV, if its breathing heavy while giving it a workout, the PCV won't help a lot due to it relying on manifold vacuum to clear the crankcase, but this is about the time there is no manifold vac due to the wide open throttle...

 

Like oldjohnno said with ring seal and fix the cause, methinks a leakdown test is a good idea.

[TerrA LX]

You will always have crank case pressure regardless of ring seal, the fact that pistons are flying up and down in the crank case upto and over 6000rpm is always going to create pressure if not adequately vented.
Holden achieved this with the PVC via direct venting the crank case to the air filter, so on the up stroke of the piston will draw in filtered air, and, on the down stroke, will blow excess pressure into the carby.
The PCV valve serves to positively vent the crank case at low rpm to keep the air filter from fuming up with any blow by.At high rpm/low vacuum conditions, the PCV valve should close...