Jump to content

12J ex mod valve cover leak

Recommended Posts

The newly rebuilt engine has been leaking too much oil, even for a Land Rover : ). The engine is a 12J from an ex MOD Defender.

I thought that it might be the rear crankshaft seal. I cleaned off the engine and disconnected the crankcase ventilation hose from the oil filler cap. I let the engine warm up and tightened up the three nuts holding the valve cover, using copper or Al crush washers. After ~20 minutes of idling, no leaks!

I reattached the hoses and went for a 10 minute drive and was met with the leakage pictured on return.

I checked the hoses and there are no blockages and the cyclone breather was ok when I put it back on the engine after the rebuild. Could the round valve (err1468) that sits above the  cyclone breather be too stiff to open sufficiently to let air go to the inlet manifold? It does open now. 

(I have attached a pdf of the system on my engine - the link is above the photo)

Would it be better/a solution to run the hose from the oil filler cap to a catch can, and from there to the air intake, bypassing the cyclone breather? 

Do the ERR1468 valves fail?

Maybe I could substitute in this: http://www.ebay.ca/itm/Land-Rover-Defender-2-5-N-A-Cyclone-Engine-Oil-Breather-/201949618819?hash=item2f0522a283:m:msAZCYkL5CuSA8CNZ_4J-qg

Are these stud holes a common oil leak spot? maybe rubber o rings to further keep the oil inside?

Does the crankcase pressure subside as the engine wears in?

I thank the collective wisdom of this site and look forward to your advice!!



Crank Case ventilation 2.5na.pdf

Oil Leak Through Valve cover stud hole.jpg

Share this post

Link to post
Share on other sites

I have exactly the same oil leak issue with a 12J engine in my 1985 Land Rover 90. It was fitted with a replacement 12J engine (from an ex MOD vehicle) about 10 years ago.

I have persistent oil leaks and have concluded that the crankcase pressure is too high and my focus is on the breather unit.  Looking at your thread and the associated photographs, I have concluded this evening that the breather may be fitted incorrectly.  In my case it is mounted vertically (like an upright mushroom) however in the photographs linked to your thread are all mounted horizontally.  I am going to test the theory tomorrow and will update.  Mike. 

Share this post

Link to post
Share on other sites

It’s a common problem, and one which led to a lot of covers being damaged by over tightening the nuts, cracking the cover near the eyes. Try rubber or bit on o-rings instead of the copper washers, with a smear of heavy grease so they don’t get dragged by the nut turning as they tighten up.

Share this post

Link to post
Share on other sites

May not be relevent please ignore if so

When I got my 58 S2 it had a s3/defender 5mb ex mil diesel fitted with the almost close breathing system.The one that doesnt have the oil filler tube on the side plate,  It used oil like  a train and had some leak issues.  I fitted, from an early diesel the side plate filler tube that has the open breather as the plug and an open breather to the top of the rocker cover.  It now uses very little oil and hardly leaks any.



Share this post

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy