Crankcase Ventilation Help Request - Defender Source
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  #1  
Old June 4th, 2016, 02:57 PM
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Crankcase Ventilation Help Request

Hoping for a miracle! Short synopsis: improved crankcase ventilation seems to have killed my rear main seal.

I have long had a small drip after shutting off my engine coming from my wading plug hole in the flywheel housing (ah, the good old days of the small drip). Yesterday I decided to check the crankcase ventilation to see if high crankcase pressure had anything to do with the leak. I have a 3.5 with dual carbs so there is a small air intake at the back of the engine and the carbs draw a vacuum from both rocker covers. I found that the filter at the intake was clogged up. So I put on a new filter and cleaned out the intake orifice (very small hole). I also checked the vacuum from the carbs and the cleaned fire traps.

When I fired her back up everything seems ok – until I shut the motor off. About 30 seconds after shutting it off it starting pissing oil out of the wading plug hole – a lot of oil. I have tried a few different things to see if I could improve it including plugging the intake hole off again but I get similar results: seems ok until I shut it off and then it pukes oil about 30 seconds to a minute later. Some changes seem to help with the amount of oil released but no where near enough to park without a bucket for parking. There is some draw at the intake (I confirmed this by putting a balloon up the intake tube) and there is some pull at the top of the rockers (pulled the tube from each rocker and felt the suction from the carb), so there is some air moving around the crankcase. Each time I shut the engine off now I probably loose 6 oz or more of oil.

Did I just blow out what was left of the rear main seal for reasons unknown to me? Or is it possible that I am adding crankcase pressure somehow which is pushing more oil past the seal. At this point I just wish I could get back to the small drip I had two days ago before cleaning the intake filter.

Anyone have any ideas of what else I could try? The real puzzling thing to me is the fact that it only seems to leak after shutting the engine off and waiting 30 seconds (which seems like it could be pressure / suction related).

Any ideas or assistance is greatly appreciated!! FYI - I already tried swearing a lot and crying a little, neither of those helped.
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  #2  
Old June 4th, 2016, 04:41 PM
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check your valley pan gasket and valley end seals: ERR7283
normally you do valve cover gaskets, valley pan and seals oil runs out of valley and since engine is sligtly tilted back it tends to flow around bell housing area giving the impression of rear main seal leak.
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Old June 4th, 2016, 07:34 PM
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thanks - I will take a closer look. I was thinking that since the oil was coming out of the bellhousing that it had to be coming around the crankshaft. Hopefully I was wrong, but it is definitely coming out of the wading plug hole.
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  #4  
Old June 6th, 2016, 01:42 PM
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I don’t know if anyone is going to read this post but I am going to keep writing incase someone refers to this in the future with similar problem. I am over 90% sure my leak is from the rear main seal. I don’t see oil leaks from other locations, I’ve have had a small leak there for a long time and I know the cross seals were replaced a while back which didn’t solve the problem. But I am still confused as to why I only see the leak a minute or so after shutting the engine off and then stops leaking about another minute later.

Theory #1 which I will call the “I am totally screwed” theory: improving the ventilation in my crankcase somehow blew out what was left of my rear main but it does not leak out of the wading hole until a minute after shutting the engine off because the flywheel creates enough suction thru the hole to keep the oil from flowing out. Then it takes about a minute to reach critical mass from gravity before it starts pissing like a large dog for about another minute.

Theory #2 which I will call the “I am only partially screwed for now” theory: my cheap oil filter is causing my problem (stay with me here – I know this sounds ridiculous). It would not surprise me if my Fram oil filter has a non-functioning anti-drain back valve. When my crankcase ventilation was clogged up oil slowly dripped by the drain back valve back valve into the oil pan and didn’t create a lot of simultaneous pressure. Once I added better ventilation to the crankcase, oil was / is able to purge down into the pan quickly when the oil pump is turned off and the purge creates enough pressure to overwhelm a weak rear main seal until the purge pressure has subsided. This might explain why I get about 4 to 6 oz flowing out after shutting the engine off – then the leak seems to stop completely. 6 oz might be the amount in the lines above the filter. I don’t have an oil pressure gauge and I would not be surprised if my oil pressure warning light did not work, so there is no super quick way to test this theory.

My plan is to unscrew the oil filter and see if anything spills out from the lines above. If nothing comes out other than what I spill out of the filter myself then the anti drain back is not working and theory #2 could be correct. Either way I need to address the rear main seal eventually. But if I can get back to the small drip it had a few days ago I hope to live with it until I need to change the clutch or something else that requires taking the transmission out.
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  #5  
Old June 6th, 2016, 06:20 PM
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One quick check: make sure that the rearmost exhaust manifold stud has a nut.

you make it sound like fixing the rear main seal is a death sentence. its not a difficult fix, just time consuming.
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Old June 7th, 2016, 11:01 AM
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I will check that tonight ... but why do you mention the rear manifold connection / port? There were a couple "anomalies" i noticed related to that connection. But i don't know enough to see a link other than to guess its something related to back pressure??
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Old June 7th, 2016, 11:38 AM
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Quote:
Originally Posted by UserName View Post
I am over 90% sure my leak is from the rear main seal. I don’t see oil leaks from other locations, I’ve have had a small leak there for a long time and I know the cross seals were replaced a while back which didn’t solve the problem.

Did you do the cross/crucifix seals?

I ask because my local Rover Guru who has many years of experience wrenching told me he's rarely seen a rear main seal leak.
Usually the crucifix seals.

His described method to me was remove the sump and use Right Stuff in place of the seals.
Let it set up.
Clean the sump for a while while the RS is setting.
Then reassemble.


.
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Old June 7th, 2016, 12:03 PM
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Yes - unfortunately the crucifix / cross / T - seals (whatever they are called) were changed around 10K miles ago. I didn't do it myself but I believe it was with the new style seal and they used the rightstuff when putting it all back together. Changing them didn't make any difference but the leak was not major at the time. I am told that visually the rear main looked ok when the bearing cap was off - but its probably hard to see much of the seal.
It would be a bummer to go thru all the work to change the rear main and then still have this leak.
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Old June 7th, 2016, 12:27 PM
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Quote:
Originally Posted by UserName View Post
I will check that tonight ... but why do you mention the rear manifold connection / port? There were a couple "anomalies" i noticed related to that connection. But i don't know enough to see a link other than to guess its something related to back pressure??
1. Old tired hotside turbo seals fail causing crankcase oil to literally drip into exhaust manifold.
2. #4 cylinder exhaust manifold is directly below the hotside turbo seal.
3. The oil in the exhaust manifold goes to the lowest point - the connection between the exhaust manifold and the cylinder head.
4. The loose or missing exhaust manifold stud/nut creates a gap at the connection between the exhaust manifold and cylinder head, causing oil to spray/leak out onto the engine.
5. The oil collects and drips from the lowest point of the engine: The bellhousing drain plug.

Looks like a rear main leak, but it isn't.

First fix is NOT to rebuild the turbo. The first fix is to put the m10 exhaust nut/stud back on the head.

A little bit of oil is nothing to be alarmed about!
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  #10  
Old June 7th, 2016, 12:45 PM
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Turbo? This is a V8.
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  #11  
Old June 7th, 2016, 01:26 PM
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Correct, V8 - no turbo.
I appreciate the advice though. The manifold could still be more likely than my theory about the oil filter drain back. I probably had all of my weight on the manifold with one hand as I reached back to change the intake filter so I could have caused an issue myself.

The thing that does not tie off though is that the exterior of my bell housing does not have oil on it. After I turn the engine off I can crawl under the engine and lie there long enough to drink about ¼ beer without any sign of a leak – then like clockwork I can watch oil start running out of the drain hole. It is definitely not running down the exterior – it comes straight out of the hole. Then it stops completely when I am about ½ way done with my beer (not easy to drink beer lying under a car so my timing might be a little off).

This morning I tried an experiment: I checked the oil which was down to the low oil line on the dipstick from the last few days of leaking. Then I started the engine and checked it again while running – the dipstick did not show any oil at all. I shut the engine off and immediately checked again – still no sign of oil. Over the next 30 seconds the oil pan filled back up to the low oil line on the dipstick. This seemed to roughly correspond to the timing of the leak out of the bellhousing. So I either learned a lesson about the viscosity of oil (oil spread all over the inside of a bellhousing takes as long to flow down as oil spread all over the inside of an engine) or the oil retuning to the pan creates enough pressure to get by my rear main seal (which stops leaking once the purge has subsided). One more clue is that leaving the dipstick out / loose seemed to slow the leak. But that could be my imagination, or the effect of all the beers consumed during testing.
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Old June 7th, 2016, 05:34 PM
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Sorry, I thought this was a 200tdi.

I just realized that you're talking about Janey!
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  #13  
Old June 7th, 2016, 07:45 PM
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Does your trans have an inspection plate? If so, remove it, wipe the rear main cap as clean as you can, fire up the engine for a few minutes to get to operating temp, shut it off, then go underneath to see we're the oil is coming from.
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Old June 7th, 2016, 08:52 PM
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Hey, I just figured it out … however I may be even more screwed than I previously suspected.
First, yes this is Janey. So CGalpin did the crucifix seals himself which is why I am sure they are not my problem.

Onto my detective work: one of the “anomalies” I mention earlier when I was fixing the crankcase breather was that I noticed one of the back spark plugs was loose – really loose. I thought it was odd – almost seemed intentional - and I just cranked it back down realizing that I have never changed the plugs or wires. I didn’t think much more about it because bigger problems soon took over (the gusher thru the rear main seal.)

So tonight I loosened that spark plug up again and guess what – rear main seal problem solved – no leak at all! So I either have so much blow by in that last cylinder that it overwhelms the crankcase with pressure and rear seal blows out. Or I have a rear main seal that can’t handle the pressure of all 8 cylinders and I also have blow by in that cylinder (2 problems instead of 1). I suspect that the previous owner figured this out, intentionally left the plug loose and neglected to tell me or forgot (not Charles - the owner after him).
I will do a leak down test this weekend to see how bad things are. The good news is that I can stop the rear main leak for now and drive her short distances (on 7 cylinders anyway). Its back to where it was before I improved the crankcase ventilation so I guess I got what I hoped for.
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Old June 7th, 2016, 09:10 PM
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It is not inconceivable that the spark plug backed out on its own and as a result was not firing. This can not only cause problems such as washing the liner with fuel and causing ring failure, it can also dilute the oil with gasoline. I would change the oil for sure. But you need to see if there is compression on that cylinder and whether anything is amiss. I would also pull the valve cover and see if there is build up. I will say Janey did quite well and would run full throttle for hours on end without complaint.
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Old July 5th, 2016, 05:16 AM
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Question

Any updates?
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  #17  
Old July 5th, 2016, 10:22 AM
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Bigger bucket? Park nose up hill? Fashion a bilge pump to pump the oil back into the engine?

Seriously, I would try fresh plugs, new filter and thicker oil (until colder weather). See what happens.

Glad to see Janey getting some love. Good luck.
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Old July 6th, 2016, 11:32 AM
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Tried to respond yesterday but could not log in for some reason.
I think I have it resolved (for now anyway): I removed the inspection plate, dropped the oil pan and removed the bearing cap to get a better look. The cross seals had shrunk about 1/4" at the bottom leaving a gap which may have contributed to the problem. But more importantly the rear main seal was also way out of whack: it had slipped back out of the housing and was against the flywheel - so about 1/3 of it was not even in the housing. I posted some photos on a different thread.
I slid it back into position tight in the housing toward the engine, replaced the cross seals with "The Right Stuff" and put it all back together. So far no leaks at all. I have not gone on any long trips yet but if it leaks again the first thing I will do is check to see if the rear main seal has slid back to the flywheel again. If it slides back again I can actually see some of it just by looking up with the inspection plate off. When it is in the correct position I can't see it at all.
Fingers crossed ... it is leak free at the moment.
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