Noticed the other day that there are a couple of leaks in both rocker covers.
Not seeping, just a show of black "powder" stain in those areas.

I was surprised as the KH has no visible leaks after 200,000 k's and the AWD has only done 40.

Is there much work in replacing these? I notice the rear is obstructed by the plenum chamber.
Is this something i should get done urgently, or does it matter if it waits a while?

Clean it, check the bolts are tight (not over tight) and watch it for a while

You really can not compare 1 car to another in this sense, the mileage really does not play a part either as a low mileage car often has had lots of short runs, many more heat up and cool down cycles thus gaskets can go hard

Noticed the other day that there are a couple of leaks in both rocker covers.
Not seeping, just a show of black "powder" stain in those areas.

I was surprised as the KH has no visible leaks after 200,000 k's and the AWD has only done 40.

Is there much work in replacing these? I notice the rear is obstructed by the plenum chamber.
Is this something i should get done urgently, or does it matter if it waits a while?

The black is carbonised oil, pretty hot there as the oil is close to the exhaust. If it gets bad, you will smell hot oil and see blue smoke rising from the rocker covers at the exhausts after a run.
Pull one of the front plug covers off, chances are the spark plug seals are leaking too.
Yes, you can't compare cars. Bought a TL with 136,000 km, leaking gaskets with blue smoke rising off the exhaust manifolds and oil showing in the plug tubes. No such problem with the TJ I bought 2 years ago with 111,000 km on it.
On the TL the rocker cover bolts were very loose. Tightening the ones I could reach to 3.5Nm with a quarter inch torque wrench solved most of the leaks, but of course I can't reach most of the rear bolts, and as there was oil down the front plug tubes, it all needs to be done.

Just had mine done on the tj, 116000km at moment, my rocker cover gaskets started doing same thing at about 104000km, i kept putting if off every service because only got worse very gradually but then it caught me off guard & started to leak slightly down side of engine & onto the headers! so at 115000km service I had them done. I should of done it earlier, would of saved me alot of engine cleaning lol!

Thanks guys, i'll check the plug sockets once the cars back from the repairer, and try tightening up the bolts.
I guess theres a tightening sequence, but i'll just be doing a quarter turn thing unless they're really loose.

If i do need to have these replaced, is there much work involved? I assume remove the plenum, plugs, covers?
What about injection rails and wiring? Is there a gasket for the plenum? Does oil need to be drained?
Apologies fir all the questions...

Don't need to drain oil.
Steel gasket on plenum, reuse.
Tightening bolts: Use a 10 mm spanner, can just get to the back ones without removing anything, might fix the problem if the tube seals aren't leaking. Only need to tighten the outer 3 bolts on each cover seeing this is the lowest point where they leak. Some of mine needed over 1 full turn to get them up to 3.5 Nm - probably gasket collapses over time.

Hmm, was just reading some posts about "thin" oils and seals which got me wondering. I used a 5W full synthetic in the last two flushes. Prior to last week i hadnt noticed these rocker cover leaks. Can there be a connection?

5w is pretty thin. Try going to a 10-50 or even a 15-60. Driving short distances often relate to this issue as the hot/cold cycles harden the gasket. I don't think oil viscosity would have much to do with it.

Prior to last week i hadnt noticed these rocker cover leaks.

Were you looking for it though? These little things sneak up on you, not smart to assume it started 60 seconds before you looked. lol
Oil viscosity has little effect, as long as your PCV system is in good condition and pulling a bit of a vacuum in the crank case. If the crankcase is running positive air pressure because the valve or hoses are blocked, leaks will appear at the weakest spots - cam covers, oil filler cap, cam/crank seals.

5w is pretty thin. Try going to a 10-50 or even a 15-60. Driving short distances often relate to this issue as the hot/cold cycles harden the gasket. I don't think oil viscosity would have much to do with it.

Its probably had a history prior to me of short trips. Now its getting a workout :) Hmm, if u dont think viscosity makes the difference then why did u say switch to 10W? Actually i wanted 10 on the last service but they didnt stock it. I may switch over again soon.


Were you looking for it though? These little things sneak up on you, not smart to assume it started 60 seconds before you looked.
Well i've been watching it occassionally. I do recall it was "as new" looking back in Jan, but i couldnt say when it started to show.

15w on a new motor. Seriously. 5w is the recommended and 10 is a good all round oil and is what I use on most cars

5w in my opinion is too thin. 10w would be better. 15w would be ok but might ne a bit thick. I use HPR10 on mine

Sorry but your opinion is better than that of the makers of the engine in question???

I am sure in your experience in an older motor 15 was better but please remember how oil works and the fact that we are talking about an engine with 60k on it

Added to thes an oil of heavier grade will not stop a leak, fixing the leak will fix the leak

we are talking about an engine with 60k on it even less, its just ticked over 40k. I was going to put Penrite 10W in it at the last service, but they only had 5W in the full synthetic. So the last two oil changes have been 5W full synthetic, and prior to that the Magnatec.
I also put the Wynns flush through after the Magnatec, all discussed here (http://www.aussiemagna.com/forums/showthread.php?t=96051&p=1508422&viewfull=1#post1508422).

Clean it, check the bolts are tight (not over tight) and watch it for a while...

Tightened up the three on the front. Needed about 1.5 turns until they were tight. Not too tight, didnt heave on them, just rotated the socket until they felt tight with light hand pressure. Was surprsed they turned so far. Cleaned off the excess oil and will monitor fir a while.

Same for rear central one. It seemed to be leaking a bit more (looked slightly wet rather than powdery). Couldnt access/see the others, but was short on time due to family stuff, so will try again later.

Noticed that too, with used rocker cover gaskets. Bolts seem to slacken off in use. Keeping them nipped up should work keep the oil seepage under control. They slacken off somewhat chronic.

How much do they slacken off, you ask?
Well, I replaced the front one yesterday, torqued the 6 bolts up to 3.5 Nm as per the manual. Started the car, no leaks.
Today I used the car, two short trips, so 2 cold starts and about 10 minutes of running each trip.
Went out tonight with my miniature torque wrench, checked all six. Most needed half a turn or more to get back up to the 3.5 Nm.
I guess the gaskets ooze or relax, or whatever, with hot/cold engine cycles, and the tension slackens.
So worth keeping an eye on, even with new gaskets.
Fortunately I can reach all six on the front cover and the three across the lower edge of the rear cover so checking them regularly once I change the gasket, tube seals and spark plugs shouldn't be too much of a problem.

I havent got a miniature torque wrench, just tightened them based on the idea that they should be tight, but not too tight.
Probably should get one.

I looked at the bolts on the high sides of the covers and dont see any evidence of any leaks there. But, yeah, couldnt get access to the other 2 lower rear bolts. They're obstructed by various bits, but will try again.

I also want to inspect the tube sockets; i assume i have to remove the plastic cover with the AWD sticker on it and then i can access them? And i can just pull on the leads to pull them out? Any leaks should be visible in the socket wells?

Remove plastic cover off engine. The spark plug covers pull up and out, bit tight to start with though. Long tube reaches down to where the spark plug is. If the tube seals are leaking, the oil will be at the top of the tube you just pulled out. Just check one, if it is ok you can assume (?) they are all ok.

Check eBay for 1/4" and 1/2" torque wrenches, surprisingly cheap, $50 or less.

Remove plastic cover off engine. The spark plug covers pull up and out, bit tight to start with though. Long tube reaches down to where the spark plug is. If the tube seals are leaking, the oil will be at the top of the tube you just pulled out. Just check one, if it is ok you can assume (?) they are all ok.

Check eBay for 1/4" and 1/2" torque wrenches, surprisingly cheap, $50 or less.
Thank you!

Remove plastic cover off engine. The spark plug covers pull up and out, bit tight to start with though. Long tube reaches down to where the spark plug is. If the tube seals are leaking, the oil will be at the top of the tube you just pulled out. Just check one, if it is ok you can assume (?) they are all ok..

hmm. Heres a photo, tell me what you guys think. I notice that the tube looks clean, but near the top it has a ring of what looks like grease or thick oil. Does this mean its leaking?

http://i1159.photobucket.com/albums/p629/Kwawd/photo.jpg

I havent got a miniature torque wrench, just tightened them based on the idea that they should be tight, but not too tight.
Probably should get one.

I looked at the bolts on the high sides of the covers and dont see any evidence of any leaks there. But, yeah, couldnt get access to the other 2 lower rear bolts. They're obstructed by various bits, but will try again.
Nope, cant get to the 2 outer bolts at the rear. My socket wont fit in the confined spaces (theres a couple of brackets blocking). They look to be leaking a little.
As far as tightening the front cover bolts; i tightened them firmly, but not forcefully if that makes sense. They feel tight now. They turned a good 2 turns each. Just using light but firm hand pressure on the wrench.

hmm. Heres a photo, tell me what you guys think. I notice that the tube looks clean, but near the top it has a ring of what looks like grease or thick oil. Does this mean its leaking?

http://i1159.photobucket.com/albums/p629/Kwawd/photo.jpg

Im thinking this must be ok? Wouldnt the oil be all over the tube if the seal was leaking?

Purchased an extension bar for my wrench and was able to get to one of the two remaining rear nuts. I cant see the other one. Im going to get a little mirror and try to position it so i can see the nut in it... lol

The top of the spark plug connector acts like a seal too, any oil that passes the spark plug tube seal under the rocker cover gets trapped at the top. I found some very thick oil at the top, but none had leaked down towards the spark plug. I'm guessing the engine oil and heat breaks down the seal at the top of the removable spark plug connector and produces that thick oil or in your case, grease like substance.

Probably best to change the rocker cover gaskets and tube seals when you can, before you need a set of spark plug leads as well.

Probably best to change the rocker cover gaskets and tube seals when you can, before you need a set of spark plug leads as well.

+1 to this. I didn't change my front rocker cover gasket and spark plug tube seals in time, and ended up with also needing to buy a set of leads as the oil had totally broken down the rubber on the spark plug lead and I was having problems with bad idles and performance issues.

Changing them is not too hard but it does require you to be careful to not overtighten or undertighten the bolts. The rocker covers are very thin around the bolt holes. I've had problems due to not proprely tightening the bolts and ended up with oil billowing out of the engine and burning away, causing some interesting smoke and smell at the traffic lights. (Great way to get attention!).

I now have a 3/8" drive torque wrench and tighten to around 4nm and no problems with crushing the rocker cover bolts. As backup, I also put an airplane grade sealant between the rocker cover gasket and the block, as well as sealing the edges (once it has been tightened down) with a permatex gasket maker. No problems with leaks again. Rather undertighten and rely on the sealer if needs be.

In a few weeks I'll post up a vid on how to replace the rear rocker cover & spark plug tube seals.

In a few weeks I'll post up a vid on how to replace the rear rocker cover & spark plug tube seals.

Looking forward to that. Done fronts but not rears on my TL.

Thanks guys, i will get them done asap. No point delaying if theres a problem which will only get worse.

I dont think i get whats happening though; the tubes reach down to the plugs through the rocker cover into what i guess are outer tubes, rught? Under the covers oil continuously bathes the outer tubes and presumably laps/splashes up against the top of the tubes. Therefore shouldn't we expect to see this ring of oil at the top where the inner and outer tubes mate, or have i got this all wrong?

. . . . all will become clear when you pull it apart to replace those pesky spark plug tube seals. lol

Piccies may help:

http://www.scripturewisdom.org/pics/sparkplugholeseals-00obw-1.jpg

Subaru ones look the same, new one on left (obviously)

They sit on the top of the metal inner tube, and close the gap between the top of tube and rocker cover. The lump at the top of the spark plug wire seals this joint from the other side, inside the metal tube. It's really like a double seal, one inside the rocker cover and the other on the outside.

I did my front and rear bank rocker cover and tube seals a few weeks ago and it's nice having a clean engine and underbody again. Anyway, as a tip, I found a few tiny drops of super glue to hold the new seal to the cover made it easy to re-seat it to the rear bank.

. .Piccies may help:

Subaru ones look the same, new one on left (obviously)

They sit on the top of the metal inner tube, and close the gap between the top of tube and rocker cover. The lump at the top of the spark plug wire seals this joint from the other side, inside the metal tube. It's really like a double seal, one inside the rocker cover and the other on the outside.
Awesome, got it, thank you!
Based on that design i dont expect to see that ring of oil at the top of the tube because the oil should not be moving across the barrier between the seals and the inside of the rocker cover. They must be worn, sagging, to allow the oil in.

Apart from the rocker cover gaskets and tube seals is there anything else i should do at the same time?

Do your spark plugs. It's not often that you pull that plenum off. Front plugs are cheap as chips so do them too.

Do your spark plugs. It's not often that you pull that plenum off. Front plugs are cheap as chips so do them too.

Great idea. Get some platnium plugs from Mitsubishi or ebay. I use IridiumIX plugs but I've been told they need to replaced every 40,000-50,000km or so.

While you have the intake plenum off, it's a good idea to clean the throttle body & isc and replace the gaskets and o-rings.

Not much else to be done really. You could clean the back of the engine or the intake plenum if you feel inclinded.

Great idea. Get some platnium plugs from Mitsubishi or ebay. I use IridiumIX plugs but I've been told they need to replaced every 40,000-50,000km or so.

While you have the intake plenum off, it's a good idea to clean the throttle body & isc and replace the gaskets and o-rings.

Not much else to be done really. You could clean the back of the engine or the intake plenum if you feel inclinded.
Thanks for the suggestions. One problem is that i dont have any place to setup a home workshop for this stufff. Maybe in the future, as it seems it would be an interesting hobby. Certainly have no tools to speak of and no time on my hands.

Couple of questions; I assume the car has the original plugs in them, are they likely to be platinum? With potential slow oil leaks past the seals, could the plugs be damaged?

Re the gaskets and rings you mentioned, do you mean for the throttle body? Does it require removal of the body to mount them?

Where is the ISC actually atrached? Anyone have a pic? I'll try and dl the manual later to see if i can identify it, but pics are a big help.

I may just ask Mal if he would do this job for me and what it might cost.

Mate, if you are going to start playing with this kind of stuff, then you need to get yourself some tools. Go to bunnings and get a cheap stanley socket set for ~$30. Also get a cheap 4 piece spark plug socket set for ~$15. There is a supatool one that I bought years ago for cheaper than that. That will include everything you could possibly need to get this job done except a torque wrench. As has already been explained, you need to get the rocker cover bolts slightly tigher than finger tight. 3-4nm is ideal but a little bit tigher than that isn't going to hurt, just don't pump all your body weight into it whatever you do. Also invest in a workshop manual from supercheap. That book has saved my arse many times.

If your car has original plugs, yes they will be platinum tipped. You should use the platinum plugs in the rear bank anyway as they have a longer life span. (100,000km or so) By the time you have to change the plugs again, the gaskets will probably be leaking again. When I buy spark plugs, I demand NGK. if they don't have NGK, I leave the shop and go elsewhere.

If you are going to take your plenum off properly, then yes you will be fiddling with the throttle body. It is fairly easy to remove and re-install if you take the time to do it. The throttle body gasket (which connects it to the plenum) does not require removal of the throttle body to replace. Just make sure you leave the tab poking out of the top like the original one, and try not to muck up your TPS.

From memory, the ISC is below the throttle body and to the left. Someone will correct me if I am wrong.

Mate, if you are going to start playing with this kind of stuff, then you need to get yourself some tools. Go to bunnings and get a cheap stanley socket set for ~$30. Also get a cheap 4 piece spark plug socket set for ~$15. There is a supatool one that I bought years ago for cheaper than that. That will include everything you could possibly need to get this job done except a torque wrench. As has already been explained, you need to get the rocker cover bolts slightly tigher than finger tight. 3-4nm is ideal but a little bit tigher than that isn't going to hurt, just don't pump all your body weight into it whatever you do. Also invest in a workshop manual from supercheap. That book has saved my arse many times.

Thanks mate. Time is the problem, not the cost. Anything enjoyable in life costs a little bit of dosh and thats fine.. Might be able to set up a home workshop in a couple of years.


If your car has original plugs, yes they will be platinum tipped. You should use the platinum plugs in the rear bank anyway as they have a longer life span. (100,000km or so) Thats good, they should be original platinum, cars only done 40ks. So long as they havent been affected by any leak past the seaks then they should be fine. Wgen i pulled that plug tube out i couldnt see any oil on it except for that small ring at the top, as can be seen in the pic i posted before. Somehow that stuff got in there, so i assume that means the seal is leaking.

Would anyone with expert knowledge confirm that this pic shows a real problem of leaking tube seaks?
I want to be sure that theres actually a problem before i try to "fix" it. The rocker covers are no longer showing any signs of leaking at all since i tightened the bolts.

Thank you all in advance.

http://i1159.photobucket.com/albums/p629/Kwawd/photo.jpg

Platinum plugs in the back, every 100,000 km. Ordinary plugs in the front, change every 45,000 km according to the manual.

Gooey oil ring around top of plug tube shows the spark plug tube seals are starting to leak. Rocker covers need to come off, so it's a good time to do front plugs, spark plug tube seals and rocker cover gaskets. No hurry, doesn't look too bad yet.

I found out the hard way that tightening the rocker cover bolts up is only a temporary fix to them leaking. Leak came back worse than ever. Once they harden they need to be replaced.

Platinum plugs in the back, every 100,000 km. Ordinary plugs in the front, change every 45,000 km according to the manual.

Gooey oil ring around top of plug tube shows the spark plug tube seals are starting to leak. Rocker covers need to come off, so it's a good time to do front plugs, spark plug tube seals and rocker cover gaskets. No hurry, doesn't look too bad yet.

I found out the hard way that tightening the rocker cover bolts up is only a temporary fix to them leaking. Leak came back worse than ever. Once they harden they need to be replaced.

Thanks mate. I'll organise to get this done soon.

Ok, I'm about to organise this! Rocker covers, tube seals, plugs, cleaning the TB, igasket, the ISC and its ring seal.
Question about the TPS, does it make sense to replace it as well while I'm doing all this?

Question about the rocker cover gasket fitting: how difficult is it? Do you need experience or any special knowledge about the 3rd gen setup?

Ok, all done. New gaskets, seals, leads and plugs.
Also replaced the ISC and TPS TB is clean.

Bugger, a couple of the rear low rocker cover bolts are looking wet :( definitely leaking again. Just noticed them tonight cos i happened to stick my head around there.
Oil level is fine and no drips on the floor, they're just "wet".

So disappointing. Why would this happen, they were properly installed and torqued to 3.5nm?
Are the gaskets stuffed when this happens, even though they're only a few months old?
Or can i just re-tighten them?

Also, i notice a thin wet oil patch on the oil filler cap, coming from around the centre screw. I've wiped it dry a couple of times but it recurs after a few days. Is the cap stuffed?

Sounds like you are getting a build up of pressure in the crankcase.
Have a look at the PCV valve and hose as well as the hose from the rear rocker cover to the intake tubing.

PCV valve can be pulled out while the car is idling and it should have a definite suck on it when you put your finger on the hole.

With engine off, I would try blowing into the PCV valve while it's off the rocker cover but still connected to the hose and intake manifold, to see if the hose is clear. Same for the spigot on the rubber intake tubing, pull the hose off and attach a piece of fuel hose to the spigot and blow, as well as blowing into the hose you've just disconnected. All 3 "blow" tests should work, ie you can easily blow air through.

If no problems there, see if the oil cap centre screw is tight, and nip up those rearmost rocker cover bolts. They will feel quite loose, but only tighten a bit, say 1/4 of a turn each.

Thanks Max, will do. But if this is the case does it mean that the blow by has forced past the gasket where the bolts are looking wet and potentially damaged it?
Do i need to replace rhe gasket again? (Even tho its only 6 months old). If it could be damaged then i'd rather replace it than worry about it, but if theres no chance of damage then i'll be happy just tightening the bolts.

Not likely to have damaged the gasket. But run your finger along the line joining the rocker cover to the head and see if any is seeping down, on both front and back. Rear one can be a b#tch, as the oil may not get onto the hot exhaust, but end up on the flexible joint of the exhaust system. Then you get the smell of barbecued oil when the engine and exhaust warm up.

Thanks again Max. i cant get to one of the rear bolts due to the plenum being in the way, and i think they all should be torqued evenly rather than leaving it, so I'm going to take it back to the place who originally did the gaskets, to do an assessment of what the problem may be and go from there. I just dont have a workspace or tools to do it properly myself.
As for the PVC, i'll do these checks tomorrow and let you know if i find something.

PVC seems fine, has plenty of suction when i put the finger over it. Its slightly oily inside, but i guess that would be normal.
I assume the cap must be leaking past its seal.

Interestingly, the bolts look wet and oil can be easily collected with a rag after a run, but once its cooled down its hard to see the residue, its dry with just a thin film of yellow colour. The Penrite 5W is pretty clean and thin.

The guys who did the job back in jan have replace the rear gasket again today. I think they did a good job.
Front seems to be ok with no obvious leaks. Also replaced the cap, no signs of blockage of PVC or breather hose.
Interestingly the car seems to have a battery problem now, so i've started another thread.

Were you looking for it though? These little things sneak up on you, not smart to assume it started 60 seconds before you looked. lol
Oil viscosity has little effect, as long as your PCV system is in good condition and pulling a bit of a vacuum in the crank case. If the crankcase is running positive air pressure because the valve or hoses are blocked, leaks will appear at the weakest spots - cam covers, oil filler cap, cam/crank seals. Crap im leaking from the oil cap.

Is it ok to just use degreaser to clean the rocker covers up?
Or do they need to be clean really well by soaking them in something for a few hours?