edwardh1

I have a 99, I had a rear valve cover oil leak which a private garage fixed about a week ago, I still see (looking up from under the car)a little oil wetting/one drop forming on the two bottom most lower exhaust manifold studs, where the stud goes into the exhaust manifold, on the passenger side. the valve cover of course is above this stud (and the head gasket is below the stud)

Is this typical? could the leaking rear valve cover gasket have leaked enough oil down to leave some residual oil there around the lower stud and under the nut that is on the stud??

cjlgarage

iTrader: (13)

...I have the exact samething going on..Changed the rear VC this week and now I can see oil driping from the exhaust studs ..I thought it might be the head....

Trini Boom

iTrader: (5)

I would like to know if that is indeed possible because I think that's whats going on in the front of mine. But someone in another thread said that it isn't possible for oil to come out from the exhaust manifold... I think we need to shed some light on this topic. Could it be valve stem seals although there is no smoke coming out of exhaust?

edwardh1

Mine- the leak is at the level of the two passenger side lower most exhaust manifold "pipes" that connects to the head, and it shows some oil residue at the top of the nut that is on the exhaust stud. My instinct is that its oi left from the months/years old rear valve cover gasket leak, but you would thing it would burn off soon.
The head gasket is below this point and seems if it was a head gasket leak that it would flow down the block, not uphill to the exhaust stud.
My car only has 108000 miles, what did nissan do wrong? bad OE gasket in 99??

cjlgarage

iTrader: (13)

I was thinking when I took the rear vc off there was leftover oil in the rear cover because of the PVC system holding more oil causeing it to pool ..So when the rear cover is removed a lil oil gets on the exhaust..I wiped down everything hopeing to see no more oil .Il will find out later today if its stopped..

Trini Boom

iTrader: (5)

Does any one else know of this problem??

edwardh1

in a new thread, cant figure how to do it in a reply.
sorry cant figure out how to do it.

Trini Boom

iTrader: (5)

Place link to the new thread here once you started it so I can continue to follow.

edwardh1

I dont think I can post? whats the trick?
What should I do? I have a pix of the oil spot.

dan1el

Oil leak guys,

Pictures are very helpful when trying to find an oil leak. If you want to load a pic you should upload it to your albums and get the link. Instead of quick reply, do an advanced reply and you can use the tool bar to include a link to your pic and it will show up in the post.

You might benefit from reading http://forums.maxima.org/4th-generat...ain-cover.html

Pay special attention to NISSANMAXIMA91's pic of the oil leak spot on his and my car. If you are saying that oil is on the exhaust manifold where it mates to the head, I think the circled area in that pic may be your leak.

At any rate, I spent a long time chasing my oil leak and replaced a lot of gaskets on my way there. If the leak is on the passenger side then you pretty much only have a few options. Please keep in mind that this info is based LARGELY on research although I have spent the better part of the last 3 months under my maxima and I know it like the back of my hand now:

-Upper oil pan (probably too low to get oil where you said it is)

-Head gasket (possible but not very common especially with only 108K miles)

-Valve cover gasket(s) (High enough, but if you already replaced it then probably not. Did the leak change at all after? Or exactly the same?)

-Front oil seal (probably too low and far to the passenger side to get any oil at all on the exhaust manifold)

-Front or rear timing chain cover (not very common from what I can tell, but in relative area)

-Oil pressure switch (I've heard that it can sort of spray when it leaks because it's pressurized. It could possibly be spraying up there.)

-O rings behind rear timing chain cover (they call it infamous so I guess it's relatively common. In fact I just got done replacing mine. It's very time consuming if you DIY and very expensive if you pay someone else so it should probably be your last resort.

Read that link I gave you above and start ruling things out.

edwardh1

my leak is at the 8 and 9 oclock locations in nissanmaxima's circle, on the lower exhaust manifold studs, only on the lowest stud on each manifold "pipe' - only on the bottom 1/2 circle of the stud under the stud nut. very very small leak. its like it leaks out of the bottom stud. oil no where else to be seen.

do all engines have as many gasket leak points as these engines?!

Afterlife

iTrader: (1)

It is still your rear valve cover gasket i would say....did you use a sealant around the bends of the valve cover gasket when installing?If not that is your problem,justy slapping on a new gasket doesnt fix the problem it will leak around the bends around the corners.When you look underneath it makes it look like it's leaking from the exhaust studs.

J.P.



BTW i just fixed the same issue with both of my maximas,use some rtv or similar gasket sealant around the corners and your good to go.

edwardh1

I hope
http://forums.maxima.org/album.php?albumid=2401[IMG]

http://forums.maxima.org/album.php?albumid=2401[/IMG]

Picture needs to be rotated to the right, clockwise 90 degrees, its looking over the c joint at one of the two exhaust manifold connections to the block

dan1el

First off all, I think all cars have head gaskets, valve cover gaskets, oil pan gaskets, and front oil seals. Most cars have oil pressure switches or something similar. Not all cars have timing chains (many have belts), but the fact that our engines often make it to 350k or more is largely due to the timing chain. Therefore the timing chain covers are pretty much necessary. Also noteworthy is that I didn’t say they are all common leak points. I was just trying to list the POSSIBLE leak spots for a passenger side leak. By no means are all these leaks common especially for only 108K miles. The only ones I have found that seem to be somewhat common are the o rings and maybe valve covers. Usually with more miles than yours.

Well, to be sure I didn’t have any oil on my exhaust manifold or studs. I had oil leaking from the circled area and down on the cv shaft, the oil pressure switch, the oil pan… pretty much everything under there, but my leak was pretty heavy considering I had 30K more miles than you (134K). FYI if it is the o rings, it WILL get worse over time. Leaks are a little unpredictable especially if you have been driving because the oil can sling up, fall down, or sling left and right. So the best way to trace it is to get some uv dye for engine oil and a uv light from autozone (maybe about $20 together). You can put the dye in with the oil and idle the car (instead of driving) until it’s leaking florescent oil. It will make it a lot easier to see the source. In fact to make it easy to see that area, once you see some florescent oil leaking out I would recommend removing the power steering pump from the timing chain cover and let it hang out of the way (like in NISSANMAXIMA91’s picture. It’s only 3 bolts and it would make it really easy to see if it really is leaking from the o rings where mine and NM91’s car’s were. For the PS pump just:

-Remove passenger front tire.

-Loosen the belt by turning the upside down 12mm bolt RIGHTY LOOSEY. It makes sense once you see it, but you have to turn like you’re tightening the bolt in order to loosen the belt.

-After loosening the belt, remove 2 12mm bolts holding PS pump bracket to the timing chain cover.

-Remove 14mm bolt from behind PS pump ( looking at it from the passenger side wheel well). If you look through the holes in the PS pump pulley and turn the pulley, you will see the end of the threads of the bolt in question sticking out maybe 1/16 - 1/8” . You have to reach around at about 7 O’clock with your left hand and feel around for it. It’s head is bout 0.5” deep and the bolt goes from the back of the pump, through the TC cover, and out the front side.

-After you get that bolt out, the pump assembly will slide down and out.

Install:

-position the pump and slide the long bolt in place as far as you can to hold the pump up.

-bolt the bracket back on.

-tighten the belt until you can’t turn it 90 deg with your fingers.

-after tightening the belt it’s much easier to get the long bolt through the pump.

Let me know if you need pics or anything, but the above should help pinpoint the leak. BTW when you say small leak what do you mean? Is it hitting the ground? When does it leak? Only after highway speeds?

Dan

Trini Boom

iTrader: (5)

Dan, I think you need to look at the pic first. That has nothing to do with the PS pump. It is new in the pic if I am correct and the leak is clearly on that stud and not on the rest of the exhaust. Doesn't appear to be valve cover either.

dan1el

I have rotated and blew up the pic a bit to avoid confusion and disorientation.
I was writing that previous post while he posted the pic so I hadn't seen it yet. The big black thing to the right of the stud a couple inches is the PS pump. In my case removing it gave me a lot clearer view of the leaking area. In Ed's case I think it will do the same for him.

dan1el

I have gone ahead and transferred nissanmaxima91’s pic to this thread as now it seems to be even more relevant. The o rings are just behind the rear TC case and 1 of them is almost right beside the exhaust stud. Depending on which of the rings and where the rings are leaking, it could easily explain oil on the exhaust stud but not the rest of the pipe. I agree with trini that the valve cover wouldn’t leak on the stud without leaking on the top of the pipe. I also have posted the FSM pic of the TC covers which shows the o rings in question.

edwardh1

Thanks dan1el for rotation!!!!!!!
this passenger side most (and bottom stud) at that location has the most oil on it.

The next manifold "pipe" connection to the head, maybe 6 inches over toward the drivers side, has a similar oil around the exhaust stud, but not near as much oil on it- it has not formed a drop yet. The passenger side one (in the pix) is borderline on forming an oil drop. I drove it for years with a slight rear valve cover oil leak.
?Could this be oil thats still coming down after the garage replaced the rear valve cover gasket?
?Or could the timing cover (TC??) be leaking onto BOTH manifold studs?
ps: I can not see the manifold studs on the drivers side of the engine , maybe dont know where to look.

? If the valve cover job the shop did was bad, you are saying that the top of the exhaust pipe and all of it would probably have oil on it? Not just coming "out of the stud",under the stud nut??
Thus this leak small as it is is coming from somewhere else? IS that the thought process? There is a drop of oil on the bottom of the power steering pump - could just be draindowm?
?How rule out a PSteer fluid leak? different color oil??
AND - so many questions- is the water pump inside/under the timing chain cover?

dan1el

Ed,

I think you’ve got mine and Trini’s idea right. The rear valve cover is above the exhaust manifold, so it makes since that any oil leaking from the valve cover would drip down onto the manifold connections. In your picture it looks like oil is coming from either below or from the right side of the stud. I would think the right side is more likely (based on the pic). The part that throws me is that you say there is oil on the middle (correct me if I’m wrong, but I think you meant the middle) manifold connection. It seems very unlikely… ni impossible that the o rings could get oil over onto that one. If the oil on the middle pipe also seems to be coming from below, then I would lean toward the upper oil pan gasket (although oil doesn’t usually go up without also going down). And in the picture the oil pan looks pretty clean.

I really think you should get some dye like I suggested. It may help pinpoint the leak. At this point it looks to me like either upper oil pan or the o rings on the TC case. The upper oil pan is just one of many steps to replacing the o rings, so it would be great if that is all you have to do. If it’s the first time you do it, I would set a whole day aside for it. It will probably take 7 or 8 hours with http://forums.maxima.org/4th-generat...n-removal.html . I’m in the middle of resealing my upper oil pan for the 6th time in 3 months (I was chasing my oil leak for a long time and replaced a few things that also required re-doing the pan) and it took me 2 hours to get the upper pan off and will probably be 3 to put it back on. The first time it took 3 days, but I didn’t have the awesome walkthrough SrgScott made for us.

If you plan on getting a mechanic involved I would ask for quotes on both jobs. If they do the o rings they will have to do both valve cover gaskets, both oil pan gaskets, both TC cover gaskets, and the o rings anyway, so your best bet may be to get them to do that if the price is right. If you do this, get them to do the front oil seal too since it’s on the way and only takes about 10 minutes extra plus the seal is $9. If they do all that then you’re pretty safe in the way of oil leaks. The only other seals are the rear main and the head gaskets which hardly ever leak. Personally I wouldn’t pay any more than $120 for the upper oil pan because a day of my time is not worth more than that. If you don’t have the tools (just sockets and wrenches and a razor knife) then you may want to pay a bit more. For the o rings I wouldn’t pay more than $400 because 3 days of my time is not worth more than that. By no means do these figures represent what a mechanic may quote. That is just the most I would pay before I decide to do it myself.

dan1el

Not sure what power steering fluid looks like, but you could take the lid off of the reservoir and compare it. Dip a little on a paper towel or something.

Water pump is inside the front TC cover there is an "access panel" sort of. It's a little black cover with a tab on the bottom left corner kind of pointing at the crankshaft pulley. You can remove this to get to the water pump without taking off the TC cover. However if you are replacing the o rings you have to take the water pump off, and I recommend replacing the 2 big o ring seals on the water pump its self. They are $5 for both at Autozone.

Afterlife

iTrader: (1)

mine looked just like the pic on both of my maxima's and it was valve cover,ask the shop that did the work if they put a gasket sealer around the bend on the end of the head where the hump is,if they didnt just a simple gasket replacement will not fix the leak,it gets in the corner drips down around the exhaust manifold and makes it look like it is dripping from the mentioned "stud" on the exhaust.When it gets worse it will drip down to the power steering pump etc...etc... and make it look like the power steering pump is leaking.If you have had to add PS fluid i would say possibly the pump "o" rings if it is bad enough to drip and down on the pump you should have a slight influx in PS fluid.If no influx i still think it's the rear corner of the valve cover leaking.Just my opinion though,i have had to fix a few of these here at the shop....including my own 2 max's.
Hope that helps you out some and good luck and keep us posted on the outcome of this.

dan1el

If Afterlife’s looked like it was coming from the stud then the valve cover gasket probably is your problem. I just didn’t think that the VC could leak around the pipe and only hit the stud while leaving the top side dry. That’s much better news than what I gave you lol.

The other thing that is weird to me is that I replaced my VC gaskets while searching for my leak and didn’t use any RTV except a little dab on the cover its self to hold the gasket in place while I positioned it. Mine hasn’t leaked at all from the VC since then.

Afterlife

iTrader: (1)

The corners around the humps is the only place i would recommend RTV to make sure they dont leak.We don't do any of them in our shop without putting some around those corners and you dont have to gob it on there either just a light coating in those corners because it will seep around the bends and eventually make a drip like mentioned.

Trini Boom

iTrader: (5)

You guys must have some good valve covers for it not to leak without using RTV sealant. I have to redo the front valve cover on mine as well since the left bottom bolt by the dipstick, I guess some shop overtightened it and stripped it so it always leaks form there now. But now that I mention it, is it easier to tap and die or have any of you guys tried helicoil to repair the hole??

Afterlife

iTrader: (1)

I personally would just tap it.

MaxiNoob98

So I'm currently changing out my o-rings right now and I took a picture of my rear exhaust studs too. Just to give someone else some more pictures.



Mine is kinda weird it has oil on the bottom studs for some reason. I hope it is my o-rings because if it isn't I just wasted allot of time doing nothing.

edwardh1

Im the OP from back in 2010.
I think over time the problem pretty much stopped or really slowed (thats strange too) .

I recently had an oil pressure switch fail that gooped up things ,but lower down in the engine.
155k miles now. I had a shop do it. OPSwitch about $25, fuel filter maybe $10, $85 labor for switch and filter install.

My Toyotas(2 Camrys ) and Hondas(2 civics ) seem tighter on oil leaks

rbuswell

I just put mine back together with new high quality gaskets but I didn't put any RTV on the corners and now I have a big leak in the back. I would have been happy to do it but I missed that instruction in the manual until now. So I guess I get to do this all over again.

I do have four questions though.

1. Why does it seem like the front valve gasket doesn't have this problem?
2. Should I take the front apart too (much easier) and put some RTV in the corners there too?
3. This is the first time I've had to do this on a car. It always seems like most car manufacturers have this valve cover gasket issue nailed and they never leak. What is it about this design that makes this happen?
4. Should I trust the factory torque settings or tighten them down more?

DennisMik

iTrader: (2)

It is not the same exact design where it meets the timing chain cover.

I wouldn't. If it isn't leaking, let sleeping dogs lie.

I'm not an engineer, but I can give you my personal opinion. Cliff notes version - it's a bad design. The rear valve cover always seems to leak where it meets the timing chain cover. I think having to seal a right angle becomes a problem if the metal is too thin and can vibrate, which I believe the timing chain cover can do. If there were bolts to hold the timing chain cover to the valve cover, I bet this wouldn't be a problem.

Do not torque them beyond specs. I can't remember id the cover bolt is a shouldered bolt or not. If it is, more torque will not compress the valve cover any further. If it isn't a shouldered bolt additional torque could either cause the valve cover to flex and lose the straight line of the gasket surface or maybe even cause the valve cover to crack. You have to remember that you are working on an aluminum engine. Over-torquing a bolt could either snap the bolt or strip the threads in the head.

rbuswell

This all sounds very reasonable.

rbuswell

OK the leak didn't appear to be from the valve cover gasket. There was no fresh oil coming from the gasket area. The oil I could see from below was on the exhaust manifold so I assumed that it had to be the gasket. I'm now not sure where that came from but it isn't coming from the valve cover gasket. I will still put the RTV around the gasket corners as recommended. The good news is that I had to pull the intake manifolds anyway because the five year old knock sensor failed when I started the car. AutoZone replaced it under warranty but I hope this was an isolated incident. If I had to buy a new knock sensor now, I would buy OEM I think.

It appears that the leak source is the upper oil pan that I just repaired with new RTV. I cleaned it meticulously and was very careful when applying the RTV, applying torque in the right order and letting it cure for several days but it's still leaking. What threw me was that there was fresh oil above the pan seal. Not sure how it got there either. Isn't there this new law called gravity? Never any evidence that the pan edge isn't flat either. It looked fine when I had it apart and I checked it with a straight edge so I think it is still good. That is a big job to do over again and I'm really bummed. Unfortunately, no one makes a real gasket for that spot. I hate RTV.

DennisMik

iTrader: (2)

The law of gravity would apply only if you did not drive the car. When you are cruising down the road, air is blowing all round the engine, so the oil is also blown around.

There are 2 possible spots for the oil to be leaking from. One would be the oil gallery that runs from the engine block into the upper oil pan. There is a rubber o-ring that sits in the upper oil pan to seal this gallery. It is known to leak. If you look at this link, about dead center is reference # 11012G. This is the o-ring.
http://www.nissanpartsdeal.com/parts...agram=110_A001

The other possibility is the timing chain cover could have a crack in it. This has also happened.

About all you can do is clean the engine in that area and then let it run for a while (no driving). Maybe get the engine rpms up to 1K so that the oil pump pressure is higher. Then check and see where you have oil.

I don't know what to recommend for time, it depends on how bad the leak is. I would think at least 15 minutes.

rbuswell

Great list of to dos here. Thanks!

So far the car has only been run on jack stands since I did all the work so the gravity part is still in play. No windage to blow it around yet.

I don't remember that O-Ring when I put it back together but, regardless, I know I didn't replace it with a new one if I put it back where it belongs. That is the exact spot it is leaking though. I assume that since it is under pressure there that oil would be able to overwhelm the RTV at the spot if the O-Ring is missing, improperly positioned or bad. I am very fastidious about saving old parts and there isn't an O-Ring in the old parts. I can also say that the oil pressure light goes out very quickly after starting so it does have enough pressure for the sending unit to be happy.

I'm pretty sure the timing chain cover isn't the culprit but I will check it too.

As for the leak, it is pretty bad. It only drips a tiny bit when the engine isn't running if that's relevant. It had fresh oil in it for several days before I started it without any leaks so it took pressure to start it leaking. I'm guessing I'll know in very short order after I start it again. However, given my inability to recall the status of that O-Ring, I may be better off just biting the bullet and taking down the upper oil pan. The evidence seems compelling that that is where I messed up.

BTW, I noticed that you are using NissanPartsDeal.com. I recently started using them for OEM parts and have found them to be VERY good to work with and their prices are quite good too.

DennisMik

iTrader: (2)

I like to use nissapartsdeal to find part numbers, the other sites are more difficult to work with. And nissanpartsdeal is up front with the part number, Courtesy Nissan and others won't give it to you.

nissanpartsdeal used to be the best, having the lowest prices. But now that is not always true. I don't know if nissanpartsdeal raised prices or if Courtesy Nissan lowered theirs. However, check the shipping charges. nissanpartsdeal is kind of high.

Another place to check on parts is nissanpartsasap.com. This is Tri-Cities Nissan in Johnson City, Tennessee. Their web site is a little tricky to work with, but they offer the best prices. Don't know how the shipping & handling charges are. I haven't ordered anything from them yet.

rbuswell

I did some comparisons and the Tri-Cities site was better for pricing as you predicted. Several of the parts I wanted were shown as out-of-stock but available to order. I've emailed them to find out what the typical delay is before they fulfill. Another question I had was about shipping. My proposed order was about $136 and when I clicked on the shipping field to find out the cost, it came back as zero. If they don't charge shipping above some minimum order amount, they are going to win hands down nearly every time, I would guess. Of course, it would be nice if they made that clear on their front page or some other obvious place.

BTW, do you agree with my logic on just taking down the upper oil pan? I don't really see an alternative but maybe you can think of something I can do to be sure that O-Ring is in there (or not) without a complete tear-down. I've found that O-Rings bathed in oil are typically life of car parts (regardless what the manuals say) but maybe I should rethink that. They always seem so pliable and in like-new condition which may have been my logic if I re-used it. It has been a couple weeks since I worked on it so I don't recall the specifics.

ef9

iTrader: (8)

Both of those O-rings (behind the timing cover) leaked on mine. My car has 174k miles. I did a complete tear-down and replaced the timing chain/tensioners as well.

DennisMik

iTrader: (2)

With the o-ring being sandwiched in between the block and the upper oil pan, I don't know how you could check for it without pulling the pan. Sorry.

As for o-rings lasting forever... I don't believe it. Some may if they are made out of the proper material, but I have see way too many o-rings that have lost their elasticity and became permanently flattened out. If I know I will be opening up something with an o-ring in it, I will have a replacement on hand. If I don't have it, I'll get it.

ef9

iTrader: (8)

O-rings don't last forever! That's impossible. Especially with them being exposed to cycling temperatures and engine oil.