Sudden Catastrophic Oil Leak! -- FIXED (bad lower intake manifold seal)

[Dono]

I really had trouble getting the rear of my valve covers to seal. The aluminum lower intake's threads tear themselves apart and cross thread if you are not really careful. I had a couple of bolts at the rear that would also torque down to spec, but not be all the way down (Bolt to long, or stuff fallen in to the threaded hole?). This is really hard to see at the firewall.

Please focus on this area. I really wonder if one of those inspection camera's would be helpful.

 

[lobo411]

I really had trouble getting the rear of my valve covers to seal. The aluminum lower intake's threads tear themselves apart and cross thread if you are not really careful. I had a couple of bolts at the rear that would also torque down to spec, but not be all the way down (Bolt to long, or stuff fallen in to the threaded hole?). This is really hard to see at the firewall.

Please focus on this area. I really wonder if one of those inspection camera's would be helpful.

Well you might have something there. I drove the car 3 places today, and every time I parked and left the car alone for 5+ mins, I found a puddle of about 1 tablespoon of oil. Is that how bad yours was?

I noticed that there are two sets of drops, roughly in a line down from the firewall end of each valve cover. However, the driver's side valve cover does not appear to be leaking. The passenger side is a bit iffy/hard to say.

My theory is now either:

A. Valve cover is leaking,

or

B. Lower intake manifold is leaking in the firewall area and dripping down both sides of the bell housing.

I'm really hoping it's not B, but it's hard to say because it's just impossible to see anything back there (I tried my inspection mirror). There was a bit of oil residue, but not much. However, if this is the beginning of the leak I'd guess that most of the oil would drip down.

I'll try retorquing all LIM and valve cover bolts, but I'm thinking it might be the LIM. Fel-Pro redesigned the LIM gasket--instead of the entire mating area being made out of metal in one piece, it is now composed of two pieces. One metal gasket for each LIM to head mating, and nothing but RTV at the LIM to block mating (used to be metal here too). They said it was "new and improved," but I had trouble installing it because where before you only had to worry about getting one LIM attached to one LIM gasket to one block/head, now you have to get the gasket for the right, the gasket for the left, the block, and the LIM all aligned without messing up the RTV at the block. If that sounds ridiculously hard for something that ought to be so simple, it is!

 

[Dono]

I hear you.
It could be lim in exactly the spot you describe.
Lets hope not.
Start with the passenger valve cover. That will take you an hour, taking your time.

I re-did my lim and everything once, and still had the same leak. I can't believe I still own the truck. I was getting a bit aggravated, to put it mildly.
I really think I just couldn't see what was happening at the rear of the valve covers.

 

[lobo411]

I hear you.
It could be lim in exactly the spot you describe.
Lets hope not.
Start with the passenger valve cover. That will take you an hour, taking your time.

I re-did my lim and everything once, and still had the same leak. I can't believe I still own the truck. I was getting a bit aggravated, to put it mildly.
I really think I just couldn't see what was happening at the rear of the valve covers.

Ya I'm debating what to do if it's the LIM. I'm thinking that it might be best to use the explorer as an around town/utility truck, and get a small passenger car for commuting. It's basically completely ridiculous to be driving a 5000 lb car 300 miles r/t on a weekly basis (think of all the money I'm spending just hauling steel back and forth!). And then you throw in that it's 18 year old steel, with plastic connectors that break when you touch them and a suspension that needs an overhaul (the boots on the front joints are shredded and I'm getting squeaks which I'm sure will later become clunks), and God knows what else lurking where I can't see it...

Also, it would be nice to keep this explorer, and fix it at my leisure. I'm sick of having to work on it with a gun to my head (this is my only car).

 

[koda2000]

yeah, it's a whole different thing when you can work on something because you want, when you want to, rather than having to fix something before work tomorrow.

 

[lobo411]

The passenger side valve cover bolts were a bit loose, with the two bolts closest to the firewall being the most loose. I snugged them up and I'll keep my fingers crossed that this addresses the leak. If not, I'll try retorqing the lower intake manifold bolts. I spent a lot of time splayed out on top of the engine trying to feel the area where the RTV seal is on the firewall side of the LIM, but I really didn't find much more than a bit of oil residue. The driver's side valve covers are completely clean and dry, so I left well enough alone.

 

[rb142]

It sounds like you are on the right track. Hope that fixes it for you. Given your description that the oil is all around the trans housing -- especially around the top -- and the streaks on the firewall indicate that the leak is somewhere above the bell housing and the oil is being blown back while you are driving. That valve cover will probably take care of it.

 

[lobo411]

It sounds like you are on the right track. Hope that fixes it for you. Given your description that the oil is all around the trans housing -- especially around the top -- and the streaks on the firewall indicate that the leak is somewhere above the bell housing and the oil is being blown back while you are driving. That valve cover will probably take care of it.

Thanks for the good wishes! Didn't work though...it's leaking just as badly as it was before I tightened the bolts.

I guess that leaves only the lower intake manifold, or possibly the head gaskets as the only two points of sealing above the oil pan.

I'm going to try retorquing the lower intake manifold bolts tomorrow. Then I'll add some UV dye to the oil and see if I can spot the source of the leak tomorrow night.

Is there any chance left that it could be the rear main? I know that the rear main or the oil pan gasket is leaking--there has always been a drop or two of oil accumulating in the places shown in the photo.

But more than that--about 15000 miles ago (well before I worked on the lower intake manifold) I noticed a thick coating of oil over the vehicle speed sensor on top of the trans. How did oil get up there? I don't know the answer, and it could just be a coincidence.

 

[Dono]

Oh man, Im having night mares of my own experiences all over again.

 

[lobo411]

Oh man, Im having night mares of my own experiences all over again.

Heh! Well, I'm hoping the UV dye will tell the tale. There are probably several leaks and it's a question of figuring out which one is the new one (or which one became a major leak). I guess valve covers are kinda the best case scenario at this point, though.

 

[rb142]

It sounds like all of the oil on the trans and speed sensor is just being blown back there from somewhere forward and above. The airflow would take it right down there.

I'd get that thing warmed up nice and hot so that the leak is really flowing. Then start checking around for the leak. That should make it more obvious. I'm not sure UV dye will help much, since you will have everything glowing.

Have you checked your PCV? Any buildup of pressure might help push the oil out.

It doesn't seem like there is much left it could be other than the valve cover or the manifold.

 

[lobo411]

OK, I'm off to Autozone. Mainly to put a load on the engine, but I'll pick up some stop leak too. I cleaned the engine spic and span with engine degreaser, fired it up, and let it idle for 10-15 mins while I looked for leaks with the UV light. I didn't get much leak action that way, so I ran the engine at idle for 5 mins @ 2000 rpm.

The valve covers are clean as a whistle. Ditto the oil filter adapter.

I have drops near the area indicated in the original photo, with no obvious source. So I'm guessing that must be rear main seal leakage, but I don't know how much of the overall problem it is.

I also spotted dye/oil at the driver's side head gasket, only on the side nearest the firewall. I'm thinking this could be one of two things: the head gasket leaking oil and not coolant (my coolant levels are constant, but I did find a tiny bit of brown pasty sludge in the coolant 3-4 weeks ago. Figured it was ordinary radiator sludge). Or it could be leak-down from the rear of the lower intake manifold.

I'll see if I can get better leaks by driving it, because idling just isn't getting the oil moving enough.

 

[rb142]

The problem with claiming it is the rear main seal is that there is no way for that to get all over the top and sides of the transmission as you reported earlier. You may be looking for more than one leak.

 

[lobo411]

Back from Autozone. There's definitely some leakage from the rear passenger valve cover gasket, but not very much. The trickle is exactly where the gasket is--it doesn't stream down the head or anything, so it's very minor.

The leak at the driver's head gasket enlarged when I test drove the car. There is now a clear line of drainage from the firewall area of the driver's side head gasket down the bell housing and to the areas where the drops have been accumulating on the bottom end of the bell housing.

So now I'm at a crossroads. I bought new valve cover gaskets but I haven't opened them yet. I could try replacing the valve cover gaskets. I could also retorque the lower intake manifold even though there are no signs of leakage (but it's definitely hard to see anything at all back there).

Or I could dump stop-leak into the system and pray. I'm letting the car cool off and then I'm going to check the radiator cap with my UV light. If I see drops of dye-stained oil, then I'll know for sure it's my head gasket about to blow.

 

[rb142]

The head gasket could be leaking without necessarily getting into the coolant.

If it is coming from the head gasket, then you have a lot of work to do. It sounds like you have it narrowed down, but if you can't actually see the source, you may still not have it. Be really sure that it isn't running down from the lower intake and just looking like it is coming from the head gasket. I think you will be replacing the lower intake and valve cover gaskets anyway -- the question is whether you have to keep going further down. Good luck.

 

[jremington59]

Did you pop off the TQ drain cap and see if there's oil in there yet?

 

[lobo411]

Did you pop off the TQ drain cap and see if there's oil in there yet?

No, I looked and but I couldn't find the drain cap. Is it pretty obvious?

 

[lobo411]

The head gasket could be leaking without necessarily getting into the coolant.

If it is coming from the head gasket, then you have a lot of work to do. It sounds like you have it narrowed down, but if you can't actually see the source, you may still not have it. Be really sure that it isn't running down from the lower intake and just looking like it is coming from the head gasket. I think you will be replacing the lower intake and valve cover gaskets anyway -- the question is whether you have to keep going further down. Good luck.

Ya, I think I'll probably just try a stop-leak type product. This car runs great but it almost failed its last smog check on NOx (fail is >800 PPM, mine was 798 PPM). I kind of don't feel like investing the time and energy and cash to replace the head gaskets when I just replaced them at 115,000 miles (but that was 10 years ago).

I just finished pulling the upper intake manifold and checked the rear of the lower intake manifold for oil leak dye with an inspection mirror. Didn't find anything, but it's really hard to see anything back there. I ordered an inspection camera from Amazon for $20 but that won't get here for a few days. So I retorqued the lower intake manifold bolts (they were a little loose) and reassembled. We'll see if that improves things any.

EDIT: I still have a bit of hope that it's not the head gasket. The LIM bolts were pretty loose considering I torqued them just 600 miles ago--probably loose by about 1/2-3/4 turn.

Anyone have suggestions for a stop-leak I should try? I bought Bars Leak Rear Main Seal fixer, but I haven't thrown anything in yet.

What I want is to get this car to be reliable enough that I can shop for a newer car just for commuting purposes on my own terms (not "I NEED A CAR NOW!!! WHATEVER'S ON THE LOT!!!" ) Then I figure I'll use the Explorer as a utility wagon/around town car, and I'll have the time to tear the whole thing apart and work on it whenever I feel like it. It would definitely be nice to avoid the need to install gaskets by moonlight in the future!

 

[koda2000]

from the head gasket? engines don't leak oil from the head gaskets. only coolant.

 

[koda2000]

No, I looked and but I couldn't find the drain cap. Is it pretty obvious?

yes it's really obvious. a large black rubber plug dead center of the bottom of the bell housing. sometimes it's missing, but then there would be a large empty hole in that location.

under my theory of "the last thing you messed with is the last thing you f'd up" i'm beginning to think that your problem is very likely a valve cover gasket that was improperly installed. it's not the type of repair that you want to do hastily and you've stated you had trouble with the rear cover & bolts. i think you need to redo this job properly. at this point, merely checking/tightening bolts may not help.