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

[jremington59]

I have a strong suspicion your problem is the rear main seal. The cap just pops off and there's probably oil on the bottom of the tranny in the front coming down between the engine and tranny. When you're driving down the road that oil can blow anywhere it wants to go. I have 2 of them to do in the spring. It's quite common with older vehicles.

 

[lobo411]

OK, I think that what's going on is a combination of problems. I retorqued the lower intake manifold bolts last night, each of which tightened a good 1/2-3/4 turn. This morning I drove the car on some errands, and took the freeway a few miles out of the way to put the car under load. No leaks at the first place I stopped, no leaks at the second place, and when I got home I had 1-2 drops. It's not perfect, but it's much better than before. In the last hour it has leaked about a teaspoon, whereas before it would have leaked a tablespoon or more.

There was a drop or two clinging to the oil pan/the VSS was coated in oil long before the catastrophic leak happened. It started years before I even touched the lower intake manifold, so that's probably a slight rear main leak.

And the passenger side valve cover gasket was probably leaking too, but that seems to be corrected.

To be honest, I think the problem is the piece of crap Fel-pro Permadry gasket I used for the lower intake manifold. It used to be composed of a single piece of metal. Now it's composed of two metal pieces (one for each bank of air intake passages, and there's NOTHING covering the rear/center area. You're supposed to use RTV and they give you a small tube of it, but the problem is that it was hard enough to position the LIM correctly on the first try given that all the wires grab at it as you're lowering it into position. Now you have to position it while keeping the left bank gasket in place, the right bank gasket in place, and you really shouldn't reposition too much because you'll mess up the RTV. Oh, and you have to do all of this in 5 mins.

Felpro says it's a "better" design. Bull. The plan now is:

1. Dump some Lucas stop leak in the oil. Why not?

2. Retorque the bolts as often as necessary.

3. Maybe redo the LIM gasket *IF* the car passes smog in May.

Also, AVOID THE NEW FEL-PRO GASKET LIKE THE PLAGUE! You can still get the better gasket under the part number MS95739. DO NOT GET THE "NEW AND IMPROVED" version, which is MS98005T.

 

[bandit11]

oil pressure sender/switch

 

[lobo411]

oil pressure sender/switch

I was hoping it would be that, but I checked and it's clean and dry.

I further tightened the valve cover bolts on the passenger side as much as I dared, so we'll see if that does anything. Maybe I'll replace them once I'm convinced that that's the problem.

I'm not entirely convinced that it's the lower intake manifold gasket anymore, just because there's not a heck of a lot of oil in that area, IIRC. My guess is that any oil that got to the joint between the lower intake manifold and the block would be very slight, since the oil pathway is Crankcase > Pushrods > Head > Crankcase, right?

I've gotten burned working on the car too much lately. The plastic connectors are too brittle and every time I touch them, one or two of them just crumble. The fuel injector electrical connectors are held on with just a prayer!

 

[lobo411]

Also I looked for a drain plug on the torque converter but I couldn't find any kind of drain plug other than the one I installed in the trans pan.

I read somewhere that you can check for a rear main seal leak by pulling the starter motor and inspecting the flywheel for oil streaking radially out. I might try that.

 

[koda2000]

using RTV on the front and rear of the lower intake manifold is the accepted method for most "V" engines and is a far better way of sealing the manifold to the block. however, you have to make sure you put down a thick enough bead (about the thickness of a pencil) and drop the manifold straight down onto it.

BTW, Felpro Perma-Dry gaskets are about the best you can buy. if you believe that's where the leak is originating, stuff a rag, or towel, back in there and see if it gets wet.

 

[lobo411]

using RTV on the front and rear of the lower intake manifold is the accepted method for most "V" engines and is a far better way of sealing the manifold to the block. however, you have to make sure you put down a thick enough bead (about the thickness of a pencil) and drop the manifold straight down onto it.

BTW, Felpro Perma-Dry gaskets are about the best you can buy. if you believe that's where the leak is originating, stuff a rag, or towel, back in there and see if it gets wet.

Ya, I repositioned the manifold once because the driver's side intake gasket slipped and became misaligned. Absolutely no chance of that happening on a single-piece gasket. But I dunno.

Anyway, I bought a $20 inspection camera (usb...basically a webcam w/ a 20' wire and an annular led lamp) and it's still hard to tell, but I think it's the firewall lower intake gasket. I started tearing things up 2.5 hrs ago and I have the valve covers off. I'm hoping to get the valve cover mating areas cleaned up tonight and possibly get the lower intake manifold gasket off. Then I can just buy the gaskets and reassemble tomorrow.

It does not appear that the valve cover gaskets were leaking at all. They were felpro permadry gaskets too. Anyway once you have the valve covers off it's silly not to replace the intake gaskets too, as long as they're in doubt. I found a pool of oil on the flat part of the block just under the firewall section of the LIM.

I heard that you're not supposed to use RTV on permadry valve cover gaskets. Should I? I did last time because that's what I've always done, and nobody said anything. But the last time I was at the parts store the guy said you're not supposed to use RTV on them at all.

I'll think about which LIM gaskets to go with I guess.

Thanks!

 

[lobo411]

OK, figured it out. I have the lower manifold off and I cleaned all mating surfaces, so tomorrow I just have to buy gaskets and reassemble.

The problem was the lower intake manifold gasket. Two things:

1. I missed an area about 1/2-1" long in the firewall rear of the LIM, so there was no sealant of any kind there.

2. I used the RTV that came with the gaskets. Big mistake. It set so fast that neither the front nor the back really had a chance to mash into a gasket before it hardened. Some areas did, but about 1/2 the area looked like I just squeezed it out of the tube. I worked as fast as I could to get the LIM on, but it wasn't fast enough.

Both 1. and 2. would not have been a catastrophic issue with the old design gaskets. The rubber would have at least stood a chance of sealing the areas that I missed, plus the RTV + rubber gasket areas would have held the gasket in place so the damn thing wouldn't slide around.

Now the question is: what to do tomorrow?

1. Valve covers. I'm going to get Fel-Pro permadry. Supposedly, RTV should not be used, but should I anyway?

2. LIM. Should I go with the old reliable pattern or the new one that's supposed to be better but failed me (and the guy in the other thread) this time? [EDIT: I decided that the new gaskets I installed were perfectly clean and sound, so I'll just reuse them]

3. RTV. I never had this kind of an issue with RTV copper. Should I use that instead of black?

Thanks!

 

[koda2000]

do not use rtv on the valve cover gaskets. it is not necessary and may lead to leaks. buy some Permatex or Loctite black rtv for the LIM. with winter temps it doesn't set up that fast. you should have a good 10 minutes to drop the intake on. be sure to pay particular attention to the corners where the block meets the heads.

 

[Dono]

Lobo411, I don't know where you live, but anywhere around freezing, the permatex black stays sticky and soft forever (Or so it seems).

Id think it would barely start to set before you dropped the lim on. Then once it's squeezed down when you torque it hopefully you will get a good seal. What I did was put permatex on the block valley, and on the lim, paying special attention to the corners where the lim meets the head.

Is this the right thing? I have no clue. I have effeminately had my issues with a leaky 4.0 ohv. I sympathize with you guys as I was ready to take my truck to the auto grave yard and walk away (Heck, I was ready to pay them to take it).

 

[koda2000]

Lobo411, I don't know where you live, but anywhere around freezing, the permatex black stays sticky and soft forever (Or so it seems).

Id think it would barely start to set before you dropped the lim on. Then once it's squeezed down when you torque it hopefully you will get a good seal. What I did was put permatex on the block valley, and on the lim, paying special attention to the corners where the lim meets the head.

Is this the right thing? I have no clue. I have effeminately had my issues with a leaky 4.0 ohv. I sympathize with you guys as I was ready to take my truck to the auto grave yard and walk away (Heck, I was ready to pay them to take it).

you shouldn't have to put the RTV on the LIM, just the block. as i previously stated, put down a bead about the thickness of a wooden pencil and you should be fine. i'd clean the block part with parts cleaner in insure a good seal.

 

[Dono]

koda2000, I tried both ways. I had mine apart many times also.
I really think my issue was a leaky valve cover though. The threads were not great, and I was torquing to spec. What that meant was that I was at rated torque and the valve cover bolt was not seated at the back.

 

[lobo411]

do not use rtv on the valve cover gaskets. it is not necessary and may lead to leaks. buy some Permatex or Loctite black rtv for the LIM. with winter temps it doesn't set up that fast. you should have a good 10 minutes to drop the intake on. be sure to pay particular attention to the corners where the block meets the heads.

K, I ended up going with permatex black. I put a good thick bead on the block in the firewall and thermostat areas, and I put a thin bead on the corresponding areas of the LIM for good measure. I also put a little RTV around the coolant ports on the LIM gasket, less because I thought it would seal well than because I wanted it to help hold the gasket in place for positioning.

I ended up going with the Fel-Pro permadry valve cover gaskets too, without RTV except for the area where the lower intake meets the head. The instructions said to use a dab there, so I did.

One issue that came up was that coolant got into the oil when I pulled the LIM. I drained the oil, which I was going to do anyway because I wanted to get the old oil (dyed green, plus it had Lucas Stop Leak in it which basically made it as thick as gear oil) out. Maybe a teaspoon of coolant came out with the oil, but it was kind of odd--the coolant came out first, then the oil. I'd have thought the coolant would come out last. I threw in about 1/2 quart of oil and let it drain out again hoping to chase out any remaining coolant. I guess I'll change the oil again after 300-600 miles just to be sure, and I want to clean out whatever stop leak and dye is still in there.

It's too soon to declare victory--everything is reassembled and the fluids are topped off as well as possible w/o bleeding, but I'm waiting till tomorrow morning to fire it up (to allow the RTV to set).

 

[lobo411]

Lobo411, I don't know where you live, but anywhere around freezing, the permatex black stays sticky and soft forever (Or so it seems).

Id think it would barely start to set before you dropped the lim on. Then once it's squeezed down when you torque it hopefully you will get a good seal. What I did was put permatex on the block valley, and on the lim, paying special attention to the corners where the lim meets the head.

Is this the right thing? I have no clue. I have effeminately had my issues with a leaky 4.0 ohv. I sympathize with you guys as I was ready to take my truck to the auto grave yard and walk away (Heck, I was ready to pay them to take it).

Heh! Well, we'll see if the fix works. I suspect it will, but the proof is in the pudding. We haven't had a winter out here, so that was probably an issue with Fel-Pro's fast-drying RTV. It was in the upper 80's when I installed the LIM the first time (mid-December), and probably around 80 when I installed the lower this morning (we topped out at 90).+

I hope I torqued the lower intake manifolds to the right spec. Haynes said 144 in-lbs, and Chilton's said 18 ft-lbs. Since the Chilton's book is 2 years older than the Hayne's book, I decided to go with the Haynes' spec.

 

[lobo411]

koda2000, I tried both ways. I had mine apart many times also.
I really think my issue was a leaky valve cover though. The threads were not great, and I was torquing to spec. What that meant was that I was at rated torque and the valve cover bolt was not seated at the back.

Ya I thought about this too, so I spent a little extra time cleaning up my valve cover bolt threads with a die, flushing the RTV buildup in the bolt holes, and tapping one bolt hole with sketchy threads. I did have a little trouble getting the sketchy thread hole to work, but eventually I got it.

Hopefully this ends well. I think I had the fuel lines/hard intake vacuum line/alternator wires routed incorrectly before, so this time I rerouted things and got a good, positive lock on the vacuum line. My hope is that I'll fire it up and it'll be like a new engine, but my constant fear is that excessive manhandling will lead to electrical problems. Won't find out till the morning!

 

[lobo411]

OK, updating. I ran the car in town today. 1-2 drops accumulated under the car every time I parked, but I didn't see any of them actually fall. I just looked when I parked and saw that the asphalt was dry, did my errand, came out and saw a drop of oil on the ground. I'm thinking/hoping this is just the oil that had accumulated on top of the bell housing working its way down. I didn't clean things because I was just too busy, and there was probably 1 tablespoon of oil pooled up there. Tomorrow's 300 mile run will be the real test.

 

[ranger7ltr]

He won't find that plug...

I have a strong suspicion your problem is the rear main seal. The cap just pops off and there's probably oil on the bottom of the tranny in the front coming down between the engine and tranny. When you're driving down the road that oil can blow anywhere it wants to go. I have 2 of them to do in the spring. It's quite common with older vehicles.

Because the 5R55E doesn't have one... Only the 4R70W in the V8 Explorer have them...I know my V6 doesn't have a plug in the case...

I fought this same problem last year after my new V6 engine lost the lim gasket and puked coolant everywhere...I could not find the oil leak after fixing the coolant so I bought another truck and parked this one and pulled the engine...After the engine was out I could see oil coming from that wonderful LIM and maybe the valve covers as well... At least your oil leak wasn't causing exhaust smoke...Mine looked like I was spraying for airborne bugs...And I thought the rear main was leaking as well..

I replaced them both and put the engine in a Ranger for a friend and so far so good...

 

[lobo411]

Still leaking. Lost about 1/4 qt over 150 miles and I have a few drops under the car. I noticed oil seemed to pool around the camshaft position sensor. Any ideas? I really doubt 2 sets of gaskets could fail in the same way in the same month.

 

[Dono]

oh no....has to be lim or valve covers.
I really am having re-occurring nightmares over this.

So sorry, I have absolutely no words of wisdom for you.

It would be really easy to see whats going on with the motor out of the truck, but who wants to live that?

 

[lobo411]

oh no....has to be lim or valve covers.
I really am having re-occurring nightmares over this.

So sorry, I have absolutely no words of wisdom for you.

It would be really easy to see whats going on with the motor out of the truck, but who wants to live that?

I wish I had a second car (or that this was my second car) so I could do stuff like drop the trans or pull the engine!

I dunno about the LIM. Last time I used the Chilton's book and it gave the torque spec for the 4.0 OHV as 18 ft-lbs. No breakdown by year.

This time I used the Haynes book and it gave the torque spec for the 1996-1998 4.0 OHV as 12 ft-lbs (actually 144 in-lbs). There were different specs for other groups of model years, but the Haynes book didn't specific the lower intake. On the installation section for the lower intake it said "tighten to the number in this chapter's specs," and in the specs it just listed "Intake Manifold." (did not specify upper or lower)

I'm waiting for the car to cool, but it seems like most sources point to 12 ft-lbs as the proper LIM bolt torque spec. I want to check:

A. Did the valve cover bolts lose their torque? [UPDATE: The valve cover bolts lost about 1/4-1/2 turn of torque. I'm torquing the the Haynes spec--72-89 inch-lbs, so I went with 80 inch-lbs]

and

B. Did I lose more oil than I normally lose? For the past year of commuting, I've been "burning" (ie losing) about 1/3 quart of oil per 300 miles. I thought it was just normal for a 150k engine.

Could be that, say, 50% of my oil loss was due to a leaking LIM/valve covers. And 25% was due to normal oil consumption. And maybe 25% was due to another age-related leak or whatever. I've been noticing lots more oil residue in the air intake tube/upper intake manifold, as well as a mysterious oil buildup around the PCV valve grommet + on the brake booster vacuum line where it connects to the upper intake manifold. Lots more blow-by?

[UPDATE: The engine lost no more oil than "normal." I burned bout 1/4 quart in 300 miles. So maybe we're getting somewhere!]

The engine still pings on hills, so I wonder about that. Maybe my valve guides are worn out and that's why I'm burning oil/pinging? I had a valve job done when I replaced the head gasket at 120k mi/10 years ago.

Aside from the oil leaks and pinging, the engine gets great mileage (20 mpg highway/15 city) and still purrs like a kitten.