Major Oil Leak, Burning On The Crosspipe. Help!!!

[Dedaw]

Fall has rolled around, which means it's time to roll up the windows and fix the burning oil that I've managed to avoid all summer (as it's gotten increasingly worse). My truck has been leaking oil for a while, and I've done different repairs, slowly, trying to stop the seepage. Fixed the valve cover and did Cruiser's valve cover mod, fixed the rear main and oil pan gasket (all with the help of my mechanic friend and Jeep enthusiast). As you can see in the pictures below, the engine is leaking BADLY, and burning off on the crosspipe, which smokes so bad that at a stoplight people look around trying to figure out who's on fire (and half of that is in the cab!). Mechanic buddies think that it's the head gasket, and I agree. However, wanted to cross reference with you guys and see if anybody else has opinions that might save me a lot of time and money. Side note: Blew the clutch slave last weekend, and my buddy checked the rear main when the tranny was out and said that it wasn't leaking from there or the valve cover.

 

EDIT: Did a compression test with a cheap @$$ Harbor Freight tester. I know they're not the best, but it's better than shooting blind.

5x crank, in order from 1-6: 120; 120; 85; 115; 100; 85

3x crank, in order from 1-6: 90; 110; 95; 120; 90; 70

 

Valve cover is covered in oil from blowby (CCV was hooked into the cold air intake, but hose is currently off) but does not seem to be enough to cause the amount of oil as seen below.

 

Not the best picture, but you can see that there is oil ABOVE the oil sending unit, leading me to believe that it is not the culprit.

 

The puddle.

 

The oil on the crosspipe, AFTER putting a heat wrap around it, hoping that might help with the burning problem.  :wall:

 

Please, help stop the burning in my throat!  :)

 

EDIT: Therorizing that head gasket is bad, causing the leak and building pressure in the crankcase which is thus causing blowby.  :hmm:

[nitroxsteve]

I would start by hooking that hose back up and is the small hose at the back of the valve cover open? They are bad to clog up and cause oil to blow out into the air filter through the hose thats missing. Check your oil filter housing to see if its leaking. You need to clean the engine up and look for the leak. If its that bad it should be easy to find.

[Dedaw]

I replaced both hoses and grommets when I did the valve cover mod. I will do the oil filter adapter and reattach the hose tomorrow, although there is oil ABOVE the adapter as well. So it might be part of the problem, but I don't think it's all of it; especially with compression readings that low.

Will be testing with a Snap-On tomorrow to confirm the readings. As far as cleaning the engine up, I've wiped it with rags, and sprayed purple power (nasty degreaser if you're not familiar) and it doesn't do much. That oil is literally burned on there. Besides yanking the motor and having it heat treated, what else is there?

[cruiser54]

Do this while you're at it.

 

We all get tired of the oil film/leak on top of our 4.0 Jeep aluminum valve covers. Many times the biggest culprit is the loose fitting oil filler cap. Here’s a real easy fix:

Remove the plastic oil filler cap and wrestle the original rubber gasket from it using a small pick or screwdriver.

Make a duplicate of the gasket out of an old bicycle inner tube using scissors and a knife or razor blade.

Install the duplicate on the cap first, and then the original over top of it.

It will be a tight fit on the valve cover the first time, and may require some persuasion with a pair of pliers, but will get easier with time.

[Keyav8r]

Check distributor gasket/o-ring, oil filter seal, oil pressre sending unit, oil filter adapter o-rings (there are three of them and they may be very hard and brittle). The adapter is sometimes a bear to get off.

Looking at your photo, there seems to be more oil on the passenger side of the crossover pipe and the pipe is back away from the RMS area. Have you checked transmission fluid level and for leakage from the transmission fill plugs or other fittings?

Are you having to add engine oil between changes?

What gasket did you use when you fixed the valve cover? If there is oil above the adapter, it's probably coming from the valve cover.

This sounds like a shotgun approach but on our trucks you need to check everything.

[mpace6a]

just because its above the sending unit doesnt mean its not the culprit. with the pressure created by your oil pump, should the sender go bad it will spray out like a garden hose. Crawl under the jeep, have someone turn it one, and watch the sender. Theyre like $2 to replace too. start with the easy stuff dude, more often than not it'll save you time, money, and a helluva headache.

[Keyav8r]

Simple test for the oil sending unit is to screw it out and replace it with a pipe plug (1/8" or 1/4")

[ParadiseMJ]

I don't know how you could possibly identify the source of any leak, or combination of leaks with all the oil all over your stuff.  I, personally, would start by a good pressure cleaning of the entire engine compartment, especially the block, valve cover and pan.  Then you MIGHT be able to find where the leak originates.  If there is only one leak you can concentrate on that.

 

P.S. My Uncle Bob thinks it's the Rear Main Seal

[mpace6a]

Simple test for the oil sending unit is to screw it out and replace it with a pipe plug (1/8" or 1/4")

Or just crawl under with a flashlight and look while someone starts it. If its bad, you'll know.

[1987Comanche]

Looks just like Maura's OE engine and, like me, I ultimately think you'll have to R&R the motor.  Your compression readings are low on a few cylinders.  How much oil are blowing out/leaking (miles/qt)?  What's your hot oil pressure?

 

  It might be worth looking at what I found so you can compare. Look at pg 2 for the OE engine autopsy results.

http://comancheclub.com/topic/27930-my-1990-and-some-pics-of-the-old-87/?hl=Maura

[Knucklehead97]

Check distributor gasket/o-ring, oil filter seal, oil pressre sending unit, oil filter adapter o-rings (there are three of them and they may be very hard and brittle). The adapter is sometimes a bear to get off.Looking at your photo, there seems to be more oil on the passenger side of the crossover pipe and the pipe is back away from the RMS area. Have you checked transmission fluid level and for leakage from the transmission fill plugs or other fittings?Are you having to add engine oil between changes?What gasket did you use when you fixed the valve cover? If there is oil above the adapter, it's probably coming from the valve cover.This sounds like a shotgun approach but on our trucks you need to check everything.

I don't mean to thread jack. Just was wondering. You said "the pipe is back away from the RMS area" by that do you mean that a RMS leak won't drip on the cross pipe? I've had a leak on the cross pipe for awhile and havn't started my search for where its coming from, but was hoping it wasn't the RMS.

[cruiser54]

I don't know how you could possibly identify the source of any leak, or combination of leaks with all the oil all over your stuff.  I, personally, would start by a good pressure cleaning of the entire engine compartment, especially the block, valve cover and pan.  Then you MIGHT be able to find where the leak originates.  If there is only one leak you can concentrate on that.

 

P.S. My Uncle Bob thinks it's the Rear Main Seal

Uncle Bob is full of $#!& as usual!! LOL.

[cruiser54]

 

Check distributor gasket/o-ring, oil filter seal, oil pressre sending unit, oil filter adapter o-rings (there are three of them and they may be very hard and brittle). The adapter is sometimes a bear to get off.Looking at your photo, there seems to be more oil on the passenger side of the crossover pipe and the pipe is back away from the RMS area. Have you checked transmission fluid level and for leakage from the transmission fill plugs or other fittings?Are you having to add engine oil between changes?What gasket did you use when you fixed the valve cover? If there is oil above the adapter, it's probably coming from the valve cover.This sounds like a shotgun approach but on our trucks you need to check everything.

I don't mean to thread jack. Just was wondering. You said "the pipe is back away from the RMS area" by that do you mean that a RMS leak won't drip on the cross pipe? I've had a leak on the cross pipe for awhile and havn't started my search for where its coming from, but was hoping it wasn't the RMS.

Use THIS to diagnose your oil leaks.

 

I'd be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.

Everybody, who doesn't own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking.

Many mechanics, friends, people on Jeep forums who can’t see your Jeep from where they’re at, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?

  A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don't jump on the RMS/oil pan gasket bandwagon right off the bat.

Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons.

First off, the engine sits nose-up and any oil will run back to the RMS area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "$hit flows downhill".

Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first.

   Revised 02-26-2013

 

[Knucklehead97]

 

 

 

Check distributor gasket/o-ring, oil filter seal, oil pressre sending unit, oil filter adapter o-rings (there are three of them and they may be very hard and brittle). The adapter is sometimes a bear to get off.Looking at your photo, there seems to be more oil on the passenger side of the crossover pipe and the pipe is back away from the RMS area. Have you checked transmission fluid level and for leakage from the transmission fill plugs or other fittings?Are you having to add engine oil between changes?What gasket did you use when you fixed the valve cover? If there is oil above the adapter, it's probably coming from the valve cover.This sounds like a shotgun approach but on our trucks you need to check everything.

 

I don't mean to thread jack. Just was wondering. You said "the pipe is back away from the RMS area" by that do you mean that a RMS leak won't drip on the cross pipe? I've had a leak on the cross pipe for awhile and havn't started my search for where its coming from, but was hoping it wasn't the RMS.

Use THIS to diagnose your oil leaks.

I'd be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.

Everybody, who doesn't own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking.

Many mechanics, friends, people on Jeep forums who can’t see your Jeep from where they’re at, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?

  A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don't jump on the RMS/oil pan gasket bandwagon right off the bat.

Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons.

First off, the engine sits nose-up and any oil will run back to the RMS area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "$#!& flows downhill".

Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first.

   Revised 02-26-2013

 

thats what I've been doing. I was just hoping maybe if its dripping on the crosspipe then it could be said that it isn't the RMS. Its the one possible leak point that I don't want to have to fix.

[cruiser54]

 

 

 

 

Check distributor gasket/o-ring, oil filter seal, oil pressre sending unit, oil filter adapter o-rings (there are three of them and they may be very hard and brittle). The adapter is sometimes a bear to get off.Looking at your photo, there seems to be more oil on the passenger side of the crossover pipe and the pipe is back away from the RMS area. Have you checked transmission fluid level and for leakage from the transmission fill plugs or other fittings?Are you having to add engine oil between changes?What gasket did you use when you fixed the valve cover? If there is oil above the adapter, it's probably coming from the valve cover.This sounds like a shotgun approach but on our trucks you need to check everything.

I don't mean to thread jack. Just was wondering. You said "the pipe is back away from the RMS area" by that do you mean that a RMS leak won't drip on the cross pipe? I've had a leak on the cross pipe for awhile and havn't started my search for where its coming from, but was hoping it wasn't the RMS.

Use THIS to diagnose your oil leaks.

I'd be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.

Everybody, who doesn't own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking.

Many mechanics, friends, people on Jeep forums who can’t see your Jeep from where they’re at, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?

  A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don't jump on the RMS/oil pan gasket bandwagon right off the bat.

Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons.

First off, the engine sits nose-up and any oil will run back to the RMS area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "$#!& flows downhill".

Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first.

   Revised 02-26-2013

 

thats what I've been doing. I was just hoping maybe if its dripping on the crosspipe then it could be said that it isn't the RMS. Its the one possible leak point that I don't want to have to fix.

Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons.

 

 

First off, the engine sits nose-up and any oil will run back to the RMS area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "$#!& flows downhill".

[Dedaw]

Replaced oil sending unit yesterday, still puking like crazy. Have already replaced rear main and oil pan gasket (less than 2 months ago), valve cover (about 6 months ago) and did the valve cover mod while I was it. Rehooked up the front crankcase hose the other day as well. Left are the oil filter adapter and distributor gasket. I popped up the distributor cap and saw no traces whatsoever of oil under there, don't know if that matters or not. Looking at the underside of the adapter, it does not seem to have enough oil around it to be the cause. 

 

What are the odds the head gasket is puking out oil? I don't want to replace that if I'm going to have to R&R the engine anyways.

 

I changed the oil last Tuesday, and was down to about 1-2qts (pinky width or less on the dipstick) this morning when I checked it; that's including one day of not driving it. So roughly 3/4 qt a day.

 

As far as oil pressure, it bounces between 0 and all the way over to the right (WAY past max)- think I have a bad ground in my cluster that I need to address.

 

Think I answered every question I saw on here. 

[nitroxsteve]

It could be the head gasket but you will just need to check and see. It should not be hard to find with 3/4 a day leaking. When you are driving oil can blow about anywhere up, down, back, and even forward. don't forget you have a timing cover and front seal to look at while your in there. Try the purple power and a car wash and try to see the sources.

[Keyav8r]

Knucklehead - Dedaw said he had changed the rms, oil pan gasket and valve cover gasket within the past six months. So I was mentioning the other potential leak sources and noted the location of the crossover pipe and the possibility of a transmission leak. I also questioned oil usage and, based on his later response, it's evident it is an engine oil leak. As Cruiser said, the rms/oil pan are the low point on the engine so almost any leak will wind up dripping from there. And it can blow anywhere.

 

As has been said above, the first step is to clean the engine to locate the leak or at least eliminate potential leak sources from the list. Start at the top, with a clean engine and work your way down.

On my 88 I did the valve cover gasket (Fel-Pro), the distributor gasket/o-ring, the oil filter adapter o-rings, oil pan gasket (Fel-Pro), timing cover gasket, front seal, and rms (Fel-Pro double lip) and she don't leak no more. I did the timing cover and front seal because the timing chain and sprockets were worn out and the vibration dampener/crank pulley was separating.

Hopefully your leak will be simpler and your workload less.

[cruiser54]

Knucklehead - Dedaw said he had changed the rms, oil pan gasket and valve cover gasket within the past six months. So I was mentioning the other potential leak sources and noted the location of the crossover pipe and the possibility of a transmission leak. I also questioned oil usage and, based on his later response, it's evident it is an engine oil leak. As Cruiser said, the rms/oil pan are the low point on the engine so almost any leak will wind up dripping from there. And it can blow anywhere.

 

As has been said above, the first step is to clean the engine to locate the leak or at least eliminate potential leak sources from the list. Start at the top, with a clean engine and work your way down.

On my 88 I did the valve cover gasket (Fel-Pro), the distributor gasket/o-ring, the oil filter adapter o-rings, oil pan gasket (Fel-Pro), timing cover gasket, front seal, and rms (Fel-Pro double lip) and she don't leak no more. I did the timing cover and front seal because the timing chain and sprockets were worn out and the vibration dampener/crank pulley was separating.

Hopefully your leak will be simpler and your workload less.

Yup. And it's hard for us to see from our monitors. Clean and check. That's why I did the write-up. So ANYONE with decent eyesight and a dim flashlight could diagnose their own leaks.

[MancheKid86]

check the bolts on the valve cover and oil pain?

could have rattled loose since your torqued them uppon gasket installs?

[Knucklehead97]

Anywhere i should be careful hitting with a powerwasher in the engine compartment? Don't wanna break anything haha

[cruiser54]

Throttle Position Sensor and distributor. Cover them with sandwich bags.