Oil inside upper and lower intake?!?!?!?
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Cargo Master
Joined: Jan 2002
Posts: 2,079
Likes: 11
From: LA and CO
Oil inside upper and lower intake?!?!?!?
Guys,
Last weekend I pulled my upper and lower intake to fix a leaky (water port) lower intake gasket. My truck has 140K miles on it and the upper and lower intake had oil in it. The EGR (I think) inlet into the bottom of the throttle body was all oily and crusty when I pulled the throttle body off.
Why is this????
Truck is a 94 with a 5.0 and mass air, etc. Look in my sig....
The truck does use a little oil between changes. What is the pipe between the pass side lower intake and throttle body? The one that's wrapped in the heat resistant cloth.
Could it be bad valve stem seals? rings? clogged cat causing the combustion pressure to back up?????
I need help! The truck runs perfect, no smoke, inside of tailpipe is spotless! You could eat off of it! No flashing check engine on dash, nothing!
It had so much oil in the upper intake it spilled a puddle when I picked it up to put it back on the truck.
Other than this the truck is perfect. 140K on the clock and the lifter valley was spotless, as was the bottom of the lower intake. No gasket leaks anywhere, just a rear main seal leak that just started.
I need help! Just want to fix this problem.
Thanks,
John
Last weekend I pulled my upper and lower intake to fix a leaky (water port) lower intake gasket. My truck has 140K miles on it and the upper and lower intake had oil in it. The EGR (I think) inlet into the bottom of the throttle body was all oily and crusty when I pulled the throttle body off.
Why is this????
Truck is a 94 with a 5.0 and mass air, etc. Look in my sig....
The truck does use a little oil between changes. What is the pipe between the pass side lower intake and throttle body? The one that's wrapped in the heat resistant cloth.
Could it be bad valve stem seals? rings? clogged cat causing the combustion pressure to back up?????
I need help! The truck runs perfect, no smoke, inside of tailpipe is spotless! You could eat off of it! No flashing check engine on dash, nothing!
It had so much oil in the upper intake it spilled a puddle when I picked it up to put it back on the truck.
Other than this the truck is perfect. 140K on the clock and the lifter valley was spotless, as was the bottom of the lower intake. No gasket leaks anywhere, just a rear main seal leak that just started.
I need help! Just want to fix this problem.
Thanks,
John
Last edited by John7894; Jan 16, 2004 at 09:52 PM.
Posting Guru
Joined: Mar 2003
Posts: 1,349
Likes: 3
From: Cloud USA
Try changing the PCV valve, You may have a bit a blowby. Also check the little filter inside the airbox that is connected to the valve cover. It may be plugged up. If it runs fine I would just leave it. My Dads 302 did the same thing starting at that mileage and it has almost twice that many miles on it now. All 3 of us kids learned to drive that truck and none of us killed it! My oldest brother has it now(87 302 EFI)
Laughing Gas
Joined: Mar 2003
Posts: 877
Likes: 1
From: Colorado, U.S.A!
The pipe is the EGR line. I'd just clean the manifold and forget about it. Between PCV and EGR the intake just gets nasty after awhile. One thing you might consider is routing the PCV line to the vacuum tree on top of the upper intake via a tee in the brake booster line because most of the PCV flow is being directed into the #8 cylinder and a lot of folks (including me) seem to have problems with that cylinder due to the concentration of PCV flow into it. Running that to the vacuum tree distributes that between all the cylinders instead of just that one. Seen lots of posts on this lately.
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Cargo Master
Joined: Jan 2002
Posts: 2,079
Likes: 11
From: LA and CO
It's got a brand new PCV valve in it. The PCV is piped into the top of the intake forward of the vacuum tree from the factory. It's not piped into #8's runner. My truck doesn't have the breather inside the filter box either. Maybe I'll do a compression test and see if that turns up some positive signs of blowby.
It's just weird though, the truck doesn't smoke at all!!
NONE!
NEVER!
Not even when floored and ran up to about 85 mph. Could it just be that it's enough blowby to nasty up the inside of the intake yet not enough to show coming out of the tailpipe?
Thanks guys, keep the suggestions coming.
It's just weird though, the truck doesn't smoke at all!!
NONE!
NEVER!
Not even when floored and ran up to about 85 mph. Could it just be that it's enough blowby to nasty up the inside of the intake yet not enough to show coming out of the tailpipe?
Thanks guys, keep the suggestions coming.
Posting Guru
Joined: Mar 2003
Posts: 1,349
Likes: 3
From: Cloud USA
The only other thing I would check is timing chain play. My 93 460 with 206,000 miles had some bad blowby were oil was getting into the air filter box and the lower intake. I replaced the timing set and it went away. I think the retarded cam timing caused the exhaust valve to stay closed too long causing increased cylinder pressures
Posting Guru
Joined: Sep 2002
Posts: 2,420
Likes: 3
From: Langhorne, PA
That is probably normal for an old intake. Just took apart my 4.9L and found the same thing. I had 150,000miles, terrible blowby, a head gasket leak, and alot of oil leaks. In fact, when I layed the upper intake on the garage floor, it dripped for a couple days.
It didn't hurt a thing, I passed emissions beautifully, all these years, and all the sensors worked. The only problem that the gunk may cause, is a diminished vacuum if any of the ports on the manifold have a buildup around the tube. The oily carbon was inside my manifold vacuum tube, I wired brushed it out, sprayed it with Fuel inj. cleaner and compressed air.
CAUTION!!! If you start spraying things with cleaners to remove the mess, don't spray the throttle position sensor on the throttle body, it will melt.
It didn't hurt a thing, I passed emissions beautifully, all these years, and all the sensors worked. The only problem that the gunk may cause, is a diminished vacuum if any of the ports on the manifold have a buildup around the tube. The oily carbon was inside my manifold vacuum tube, I wired brushed it out, sprayed it with Fuel inj. cleaner and compressed air.
CAUTION!!! If you start spraying things with cleaners to remove the mess, don't spray the throttle position sensor on the throttle body, it will melt.
Post Fiend
Joined: Oct 2003
Posts: 6,214
Likes: 13
From: New Jersey
CAUTION!!! If you start spraying things with cleaners to remove the mess, don't spray the throttle position sensor on the throttle body, it will melt. [/B]
Sadly, I learned that the hard way a few weeks ago
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Tuned
Joined: Jun 2003
Posts: 489
Likes: 1
It's blowby. It isn't straight oil thats getting pushed there, but very oily gas that turns back into liquid. At 140K it isn't surprising that you would have it. I would do the suggested reroute of the PCV line to the intake plenum...it will ease your #8 cylinder which has been taking all the gases thus far. Blowby is caused by the rings getting more worn as time goes on...it is internal to the engine which is why you don't see it our your pipe. You should have a breather element in your airbox on your year...and you should keep an eye on it. You can run a long time this way, so unless your truck runs poorly, you might as well just leave it. I would keep an eye on your air filter/pcv/breather filter a little more often than you might have in the past.
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Cargo Master
Joined: Jan 2002
Posts: 2,079
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From: LA and CO
Maybe I'll have to take some pics to show you guys. My PCV is already routed into the intake plenum from the factory, almost dead center, yet forward of the vacuum tree. All intake runners were oily, not just #8.
Also, my truck does not have a breather in the air filter box.
My truck is factory mass-air equipped if this will explain anything. Someone told me it was rare for a 94 w/5.0 to be mass-air equipped. Maybe I got an early CA smog package truck.
Only piping that goes to my airbox is the intake snorkel from the top of the radiator support and the tube to the throttle body.
I'll do a compression test and check it out, maybe a leak down test too.
Blowby makes sense to me, since it was oily yet crusty like the EGR looks like.
Let me pose this question:
Do you think I could have a partially clogged cat as a result of this. If I've got this oily residue coming in from the EGR and the intake looks oily do you think the cat could be partially clogged with burned oil residue? My gas mileage does kind of suck and the truck seems like it could have a little more power than it should.
John
Also, my truck does not have a breather in the air filter box.
My truck is factory mass-air equipped if this will explain anything. Someone told me it was rare for a 94 w/5.0 to be mass-air equipped. Maybe I got an early CA smog package truck.
Only piping that goes to my airbox is the intake snorkel from the top of the radiator support and the tube to the throttle body.
I'll do a compression test and check it out, maybe a leak down test too.
Blowby makes sense to me, since it was oily yet crusty like the EGR looks like.
Let me pose this question:
Do you think I could have a partially clogged cat as a result of this. If I've got this oily residue coming in from the EGR and the intake looks oily do you think the cat could be partially clogged with burned oil residue? My gas mileage does kind of suck and the truck seems like it could have a little more power than it should.
John
Last edited by John7894; Jan 20, 2004 at 12:14 PM.
Senior User
Joined: Dec 2003
Posts: 404
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From: Groton, CT
John, you nailed it about the vacuum source for your PCV. When Ford redesigned the system for Mass Air, they finally changed the crappy design of the PCV system. 94 and up engines (late 94 with Mass Air) moved the PCV vacuum nipple from the back of the intake to the spot where yours is, just forward of the "vacuum tree"
I guess Ford engineers read the forum too. Ford Truck owners figured this one out years ago. I modified my 86 the same way the others describe. My 96 has the new PCV system, which solves the problem.
As far as the cat goes, I don't think that blowby necessarily contributes to a clogged cat. 140K miles of hard driving certainly will though. Loss of performance is one of the early signs of a clogged cat. There are many high flow cats on the market. I have a Magnaflow in mine.
I guess Ford engineers read the forum too. Ford Truck owners figured this one out years ago. I modified my 86 the same way the others describe. My 96 has the new PCV system, which solves the problem.
As far as the cat goes, I don't think that blowby necessarily contributes to a clogged cat. 140K miles of hard driving certainly will though. Loss of performance is one of the early signs of a clogged cat. There are many high flow cats on the market. I have a Magnaflow in mine.
Last edited by BigRedBronc; Jan 21, 2004 at 08:09 PM.
Tuned
Joined: Jun 2003
Posts: 489
Likes: 1
Blowby in itself won't cause anything with your exhaust...so it wouldn't be the reason to replace the cat. If you truck has run rich for a long time it could have clogged it. Easiest way to tell is to put a vacuum guage on the intake and drive the truck around. If you see the vacuum not returning to 19 - 21 quickly when you stomp on the gas, you have an exhaust restriction. Actually, as you increase the RPM's, the vacuum goes down and stays lower...at least that is what happened to mine when it clogged...due to running real rich.
Thread Starter
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Cargo Master
Joined: Jan 2002
Posts: 2,079
Likes: 11
From: LA and CO
Thanks guys,
I'll do the vacuum gauge test and see if it is a clogged cat. I've been wanting to go aftermarket with the exhaust anyway, maybe this will force me to.
This oily intake problem just threw me for a curve because my truck has always run real well since I got it in '96. It's never run rich but it has done alot of towing so I'll have to get the cat checked out.
Thanks again!
I'll do the vacuum gauge test and see if it is a clogged cat. I've been wanting to go aftermarket with the exhaust anyway, maybe this will force me to.
This oily intake problem just threw me for a curve because my truck has always run real well since I got it in '96. It's never run rich but it has done alot of towing so I'll have to get the cat checked out.
Thanks again!
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