Fordnatics List Archive

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Mail From: (email redacted) (Eric F. Riggert)


In keeping with my promise to summarize responses to my 'Smelly 5.0L'
question last week, I have logged all replies (minus headers and
references to the original request) in the file below. Also attached
is a portion of the original problem.

The culprit (drumroll please...): The PCV valve was not in the intake
anymore. Judging from when this all started, I'd say the dealer
probably left it out when they had the intake off (another story). It
could have blown out on it's own, I suppose, although that is less
likely.

Many of the responses mentioned this - so I checked it first and bingo!
Thanks (to the whole list) for such a quick answer. To those of you
who are experiencing similar smells, take a look at that PCV valve!

Eric Riggert - '66 Mustang GT, '94 Mustang Cobra Coupe
(email redacted)

- -------------Summary of original Problem---------------------------
On a related note, I thought I should find out what this type of oil
usage should SMELL like. My '94 is going through one quart of (10W30
Valvoline) oil every ~2400 miles. Every time I drive this car I notice
a 'burning oil' smell after a few miles, when the engine has warmed up.
This smell is at its worst at stoplights, when the car is standing still
for a prolonged period of time (the smell makes its way through the
vents to the interior - where it nauseates me and any passengers...).
When we're moving, it's less noticeable (more fresh air). I can
minimize it by driving like an old lady (shift at about 2k to 2.5k,
light on the gas). Driving the car any harder makes it worse.

- -----------------Responses-----------------------------------------
Date: Wed, 14 Dec 1994 13:37:18 -0800
From: (email redacted) (Chuck Fry)

My '89 used to leak oil past the back end of the passenger side valve
cover. This looked like a rear main seal leak til I fixed it. That's
when the rear main seal *really* started leaking. :-(

The locations mentioned above are the most common places for a 5.0 to
leak oil. Rear main seal leaks tend to spray oil on the underside of
the tranny and onto the light-off catalysts. The latter location is
where my "burning oil" smell came from. Take a second look at the
underside of the car the next time you have it up on jacks.

A plugged-up PCV system can worsen existing oil leaks. Or (as has
happened to me) perhaps the PCV valve has popped out of its hole,
creating its own leak. PCV valves are cheap, although not easy to
locate on EFI 5.0s. The PCV valve on '86-'93 5.0s is at the rear of the
intake manifold, where it's difficult to see and only slightly easier to
reach. I imagine the '94-up motors have it in the same location, but I
haven't looked at one close up.

You mention the problem is worst just after an oil change. Is it
possible you're overfilling the engine with oil?

- -------------------------------------------------------------------
Date: Wed, 14 Dec 1994 15:26:21 -0700
From: Shannon Shirk <(email redacted)>

To me it sounds like a clogged cat converter. it could also be a faulty Ox
sensor, causing a rich fuel mixture, which in turn would cause the cat to
smell bad.

- ------------------------------------------------------------------
Date: Wed, 14 Dec 1994 15:43:24 -0700
From: Shannon Shirk <(email redacted)>

A competent dealer should be able to test it for you. Plus (it is a 94, right)
it should be under warranty and it should be free for the test and the fix.
If it is a definate oil-smelling thing, try the PCV valve--it could be clogged
or something.

- -------------------------------------------------------------------
Date: Wed, 14 Dec 1994 15:53:20 -0800
From: (email redacted) (George Chang)

Hi Eric,
I've never had a Mustang, but I have had three 5.0 liter
engines (in a Fairmont and two Crown Victorias). The only time I've ever
smelled burning oil is when some petroleum based fluid or grease gets on
some part of the exhaust system.
Transmission fluid can give you such a smell. So can grease from
a messy lube job or power steering fluid. I suppose air conditioner
lubricant can also do it, but I've never had THAT trouble.
I do have a bit of trouble with the filler cap/PCV holder on a
351W. After the gasket disintegrated, I improvised a gasket out of a
piece of cardboard. This "gasket" leaks a bit, so I either wrap a little
rag around it or I wedge a small rag below it between the valve cover and
the spark plug wiring. I estimate that I lose about a teaspoon every
thousand miles from this leak. From your description, you may well have
a leak like mine.
The most annoying time I ever had with oily smoke was when the
little 2" long cork gasket at the REAR of the intake manifold of a 289
started to leak. It took me the longest time to locate it because it
was behind everything. And it didn't take very much oil to make lots
of smoke.

- -------------------------------------------------------------------
Date: Wed, 14 Dec 1994 18:40:51 -0500 (EST)
From: JIM HURD <(email redacted)>

Hi Eric (and the list!)

I have been experiencing this same oil smell, but it is a 3.0L Topaz.
Can't find any leaks! Uses about a half quart of oil between changes
(3000 - 3500 miles), and used extra precautions on the last oil change
to be *sure* I did not spill any oil on refill or during filter change.

It seems to me that we (this is the wife's car) that first noticed
it about 6 weeks ago as out daytime temperatures begin to stay below
40-45degrees. Also, it is only noticable when we come to a stop light
or let the car idle for a few minutes - after it has warmed up. Can't
cpount the times I have raised the hood expecting to see oil running
down over a hot pipe!) Sorry to ramble on....

- -------------------------------------------------------------------
Date: Wed, 14 Dec 1994 16:52:58 PST
From: (email redacted)

I don't want to simplify too much, but does everyone know that the 5.0
has two oil drain plugs? I seem to remember someone having this problem
before and that was the culprit (not draining both sumps, but adding
the usual five quarts afterwards).

- -------------------------------------------------------------------
From: Mike Ford <(email redacted)>
Date: Wed, 14 Dec 1994 23:21:24 -0800 (PST)

One of the nice things about running synthetic oil is that it doesn't stink or
smoke like dino oil. I have noticed this with mobil 1 and Redline.

BTW the 69 cent a quart oil at Chief really stinks. I learned this by pouring
from the plastic bottle the wrong way and putting a good splash on the
headers.

- -------------------------------------------------------------------
Date: Thu, 15 Dec 1994 07:02:14 EST
From: (email redacted)

Eric,
I have a suggestion for you. Have you checked the PCV valve. The PCV valve
is located (in the worst place posible) at the rear of the lower intake
manifold. It plugs into a rubber grommet that doesnt always hold it in
very well. The rubber grommet even has the tendancey to fall out. This
sounds like your problem. The PCV valve could also be faulty. Pick up
a new one for 3 bucks at the Ford dealer, and try popping it in. Look
under the car and see if you have any oil dripping down the back of the block.
You will probably get some on the transmission crossmember. I blew my PCV
valve and the grommet out under boost a couple of times......

- -------------------------------------------------------------------
Date: 15 Dec 94 08:02:00 EST
From: "MIC DR. JAMES ROGERS, PH. D" <(email redacted)>

89 GT
I have the same problem. It seems to be worse after a long drive at
freeway speeds. I have seen a little oil around the rear of the pan
recently and will be going under the car soon to see if I can find
anything else. my consumption is about 1 quart every 3k, but this is just
an estimate. I have not seen any other evidence regarding a leak.