'96 aerostar 3.0 crankcase pressure?

[dying_aerostar]

Hi all,
Hope I have posted this in the correct spot, am new around here..
Been reading many posts here for a week or more trying to determine cause of problem with my aerostar. Have a 96 aerostar,3.0 motor, 138k miles. I bought it new. It has begun blowing oil from the dipstick holder, pcv valve was changed, all vacuum lines clear, no change. Great deal of fumes from breather tube which connects to fresh air intake behind air filter. Engine does not and never has smoked. Very little oil use since new, quart every 3k or so. Engine has never been even opened for work, has just been a rock until now. This all started about a month ago when this van
which started the first time every time became hard to start.
Frankly I figure there is so much blow-by the pcv system can't
clear it and the motor is near finished, but thought I would
post anyway. Only being driven sparingly now, oil from
dipstick gets on manifold and I'm crop-dusting. Any ideas out
there on how I might proceed, or maybe someone who has run
into this with a aerostar before?

Thanks

 

[StevieC]

to BITOG!

You have complete blow-by on one cylinder and its leaking all the compressed gas/air mixture into your crank case...

Check for compression on all cylinders one of your pistons has a hole in it or you have bad rings on one cylinder and this will lead to low or no compression on that cylinder compared to the others.

Highly unlikely that it's a valve problem because this wouldn't lead to lots of pressure into the crankcase as you are experiencing...

Either way that engine is now due for a rebuild...

Sorry the news isn't better...

 

[Chris142]

Is the PCV valve getting vacuum? Could the hose be colapsed or plugged? If not then you have major problems.

 

[Jeff3126]

I have an Aerostar w/ 110k miles and wonder about a rebuild when the time comes. I think it is cost-prohibitive.

 

[dying_aerostar]

Well I've thought that the motor might need a rebuild. The pcv
is getting great vacuum. Without a tester is not possible to
check compression at this point. Just don't have the equipment
here. Engine is not missing or have significant loss of power after it warms up. Although it is not like new, the power is
still pretty good. Probably time to decide if it is worth it
to dump any more $$ into the old van.

 

[StevieC]

You can try running the van and disconnect 1 spark plug wire at a time from the distributor cap/coil pack and see what kind of shaking response you get from the engine... If you get next to no response or none at all from one of the cylinders you will have pinpointed the problem.

 

[dying_aerostar]

Well StevieC that's a good idea. I just may try that. Actually,
I drove the van a short time ago. Took three tries to start,
misses in the beginning, then power increase. Felt quite
strong while driving it, but more oil spurting from dipstick
tube. Have felt the van miss before, seems that is not
happening here, but a cylinder could be weak as you suggest.
Luckily I don't depend on the van as have other transportation,
so can fool with this, even though it looks like 'the end'. It's
been a nice run with ol Aerostar. Own it fourteen years, no room to complain.

 

[fdcg27]

The Vulcan should not be worn out at only 138K.
Also, you note little smoke or consumption.
I think if you had a holed piston, you'd have plenty of smoke and consumption.
Take another, closer look at the PCV system.
Also, even if you had a compression gauge, testing compression on all six on an Aerostar would not be a fun project.

 

[StevieC]

Lots of engine I have seen with no compression on one cylinder from bad rings or holes in the piston produce no smoke.

 

[brianl703]

A cylinder with no compression on that engine would have the CEL blinking along with a misfire code. It's OBD II.

 

[StevieC]

Originally Posted By: brianl703
A cylinder with no compression on that engine would have the CEL blinking along with a misfire code. It's OBD II.
Didn't do it on my neighbours Ford Ranger that is a 99 with the same problem when it had it.

 

[dying_aerostar]

Well I didn't mention it before but I have no 'check engine'
light on. The motor is a bit tired though, definitely not
what it was, but I would notice a miss for sure, but maybe not
a weak cylinder due to blow by. From time to time this engine
has missed now and then, and the computer system is pretty
aggressive, puts the light on, it blinks and the darned thing
stays on for days when it happens. Usually a reset is needed.
There is a great deal of gas in the crankcase though, pcv has
super vacuum at idle, when pulled from the valve cover. The
gas then pours from the empty hole, as well as the fresh air pipe
connected to the air intake behind the air filter. Not good.

 

[brianl703]

Originally Posted By: StevieC
Didn't do it on my neighbours Ford Ranger that is a 99 with the same problem when it had it.

It should have; the Ford misfire detection senses the deceleration of the engine that occurs when the cylinder doesn't fire.

 

[StevieC]

I hear you and I have seen it blinking in Ford Crown Vic Taxi cabs where the engine is clearly "done" but I just wanted to let everyone know the possibility that it doesn't necessarily set a light as my neighbours Ford Ranger didn't.

Maybe he has enough compression but it's weak and letting most of the compression leak into the crank case.

 

[mechtech2]

I believe that you have a 'waste spark' ignition.
You can't just yank a wire and see if a cylinder is weak, because you are affecting TWO cylinders at once.
You can unplug injectors, though . Only for a short time. You may throw a code, which will have to be cleared.

From where I sit right now, the engine appears to be worn.

 

[StevieC]

Originally Posted By: mechtech2
I believe that you have a 'waste spark' ignition.
You can't just yank a wire and see if a cylinder is weak, because you are affecting TWO cylinders at once.
You can unplug injectors, though . Only for a short time. You may throw a code, which will have to be cleared.

From where I sit right now, the engine appears to be worn.

HUH?

If you unplug the wire to that cylinder it only affects that cylinder...

You would be right if he was un-pluging the power to the coil for that cylinder.

 

[brianl703]

He's right, it's a waste spark ignition ('96 wasn't coil on plug and Ford did away with distributors by then) and two plugs are wired in series, so pulling a plug wire will kill two cylinders.

If it's a V6, there are only 3 coils. Two cylinders per coil. The secondary of one coil is connected to two sparkplugs, therefore both sparkplugs fire at the same time and both wires must be connected for that to happen.

 

[StevieC]

I have done this on waste spark systems... Both don't have to be connected for it to work unless this particular engine is different pulling 1 wire will not affect the other cylinder.

Think about it for a moment... What if a wire was defective or a plug... Both cylinders would die? That would be 50% of the engine in a 4 cylinder.

 

[brianl703]

If you have access to a good scantool, you can run a cylinder balance test. If not you can do it manually:

1)Put a coin between the throttle stop screw and the stop.

2)Connect a tachometer or use a scantool to read the engine speed.

3)Disconnect the idle air control valve.

4)Unplug one injector at a time, noting the RPM drop for each injector. Write it down. A cylinder that does not drop the RPM as much as the others has a problem: Plugged/faulty injector or mechanical damage to the cylinder.

You could also do a compression test.

 

[mechtech2]

For anybody out there:

A 'waste spark' ignition fires TWO spark plugs at once.
One +to-, and the other -to+. They are in series.
[BTW, this is why some factory spark plugs are different for different cylinders. They only use platinum tips on the necessary side - replacements are double plats]
Yanking a plug wire will kill two cylinders. [And may hurt your coil.] The 'test' will therefore be inconclusive.