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Technician's advice sought: Terrible smoke even after stem seal replacement!

15K views 14 replies 6 participants last post by  FairlaneGreg 
#1 ·
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Hi guys, newbie here.....

I have a '95 4.0 litre NF Fairlane with 310,000 km on the clock. Its duel-fuel and regularly serviced.

6 months ago I put a reconditioned head on it and a month or so ago it began blowing smoke soon after start-up, as I drove away from home each morning.
So I took it back to the head reconditioner and he (free of charge) replaced all of the valve stem seals.

It still blew smoke, only after it has sat for 8-10 hours or more, in fact a month later it seems worse than ever now, actually quite embarrassing in fact!

I did a compression check on it a few days ago and it returned pretty good figures (considering the motor's age) of 180-195psi across all six cylinders. This represents a variation of less than 8%, quite acceptable I think.
So it seems that the compression rings, at least, are ok. Is there a check for oil rings?

As a matter of interest, No.4 spark plug was darker than the others, with oil residue around the base of the thread, so it seems its the problem.

NB: The car doesn't blow any visible smoke after it has been running for about 30-40 seconds, under acceleration or deceleration. It only blows smoke when its cold.

What is wrong with my car? I am tearing my hair out (what's left of it!) over this!

HELP!!!

Cheers,
Greg
 
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#3 ·
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(BTW Thanks for the response Lance)

What condition were the stem seals in that got replaced.
I think they said they couldn't see any real damage. They had intended to check each one and replace any damaged ones but (they reckon) they replaced them all just in case.

Is the rocker ratio and camshaft lift still original spec?
Completely stock motor mate. Haven't changed a thing.

Cheers,
Greg
 
#4 ·
It could be worn guides as opposed to poor seals. When the guide is worn the stem can rack over causing the seal to lose good contact and then the oil gets past.

I'd also be looking at leaking injectors.

Am I right in saying it only blows smoke on cold startup and then clears? You don't get smoke after idling for a minute or so like when you pull away from the lights or after a long downhill run with the throttle closed and when you get back on the gas you don't get a puff behind you?

If it's only doing it after sitting, it's not likely to be compression rings (the oil can't flow uphill). But you can recheck the compression and squirt a little ATF down the plug holes and see if the pressures improve much - the ATF will help seal worn rings but will burn off quickly on startup.
 
#5 ·
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Am I right in saying it only blows smoke on cold startup and then clears?
No, not right away. I can idle it for up to a minute or two then as I drive away it starts blowing the smoke. This only happens when the car has sat for 8-10 hours plus.

You don't get smoke after idling for a minute
No, though I did one time when I decided to rev it a little during warming up, rather than idleing it for a couple of minutes.

or so like when you pull away from the lights or after a long downhill run with the throttle closed and when you get back on the gas you don't get a puff behind you?
No, it's never blown any (visible) smoke after that intial take off in the morning. Once its warm there is no smoke in any situation.

To confuse matters even further, it didn't blow any smoke at all when I started it up this afternoon after work. (10 hours parked.)

Man, this is bizzarre. I must sound like I'm full of s...t! LOL! (I'm definatley NOT BTW!)

Cheers and thanks for all perserverence!

Greg
 
#6 ·
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No, not right away. I can idle it for up to a minute or two then as I drive away it starts blowing the smoke. This only happens when the car has sat for 8-10 hours plus.


No, though I did one time when I decided to rev it a little during warming up, rather than idleing it for a couple of minutes.


No, it's never blown any (visible) smoke after that intial take off in the morning. Once its warm there is no smoke in any situation.

To confuse matters even further, it didn't blow any smoke at all when I started it up this afternoon after work. (10 hours parked.)

Man, this is bizzarre. I must sound like I'm full of s...t! LOL! (I'm definatley NOT BTW!)

Cheers and thanks for all perserverence!

Greg
I reckon leaking injectors. The smoke is black not blue?
 
#7 ·
Agree with "yeah right" , if the valve guides or seals are gone you get blue smoke every time the car has idled for a short time and then revved up . Like the example of sitting at lights , then pulling away . It also tends to get worse as engine warms up to normal running temp . Leaking injectors sounds like a very feasible cause .
 
#9 ·
I think if it were a PCV issue, it would smoke all the time.

It really sounds like the classic symptoms of worn valve guides or bad valve seals, or both.

You say you put a reconditioned head on it a few months ago. Was it smoking before this? Why did you change head?
 
#10 ·
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No, it wasn't smoking back then.

I replaced it because the head gasket had blown and I took the head to be faced and found it had been overheated/softened by the previous owner.
The serviceman showed me that it was soft (drop ball test) and recommended I put a reco one on.

Greg
 
#11 · (Edited)
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Good news!
I think I have found the source of the problem....

I had the inlet manifold top off today while I put a coolant/heater hose kit in the car. (Taking it off gave me access to the two heater hoses that go through the firewall.)

Check out this photo........



Correct me if I'm wrong, but by my way of thinking this oil could only get there by one method; from the PCV hose through a (faulty) PCV.

The facts:
1. This "well" (the one with the oil sitting in it) is right where the PCV hose connects to the manifold.
2. As I stated in my first post; No.4 spark plug was darker (ie. oily).
3. The smoke only happened as I took off (accelerated).
4. Centrifugal force would send the oil towards the back of the manifold under acceleration, over the hump in the manifold .... into ..... you guessed it ..... No. 4 inlet port! (If not over the hump then perhaps between the inlet butterfly centre shaft and the hole it rotates in as vacuum rises under acceleration.)
5. The smoke has only happened once since I replaced the PCV. I believe this was due to the oil that remained in the manifold from before.

I have cleaned what remained of the oil from the manifold. I reckon my smoking days are over!

Greg :driver:
 
#12 ·
probably not. Why did you replace the head ? A new head seals up the top end and now
your oil is being sucked up from the bottom. Blow By. You have a lot of miles on that motor. You could get 6 months befor you will start burning oil again, Maybe. Upon acceleration you loose vacuum.
 
#13 ·
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thanks for the response chipset!

Why did I replace the head? (In December 2009 BTW) ..... http://www.fordforums.com/1339201-post10.html

You may well be right, but I'm still sticking to my theory. No.4 is the wet, oily plug, all others are beautiful (dry) light grey.

Surely blowby would happen when the motor is hot as well as cold?

If you read back over my original thread you'll see that this only happened when I took off on a cold motor, never again for the rest of the day unless the car had been parked for 8-10 hours and gone cold again.
I could drive it all day and it wouldn't blow smoke at all, not under acceleration or deceleration, hot start-ups, nothing.

Anyway, i'm just stoked that the new PCV has (it appears) fixed the problem.
Fingers crossed!

BTW, I know you are right about the drop in vacuum under accleration, I remembered that (ie realised I had typed the wrong thing) as I was driving to work this morning. :doh:

Cheers,
Greg
 
#14 ·
There are so many reasons or possibilities to your problem. A hot engine expands things.
Things get tight. One fouled plug tells me many things. anything form bad ignition to a
leaking compression problem to a leaking intake to a plugged oil return in the head. Do a
leak down test on the suspected cylinder. Are you sure it's oil and not antifreeze ? I've
actually seen an engine where the rings rotated and lined up. The oil burn or blow was
pretty bad but after a while the rings rotated again and everything was as good as gold.
I've only seen that twice in 50 years. Keep in touch. Never know. Maybe i can help.
Just saying what could be. what i've seen.
 
#15 ·
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Thanks chipset,

I have a leakdown test kit here so I'll do a test when I find a bit of time.

I don't think its an ignition problem because I fitted new plugs, (high performance) leads and a coil/distributor pack to it recently.

Yeah, it was definately oil, I dipped my finger in it before I soaked it up with a rag.

Your ring rotation theory sounds feasible. I guess there's no real way of checking this without pulling the motor down.
A piston with that many kms on it will have overly worn ring grooves i suppose, which could allow the rings to spin around more easily than a new piston I would imagine.
(Shame car pistons don't have ring holding pins in them like bike pistons do!)

I'll just keep driving the bugger I think. The smoke appears to have stopped now and unless it comes back and I get fined for it I might leave it alone!

Greg
 
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