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Old 08-17-2010, 04:35   #1 (permalink)
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Technician's advice sought: Terrible smoke even after stem seal replacement!

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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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Old 08-17-2010, 19:34   #2 (permalink)
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Re: Technician's advice sought: Terrible smoke even after stem seal replacement!

That is a little strange. What condition were the stem seals in that got replaced. Were thye damaged?. Just wondering if something is damaging the seals. Is the rocker ratio and camshaft lift still original spec?.
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Old 08-18-2010, 13:08   #3 (permalink)
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Re: Technician's advice sought: Terrible smoke even after stem seal replacement!

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(BTW Thanks for the response Lance)

Quote:
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.

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

Cheers,
Greg
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Old 08-18-2010, 23:07   #4 (permalink)
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Re: Technician's advice sought: Terrible smoke even after stem seal replacement!

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.
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Old 08-19-2010, 04:56   #5 (permalink)
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Re: Technician's advice sought: Terrible smoke even after stem seal replacement!

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Quote:
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.

Quote:
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.

Quote:
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
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Old 08-19-2010, 05:16   #6 (permalink)
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Re: Technician's advice sought: Terrible smoke even after stem seal replacement!

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Originally Posted by FairlaneGreg View Post
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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?
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Old 08-19-2010, 05:26   #7 (permalink)
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Re: Technician's advice sought: Terrible smoke even after stem seal replacement!

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 .
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Old 08-19-2010, 13:18   #8 (permalink)
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Re: Technician's advice sought: Terrible smoke even after stem seal replacement!

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Yes, I'm hearing what you are saying, but this happens on LPG too! (Injectors are bypassed on LPG.)

Someone has suggested possibly a faulty PCV. I might look into this.

Greg
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Old 08-19-2010, 13:53   #9 (permalink)
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Re: Technician's advice sought: Terrible smoke even after stem seal replacement!

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?
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Old 08-20-2010, 18:43   #10 (permalink)
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Re: Technician's advice sought: Terrible smoke even after stem seal replacement!

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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
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