White Smoke help!

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Allanxantia
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Post by Allanxantia »

When I took the head off and skimmed it I never lapped the valves back in as I was not disturbing them. The soot in the inlet tract would explain if the inlet valve on cylinder two was not seated properly, allowing soot up into the inlet, it would also not fire well at idle due to low compression. Is the valve likely to reseat itself over time?
bxbodger
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Post by bxbodger »

You could leave the injector soaking in petrol overnight, it may help.
Valves don't normally reseat themselves- it would be nice if they did!!
jeremy
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Post by jeremy »

I'm with bodger on this - I saw the reference to oily soot in the inlet tract and had assumed you had ment the exhaust. Yes it can only get there due to a leaky inlet valve - and when you get it apart you will find that the valve and the seat is made of incredibly hard metal and is virtually ungrindable.
I always find a professional to cut the seats and reface the valves for me as I can't make a satisfactory job myself. Its also worth having a reaaly good look at the seat as it may be cracked. It is replaceable.
All the valves should be seated and ground in - as if one has gone the rest may not be far behind. the camshaft will have to be re-shimmmed (which can be done on the bench) and the guides should be examined for wear and if it has seals on the valve stems these should be replaced.
jeremy
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Post by NiSk »

Isn't the obvious next move to check the cylinder compressions before you rip it apart again?
//NiSk
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fastandfurryous
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Post by fastandfurryous »

Personally I'd have said that not pulling the valves apart and grinding them in while you had the head off was probably false economy. You will probably find that the compression is down, and that the valves have pitted corrosion in their seat area, especially the exhausts. You may also find that if the engine has been stored for a period, the valves that were open while the engine was stored won't seat properly now.
A leakdown test will confirm this too. This is where compressed air is piped into the cylinder while at TDC. You then see where the air is leaking.
If you do find the injectors are a bit beyond their best, then they're usually under £20 each for recon ones.
Allanxantia
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Post by Allanxantia »

yeah I am getting a loan of a compression guage, the machine shop that skimmed the head allegedly did a compression test and confirmed that the valves were seated correctly, will take the cam out and check that the valve spring, shim etc is OK. I will also stick some injector cleaner in just in case the valve is just a bit sticky.
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Post by Peter.N. »

Could just be that the valve is not seating due to lack of clearance but its strange that it should suddenly happen, I suppose its not bent?
G4EIY
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Post by G4EIY »

Hi Alan,
No need to do a compression test, just disconnect the electrical connection from the stop solonoid on the pump, then crank the engine over and listen to all the 4 pulses. If a cylinder is low on compression you will get a different faster pulse on that one.
You should get all the compression pulses similar.
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Brian
Allanxantia
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Post by Allanxantia »

I'll do that test and will take the cam cover off and check the clearance, if it is the valve seat, I am afraid I am not taking the head back off, Will just change the oil whack tons of injector cleaner down the inlet tract to try and get rid of any carbon on valve seat and run it till the MOT is up. The whole point of the car was a sub £200 economical runner as my office has moved and Imprezas do about 18mpg!
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Post by G4EIY »

Alan,
I have never used injector cleaner down the inlet, this will not clean the injectors, although it may work on valve seats.
Carry out that test I suggested, then you will know if it is a compression low.
If all compression are near equal, then it will most likely be an injector.
To determine which one it is, run the engine at tick over, and crack each diesel union in turn on the top of each injector, an the one or ones that make little or no difference to the running will be the culprit /s.
Cheers
Allanxantia
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Post by Allanxantia »

Thats my thoughts anyway Brian, I will not break the £200 budget. Even if it smokes a little bit it will do until Dec. Redex is fantastic stuff. Also if valve seat are not clear I reckon turning engine over until Cyl 2 inlet valve should be closed and pouring a ton of injector cleaner/redex might help!
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Post by citronut »

if you had lots skimed from head face and did not have valves sunk to corect depth you have probably bent some valves,or if you didnt have head presure tested whils of you may have a cracked head,also machine shop cant do a compretion test with head off the car regards malcolm
Allanxantia
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Post by Allanxantia »

What I should have said is the the machine shop did a pressure test on the head and also checked that the valves all seat OK. I called them today, They measured what they took off and assured me than since it was previously a 2 notch gasket that a five notch will definately be OK. They are very well respected and know their stuff. I suspect a weak valve spring or some deposits in the seat etc.
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