White valves

[beforethevision]

Gday All,

I have pulled the head of my rover 1.8L K4, from a freelander used monthly as a rally car.

The head has been ported, new valves, cut cams, vernier timing etc, and has been running very well. Recently it was hard to start and misfired after a cold start. I suspected the head gasket so pulled it.

I found 3 things,
1) as expected, leakage of oil and water across the barrier of cylinders 1 and 2.

2) the exhaust valves of cyl2 are white...

3) the exhaust valves of cyl2 are not returning nicely, ie not always fully returning. This head has had interference damage, but has been remachined and valved since.


My questions is, whats making the exhaust valves white? and why would they not be returning? Would uprated springs be an easy solution?

Cheers!
Colin.

PS. sorry if it seems a stupid question...

[kimbo]

Obviously from the pictures something specifiic to No.2, therefore not fuelling.
If you suspect your head gasket was blown, possibly water getting in to No.2.
Guess that the valves and / or guides are gummed up (K series are prone to this IIRC).
Head gasket failure probably due to a dropped liner (again, something that the K series is well known for).
Kim

[beforethevision]

the cyl liners are nice and stable, but yes, i was running the standard duty gasket at the time, so im not suprised.

Im just interested in what burns them to a white colour? It could be glycol, oil, or torched from an exhaust valve not closing properly.

I doubt fuelling, as it would idle smooth after about 30 secs from start.

Interesting what you say about the K series valves, ive never had the issue, but you suggest the guides get pretty sludgy? Does this also effect the hyraulic lifters? I use 5-10W30 oil, and change it often, although it does get heavy offroad use.

Worth fitting uprated springs?

Cheers!

[phoenix]

It looks to me like cylinder two is running lean - this could also explain the msifire on cold startup. Could it be an injector??

[beforethevision]

Originally Posted by phoenix

It looks to me like cylinder two is running lean - this could also explain the msifire on cold startup. Could it be an injector??

I dont think it would be fuelling, but i will connect up the fuel rail and pulse them, see what happens. The change in spray pattern should be obvious? Anything else that could make it run lean? Would the exhaust valve not clsoing fully allow exhaust gas back in?

Cheers!

[kimbo]

Agree that colour would normally show lean mixture. Possibly a duff injector.
Or possibly effect of water getting involved in the combustion process.
Valve gumming up can be caused by oil burning, i.e passing the rings, or down the valve guides. On inlet valves also sometimes caused by poor quality petrol depositing impurities on the back of the valve.
Kim.

[banger_racer]

Lookslike its a fuel problem to me, have to agree with others who have said its a injector problem. Don't just check spray pattern check amount of fuel flow it and check it matches others.

[ss_collins]

when I read the thread title I just though Lean... would be my first port of call. Hard to see from that pic but what are the plug electrodes like?

[beforethevision]

Ok, thanks for the replies!

I have pulled the injectors to take them somewhere for a proper inspection.

I have since stripped the head down, here are the pics of the plugs, in order, 1 being closest to the camera.

The electrodes, especially the tips are clean.

[NiG_21]

No 2 plug is also showing sign of running lean... so getting those injectors back nice and clean will more than likely help.

[tristancliffe]

If the exhaust valves aren't closing fully (if that is what you mean by not returning) then that will complete alter what happens in the cylinder. Lower compressions (through leakage) could result in incomplete combusion, and give the impression of running lean.

Whilst there is no harm checking the injectors, I'd sort the value problem out and retest...

[AU N EGL]

Or the reverse:

Cylinders 1, 3 & 4 are too dark. too rich and incomplete combustion. When we pull heads and see that dark scoring, our first though is poor combustion, and too much carbon build up as a result.

Did you do a leak down test?
Compression test before removing the head?
What was the AFR?
and the Octane you run?

[Al Weyman]

That looks leaned out to me. Could the reason they are not returning be that they have got so damned hot they have stuck in the guides?