Valve adjustments
 

Checked my valves the other day, and I just want some advice on what to adjust them to. My car always sounds a bit 5 cylinder, so I was hoping to find some of them very tight.

I checked them hot, following the advice in this thread (1.6TD):
http://www.brick-yard.co.uk/forum/th...opic33228.html

I'm confused by the figures shown though in the book. Why are the figures WIDER for a hot engine? I thought the rule was that everything expands, so clearances get less on a hot engine?

Cold Engine:
Intake = 0.15-0.25mm
Exhaust = 0.35-0.45mm

Warm engine:
Intake = 0.20-0.30mm
Exhaust = 0.40-0.50mm



These are my values at the moment. They all look to be at the low end, or just below spec, apart from 11&12, which are a bit tight. Is this enough to cause my engine to sound a bit 5 cylinder at idle when hot?


1 (ex) - 0.40 - 3.70
2 (in) - 0.22 - 3.90

3 (ex) - 0.41 - 3.85
4 (in) - 0.21 - 3.90

5 (ex) - 0.43 - 3.85
6 (in) - 0.25 - 3.85

7 (in) - 0.23 - (shim wouldn't come out)
8 (ex) - 0.43 - 3.80

9 (in) - 0.25 - (shim wouldn't come out)
10 (ex) - 0.41 - 3.85

11 (in) - 0.22 - 3.80
12 (ex) - 0.36 - 3.80

Some of those do look a little tight but probably not enough to cause much in the way of noticeable effects. Worth getting them into spec though and it might help a bit. Sometimes starting can improve too. With the valves the looser end of the spec is better than the tight end since the clearances grow smaller with time and miles (though slowly).

They give a warm spec and a cold spec but can be a good idea to check when cold since then the temperature is uniform. If you check on a warm engine, the first valves you measure will be at one temperature, then by the time you check the last ones, the engine temperature could change. More so if you get interrupted during the work, or spend some time fighting a stuck shim, etc. Those measurements won't cause any harm regardless but all else equal a cold engine may give slightly more consistent readings.

With these engines having a tall aluminum head with the cam mounted at the very top, I think the reason for clearance increasing on the warm engine is because the aluminum expands more than the ferrous metals used for the valves, lifters, and shims. There may be a more thorough explanation.

Yeh, I didn't think any looked particularly bad - only really 11&12 which looks obviously tight. I remember the last time I checked (5 years ago) they were right on the low end of spec. That's also the cylinder with the lowest compression reading.

I've ordered a few shims, so I can hopefully get them up into the higher end of spec. I'll do them cold this time, so it's not a race against time! Only did them hot, because that JX thread said they have to be checked with the engine "stinking hot".

Starting not really an issue - for an old bus with 228,000, and is a bit lower compression than she really should be, she starts really well.

This was this morning, completely cold engine, 3C outside:
https://youtu.be/GcIr7SvQvJ0

That does start very well. Has to be good shape all in all to allow it to do that.

Don't know why they would suggest to do it hot, cool engine is well accepted as the preferable way both for reasons of accuracy and easier/more pleasant work. Many engines only provide a cold spec... I suppose the only reason they gave a warm spec for these was to allow garages to work on them promptly when they came in for service without having to wait overnight.

Interested to hear if bumping up the clearance on that one cylinder improves it.

Perhaps I am not using the best tool choices for removing the valve cover but by the time I would finally be able to get the valve cover off, the engine would be way cooler than operating temp.! And approaching ambient by the time I measured the last few valve clearances!

BTW I use a combination of 1/4" drive 10mm socket + extension + 1/4" drive ratchet and/or pivot-head "breaker bar." I like to do final removal of the nuts with a magnetized socket, since I have managed to lose a few nuts thru the void between the intake manifold and head or elsewhere. :mad: Too bad the magnetic socket (think they call it nutdriver) is not deep enough to use for the whole process. Also it is not thin enough for the very frontmost corner nuts where access is limited by the rear plate of the front belt cover.

Has anyone come up with a more efficient method? Sorry for highjacking the thread. :o Needless to say, I have only measured valve clearances cold!