Decoke + 500 miles = reset tappets?

[badfelafel]

A previous owner of my little car emailed me to say that the car hasn't covered many miles since he decoked the unleaded engine.

Therefore within 500 miles or so the tappets must be reset or the cylinder head gasket may fail.

What does this mean and why does it happen???? I'm learning, but this is way beyond me!

Any help, as ever, would be very much appreciated!

Thanks

Badfelafel

PS Have added a gallery to my webpage (see my signature)

[bigginger]

I'm not entirely sure why, but I guess the valve clearances change in that time, meaning the tappets need to be reset. It's an easy job if you have aset of feeler gauges, spanners and a largeish flat head screw driver, and is covered comprehensively in the Haynes manual. If you don't have one of them, A) get one and B) Ask here, and the procedure will be magically explained.

[Willie]

It is usual practice to re tighten the head nuts after a top overhaul as the new
gasket settles in very quickly, especially if it is a copper type head gasket.
Since tightening the nuts will reduce the valve clearances it will then be necessary to readjust them. The head nuts are tightened in a specific order
so you would be wise to obtain a manual.

[badfelafel]

Thanks! I have an elderly Haynes manual - are the newer ones improved or just the same?

thx

[bmcecosse]

Tighten the head down in the correct order to the correct torque setting - 44 ft lbf - and then reset the valve clearances. But why did he 'decoke' the head - this is not something normally done these days - and is this related to the overheating I wonder ??

[bigginger]

Thanks! I have an elderly Haynes manual - are the newer ones improved or just the same?

thx

Just the same, bad pics and all. The section you need is very clear though

[badfelafel]

time to put on my learning hat then and get some proper tools!

have never done anything more interesting than change an air filter

resetting valve clearances sounds interesting; and tightening the head sounds straight forward enough (i hope)

*is anything actually straightforward* !!

also looks like i'll testing the radiator out - but someone has offered me one that he thinks is A1 for £10, might be easier just to grab it!

[bigginger]

you'll need a torque wrench to tighten the head nuts - maybe borrow BMC's?

[Onne]

Do they do torque spanners then Andrew?

[bmcecosse]

Who are 'they' ??

Spare rad is always a good thing - for £10, grab it!

[Onne]

as in suppliers, and a pinch of salt

[Packedup]

Do they do torque spanners then Andrew?

Any spanner can be a torque spanner, if you have a series of springs, weights, measuring equipment... ;)

I used to use ratchet tight on everything, and have to say I've never had a head or crank bearing failure as a result, and I have a very heavy right foot. But I now very much stick to the torque wrench for major items like that, as I'm sure the poor accuracy (I have a 15 quid Argos thing) is still closer to the mark than my "Feels about right" approach!

[Onne]

Any spanner can be a torque spanner, if you have a series of springs, weights, measuring equipment... ;)

I guess in principle, that is all a torque wrench is!

Another bad joke down the drain...

[iddy]

I needed to buy a torque wrench when I had the head repaired - I took it to work to have the guys check it on their calibrater and it was 5 lbs out at 45 lbs. It was a cheapish one from Machine Mart, so I suppose I shouldn't be suprised.