engine shakes violently when idling

[kevtherev]

I've just adjusted all the tappets,

Can you tell us what you did there?

or is it a reconditioned engine?

Engine seems to run fine but when warm and idle speed drops the engine swings violently from side to side.

the tickover speed could be too slow...it's quite high in these vans

[HarryMann]

Regardless, take the hint that one cylinder (hopefully they told you which one) is not working well at idle, burnt valve, or bad compressions for one reason or another... presumably they could see (On Crypton) good sparks to all 4 else they wouldn't have suggested a stuck tappet ?

Poor compression or plug oiling on one pot will often cause an uneven idle, but as the engine speeds up, compressions will improve (less time for escape) or an oiled plug will start firing

[scamperman]

Not as technical as engine probs i know but when i brought my van the engine moved excessively on tickover,new rear engine mounts and now rock steady.Just a thought,and a easy/cheap diy job aswell.

[lambrettalee]

the engine was running rich when i bought the van, could that lead to a burnt valve? a hand over the spark plug hole will test for compression right? other than that any ideas for testing the cylinders operation or is it a garage job.

a weak mixture would burn valves... gunsons do a cheap compression tester, try ebay for a second hand one or any motorist centre, very handy to have in your tool box, just screws in your plug hole and turn the engine over to get a reading

[HarryMann]

the engine was running rich when i bought the van, could that lead to a burnt valve?

Nope, unless apparently rich on idle, but weak under power.

Beg, borrow or buy a compression gauge as you must know whether No. 4 is down and then why? You cannot get an engine with a poor cylinder running right, so focus on that, you want to know the extent ... and does it show any signs of overheating under load.