Yet another head gasket failure

[Nevis]

I know of 3 Dexta's within a mile of where I live and so far all, including mine, have succumbed to head gasket failure!
I am going to help put the head & gasket on the latest at the weekend.
The chap had the valves done and replaced the head himself but it started leaking again very soon after.
He tells me that he head was not skimmed so what is the best way of checking that the head is flat and what limits would be recommended as I want to be able to check the head flatness before starting any work.

Regards Andy

[YorkshireDextaMan]

I don't think there are any limits . it needs to be flat. You could start checking for any low spots with a spirit level. they are quite flat. If the Gasket is blown there should be an indication on where to look . e.g between the cylinders,

[davysdexta]

hi,,you say the head gasket has gone ????? can you tell me is it building up water
pressure ,an air bubbles at radiator ,am interested to know ,,just had new valve
guides ,,n ,,valves ,,head gasket in mine ,,,perhaps i should have had it skimmed
and tested at same time ,,,am not sure yet if its ok ,,am havin doubts,
davy,,,

[Nevis]

I haven't seen this tractor yet so I don't know what it was happening.
Head gasket failure on my tractor only showed up by a few bubbles from the gasket area on the engine side - the cause was that the gasket had been replaced before but the head bolts were replaced upside down so there was not enough thread to protrude through the nuts and so the torque and therefore clamping force was too low. I had the valves done and the head skimmed as a matter of course and so far I've had no trouble.
On my friends Dexta which was sending plumes of water out of the radiator cap, we simply replaced the gasket without doing anything to the head and that has been fine also.

[Nick]

Hi there, i used a more antiquated way of checking the flatness of a head. Take a small oil can and fill it with diesel + paraffin and a bit of oil, put a small piece of cloth in the top and light it. Black the face of the cylinder head completely. Get a straight edge and scrape it along all surfaces and it leaves the pitted bits black!