Then one day no compression on said cylinder, Out with the spanners and off with the valve covers to find that the exhaust valve was stuck open, a flick with a screwdriver and the valve sprung back and it was up and running again, this became more frequent as time went by until a flick with the screwdriver no longer worked. Turning the valve with a spanner released the valve and away again.Having been unable to devote the time need to investigate and cure the problem, it was inevitable that it would finally fail and force me into sorting it.
The day finally came, I need to make a trip to our local Houshold Waste Recycing Centre, a trip that the Bradford makes more frequently after changes meant that taking a trailer needed an appointment and was practically imposible if you worked a normal 8 hr day, it was cold windy day with the wind blowing from the North onto my north facing drive, when the valve was completely stuck.
Off came the inlet manifold to reveal (as i suspected ) the manifold gasket was leaking water into the inlet, this had never been enough to emulsify with the oil or cause a hydraulic lock on the cylinder, more I feel as a weep through the gasket which is a cork type of material about 3mm thick, supposidley compatable with the fluids that it comes into contact with
The gasket after removal. the middle section crumbled away to nothing
The cylinder head was then removed and the cylinder unbolted and removed , a bit of a fiddle but it does come off, the plate on the inner wing needs to be removed if it is still fitted.
The cylinder on the bench with the valve stuck
Surface corrosion can be seen on the inlet valve and the surrounding area
The valve after removal with little evidence of the cause of the problem.
There was a build of fine rust on the last 10mm of the valve guide, you may be able to make out the brown on the valve guide.
This was cleaned out with a reamer the deposits on the valve were cleaned off and then polished up in a lathe
The above photo shows the cylinder after its inital scraping to clean of the surface, what is left showing is the rusty pitted surface around the exhaust valve area, as with most rust build up it looks much worse that it actually is
The cylinder head shows some light rusting but no pitting
The same thing after about 30 secs of work with a small grindstone in a dremmel
Note the condition of the exhaust valve seat
The engine was still running before the valve finally stuck , although on my last trip it certainlly was not right at all
Although the valve seat looks bad, again it was mainly rust pitting and quick regind with a seat cutter and the seat was restored to good condition,
The valve and seat were lapped back to one another again using a battery drill as the driver
The inlet valve was also re-lapped but required little attenion to achieve a good contact line
Inspection of the flange faces on the manifold revealed further corrosion with virtualy no material left between the inlet and water pipes right at the end.
Repairs had been effected previously in this area but further corrosion had taken place.
The manifold was set up on the milling machine and the flange faces skimmed to get at least a continuious face for the gasket to seat against.
Approximatly 2mm of material was removed to clean up the faces and bring them onto the same plane as one another.
both flanges were lower on their inside edges.This is realy a temporary solution, the maninfold will need welding up and remachining again fairly soon I feel.
Everthing was reassembled and the engine now runs much better than it has done for some time.
In fact it now ticks over slower and smother than it has done in the 40+ years that I have been it keeper.
It had always had a hick-up before which upset the tickover.
It has now been 5 weeks since this repair and everthing is still working well, with the engine running on both cylinders every time it is stared
I am puzzled by fact that if this problem has been caused by water leaksge from the manifold joint, why was there no corrosion on the inlet valve and seat also there was no trace line of rust showing where water had run down.
There was slight emulsification of the oil that was in the barrel but little other evidence.
The corrosion also took place it the upper area of the combustion space well away from where the water would have run to.
Maybe that time will present a different answer if some thing else presents itself.
The whole job took around five hours
Steve Gray
