+- Austinsevenfriends (https://www.austinsevenfriends.co.uk/forum)
+-- Forum: Austin Seven Friends Forum (https://www.austinsevenfriends.co.uk/forum/forumdisplay.php?fid=1)
+--- Forum: Forum chat... (https://www.austinsevenfriends.co.uk/forum/forumdisplay.php?fid=14)
+--- Thread: Working out a head gasket failure (/showthread.php?tid=9551)
RE: Working out a head gasket failure - John Cornforth - 01-09-2024
Hi Andy
If you raise the CR, and possibly also raise the effective compression by restoring valve sealing etc, you will increase the peak pressure in the cylinders when they fire. Its this pressure peak that generates harsh or rattly noises, especially around 2000 RPM / 30 MPH in top when the throttle is open for acceleration or hill climbing. It's not actually pinking if you are using normal petrol, its octane is way more than needed for a seven even with a "high" compression head.
Reducing the advance a tad will tame the peak pressure without dropping the mean pressure very much. Set the timing to wherever the engine feels happiest on the road.
RE: Working out a head gasket failure - Ian Williams - 02-09-2024
littlie well kneaded plasticine will tell you if you have enough valve clearance.,
RE: Working out a head gasket failure - Terrytuned - 02-09-2024
On an assembled engine turn over on handle untill valve is at full lift then lever up the tappet to check how much clearance between valve and c/head. Terry.
RE: Working out a head gasket failure - Andy Bennett - 08-09-2024
Finally had the opportunity to have a free couple of hours to tinker.
Timing all sorted after a few runs and minor adjustments and all running nicely now. Had a couple of runs out and head seems to have settled.
But...
I have had an oil leak from the rear of the engine for a while now. I had previously had a loose nut between block and crankcase which had resulted in similar, I also wondered if it was the valve cover seal.
As I had added water to the area from removing the head I thought I would take the valve cover off to check and reseal etc and investigate the oil leak. Long story short, the nut was tight and I resealed the cover. In then cleaning everything up and running the engine the source of the oil became clear:
I haven't had to replace an oil pump before but if my understanding is correct this is just a 'loose' cover with gasket underneath and which is held in place by the block?
If so, other than removing the block to gain access to renew the seal it seems I have little choice but to add something like RTV silicon in the hope that it covers and seals?
Andy
RE: Working out a head gasket failure - Ruairidh Dunford - 08-09-2024
Clean the surface with carb/brake cleaner (compressed air helps) and smear a small amount Sikaflex around the joint area.
Leave over night and it should stem the flow…
RE: Working out a head gasket failure - Andy Bennett - 08-09-2024
Thanks Ruairidh
I guessed gunk of some type was my short term option. Will give it a go.
Andy
RE: Working out a head gasket failure - Andy Bennett - 09-09-2024
Just to round this one off. Sikaflex applied last night. Run this morning and nice and dry.
All I need now is that Indian summer we have been promised.
Andy