    
Bob uk
Unregistered guest
Posted From: 94.197.122.73
| | Posted on Thursday, 02 October, 2014 - 11:02: |    |
Gaskets are non dynamic which counter irregularity in the mating surfaces and or slight movement due to thermal creep or movement caused by flexing due to the load of the mechanism working.
In the main paper or cork is used. Paper includes thick cardboard. Some paper gaskets are coated which when squeezed and heated bonds the gasket. This can be supplanted with gasket gloop when non coated paper is used.
Seals are generally dynamic. Some engineers think of static o rings as gaskets.
Seals come is all sorts. The type that us car owners are interested in are lip seals which seal rotating shafts.
Lip seals need lubrication and should weep slightly. Lip seals will wear the surface of the shaft. Cheaper stuff runs the lip direct on the shaft. More expensive stuff use a seal runner which is a sleeve that can be changed. Cheaper stuff can be sorted by not pushing the seal fully Home so that the lip runs on a new bit. If a seal is fitted to a grooved shaft then the lip may wear quick(er).
Newer rubber type gaskets are better than cork but if an engine that had cork gaskets is assembled properly then there's not a lot in it.
So if you have cork gaskets don't worry about it they will Work the same as when the car left the factory.
Scroll seals are simply a coarse screw thread that flings oil back in the engine. They work well and don't wear out ever. IMO they are superior to a lip seal. If a lip seal is used to counter excessive crankcase pressure the seal will leak.
There must be a way for oil from the rear main brg to drain away from the scroll or seal side to run away. Some engines have slots some holes some a gap.
Head gaskets are special gaskets made from copper, copper and fibre inside or compressed fibre with soft metal reinforced holes. Some gaskets are coated which bonds when squeezed and heated. Coated gaskets are the norm and must be fitted dry. No gasket gloop unless the makers say. On way to cure a blowing head gasket is not to fit one. I have done this with two strokes and a Ford cross flow engine, hermite gasket gloop only
Valve guide seals can be string ,an o ring or a rubber cap with a spring around the top. The last one is the most used and the best. A bit to good sometimes.
Water pump seals are usually carbon with a spring thrust. Sometimes covered with a rubber bellows that is also a seal to keep dirt away from the carbons. Eventually dirt gets past the bellows and may damage the carbons which eventually allows water to drip from the drain which is a new pump or overhaul.
Adhere always to the correct torque figures to ensure that the gasker has the correct nip, if the gasket is leaking then tightening more will not fix the leak, it can bend that area in and lift the bit next to it thus making the leak worse. So it's a strip down I am afraid. Check torque on bolts first especially sump pans. I have seen many not quite tight sump bolts on many different engines.
Silicon sealers are magic but be careful that it doesnot squeeze into the engine by using excessive amounts. I like to apply a thin bead bolt the bit on loosely to even the bead, allow the silicon to set a bit then torque up. No leaks. Do not use on autoboxes. Black colour is best because it doesn't show out like lurid orange stuff. Wynns do a self propelled sealer in a can which is good stuff.
All engines gearboxes rear axles leak oil, if it isn't leaking somewhere then the oil has leaked out already.
An excessive oil leak is a leak that drops oil on the floor.
"rubber" hoses are their own gasket. In general a hose in good condition fitted to a pipe in good condition should seal and not leak under a pressure of say 1 or 2psi.
Meaning that a Water hose should not leak with the radiator cap off before the hose clip is tightened. If it leaks before the clip is tightened then the joint is less than perfect. Although often tightening the clip cures the leak its not right because the clip is intended to stop the hose from expanding and sliding off. Clips don't need to be very tight just enough to lightly clamp the hose behind the lip off the pipe. The pipe and clip cannot go over the lip because the clip is too small.
I like to use wide stainless worm drive with 7mm af hex head and hide the buckle underneath the hose so that only a shinny band shows to give that uncluttered sleek look. Uncluttered engines are impossible on a RR V8, I try not to add to it. Some where under the bits is a RR engine.
(Message approved by david_gore) |