Thats an interesting comment Malcolm, I'm not exactly sure which mechanism your talking about (I assume its the timing belt tensioner and I assume its loaded hydraulically?) but I will be very grateful to you and everyone else at Ryhope for your opinion. One thing I will say is that it is totally regular, suggesting a tappet and to my ear is nearside on the back rank of cylinders. See you soon.
Tappet rattle
Re: Tappet rattle
Re: Tappet rattle
A tappet is a small piston within a cylinder that sits over the valve stem and under the lobe of the camshaft. When the cam rotates it pushes the tappet down which opens the valve. Because engines expand as they get hot, the distance between the cam and the valve can change causing a gap to form between the tappet and the camshaft. It is this gap that causes the tapping noise, hence ... tappet. The change is usually an expansion and is 0.000014 inches for every degree F of temperature rise for every linear inch of metal (aluminium). Steel is about a third of that expansion rate. The expansion of the cylinder head tends to open the gap, whilst the expansion of the cam, tappet and valve stem combined, tend to close it again as they heat up, but because of the difference in the linear co-efficient's, the aluminium head always wins and you get an increase in gap clearance.fuerte wrote: ↑Tue Oct 09, 2018 8:11 amI know the name tappets but not sure where they are?Does the fuel get to them if sobworth putting a tank of v power by shell.It is supposed to clean up ceetain parts and it is generally agreed by some worth putting in occasionally even just a quarter of a tank.
When engine design changed to overhead camshafts, some clever chap invented (or borrowed) the hydraulic tappet which allows a little engine oil to enter the annular space (gap) between the tappet piston and cylinder, and take up the variable difference in clearance as the engine heats and cools. Thus when the tappet is working correctly, there is never a clearance and thus never a noise from the tappet. Clever stuff that helps an engine rev very fast but sound as smooth as the Probe does! My tappet is stuck for some reason! If you had fuel in that mechanism, you'd be in all sorts of trouble, Elaine. Its a gungy oil or wear thing! Or possibly Malcolm's belt pin. Time will tell and I'm sure the lads at Ryhope will be able to tell me!
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fuerte
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Re: Tappet rattle
Sunfly wrote: ↑Tue Oct 09, 2018 6:02 pmA tappet is a small piston within a cylinder that sits over the valve stem and under the lobe of the camshaft. When the cam rotates it pushes the tappet down which opens the valve. Because engines expand as they get hot, the distance between the cam and the valve can change causing a gap to form between the tappet and the camshaft. It is this gap that causes the tapping noise, hence ... tappet. The change is usually an expansion and is 0.000014 inches for every degree F of temperature rise for every linear inch of metal (aluminium). Steel is about a third of that expansion rate. The expansion of the cylinder head tends to open the gap, whilst the expansion of the cam, tappet and valve stem combined, tend to close it again as they heat up, but because of the difference in the linear co-efficient's, the aluminium head always wins and you get an increase in gap clearance.fuerte wrote: ↑Tue Oct 09, 2018 8:11 amI know the name tappets but not sure where they are?Does the fuel get to them if sobworth putting a tank of v power by shell.It is supposed to clean up ceetain parts and it is generally agreed by some worth putting in occasionally even just a quarter of a tank.
Thank you for taking the time to explain how things work.I have to rely on garages so .knowledge is power 2.i like to learn and know how stuff works.good luck with your car.i think probes never perfect and all different which is part of their charm which means we all have a unique car.they test you but it is worth it in end.
When engine design changed to overhead camshafts, some clever chap invented (or borrowed) the hydraulic tappet which allows a little engine oil to enter the annular space (gap) between the tappet piston and cylinder, and take up the variable difference in clearance as the engine heats and cools. Thus when the tappet is working correctly, there is never a clearance and thus never a noise from the tappet. Clever stuff that helps an engine rev very fast but sound as smooth as the Probe does! My tappet is stuck for some reason! If you had fuel in that mechanism, you'd be in all sorts of trouble, Elaine. Its a gungy oil or wear thing! Or possibly Malcolm's belt pin. Time will tell and I'm sure the lads at Ryhope will be able to tell me!
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