Hi Fellas, Ever since I had my 2.9 12v it has had one ore two noisey tappets, not too bad but enough to notice, then yesterday I serviced the engine, all the usuals including fully sinthetic oil made for Older engines, the car sounded a bit tapepety as usual when I finished last night, then this morning when I started the engine I thought that the usual noisey tappet was about to fall out of the engine, what a noise ! I thought right this is too much for me I will take it to my local friendly mechanic mate, 500 yards down the road at a slow pace the engine went totally quiet and I think even quieter than before !
I havnt started it since, should I be worried for the future and what should i Do if it happens again ?
Sam, The 12V engines have hydraulic tappets set into the engine block. The reason that this was done is to make the tappets self-adjusting and to reduce emissions. They work by interposing a closed chamber of oil inside the hollow tappet, so that as wear takes place up on the pushrods and rockers the oil fills the gap and maintains the proper clearances. A common situation is that the tappets themselves wear and need more oil in order to fill the hydraulic chamber, while the oil pump itself is also wearing and unable to bring the pressure up enough to fill the tappets. This delay in filling the tappets is why you hear the rattle - it is empty tappets clattering until the oil fills the chambers - until they are full and then the engine goes quiet as you describe. Extended use of cheap oil or lack of oil changes can also cause the oil galleries to partially block with gunge, tar and oxidants, exactly like furred arteries in a human, the flow of oil is reduced and lengthens the time to fill the tappets. Another cause is to use an oil that is too thick for the engine when cold, or an oil that is too thin and causes the tappets to drain completely into the sump while standing overnight. I notice that you used a synthetic oil - that is good, but what viscosity was it? It is best practise to use the recommended grade of oil - (ie 5W-30 as the original grade, later revised to 10W-30 in semi-synthetic), and only go up one grade of oil ie 10w-40 as the engine has worn. Too great a shift of oil grade can cause noisy tappets.
Check the viscosity of the oil you used. If the tappets remain very noisy when you start it, you might consider using and Oil Treatment before the next change and this might help to remove some tar from the oil galleries.
The only real cure for this would be to recondition the engine. A high mileage engine has wear in the main bearings, oil pump and tappets and this all contributes to a loss of oil pressure at starting.
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There is also 1 more thing it could be...... Mine did exactly the same thing andbit turned out to be the oil preasure release valves on the top of the engine. I had them replaced at about £30(parts only no labour). wulla noise stop & now sweet as a nut.
Thanks Fellas for your replys, Its funny since the first time this clattering happened it has done it once again from cold and twice when warm and left for about 2 hours in between, all of this within the last week, since then being the last 3 days, no rattle, nothing from cold or warm situations, sounds like it could have been a blocked oil gallery or similar anyway as far as i can tell all is back to normal, as normal as it can be !
Eric for your info it has 10w - 30 fully sinthetic saying on the tin " specially designed for high mile engines" I will consider changing oil preasure release valve if the problem continues !
Yes - I could have kicked myself when I saw your last - I have read somewhere that after changing oil from ordinary to synthetic there can be some frothing as the oil mixes, especially in closed chambers like the hydraulic tappets. The new oil takes some time to replace the old stuff inside the tappets and this would cause the tapping until it does. This is what it appears to be.
From now on stick to the synthetic - I've used semi-synth Magnatec now for 7 years and the inside of my engine is as clean as a new pin.
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