Tappet noise on start up, opinions and thoughts Please.
Discussion
Hi All, I have a 987 Gen II Boxster that has done 14000, its just three years old, full OPC history and still under warranty.
I work in Afghanistan from time to time and can be away for up to three months. I have owned 7 previous Porsche, from 964,993,996,986,987, all have been cherished and had similar use. My current car however is presenting with a horrendous top end rattle, I am guessing sticking Hydraulic tappet, when I leave it for a month or so when I am away. Now I am fully aware of how the hydraulic tappet works and understand oil drain off if let standing. I also understand that it may take a few moments for pressure to build up, an couple of minutes maybe, but would you say that TWENTY MINUTES is reasonable?
Each time I get back to it from being away the time it takes to clear gets longer, has anyone else suffered this problem, surely a tappet running dry for twenty minutes must be causing wear.
My OPC have been brilliant, but their hands are tied by Porsche , who have told me that there is noting wrong with my car, and that I should use it more often, that is seriously their response!!! So it appears you can't work overseas if you own a Porsche. Seriously I would appreciate any constructive feedback
I work in Afghanistan from time to time and can be away for up to three months. I have owned 7 previous Porsche, from 964,993,996,986,987, all have been cherished and had similar use. My current car however is presenting with a horrendous top end rattle, I am guessing sticking Hydraulic tappet, when I leave it for a month or so when I am away. Now I am fully aware of how the hydraulic tappet works and understand oil drain off if let standing. I also understand that it may take a few moments for pressure to build up, an couple of minutes maybe, but would you say that TWENTY MINUTES is reasonable?
Each time I get back to it from being away the time it takes to clear gets longer, has anyone else suffered this problem, surely a tappet running dry for twenty minutes must be causing wear.
My OPC have been brilliant, but their hands are tied by Porsche , who have told me that there is noting wrong with my car, and that I should use it more often, that is seriously their response!!! So it appears you can't work overseas if you own a Porsche. Seriously I would appreciate any constructive feedback
Thanks Guys for your replies.
Scary is a very accurate word, can't change the oil as is still under warranty and if you don't run with what they put in it you will invalidate the warranty.
Customer service from Porsche not the dealer is disgusting, I wrote to Christopher Craft the MD, and didn't even get a an acknowledgement, got a young lady from Customer services telling me to start it more often. This is what the technical department are apparently supposed to have said.
Wrote to the their head of PR here in the UK and didn't even get the courtesy of a reply. Arrogance and discourtesy seems in bread in Porsche UK, we will see what Germany has to say. Thanks again
Scary is a very accurate word, can't change the oil as is still under warranty and if you don't run with what they put in it you will invalidate the warranty.
Customer service from Porsche not the dealer is disgusting, I wrote to Christopher Craft the MD, and didn't even get a an acknowledgement, got a young lady from Customer services telling me to start it more often. This is what the technical department are apparently supposed to have said.
Wrote to the their head of PR here in the UK and didn't even get the courtesy of a reply. Arrogance and discourtesy seems in bread in Porsche UK, we will see what Germany has to say. Thanks again
PGSouthern said:
Hi All, I have a 987 Gen II Boxster that has done 14000, its just three years old, full OPC history and still under warranty.
I work in Afghanistan from time to time and can be away for up to three months. I have owned 7 previous Porsche, from 964,993,996,986,987, all have been cherished and had similar use. My current car however is presenting with a horrendous top end rattle, I am guessing sticking Hydraulic tappet, when I leave it for a month or so when I am away. Now I am fully aware of how the hydraulic tappet works and understand oil drain off if let standing. I also understand that it may take a few moments for pressure to build up, an couple of minutes maybe, but would you say that TWENTY MINUTES is reasonable?
Each time I get back to it from being away the time it takes to clear gets longer, has anyone else suffered this problem, surely a tappet running dry for twenty minutes must be causing wear.
My OPC have been brilliant, but their hands are tied by Porsche , who have told me that there is noting wrong with my car, and that I should use it more often, that is seriously their response!!! So it appears you can't work overseas if you own a Porsche. Seriously I would appreciate any constructive feedback
First I'd change the oil. The odds are the oil is diluted with unburned gasoline and water which makes the engine noisier at start up and at other times as well.I work in Afghanistan from time to time and can be away for up to three months. I have owned 7 previous Porsche, from 964,993,996,986,987, all have been cherished and had similar use. My current car however is presenting with a horrendous top end rattle, I am guessing sticking Hydraulic tappet, when I leave it for a month or so when I am away. Now I am fully aware of how the hydraulic tappet works and understand oil drain off if let standing. I also understand that it may take a few moments for pressure to build up, an couple of minutes maybe, but would you say that TWENTY MINUTES is reasonable?
Each time I get back to it from being away the time it takes to clear gets longer, has anyone else suffered this problem, surely a tappet running dry for twenty minutes must be causing wear.
My OPC have been brilliant, but their hands are tied by Porsche , who have told me that there is noting wrong with my car, and that I should use it more often, that is seriously their response!!! So it appears you can't work overseas if you own a Porsche. Seriously I would appreciate any constructive feedback
Next the zero lash lifter it not running dry as it is fed high pressure oil from an oil hole that is fed by an oil galley. The lifter is noisy as it has a bit of air trapped that causes the ticking. Under some conditions it can take some running to remove the air. 20 minutes is towards the upper end of what I have heard about 2nd hand.
If the engine is otherwise behaving ok and there is no CEL then Porsche is not likely to do anything. It doesn't help your case that the car sits unused for long periods of time. These cars, really all cars, like to be run once in a while and months idle is not the best thing for them.
Unless the oil/filter is prohibited or voids the warranty I'd have the oil/filter service done. Use whatever oil the OPC recommends: Probably Mobil 1 0w-40. A heavier oil is not really going to help. All you have available to you is a 5w-40 oil or possibly a 5w-50 oil. These over a long period of inactivity will drain away just like 0w-40.
One thing you might consider is using an oil additive. While Porsche does not recommend any and I am reluctant to advise one use an oil additive, Porsche techs have told me that for cars that see very infrequent use, they recommend Swepco 502 oil treatment. This has "Micronized Molybdenum Disulfide" which among other things helps reduce engine noise upon startup. I tried this additive a couple of times but noticed no change. However, my cars get used very frequently, seldom going more than a few days between use, and engine noise at startup is not a real issue. (However, as I touched upon above, both cars' engines are noticeably quieter upon startup after an oil/filter service. The oil as it is used gets thinner from the build up of unburned fuel and water.)
I think most of us can see that the oil pressure applies to the tappet and why it empties sometimes at the tappet left sticking down in the cylinder against the valve spring pressure if left for a long time - but I wonder if readers realise that the tappet itself only uncovers the hole that feeds it with oil under pressure for a short period when the camshaft lobe is not pushing the valve open. This is the problem when the oil is cold and there is already an air gap in the tappet - because the oil is too thick and flows too slowly to fill the tappet and expel the air in the short time it uncovers the feed hole - the air inside compresses instead and only expands again when the feed hole is aligned with the tappet but not long enough to gain ground on filling it - hence it takes a long time.
Older models with hydraulic tappets often had such a problem that you either had to leave them ticking over for half an hour - or if you drove them hard (to increase the oil temperature and reduce the viscosity) you could eventually get them to fill.
Thicker oil can be both a benefit and handicap. Once the tappet is full thicker oil will resist emptying longer when you switch off - on the other hand it also needs getting hotter to overcome the air pocket and fill the tappet once again if it has emptied. If you know you are about to leave the car for a period - driving it home the last 10 or 15 minutes on a light throttle and high gear (but highish speed) will help cool the oil (and the head temperature to reduce heat soak) and resist the speed that the tappet empties when you switch off.
The circumferential fit of the tappet in the housing is also an issue as is the pressure tightness of the actual tappet but usually changing them in such a low mileage engine makes no difference.
The 997 should not be as much of a problem as a 996 3.4 because the oil gallery feeding the tappets is less drained by the variocam unit than the 996 where the gallery that feeds one cylinder set also feeds the variocam unit directly and the hydraulic chain tensioner as well - so runs lower than system pressure and has several feeds to overcome.
The engine will empty the tappet within a short time of leaving the car from hot so starting it up during the period it is not being driven may not help except by hoping it comes to rest in a different crankshaft position that puts pressure on a different tappet than the one causing the problem. Unfortunately engines seem to like to stop in one or two positions every time due to different cylinder compression's on shut down.
I would suggest you arrange for someone to start and leave ticking over for 30 minutes once a week while it is otherwise out of commission and then you can tell if it indeed has a faulty tappet or the main agents (and some other contributors) are right - that it is because you are leaving it too long between drives.
Baz
Older models with hydraulic tappets often had such a problem that you either had to leave them ticking over for half an hour - or if you drove them hard (to increase the oil temperature and reduce the viscosity) you could eventually get them to fill.
Thicker oil can be both a benefit and handicap. Once the tappet is full thicker oil will resist emptying longer when you switch off - on the other hand it also needs getting hotter to overcome the air pocket and fill the tappet once again if it has emptied. If you know you are about to leave the car for a period - driving it home the last 10 or 15 minutes on a light throttle and high gear (but highish speed) will help cool the oil (and the head temperature to reduce heat soak) and resist the speed that the tappet empties when you switch off.
The circumferential fit of the tappet in the housing is also an issue as is the pressure tightness of the actual tappet but usually changing them in such a low mileage engine makes no difference.
The 997 should not be as much of a problem as a 996 3.4 because the oil gallery feeding the tappets is less drained by the variocam unit than the 996 where the gallery that feeds one cylinder set also feeds the variocam unit directly and the hydraulic chain tensioner as well - so runs lower than system pressure and has several feeds to overcome.
The engine will empty the tappet within a short time of leaving the car from hot so starting it up during the period it is not being driven may not help except by hoping it comes to rest in a different crankshaft position that puts pressure on a different tappet than the one causing the problem. Unfortunately engines seem to like to stop in one or two positions every time due to different cylinder compression's on shut down.
I would suggest you arrange for someone to start and leave ticking over for 30 minutes once a week while it is otherwise out of commission and then you can tell if it indeed has a faulty tappet or the main agents (and some other contributors) are right - that it is because you are leaving it too long between drives.
Baz
Edited by hartech on Tuesday 1st April 15:08
Baz, Many thanks for taking the time to give such a detailed description. Having had seven previous Porsche models over the past 14 years, and having lived a similar life of being away, and never having had this on any other models I was very concerned. However it would appear from what you tell me that I am going to have to make arrangements. I still think its crazy when my dear old mums ten year old Corsa can sit in her garage for three months over the winter and start as sweet as anything, yet my Porsche has to be started each week, something wrong somewhere.
But I bow to your knowledge and I thank you again .
Pete
But I bow to your knowledge and I thank you again .
Pete
PGSouthern said:
My OPC have been brilliant, but their hands are tied by Porsche , who have told me that there is noting wrong with my car, and that I should use it more often, that is seriously their response!!!
I think they are right, do you want me to give her a good old ragging for you? My rates are competitive.hartech said:
I think most of us can see that the oil pressure applies to the tappet and why it empties sometimes at the tappet left sticking down in the cylinder against the valve spring pressure if left for a long time - but I wonder if readers realise that the tappet itself only uncovers the hole that feeds it with oil under pressure for a short period when the camshaft lobe is not pushing the valve open. This is the problem when the oil is cold and there is already an air gap in the tappet - because the oil is too thick and flows too slowly to fill the tappet and expel the air in the short time it uncovers the feed hole - the air inside compresses instead and only expands again when the feed hole is aligned with the tappet but not long enough to gain ground on filling it - hence it takes a long time.
Older models with hydraulic tappets often had such a problem that you either had to leave them ticking over for half an hour - or if you drove them hard (to increase the oil temperature and reduce the viscosity) you could eventually get them to fill.
Thicker oil can be both a benefit and handicap. Once the tappet is full thicker oil will resist emptying longer when you switch off - on the other hand it also needs getting hotter to overcome the air pocket and fill the tappet once again if it has emptied. If you know you are about to leave the car for a period - driving it home the last 10 or 15 minutes on a light throttle and high gear (but highish speed) will help cool the oil (and the head temperature to reduce heat soak) and resist the speed that the tappet empties when you switch off.
The circumferential fit of the tappet in the housing is also an issue as is the pressure tightness of the actual tappet but usually changing them in such a low mileage engine makes no difference.
The 997 should not be as much of a problem as a 996 3.4 because the oil gallery feeding the tappets is less drained by the variocam unit than the 996 where the gallery that feeds one cylinder set also feeds the variocam unit directly and the hydraulic chain tensioner as well - so runs lower than system pressure and has several feeds to overcome.
The engine will empty the tappet within a short time of leaving the car from hot so starting it up during the period it is not being driven may not help except by hoping it comes to rest in a different crankshaft position that puts pressure on a different tappet than the one causing the problem. Unfortunately engines seem to like to stop in one or two positions every time due to different cylinder compression's on shut down.
I would suggest you arrange for someone to start and leave ticking over for 30 minutes once a week while it is otherwise out of commission and then you can tell if it indeed has a faulty tappet or the main agents (and some other contributors) are right - that it is because you are leaving it too long between drives.
Baz
While it is true the oil hole in the lifter bore is only aligned with the oil groove/hole in the lifter bucket at one point in the lifter bucket's travel up and down in the lifter bore, the lifter spends most of its time at the oil hole. I'm sure you are aware the cams turn at half the crankshaft's speed, so the valves remain closed the lifter stationary for a long time (relatively speaking) between the cam lobe coming around and pushing down on the lifter and moving it away from the oil hole. I observe from the lifter bucket at my desk the oil grove and hole are located towards the open end of the lifter bucket, away from the face against which the cam lobe presses. I expecd then this results in the oil hole in the lifter bore aligning with the oil groove/hole in the lifter bucket while the lifter is at its resting position with the valve fully closed.Older models with hydraulic tappets often had such a problem that you either had to leave them ticking over for half an hour - or if you drove them hard (to increase the oil temperature and reduce the viscosity) you could eventually get them to fill.
Thicker oil can be both a benefit and handicap. Once the tappet is full thicker oil will resist emptying longer when you switch off - on the other hand it also needs getting hotter to overcome the air pocket and fill the tappet once again if it has emptied. If you know you are about to leave the car for a period - driving it home the last 10 or 15 minutes on a light throttle and high gear (but highish speed) will help cool the oil (and the head temperature to reduce heat soak) and resist the speed that the tappet empties when you switch off.
The circumferential fit of the tappet in the housing is also an issue as is the pressure tightness of the actual tappet but usually changing them in such a low mileage engine makes no difference.
The 997 should not be as much of a problem as a 996 3.4 because the oil gallery feeding the tappets is less drained by the variocam unit than the 996 where the gallery that feeds one cylinder set also feeds the variocam unit directly and the hydraulic chain tensioner as well - so runs lower than system pressure and has several feeds to overcome.
The engine will empty the tappet within a short time of leaving the car from hot so starting it up during the period it is not being driven may not help except by hoping it comes to rest in a different crankshaft position that puts pressure on a different tappet than the one causing the problem. Unfortunately engines seem to like to stop in one or two positions every time due to different cylinder compression's on shut down.
I would suggest you arrange for someone to start and leave ticking over for 30 minutes once a week while it is otherwise out of commission and then you can tell if it indeed has a faulty tappet or the main agents (and some other contributors) are right - that it is because you are leaving it too long between drives.
Baz
Edited by hartech on Tuesday 1st April 15:08
Even though the lifter is pushed down and the oil groove/hole move away from the oil hole in the lifter bore, the hole is never uncovered. I would expect though a bit more oil escapes through the "gap" between the lifter bucket and the bore but this is on purpose, to splash lubricate the lifter bucket face as the cam lobe presses against it as the valve is opened.
Upon starting an engine that has sat a while unused and was shut off fully up to temperature, so the oil has plenty of time and the right conditions to drain away, the valve clatter and chain noise goes away after just a moment or two, even I note with my Boxster engine and its 277K+ miles. The oil flows quite readily to the oil passages even in the heads and then on to the lifters.
In the case of the OP I think something a bit extraordinary is going on. Say the engine was stopped with the lifter holding the valve open. This I'm sure will over time force the oil out the zero lash adjuster. However, no air will flow in until the engine is restarted. If there is a bit of an air pocket in the oil galley then this air can inflate (so to speak) the lifter. This air can be helped along by the onrushing oil from the pump.
Even with no oil film the lifter fit is such the zero lash adjuster will keep air in and act as an air spring even at my desk, where I have a new intake lifter from a VarioCam engine and a new lifter from a VarioCam Plus engine (this lifter with its variable lift feature). Both have been degreased and yet still the zero lash portion is springy when assembled and I attempt to squeeze the two ends of the zero lash adjuster together. The fit is very close, a very precise/sliding fit. This is the only seal that keeps the oil in the zero lash adjuster from being pressed out while the lifter is under pressure as the valve is opened.
Anyhow, so what happens is some air gets trapped in the zero lash lifter portion. Obviously, this lifter will not be dry but have a good film of oil, and thus this air is going to have a tough time getting out.
It will take some running and some oil above cold to replace this air with oil.
This is what I think is happening in the case of the OP's car.
Although the engine wouldn't work of course if the cams ran at engine speed it would actually not make any difference to the tappet fill rate if it could being twice as often for half the time.
The holes do align for about two thirds of the time but then with a cam lift of about 11mm and 3mm holes it does not when the lifter is under increased valve spring pressure.
The air compresses under lift so when the holes align again the pressure fights against the incoming oil and with such a small hole thick oil flows more slowly - slower than the rate that colder thicker oil can escape from the tappet allowing the air to escape with it - often failing - hence you can shorten the time to fill the lifter by driving the car fast and getting it really hot. I wouldn't necessarily advise this it is just a fact that experience brings and demonstrates that the viscosity, flow rate and temperature are factors. It would be almost impossible to bleed the tappets if they did not have a small leak path via the fit of the parts and the gaps enabling them to move but if old ones leak more readily than new ones - the problem can become worse.
Sometimes if the owner never drives the car fast or under high acceleration - the lifters never recover.
Baz
The holes do align for about two thirds of the time but then with a cam lift of about 11mm and 3mm holes it does not when the lifter is under increased valve spring pressure.
The air compresses under lift so when the holes align again the pressure fights against the incoming oil and with such a small hole thick oil flows more slowly - slower than the rate that colder thicker oil can escape from the tappet allowing the air to escape with it - often failing - hence you can shorten the time to fill the lifter by driving the car fast and getting it really hot. I wouldn't necessarily advise this it is just a fact that experience brings and demonstrates that the viscosity, flow rate and temperature are factors. It would be almost impossible to bleed the tappets if they did not have a small leak path via the fit of the parts and the gaps enabling them to move but if old ones leak more readily than new ones - the problem can become worse.
Sometimes if the owner never drives the car fast or under high acceleration - the lifters never recover.
Baz
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