993 Double Topic - Oil v leaks & Fan belt(s)
Discussion
So I was off on a France & Belgium tour with my 3 boys last Saturday in my aging and leggy 911 and amongst the madness of packing for a trip away forgot to check the oil etc before I left. Having covered more miles than most it loses a fair bit of oil, which I am reminded about on most trips now as it drips onto the heat exchanger and smokes away in traffic, somewhat embarrassingly.
So On arrival in France I pulled into the first garage I came to to buy a couple of small (2L each) bottles of oil to top it up on the level waiting for the gauge to register and after about 2.5L I'm back where I should be. I usually follow the hundreds of discussed topics on the right Oil and (I think, from memory) use 10W60 which most seem to agree on. However, availability in the french petrol station was limited to 10W40 - I figured better to have that in there than run the engine too low.
Whilst in there, I also was a little shocked to see one of the two fan belts just lying there minding it's own business. Gave the appearance it had been that way for a while. Being a Saturday in August in France, there wasn't a great deal I could do about it, the fan was doing it's job and no battery lights on so had to presume the alternator was also doing its job and decided to plod on to our destination in the (probably false) security that at least I had taken out an RAC Euro policy for the trip.
800 miles later I have 2 observations to make for discussion.
1. Why are there 2 fan belts - I seem to be functioning perfectly well on just the one. Car ran beautifully in 35 plus degrees so no problem with cooling and a week and 800 miles would have been plenty to prove the alternator is functioning 100% surely?
2. On the oil front, I know it's not the optimal choice, but it seems to have also stopped leaking, presumably because 10W40 is that much "thicker" (I'm sure there's a better word), that it's not getting through whatever gaps the 10W60 was getting through? Now I have a conundrum - do I stick with the current oil and have no leaks, or go back to the "correct" oil and have to keep topping up (very) regularly, until I get the leaks fixed? On a 215,000 mile engine, the fix is probably going to be a rebuild and if that's the case then what's the harm in a bit of time on the wrong oil that defers getting the rebuild time as future rebuild would presumaby address anything that the 10W40 causes anyway...???
I may be spouting a load of complete tripe, and am happy to be told as such - let the debate begin!
So On arrival in France I pulled into the first garage I came to to buy a couple of small (2L each) bottles of oil to top it up on the level waiting for the gauge to register and after about 2.5L I'm back where I should be. I usually follow the hundreds of discussed topics on the right Oil and (I think, from memory) use 10W60 which most seem to agree on. However, availability in the french petrol station was limited to 10W40 - I figured better to have that in there than run the engine too low.
Whilst in there, I also was a little shocked to see one of the two fan belts just lying there minding it's own business. Gave the appearance it had been that way for a while. Being a Saturday in August in France, there wasn't a great deal I could do about it, the fan was doing it's job and no battery lights on so had to presume the alternator was also doing its job and decided to plod on to our destination in the (probably false) security that at least I had taken out an RAC Euro policy for the trip.
800 miles later I have 2 observations to make for discussion.
1. Why are there 2 fan belts - I seem to be functioning perfectly well on just the one. Car ran beautifully in 35 plus degrees so no problem with cooling and a week and 800 miles would have been plenty to prove the alternator is functioning 100% surely?
2. On the oil front, I know it's not the optimal choice, but it seems to have also stopped leaking, presumably because 10W40 is that much "thicker" (I'm sure there's a better word), that it's not getting through whatever gaps the 10W60 was getting through? Now I have a conundrum - do I stick with the current oil and have no leaks, or go back to the "correct" oil and have to keep topping up (very) regularly, until I get the leaks fixed? On a 215,000 mile engine, the fix is probably going to be a rebuild and if that's the case then what's the harm in a bit of time on the wrong oil that defers getting the rebuild time as future rebuild would presumaby address anything that the 10W40 causes anyway...???
I may be spouting a load of complete tripe, and am happy to be told as such - let the debate begin!
....best to do this in bits (to get my post-count up obviously.)
I'm not going to go mad into oil detail, but basically
For the UK climate, 10w40 is the 'correct' oil for that engine, according to the Porsche-of-old engineers that built it - the 10 is the effective viscosity when the engine is cold, rising to 40 when hot.
(aside note - we can argue later about the 10, and it can be 5, and some people say 0, but not many)
There is an old skool of thought that as engines wear, you increase the viscosity to 'fill the extra space' between all of the slightly worn moving parts in the engine.
Porsche, who used to insist on putting 0w40 into the 993 when they were selling and servicing the 996, now insist that you use their branded 10w60, no matter whether your engine is worn or not.
A few people in the States when tearing down the 993 engine at high mileages report very little wear - therefore I can't see the argument for using an oil that's too thick. All this does is rob the engine of power.
If you spend long periods with the engine at high revs, i.e. racing, I would use a 50 oil, but a 60?
Anyway - with your 215k mile engine, I would say as long as you use a quality oil, neither 40 nor 60 will do any harm, but ring up a few of the well-known indy servicing gurus, and ask their opinion.
So - management summary:
Question 2
10w40 is 'thinner' than 10w60 when it's at temperature.
10w40 is IMO the better oil.
What I would do is try and find where the oil is leaking from regardless of viscosity - common area is the lower cam-cover gaskets, which are cheap and it's only a few hours labour if that is where the oil is leaking from.
I'm not going to go mad into oil detail, but basically
For the UK climate, 10w40 is the 'correct' oil for that engine, according to the Porsche-of-old engineers that built it - the 10 is the effective viscosity when the engine is cold, rising to 40 when hot.
(aside note - we can argue later about the 10, and it can be 5, and some people say 0, but not many)
There is an old skool of thought that as engines wear, you increase the viscosity to 'fill the extra space' between all of the slightly worn moving parts in the engine.
Porsche, who used to insist on putting 0w40 into the 993 when they were selling and servicing the 996, now insist that you use their branded 10w60, no matter whether your engine is worn or not.
A few people in the States when tearing down the 993 engine at high mileages report very little wear - therefore I can't see the argument for using an oil that's too thick. All this does is rob the engine of power.
If you spend long periods with the engine at high revs, i.e. racing, I would use a 50 oil, but a 60?
Anyway - with your 215k mile engine, I would say as long as you use a quality oil, neither 40 nor 60 will do any harm, but ring up a few of the well-known indy servicing gurus, and ask their opinion.
So - management summary:
Question 2
10w40 is 'thinner' than 10w60 when it's at temperature.
10w40 is IMO the better oil.
What I would do is try and find where the oil is leaking from regardless of viscosity - common area is the lower cam-cover gaskets, which are cheap and it's only a few hours labour if that is where the oil is leaking from.
Edited by Orangecurry on Monday 19th August 13:05
Thanks OC - I had a funny feeling you'd be one of the first to reply on this one, especially on the oil part of the question!
So if I understand you correctly, 60 is actually "thicker" than 40? If that's the case I wonder why the leaks suddenly stopped? Or did I understand you wrong? Regardless, good to know that I can carry on using that oil.
and lower covers is what I had suspected (and hoped for too) - I'll get round to properly investigating one of these days...
So if I understand you correctly, 60 is actually "thicker" than 40? If that's the case I wonder why the leaks suddenly stopped? Or did I understand you wrong? Regardless, good to know that I can carry on using that oil.
and lower covers is what I had suspected (and hoped for too) - I'll get round to properly investigating one of these days...
60 is 'thicker' - why has a 'thinner' 40 stopped your leaks? Who knows (from a distance) but if you've only just noticed one of your belts has shredded 
perhaps you'd best give it a bit of time/use to check for leaks.
Question 1 is best answered by using google next time
perhaps you'd best give it a bit of time/use to check for leaks.Question 1 is best answered by using google next time
Pelican said:
The older Porsche's use a single belt to run both the cooling fan and the alternator. As displacement increased and there became higher demands on the electronic systems, Porsche designed an independent pulley system for the 993 alternator and cooling fan. The alternator fan pulley is smaller; meaning it will spin faster at idle to provide for the demands of the electrical system while the cooling fan pulley is designed to place the correct volume of air over the motor for the entire RPM range.
There are three belts on the 993 engine that drive the A/C compressor, the alternator and the cooling fan. The A/C compressor belt is the outer most belt and needs to be removed to replace the other belts. These belts like any belt will wear out over time. You should inspect all of your belts every six months for signs of drying out, glazing, cracking or separation and replace them at the first signs of deterioration.
https://www.pelicanparts.com/techarticles/Porsche-993/25-BASICS-Cooling_Fan_Belt_Replacement/25-BASICS-Cooling_Fan_Belt_Replacement.htmThere are three belts on the 993 engine that drive the A/C compressor, the alternator and the cooling fan. The A/C compressor belt is the outer most belt and needs to be removed to replace the other belts. These belts like any belt will wear out over time. You should inspect all of your belts every six months for signs of drying out, glazing, cracking or separation and replace them at the first signs of deterioration.
...and to add - buy your new belts from Porsche - yes you heard me correctly.
Porsche don't make belts, so why should I?
Well Mr Ocho, it seems that the aftermarket belts without the Porsche marking seem to be a tiny bit wider - sounds ludicrous I know, but many people who've fitted non-Porsche Gates, Continental or whatever, report the belts catching and snapping, so the advice on this occasion is buy Porsche.
Your next problem is 'what length'?
It's no good going by your VIN or asking the OPC - there was also a pulley revision which your car may or may not have - can you read the part numbers or length-markings off of the old belts? I hope you kept the shredded one.....
Porsche don't make belts, so why should I?
Well Mr Ocho, it seems that the aftermarket belts without the Porsche marking seem to be a tiny bit wider - sounds ludicrous I know, but many people who've fitted non-Porsche Gates, Continental or whatever, report the belts catching and snapping, so the advice on this occasion is buy Porsche.
Your next problem is 'what length'?
It's no good going by your VIN or asking the OPC - there was also a pulley revision which your car may or may not have - can you read the part numbers or length-markings off of the old belts? I hope you kept the shredded one.....
Ah, so presumably there's some sort of rudimentary clutch that means one belt will spin them both albeit and sub-optimal speeds and if you add the second you then get the spin speeds correct regardless of engine speed. Been mainly motorway driving so that would explain why no issues I guess.
It's used very much as a daily (hence the mileage!), so I don't open the tailgate to inspect as often per trip as many 993 owners I guess.
The oil change v leaks will have to remain a mystery then!!!
Thanks again OC.
It's used very much as a daily (hence the mileage!), so I don't open the tailgate to inspect as often per trip as many 993 owners I guess.
The oil change v leaks will have to remain a mystery then!!!
Thanks again OC.
Ocho said:
So I was off on a France & Belgium tour with my 3 boys last Saturday in my aging and leggy 911
.......
800 miles later I have 2 observations to make for discussion.
By the way, I sincerely love what you did/do, and it shows how well built, or over-engineered (in a good way) the old air-cooled engines, as well as your old-skool attitude to 4-up in a 993 across continents...........
800 miles later I have 2 observations to make for discussion.
Chapeau.
I went through a series of 3 belts at one point, the bearing on the fan was on its way out which snapped the belts through the drag.
I always carried a spare belt in the front and the bit needed to remove the lower pulley, never needed it in the end!
I’m sure I also saw the leaks lessen when I moved away from zero rated oil (100K miles).
I’d put billet lower cam covers on which leaked a lot, I switched these back to the formal Porsche ones and 90% of the leaks stopped. You need to do all the individual grommets around the mount holes at the same time.
Might be worth trying that also on yours.
Good on you for using the car well!
With 2 kids we also went touring around the UK and I fit a top box to carry the extra bits. Made a lovely tourer.
I always carried a spare belt in the front and the bit needed to remove the lower pulley, never needed it in the end!
I’m sure I also saw the leaks lessen when I moved away from zero rated oil (100K miles).
I’d put billet lower cam covers on which leaked a lot, I switched these back to the formal Porsche ones and 90% of the leaks stopped. You need to do all the individual grommets around the mount holes at the same time.
Might be worth trying that also on yours.
Good on you for using the car well!
With 2 kids we also went touring around the UK and I fit a top box to carry the extra bits. Made a lovely tourer.
Orangecurry said:
By the way, I sincerely love what you did/do, and it shows how well built, or over-engineered (in a good way) the old air-cooled engines, as well as your old-skool attitude to 4-up in a 993 across continents....
Chapeau.
Thanks - my 3 boys (17, 14 & 13) are quite happy to travel in style even if it does mean being somewhat cramped and hot (no A/C). The 14 year old is so good - I noticed at one point he was sitting awkwardly in the back and asked him why he didn't just sit back - his reply? "Daddy, I haven't been able to sit back for a couple of years - there isn't enough headroom!" - but they (he included) still want to go everywhere in it!!! Chapeau.
On the subject of belts, I have found that the belt OPCs supply for the air-conditioning compressor is actually too wide and therefore sits higher in the pulley's "v", which in turn means it doesn't allow sufficient adjustment of the belt tension and is always too taut.
An AX41 belt is what I now use and appears to be the perfect fit, and is also dimensionally a match for the original belt I removed. The original belt was, I believe, the factory-fitted one.
My car is a '94 C2. Later models may vary, of course.
An AX41 belt is what I now use and appears to be the perfect fit, and is also dimensionally a match for the original belt I removed. The original belt was, I believe, the factory-fitted one.
My car is a '94 C2. Later models may vary, of course.
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