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Car Forum / BMW Cars / April 2004Unleaded Gas in an Euro 82 635.
I heard from someone that older european cars should not use unleaded gas, Or you should add lead treatment to the fuel. Is there any truth in this? I have been using unleaded in my 82 635csi and I just want to make sure I am not damaging the engine or anything like that. thanks. "haunts" <sundu@bellsouth.net> wrote > I heard from someone that older european cars should not use unleaded > gas, Or you should add lead treatment to the fuel. Is there any truth > in this? I have been using unleaded in my 82 635csi and I just want to > make sure I am not damaging the engine or anything like that. There is *no* truth in that; at least for all BMWs. Floyd When unleaded gas started to appear, there was some worry that lack of lead in the gas would damage the valve seats. For more info do a google search on +unleaded +"valve seat" > I heard from someone that older european cars should not use unleaded > gas, Or you should add lead treatment to the fuel. Is there any truth > in this? I have been using unleaded in my 82 635csi and I just want to > make sure I am not damaging the engine or anything like that. > > thanks. Yes. If motor ok then just the timing had to be adjusted. I had a Merc that was 'converted' from leaded to unleaded. 3 HP loss in power, totally unnoticeable. If you are running fine now (no pinging) that you're probably ok. DAS  SignatureFor direct contact replace nospam with schmetterling --- > When unleaded gas started to appear, there was some worry that lack of > lead in the gas would damage the valve seats. [quoted text clipped - 7 lines] > > > > thanks. > I heard from someone that older european cars should not use unleaded > gas, Or you should add lead treatment to the fuel. Is there any truth > in this? I have been using unleaded in my 82 635csi and I just want to > make sure I am not damaging the engine or anything like that. It'll be fine on unleaded. Nice car :-) SignatureWho needs a life when you've got Unix? :-) Email: john@unixnerd.demon.co.uk, John G.Burns B.Eng, Bonny Scotland Web : http://www.unixnerd.demon.co.uk - The Ultimate BMW Homepage! Need Sun or HP Unix kit? http://www.unixnerd.demon.co.uk/unix.html > > I heard from someone that older european cars should not use unleaded > > gas, Or you should add lead treatment to the fuel. Is there any truth > > in this? I have been using unleaded in my 82 635csi and I just want to > > make sure I am not damaging the engine or anything like that. > > It'll be fine on unleaded. Nice car :-) Are you sure John? 1982 was long before even LHD European markets mandated catalytic converters. I know that by 1986/7 the cars were OK to run on unleaded... > Are you sure John? 1982 was long before even LHD European markets > mandated catalytic converters. I know that by 1986/7 the cars were OK > to run on unleaded... Most cars, no matter how old, that have aluminium cylinder heads are ok with unleaded - the material the valve seat inserts is made of is usually hard enough in practice for all but the very hardest driven vehicles. The main problem is with cast iron heads with no inserts. Signature*No husband has ever been shot while doing the dishes * Dave Plowman dave.sound@argonet.co.uk London SW 12 RIP Acorn Sometime in the mid 70s, continental Europe started using unleaded fuel, for some reason they didn't mention it to us Brits straight away, consequently when we took our cars on the continent we started having a few problems with cars burning out valves due to pinking (pinging) and in some cases seized engines, The lead in petrol acts as upper cylinder lubrication and increases the octane rating of the fuel, To overcome this problem, we added 1 or 2 shots of RED X fuel additive to a tank of fuel, This worked a treat on the cars of that decade, Until someone came up with the idea of re-routing the crank case breather pipe back in to the air filter box instead of breathing to atmosphere, this re-route helped enormously with the upper cylinder lube system, and also helped reduce the possibility of valve damage, and a small adjustment to the ignition timing , smoothed things out , So from the early 70s the continental European cars where built with this upper cylinder lube pipe system, and where quite happy running on either leaded or unleaded fuel or even a mix of both, all the 3s 5s 6s and 7 series models of that time could run on both fuels, as could the 2500s 2800s 30s 3.3s before them, Please feel free to correct any inaccuracies Regards Fitzy > > Are you sure John? 1982 was long before even LHD European markets > > mandated catalytic converters. I know that by 1986/7 the cars were OK [quoted text clipped - 4 lines] > hard enough in practice for all but the very hardest driven vehicles. The > main problem is with cast iron heads with no inserts. > Please feel free to correct any inaccuracies There are so many.;-) Pinking isn't caused by unleaded petrol as such - it's caused by using too low an octane - or by too much ignition advance. Many older UK cars have cast iron cylinder heads with the valve seats just being cut from these, and a fairly soft material used for the exhaust valves. Without lead, they quickly burn. You can either use a lead replacement - and Redex upper cylinder lubricant won't help, it has to be designed for the job. There are several products on the UK market. For a permanent cure, you need to have the head machined and hardened valve seats fitted, as well as sometimes harder exhaust valves. If you suffer from pinking on the UK 'normal' 95 octane, you can either use 97/8 'super', or retard the ignition, or use an additive to boost the octane. Probably the worst UK engine for suffering valve seat failure due to unleaded petrol is the good ol' BMC A Series dating back to the '40s as fitted to Minis, Morris Minors etc and therefore still plentiful. Later units were modified at the factory. More expensive units like the Jag XK are reasonably ok unless driven extremely hard - as is the ex Buick Rover V-8, but both of these have aluminium cylinder heads therefore fairly hard seats already fitted. Signature*It sounds like English, but I can't understand a word you're saying. Dave Plowman dave.sound@argonet.co.uk London SW 12 RIP Acorn > > Please feel free to correct any inaccuracies > [quoted text clipped - 3 lines] > low an octane - or by too much ignition advance. >>>snip>>> ...................................... Fitzy wrote,,, problems with cars burning out valves due to pinking (pinging) and in some cases seized engines The lead in petrol acts as upper cylinder lubrication and increases the octane rating of the fuel, .................................... Fitzy wrote,,,, and a small adjustment to the ignition timing , smoothed things out , ............................................................................ ....... Sorry for cutting & pasting, but it sounds like we are saying the same things here Dave !! Do we agree that the noise we hear (pinking or pinging) is caused by the valves being exploded back on to there seats due to advanced ignition settings, and/or low octain fuel, and when the explosion occures within the cylinder, some of the hot gasses created, escape past the still partialy open valve, this is what causes the damage to valves and/or seats, Fitzy > Do we agree that the noise we hear (pinking or pinging) is caused by > the valves being exploded back on to there seats due to advanced ignition > settings, and/or low octain fuel, No. ;-) It's caused by the mixture 'exploding' rather than burning evenly. If the valves were forced back onto their seats, something would bend. > and when the explosion occures within the cylinder, some of the hot > gasses created, escape past the still partialy open valve, this is what > causes the damage to valves and/or seats, It's the exhaust valves that suffer, and these are closed when the spark occurs. As I said, unleaded petrol of the correct octane will stop pinking on a vehicle designed for leaded - which was commonly in the UK of a higher octane than the standard unleaded these days. But even the high octane unleaded will allow valve seat regression on an engine where the valves bear direct on a cast iron head. Signature*INDECISION is the key to FLEXIBILITY * Dave Plowman dave.sound@argonet.co.uk London SW 12 RIP Acorn "I am enlightened" ;-) I agree Dave, about the exhaust valves being the hard working valves, but I have seen inlet valves burn out , almost like someone has had a oxy acetylene torch on them, indicating that the valve had not closed fully when the explosion/burn occurred now this could be because the valve adjustment was incorrect or the engine was subjected to prolonged pinking, Fitzy > > Do we agree that the noise we hear (pinking or pinging) is caused by > > the valves being exploded back on to there seats due to advanced ignition [quoted text clipped - 15 lines] > unleaded will allow valve seat regression on an engine where the valves > bear direct on a cast iron head. > but I have seen inlet valves burn out , almost like someone has had a > oxy acetylene torch on them, indicating that the valve had not closed > fully when the explosion/burn occurred now this could be because the > valve adjustment was incorrect or the engine was subjected to prolonged > pinking, Dunno. The usual result of prolonged pinking is broken piston rings or burnt crowns. Signature*Nostalgia isn't what is used to be. Dave Plowman dave.sound@argonet.co.uk London SW 12 RIP Acorn > > > I heard from someone that older european cars should not use unleaded > > > gas, Or you should add lead treatment to the fuel. Is there any truth [quoted text clipped - 6 lines] > mandated catalytic converters. I know that by 1986/7 the cars were OK > to run on unleaded... John, as usual, is correct. The two problems associated with unleaded fuel are valve seat recession in cast iron heads (no problem with BMW's alloy heads with hardened valve seats since - 1962?) and less resistance to detonation (again, no problem if ignition timing is adjusted to compensate). A catalytic converter introduces a *reverse* problem: it *must* have unleaded on which to operate so as not to destroy the catalyst. Not having one simply means you *can* run either leaded or unleaded fuel as long as these other two issues are considered. -- C.R. Krieger (Been there; done that) |
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