E28s have odd-sized headlights but E28-based E24s have the same-sized headlights.

Interior is different as well (door cards, dash pod etc), front suspension is different, rear suspension is different, front wheelarch flares are slightly larger on e28-based cars.

Check your VIN on realoem.com and look for parts compatibility- they are dated.

hth

cheers

AndyS wrote: Or just look at the back bumper

...which on an E12-based car is as-near-as-dammit identical with the E28-based "Highlines".

The rear panel on an E12-based car (which houses the taillights and number plate) is the same as the "Highlines".

The other difference between "E12" and "E28" cars is the plastic A-pillar gutter end: "E12" cars have much smaller ones, whereas "E28" cars have lengthened ones, with two holes for the bolts that insert into the front wings.....

Drew540i wrote: E28 engine will have 3.2/3.5 cast into inlet manifold.

-true enough, but an unreliable indicator of E28-ness; the '80-'82 model (E12 base, motronic) 635 has this style of manifold also. Only the L-jet 635s ('79-'80) had the earlier 'cupped hand' inlet manifold.

cheers

Why don't you post a couple of pics, and then you can end this debate accurately.

BMW's ETK lists the changeover as 5/82 between E12 and E28-base cars. I daresay there are a few oddballs out  there, maybe they had to use up a few bits and pieces, but a 7/82 build date car should be an E28 base without doubt.

cheers

This car now lives in Australia.....

on the subject, my car is a late E12 based 1982 car and has the 3.2/3.5 manifold casting and motronic engine mangement, though with an auxillairy air valve rather than the idle stabilisation unit of the later motronic systems.

Does this make it a 3430 or a 3453 engine? and what is the engine code for my engine, the B34/ B35 number? I'm looking for a new cam and am trying to work out what will be compatible. Extra info: on the dizzy, the leads all come out of the side rather than the earlier circular pattern of HT leads with the king lead in the centre.

thanks

for telling an E12 car I would look mostly at the interior as here the difference is very marked in the door cards, the heater controls and the clocks unit.

my parts car is an '81 and this has the 3453cc engine, apparently... I don't know when they changed over to the 3430cc type. Cam drives changed at some odd point (83-84?) and are incompatible before and after due to the drive arrangement. I'm told the cam fitted to the 3453cc engine is 'friskier' but I have not seen a posting anywhere that actually details lifts and durations for the various cams that are fitted to M30 engines; would make interesting reading....

cheers

Brucey wrote: ... I don't know when they changed over to the 3430cc type.....

May 1982

cool, so I got the 3453 block with bosch motronic injection then.

will do some research on cams for the M30....

Don't mean to contradict, coz I know you know your stuff, but my '81 635 with the 3453cc block has the '3.2/3.5' marked inlet manifold.

Did I miss read your post?

Jimbob is right; my parts car ('81) has the one-piece manifold too; all motronic M30s have this type so far as I know and 6ers went motronic in 1980, with the original engine size. Ivan seems sure that the smaller engine came in may '82 but I have yet to see any evidence of this; there is little external difference between the E12 motronic lump and the E28 version that followed it.

cheers

Brucey wrote: ....Ivan seems sure that the smaller engine came in may '82 but I have yet to see any evidence of this.....

Here's some evidence. A contemporary road test report, dated "week ending 10th July 1982":

Any good?

good article Ivan, but it doesn't say when the various changes took place. It says that the new engine is smaller capacity and higher compression and has digitally controlled injection and ignition (motronic) but it doesn't say whether all of these changes were introduced at the same time or seperately.

Oh yes, the starting problem - NOT related to getting low on fuel at all in the end; distributor and rotor arms (1981 originals) had given up. All wonderful again now new replacements fitted.

Cheers for the advise though (and for asking)

Drew21 wrote: good article Ivan, but it doesn't say when the various changes took place. .....it doesn't say whether all of these changes were introduced at the same time or seperately.

2nd paragraph: "similarly updated 635 and 628CSi coupes...began to appear in ....showrooms last month....."

That means June 1982.

ok, I missed that bit.....

d'oh

Whats that bit about shutting the fuel above 1200 RPM when you have your foot off the gas in that article?

When they say 'shuts the fuel supply', I take it it just means the throttle is as closed as much as possible.... which is what would normally happen? or am I wrong.

What is the difference in economy between the two cars (E12/E24 based 6) - I would say engines, but 5's 6's and 7's all have different weights, and thus fuel economies.

Thanks Ivan, v interesting.

Also interesting re. motronic lumps with 'banana' manifolds, never seen one myself, live and learn etc....

motronic cars are meant to be more economic because of the improved over-run fuel cut-off and a lower idling speed. E28 base E24s are lighter in weight and many are taller geared too. Both these help fuel economy considerably. However the biggest change comes with the 4-speed auto vs the earlier 3 speed (although not strictly an E28 thing). E12 base cars with the auto box struggle to do better than 20mpg round town and 25mpg everywhere else...

cheers

come to think of it, that makes perfect sense so as far as the consumption dial behaviour is concerned; i.e touch the gas and the econometer goes east.

Another point in this department - if BMW designed what was a pretty clever piece of electronics for the early 80's, they also designed a fairly poor cruise control system, since the economy loss is huge when on cruise, as it seems to be pretty heavy on the gas to maintain speed. It is a shame that the cruise does not have a setting to not have to change to 3rd to speed up, rather instead gently use 4th to gather speed, and thus save some fuel that way.

phb10186 wrote: come to think of it, that makes perfect sense so as far as the consumption dial behaviour is concerned; i.e touch the gas and the econometer goes east. Another point in this department - if BMW designed what was a pretty clever piece of electronics for the early 80's, they also designed a fairly poor cruise control system, since the economy loss is huge when on cruise, as it seems to be pretty heavy on the gas to maintain speed. It is a shame that the cruise does not have a setting to not have to change to 3rd to speed up, rather instead gently use 4th to gather speed, and thus save some fuel that way.

in 'E' you should be able to use about 1/3rd throttle above 62mph without provoking a downshift from 4th. If your does anything different I suspect the most likely cause is a worn throttle potentiometer- this is used as one of the signals for the gearbox computer and is a commonly faulty part on older cars.

cheers

No it is like you have described - and the cruise is working as it should be, clearly the emphasis was never on economy, which I knew anyway.

-eh? your (and my) model 6er have the tallest gearing going, for economy. Mine does 30mpg on a run which is pretty good for this size engine. On the motorway it accellerates in top gear quite adequately without kicking down into third; once above an indicated 70mph it takes more than 3/4 throttle to get it to kick down. I don't have cruise on mine, but on other vehicles I have owned it was very rare for the cruise control to apply more than half throttle under accelleration. I can't help but think there might be something amiss if yours tends to kick down when you don't want it to when driving at speed.

cheers

Well - my car is defo in need of a tune up, something which I havn't had the time to get round to due to work pressures. I get about 25 mpg tops - even though the econometer suggests 30 or so, the pumps tell me its about 25.

I have never driven another BMW with cruise, and so could not compare it to mine - in any case I hardly ever use my CC due to the fact that the roads in this country are too busy most of the time. I tend to use it when my foot gets tired!

As far as the down change goes, this happens when the CC stalk is pushed forward. It accels for about 5 secs in top, and then seems to change down in to 3rd and keep on. However the 10 or so times I have used the accel function have been at about 60 mph - so that could explain this  - at 80 i suspect it wouldnt change down.

I used to own a Honda Accord with a vacuum operated CC system, with buttons on the sterring wheel - although mechanically different, in practice it did the same thing as the 6 does, and was also never as economical when running on cruise. Incedently the Accord did not have an econometer at all, so I went by the fuel gauge on a common journey I used to do!

This was an '87 Saloon 2.0 EXi with a 12 valve engine - and it never did more than 30 mpg on the motorway either. Although on the combined cycle I did fare much better than the 6, which does about 12-15mpg in urban conditions as far as my experience goes. 

Actually, now that I remember the Honda, the vacuum system moved the accelerator pedal, which you could feel and see, whereas the BMW system does not have that feature.

I just wonder how the manual 6's fare on motorway economy compared to the autos.

phb10186 wrote:   This was an '87 Saloon 2.0 EXi with a 12 valve engine - and it never did more than 30 mpg on the motorway either. I just wonder how the manual 6's fare on motorway economy compared to the autos.

I had an aerodeck with the same engine; 30mpg was average, did nearer 35 when driven at 70-75mph on cruise.

Manual 6ers with the same 3,07 diffs and the overdrive box do the same or better than the 4 speed auto cars (although the top gear ratio is slightly lower). With the dogleg manual box, shorter diff ratios, or the three speed auto the fuel consumption is significantly worse.

cheers

I used to like the Aerodec, it is indeed a true classic car - I had the saloon, which was probably a bit heavier - this might have accounted for the economy difference, although I probably drove 80 or so, and often had the AC on (which was so cold in that car it used to freeze condensation on the windscreen - always remember that).

I was gutted when I wrecked my first aerodeck on diesel; it was a manual EXi in silver. The second one I had was never as good as the first... and eventually began to rot. A chum ran it for another 70000 miles and eventually someone ran into him and that was the end of it. Very few left now; hardly any in good shape with manual gearboxes. Preferred the earlier trim (stripy); just a few with this trim and cruise...

cheers

Mine was an auto, so more fuel there.  lets see.....

That doughnut shaped thing next to the timing belt cover is the vacuum pump for the cruise control

The engine was amazing, and it looked new even when I got rid of it about 2 years ago. The only thing was the rear sills, a honda design fault accross all their models, even the newer ones. I aggree with you Brucey an EXI manual before they did the face lift was great, funnily enough a close neighbour still has one, although its just an EX. For some reason the Aerodecs had slightly less kit than the saloon equivalent, despite being the same model, e.g AC and cruise.

Unfortunately the gearbox went; 'Hondamatic', and its pretty complicated as far as I was lead to believe, so I moved on.

One of those cars (Like the 635), that when you look at a picture once its gone you say to yourself 'that was a really nice car'.

Perhaps we ought to rename this section the Aerodeck forum.....

Still, when do we get to see the photos of your Mazda with its bra on, Ben?

Couldnt resist that last night!

 Late '87 aerodecks got 14" wheels, cruise, but no air con. '88 models got horrible upholstery and most were autos. I had a manual, and it was very good; rust was the enemy in the end. In the USA they got a 'fastback' model too, with the same front (pop-up headlights etc) as the Aerodeck.

 Under the bonnet; the small thing with the yellow dot on it to the left of the airbox is the cold idle auxiliary air valve. Over time this wears and needs adjusting, but even the Honda manual tells you not to do this (rarely incorrect, but on this occasion...). This little blighter is often the kiss of death for an auto box; if it goes out of adjustment, then on cold starts the engine hunts between 2000rpm and 500rpm or just idles too high (1500rpm). On the manual box it is just irritating, but with the auto it works the box in a bad way- sometimes damaged just by selecting 'drive'.  

Sorry about the Aerodeckness, wrong place and all that...I think I've got it out of my system now....

cheers

moving on then...