Discovery on the underside of my engine air cleaner housing

dj_efk · Mar 22, 2019

Hi Gang,

Today was the last day of a trip back to the U.K. to see my parents, in whose garage my 69 2800CS slumbers under a cover - so of course I wasted no time in whipping the cover off, whacking the battery on and starting the old girl up once I’d whipped the plugs out and popped a slug of oil down the bores!

Whilst doing this I removed the air filter housing and discovered there is something electrically powered (two male spade connectors with no corresponding lost-looking wires anywhere in sight) set flush into the housing. Apologies for not taking a picture, but from this description I wondered whether anyone could enlighten me as to what this could be? I already have a vacuum connection for the cold / warm air intake, is this a heating element for that?

It may not be the correct housing for the car, as although it clearly wears the original factory paint, it’s not in that grey / green shade I’ve seen on all other carburettored cars....

Thoughts?!

Markos · Mar 22, 2019

If I had to guess it is a temperature controlled solenoid that diverts air away from the cold air duct. There is a hidden warm air duct that connects to the heat shield on the exhaust manifold. I don’t know anything about it and for some reason I didn’t realize that it was electric.

Markos · Mar 22, 2019

Ok I’m not crazy. It is controlled by a thermostat

http://e9-driven.com/Public/Library/BMW-E9-Manual/pages/en/13730040.html

Stevehose · Mar 22, 2019

Yes but it's not electrically controlled, expands with heat. Please post pics.

Markos · Mar 22, 2019

Stevehose said:
Yes but it's not electrically controlled, expands with heat. Please post pics.

Oops sorry my previous post was an attempt to correct myself with the manual reference.. I meant I wasn’t crazy in thinking that it isnt electrical.

dj_efk · Apr 18, 2019

See the top of this pic. Note that is not a pic of my housing, which is black - but it is otherwise identical to the one I have.

I’ve had a suggestion it could be from an E3?

dj_efk · Apr 18, 2019

Edit, my housing is exactly the colour the one on this car is, perhaps it is the correct colour for 69 coupes?!

https://losangeles.craigslist.org/lac/cto/d/los-angeles-1969-bmw-2800cs/6857441806.html

deQuincey · Apr 18, 2019

dj_efk said:
See the top of this pic. Note that is not a pic of my housing, which is black - but it is otherwise identical to the one I have.

I’ve had a suggestion it could be from an E3?

wow that is spectacular !
never seen a similar one

HB Chris · Apr 18, 2019

E3 and E9 air cleaners are identical and came in early and late versions. The early version has a 60mm fresh air opening and a rubber plug above the thermo valve. The later version is 70mm and there is no rubber access plug. The preheat hose from the exhaust cover also changed from 50mm to 60mm.

dj_efk · Apr 22, 2019

deQuincey said:
wow that is spectacular !
never seen a similar one

Can anyone shed light on what this electrical connection is for and what is the consequence of it not being hooked up?

stphers · Apr 22, 2019

It is a thermo switch which works with carbs that have the heat sensitive bypass system ( this system takes the place of the stepped system in the choke housing ) There are a number of bits that go with this system There is also a temp controlled vacuum switch in the thermometer splitter housing and a thermo time valve that sits between the intakes . If I remember right, this was only on early cars , 2500, 2800 and early 2800 Bavs If you don't have all the other " stuff " don't worry about it, probably has had the air cleaner housing replaced at one tine and yours is black which indicates early cars 2800 and 2500 There is quite a bit of info on the system in the blue books. I have only seen one in my time ( thank you ) like early emissions control, a lot of crap that really didn't do that great a job

dj_efk · Apr 22, 2019

Thanks @ stphers, as my car is an early one I’m wondering if this is in fact the correct figment in that case.

I’m not sure where you mean by thermometer splitter housing, could you elaborate? Also same goes for “between the intakes” when describing the thermo time valve?

Perhaps if there existed a diagram of the system all would become clear!

stphers · Apr 22, 2019

Yes there is as I said in my earlier post, there is quite a bit of info in the Repair Manual in section 13 11 065 is where it starts Checking heat sensitive bypass starting device It goes on to tell you how to check all the components and where they are. The thermostat splitter housing is what I call it sorry, it is the housing where the eng temp switch sits where the top rad hose connects to.

HB Chris · Apr 22, 2019

stphers said:
It is a thermo switch which works with carbs that have the heat sensitive bypass system ( this system takes the place of the stepped system in the choke housing ) There are a number of bits that go with this system There is also a temp controlled vacuum switch in the thermometer splitter housing and a thermo time valve that sits between the intakes . If I remember right, this was only on early cars , 2500, 2800 and early 2800 Bavs If you don't have all the other " stuff " don't worry about it, probably has had the air cleaner housing replaced at one tine and yours is black which indicates early cars 2800 and 2500 There is quite a bit of info on the system in the blue books. I have only seen one in my time ( thank you ) like early emissions control, a lot of crap that really didn't do that great a job

Is this a feature on 74 coupes only? Early cars never had this and our 2800 doesn’t have it. The early housing has the rubber plug on top, does yours have that dj?

HB Chris · Apr 22, 2019

I’ve never seen a water divider with these hoses either. Just checked the manual, it says 2800 and 3.0 liter with Zenith tag number 1 262 769 has this heat sensitive bypass starter. There are 17 different Zenith carb numbers/tags, perhaps this is for countries with very cold climates, it is not listed for US 2500/2800/3.0 motors.

dj_efk · Apr 22, 2019

HB Chris said:
Is this a feature on 74 coupes only? Early cars never had this and our 2800 doesn’t have it. The early housing has the rubber plug on top, does yours have that dj?

Yes it does

dj_efk · Apr 22, 2019

HB Chris said:
View attachment 63294 I’ve never seen a water divider with these hoses either. Just checked the manual, it says 2800 and 3.0 liter with Zenith tag number 1 262 769 has this heat sensitive bypass starter. There are 17 different Zenith carb numbers/tags, perhaps this is for countries with very cold climates, it is not listed for US 2500/2800/3.0 motors.

My car was one of the very early UK cars that were built in Euro / LHD spec and then converted to RHD by the importer / sold by Dick Lovett once they arrived. Therefore I would suppose it was built to domestic German spec at the factory, Germany of course has mountainous terrain so if all domestic cars got this system then mystery solved!

HB Chris · Apr 22, 2019

I think it is a rare option. Do you have the water divider with hoses?

dj_efk · Apr 23, 2019

No I don’t think I do

HB Chris · Apr 23, 2019

dj_efk said:
No I don’t think I do

Then your housing was most likely replaced or the thermo start mechanism was removed.

Discovery on the underside of my engine air cleaner housing

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