'75 BMW 2002 starting issues, choke? oil?

[2002Diver]

Hey group! 

New owner here! Just purchased a 1975 BMW 2002 and its beautiful, I'm very happy but its not without its quirks.

 

1st) Engine is turning over however it is having trouble on cold start. Checked battery, check distributor and plugs, checked carb (as much as I could with my knowledge). Everything looks good to go. This is the issue, its its turning over however it is not starting unless I'm pushing the choke in. I live in the Bay Area (northern CA) so I dont think its too warm or too cold. It turns over but it doesnt catch, however when I push (not pull) the choke it it sucks in that extra air and starts right up! I'm not sure if its a choke problem or a carb issue or an ignition issue. First I wasnt sure if it was electrical so I ordered points and condenser and I plan to replace both of those this weekend. 

 

2) Ive been searching the forums and seen this problem elsewhere but when I am cruising on a warm engine (lets say getting off the freeway) and I switch from gear to neutral to coast to a stop and I apply the break pedal I'll get a low pressure warning. I have an external/aftermarket oil pressure gauge which confirms the dash mounted light, oil pressure is dropping under breaking or sometimes even at idle after a few mins of driving (30 mins or 2 hours). My external oil gauge is confirming that when the gas pedal is pushed pressure is increasing, that is to say, when it starts to choke if I give the engine gas the low oil light will go off, so I am not sure if its an oil pump problem or I am using too thin of oil ( currently mobil 1 15w50 full synthetic). I am going to switch to 20w50 this weekend. Anything else I might be missing?

 

3) where can I find DIY write ups or articles on oil pump trouble shoot or swap, I have the bentley manual and it shows the pump but not its location. 

Where can I find info on how to adjust choke? The manual shows carb tuning but not necessarily how to/and the location of the choke. 

 

Any info greatly appreciated! Ill be at SF Bay Area Neue Klasse and Kaffee in my tan BMW with a wooden roof rack, gold honeycomb rims.. Definitely come up and say hello!

 

-Mirko

[Stevenc22]

1) check the tension on the choke plates. With a cold engine press the gas pedal in and out once. Then check the choke plates. They need to be closed but not closed with alot of tension. Just closed. Think Goldy locks.

[torquewrench80]

10 minutes ago, Stevenc22 said:

1) check the tension on the choke plates. With a cold engine press the gas pedal in and out once. Then check the choke plates. They need to be closed but not closed with alot of tension. Just closed. Think Goldy locks.

I concur fully. Also, I would ditch the synthetic in favor of a mineral based oil with a high level of zinc. That synthetic is meant for newer technology cars, as opposed to older technology, which the 02 certainly is. Shell Rotella is supposed to have a high level of zinc. Just had the engine in my `72 tii rebuilt and that is what I will be using. Btw, what is the oil pressure reading on the gauge installed on your car?

[2002Diver]

7 minutes ago, torquewrench80 said:

I concur fully. Also, I would ditch the synthetic in favor of a mineral based oil with a high level of zinc. That synthetic is meant for newer technology cars, as opposed to older technology, which the 02 certainly is. Shell Rotella is supposed to have a high level of zinc. Just had the engine in my `72 tii rebuilt and that is what I will be using. Btw, what is the oil pressure reading on the gauge installed on your car?

 

Im within spec when warm, I have to go home and check for exact numbers but I have the manual so the first thing I checked was oil pressure. I THINK its 7 or 8 psi at 700-900 RPM. 

 

 

I'll check choke plates when I get home. Thanks a bunch for the quick replies!

Edited June 15, 2017 by 2002Diver

[bitbckt]

re: 2) I prefer either Valvoline VR-1 or Brad Penn, both in 20W50.

[Son of Marty]

Your on the low end on oil pressure at idle but still in there, I would start with a oil change to 20w50 especially if you find your over-choking as there may be gas diluting your oil  and set idle speed at 950 rpm warmed up oil pressure should be around 15 psi IMHO. 

[torquewrench80]

6 minutes ago, bitbckt said:

re: 2) I prefer either Valvoline VR-1 or Brad Penn, both in 20W50.

They both sound like good choices, maybe even better than the Shell Rotella, don't know for sure. Would have to compare additive package quantity.

[2002Diver]

3 minutes ago, Son of Marty said:

Your on the low end on oil pressure at idle but still in there, I would start with a oil change to 20w50 especially if you find your over-choking as there may be gas diluting your oil  and set idle speed at 950 rpm warmed up oil pressure should be around 15 psi IMHO. 

 

Ok so if i am understanding you guys I should:

 

1) oil change

2) check choke plates

3) if still idling low adjust idle speed screw on linkage

 

are those some good first steps?

 

[Son of Marty]

Yeah thats a good start then you can get a good idea where you stand.

[TobyB]

Quote

I would ditch the synthetic in favor of a mineral based oil with a high level of zinc

Mobil 1 15-50 still has enough zddp.  

And there is no reason at all not to run it, except expense.

 

Bump your idle up to 850- 900 first and see if the

oil pressure comes up.  If it makes it into the mid- teens, you're just fine.

There's a HUGE difference in oil pump pressure between

700 and 900 rpm...  and sometimes, coming off the freeway, especially 

nose- down, idle drops quite a bit lower than usual.

 

I have run M1 15-50 and VR1, and the VR1 makes a significant amount

of extra oil temperature over the Mobil 1...

 

t

 

 

[torquewrench80]

13 minutes ago, TobyB said:

 

I have run M1 15-50 and VR1, and the VR1 makes a significant amount

of extra oil temperature over the Mobil 1...

 Any idea why? Ever try Amsoil? According to information I have read on the internet Amsoil is the only 100% synthetic. Lucas Oil Products makes a zinc additive, part # 10063, that can be used in conventional motor oils and synthetic.

[bitbckt]

I was providing options for the OP to consider based on price and availability, not intending to derail their troubleshooting with oil debates (that's why we have BITOG).

[TobyB]

Low oil pressure is often linked to low idle.

Mobil 1 15-50 is plenty thick to provide decent oil

pressure at idle- if Mirko's current pressure is below 10

at 900 rpm, hot, he's probably got problems beyond oil choice.

Thus, my post.  It's not an oil problem, UNLESS the current

oil is more fuel than oil.

 

nope, never tried amsoil.  

 

Big Interested Toenails On Grout?  

 

t

 

 

 

[Son of Marty]

When you change the oil for the first time it takes 4.5 qts with the filter and seeing as this car is new to you I would be fairly accurate with the .5 qt start the car until the oil light goes out and check for leaks go have a beer for a good job done and then pull the dip stick and make sure the oil level is to the mark on the dip stick, I say this because their are at least 3 major mods to the dip stick/holder and the parts don't interchange, you'll sleep better knowing its spot on. 

[torquewrench80]

Another good idea when you change the oil and filter is to make certain the filter is filled with oil before you screw it on so the oil pressure comes up quicker when you start the engine.