Not joined yet? Register for free and enjoy features such as alerts, private messaging and viewing latest posts and topics.

Diagnosing long crank on cold start N52 engine

Discuss problems you have had or are having with your Z4
Mangozac
Senior Member
Senior Member
Posts: 1103
Joined: Sat Aug 08, 2009 5:33 am
Location: QLD, Australia
Contact:

Diagnosing long crank on cold start N52 engine

Post by Mangozac » Mon Mar 14, 2016 6:37 am

Well I've still been having the long crank on cold starts issue and it's still irritating me quite a lot. I'm certain that I've ruled out any problems with the fuel supply (fuel pump, filters and injectors), the ECU immobiliser functionality and the VANOS (solenoids were perfectly clean and working properly). I have been continually on the lookout for other symptoms or ideas but nothing else has arisen.

I was thinking about the problem this morning and it got me wondering if oil pressure could be to blame? My line of thought is this:

The N52 engine has several valve/timing related functions that rely on oil pressure for operation, not least of these are the VANOS and the hydraulic lifters. What would happen if it took longer than expected for oil to come up to pressure upon starting? Without sufficient oil pressure the VANOS cannot adjust the timing to the appropriate position. Likewise if the hydraulic lifters are not pressurised then the valves won't depress fully (please correct me if I'm wrong there). It just takes a few cranks for the engine to bring the oil pressure back to spec and then the engine can start fine.

Could it be possible that the oil pressure nonreturn valve is not operating as well as it should? Similarly, could an unsuitable oil viscosity drain too fast? The last oil service before I bought the car was done at standard mechanic, not even a Euro specialist, so it's very possible that something incorrect has been used. I'm thinking a quick DIY oil change to some known good stuff could be worthwhile.

Can anybody comment whether I'm barking up the wrong tree with this line of thought?
Current: 06 E85 M Silbergrau
Previous: E85 3.0si Silbergrau, 03 E85 2.5i Maldives Blue.
Mods: Gaptech OTH+R, Dension Gateway 300 with USB, CDV-, clear side indicators, euro tails, stubby, MFSW retrofit, OEM Bluetooth/VR

GnomeDoctor
Newbie
Newbie
Posts: 7
Joined: Tue Sep 03, 2019 11:27 pm

Diagnosing long crank on cold start N52 engine

Post by GnomeDoctor » Fri Jun 04, 2021 4:44 am

Mangozac, Where you able to fix this? I’ve been having the same issue for months and haven’t found the culprit.

Mangozac
Senior Member
Senior Member
Posts: 1103
Joined: Sat Aug 08, 2009 5:33 am
Location: QLD, Australia
Contact:

Diagnosing long crank on cold start N52 engine

Post by Mangozac » Tue Jun 08, 2021 1:47 am

Sorry mate, I never did get to the bottom of it. I sold the car a few months later and upgraded to a Z4M!
Current: 06 E85 M Silbergrau
Previous: E85 3.0si Silbergrau, 03 E85 2.5i Maldives Blue.
Mods: Gaptech OTH+R, Dension Gateway 300 with USB, CDV-, clear side indicators, euro tails, stubby, MFSW retrofit, OEM Bluetooth/VR

GnomeDoctor
Newbie
Newbie
Posts: 7
Joined: Tue Sep 03, 2019 11:27 pm

Diagnosing long crank on cold start N52 engine

Post by GnomeDoctor » Tue Jun 08, 2021 11:38 am

Cool man thank you any way. I guess I'll keep on looking. Congrats on the upgrade!

GnomeDoctor
Newbie
Newbie
Posts: 7
Joined: Tue Sep 03, 2019 11:27 pm

Diagnosing long crank on cold start N52 engine

Post by GnomeDoctor » Mon Jun 28, 2021 1:40 am

Problem fixed. It was a leaking injector. Posted my experience. Link to the post below. Hope it can be of help.

viewtopic.php?f=3&t=130013

Post Reply