JohnHunt83

Car made it home but won't run at all now. Any suggestions would be appreciated. And maybe a lead on a good MBZ shop in Tacoma WA.
2007 SL550 w/keyless go 187000miles

Previous symptoms that may not be related:
Car sometimes struggled to start cranking but would go after a second. Almost as if struggling to get over a compressed cylinder.
Dealer has reported issues connecting to the passenger sam over the last few years. Never impacted usability of car.
Dealer disconnected the alarm system several months ago as it was draining the battery

Yesterday:
Ran fine. I let it idle for 20 minutes while on a phone call. Drove to gas station, parked and it didn't want to crank 5 minutes later. After several attempts it cranked and ran normally. Drove 10 minutes home. That was the last time it started.

Today:
Powers on great. Dash lights look strong. Battery charger puts both batteries at 100%. Keys unlock and lock car. Windows and lights work. Press keyless go or cranking key (tried both keys) and the car makes normal whirs and noises.... just starter doesn't crank. With power on I can move shifter to neutral (no effect). Brake lights work. No messages on dash.

I removed the starter relay cover and manually closed the contact (saw a small spark that indicated power). But it did not crank.

Tomorrow:
Try and find someone with a test book to check EIS and SAM
Have starter battery load tested
Find a shop to get it on a lift and test voltage at the solenoid and starter motor
Crawl under it and whack the starter with hammer


This car has 1000 fuses any chance someone can narrow down the ones I should check?
Any other ideas? Am I approaching the logic right? My gut says starter but the SAM is in the way after that relay.
Thanks,

John Hunt

C2 Turbo

Look into CPS (crank position sensor) or the fuel pump, it's one or the other. same thing happened to my 2002 E55 and CPS replacement fixed the problem.
Good luck

JohnHunt83

Thank you for the quick reply. Wouldn't either of those allow for a least a little bit of engine crank? Or did it not turn at all for you?

Thanks,

-John

DavidCA

I think you will find it is the starter motor, not too expensive and easy to replace.

Tom Manning

Doesn't the hot contact on the starter relay go directly to the starter solenoid? Someone will know, but IIRC it does. The slow cranking is a classic sign of a weak starter battery or starter motor.

A failing or failed CPS will disable both spark and fuel, which is a good reason to change it while it's still good, before the engine cuts out on the freeway. For this critical part, I use only Bosch...

g0rsq

100% agree. If you get a poor crank speed after directly operating the starter relay, then fault is either, bad starter battery, bad starter battery/starter motor connection, bad earth, or bad starter motor.

Really no need to look further!

ChrsBowman

I'm in Federal Way....just had this issues...actually I'm still having it. Last month, I replaced the crankshaft position sensor...and that fix the issue. Then a couple of weeks ago....we were driving, stopped at a light, proceeded to go, the car died. Tried a few times to start...it would crank, and after. Min....it would start, then die again. I changed the intake manifold...last night....after putting it all back together, when to start it....and no luck turning it over. Thinking about replacing all the cam shaft position sensors...if that doesn't work...possibly look at a new ECM(or clone one).

JohnHunt83

Just to follow up.
I picked up a new Bosch starter from AutohausAZ for a couple hundred bucks and had it installed. Everything works great. Turns out the old starter had been failing for some time considering how strong this new one is.

Thanks to Spec German for installing it and fixing some addtional bits with there test book.

-John

Carpedmman

@JohnHunt83 Happy to hear that a new starter motor solved your issue! Ironically, my 2007 SL 550 decided not to start yesterday after shopping at Costco! Luckily my GF was getting gas and was able to get our frozen/cold food back to the house while I fiddle farted around with the car. My car is at the repair shop now....I hope it's the starter as it was with yours. Happy Holidays!

Carpedmman

I just received the call from the independent repair shop and they confirmed that the starter was shot. Cost to replace the starter with a new Bosch unit will be $800! Doesn't this seem high? Autohaus sells the Bosch starter for $190. I may be looking for a new repair shop.....

JohnHunt83

I paid $600 to a local shop to replace mine (I bought a new unit from Autohaus). Tried in my garage but just don't have the proper (ie safe) tools anymore.

-John

Carpedmman

Thanks @JohnHunt83 ! I guess that the price is in line....

g0rsq

One engine mount needs disconnecting, and engine lifting, before the starter can be removed from below, so not a five minute job.

Carpedmman

@g0rsq Thank you for letting me know! I feel better knowing that this is a more complicated R/R than I expected.