When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Reoccurring: Dead battery after night of sitting. I replaced both batteries and the problem disappeared for about a month and has since resurfaced, I’m thinking the problem going away was simply coincidental. Alternator tested fine, nothing is being left on. Parasitic drain of some sort, I’m hoping there is some commonly known component that fails and causes this but I doubt I’m that lucky.
New problem: oil leak, seems to present its self near the center jackpoint underneath the car. Not visible anywhere from engine bay. First sighting was today after owning the car for about 2 months. Also seems to be some coolant visible that’s not mixed in with the oil, hoping it’s just a separate leak making it’s way to the same place.
Any help would be greatly appreciated, even if it’s things that I need to look out for in the future, car has 125,XXX miles if that’s helpful. Service records indicate there was some work to the camshaft/camshaft sensors in the past.
How much is the parasitic drain? Was the vehicle locked/closed for at least up to 2 HRS? Some components/control units will take some time to go into `sleep`mode.
How much is the parasitic drain? Was the vehicle locked/closed for at least up to 2 HRS? Some components/control units will take some time to go into `sleep`mode.
yes, each time that I’ve had an issue has been over night, the problem has never presented itself during day to day activities. Also I have not yet had a chance to pull a reading, this problem just resurfaced two days ago. This weekend I am hoping to troubleshoot further
You are locking the car at night, correct?
you definitely need to track down those leaks, especially since they are both oil and coolant. There are no known trouble sources for leaks on the M278 that I am aware of other than what has already been replaced on your car.
Oil leak if minor usually comes from the timing chain cover.
At least that is what I read as most common, including on my M276 3.0 TT. Super mild leak which makes engine looks dirty and not dripping kind of leak for me, because I am at 35,000KM only.
Coolant leak if not coolant pump related , I have super minor minor one from coolant reservoir of the turbo circuit. The hose clip into the reservoir has o-ring and when I push hard the engine few drops will form
as BLUEish residue, again no dripping leak yet on mine. Can't buy that o-ring, must buy the complete hose. I replaced the o-ring with best closest matching size and silicone not EPDM, still 2 drops leak last Tuesday when driven
decently hard at the track ( fun drive only approx 16 or so laps ). 20 drops is equal to 1 milliliter.
Clean all first and start tracking down the source. Cleaning can be A LOT of work to get to all locations.
Last edited by S-Prihadi; Jan 13, 2022 at 10:25 PM.
Reason: add corrected info
Yes, coolant should be BLUE - part no. Q103-0004. Buy first container from dealer using vin to confirm color (worth the extra few $). Match part # on receipt to bottle (my dealer gave me wrong bottle since previous colleague placed colors incorrectly on shelf.) Buy as concentrate (plus distilled water) until you solve the coolant problem. Remove the underbody "soft" panel on one side and see if it contains coolant. If so, leak is flowing down firewall to underbody panel. (I have a more detailed post elsewhere.) Monitor coolant reservoir when cold. (one of the hardware pieces holding panel is a small body trim screw. All others are bolts removable by socket)
Oil leak - remove the "hard" underbody panels. All of them. Answer will be more obvious then. Monitor oil dipstick, mileage and oil usage now. This will help determine rate of loss and how urgent the problem may be.
On my setup, I could lift one side of car, place jacks safely front and back, then remove relevant underbody panels.
Use the Operating Fluids site (formerly bevo site) to identify correct coolant. Zerex is an approved brand, you need to choose the right product. 2014/2015 was a changeover point from one color to the other.
Oil leak on M278 can come from oil supply lines to turbos. As S-Prihadi mentioned, spend lots of time with a bright LED flashlight looking at the front of the engine. Remove the upper covers and do a thorough inspection, you will find the leak.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
