My 2003 SL55 118,000km failed to start when hot last Thursday.

It was hot after an hours run; I turned it off to collect something and when I returned 5 minutes later... a few coughs then no start.

The starter motor was spinning but no action... probably 10 attempts over a few minutes.

The problem seemed familiar as I had replaced the crankshaft position sensor in my wife's ML 500 a few years ago. Similar symptoms but eventually it would start.

I poured a bottle of water down the back of the engine but still no start to the amusement of several shipwrights at the marina.

Being 60km north of Sydney and a long tow home on a truck I banked on it being the CPS which I suspected would be OK when things had cooled down.

I walked a few k's to my marina, spent a few hours working on the boat and walked back again.

Started first time.

I was home just in time to order a CPS from Silverstar spares for $110.

Started fine next morning... drove to work at 7 then drove 16 minutes up the road at 11 to have an exhaust hanger welded back on. Parked the car across the footpath as the driveway was occupied, found that the mechanic had gone home sick, tried to start the car... no start.

6 watering cans of water this time down behind the left hand cylinder head made no difference.

Rolled the car back onto the street and with the aid of two other customers and the owner pushed it up onto the nature strip and caught a taxi back to work.

My wife drove be back to the car at 7pm after work and it started first time, and again the next morning and Sunday night and yesterday, twice... all cold starts.

I replaced the CPS this morning and it started hot at lunchtime

Here's how to do it:

Thanks to a post on the E55 forum and my previous job on the ML500

It will take you about 30 minutes, an E8 Torx 1/4" drive socket and a few extensions. A universal joint would be handy.

I wouldn't try to do it if the car's hot or you have big hands or if you are clumsy.

The pictures showing the sensor in position make the job seem easy but they were taken with an iphone level with the back of the rocker cover. In actual fact you can't see the sensor at all and the entire job must be done blind.

1. Remove the engine cover at the front of the engine
2. Remove the two air ducts by sliding the back end forward and lifting them out
3. Remove the air cleaner plenums both sides together by lifting them at the front and disconnecting the two tabs at the inlet to the throttle valve. Disconnect a rubber pipe from underneath the left side at the back.
4. Slide the heat shield up and off the sensor as far as you can.
5. Unplug the electrical socket by squeezing a tab at the top and pulling it off.
6. With the E8 torx socket on the end of your extensions feel it onto the head of the bolt that is on the down side of the sensor (see the last photo)
7. Undo the bolt with a ratchet initially (it's tight) being VERY CAREFUL not to drop the screw. I suggest not lifting off the socket until you jam the screw into it with a spare finger.
8. Remove the sensor with a bit of twisting.

To replace the sensor:

1. Insert it into the hole you can never see and line it up so that its long axis is along the long axis of the car.
2. Gently jam the bolt into the socket with a tiny piece of rag so it doesn't fall out.
3. VERY CAREFULLY lower the bolt/ socket/ extension setup down with your finger retainging the bolt in the socket until you have located the bolt into the hole
4. Tighten it by hand and finish off with the ratchet
5. Attache the plug and slide the heat shield back onto the sensor
6. Everything else just goes back in reverse order

The nerve wracking bit is worrying about whether you will lose the bolt

The photos illustrate the procedure.

Hope this helps someone!

Peter

 

Final Photos

 

Thanks for taking the time for the write-up.

Aaron

 

+1 for sticky!!!!

 

Here I am 6 weeks later and the car has not missed a beat... Until it won't start today

A 45 minute drive and a two hour stop and it started fine.
Another 45 minute drive and 30 minute stop. Ditto
15 minute drive, 30 minute stop and it won't start.

Left it 3 hours and it still won't start. Engine Temperature is still about 50 degrees C

Just to recap: the CPS is new, it's 27 degrees C

Any ideas???

Thanks,

Peter

 

After it had cooled for 5 hours still no start.

I called roadside assistance expecting to get a tow

Helpful guy, worked out that their was no fuel in the fuel rail ( take off the plastic cover on the front of the engine and stuck a screwdriver in what looks like a tyre valve... Fuel should come spraying out)

He squirted some fuel down one of the vacuum lines at the back if the supercharger and the engine started and ran for a few seconds

We both thought about giving the fuel pump a hit but its not visible ( I thought it was near the filter in front of the back axle LHS but some suggest its in the tank)

Currently waiting for a tow on a flatbed to the dealer

 

The tow truck finally arrived at 8.30pm and we dropped the car off at the dealer

When I called them this morning to explain my car in the parking lot the service manager wondered why it was there as he had been out, started it and taken some details.

They drove it onto the ramps, hooked up the computer, decided that it was the fuel pump and it hasn't started since.

The pump is $800 (typical Australian 100% mark up on US prices) and they reckon it will take 5 hours to do as they have to remove the rear axle.

This sounds a bit opportunistic to me... the WIS doesn't mention anything about dropping the axle

A bit more annoying is that the part is currently living in Singapore and it will take 5 - 6 days to arrive

The local OEM suppliers don't carry stock but would charge $500 - 600 if I wanted to wait a few weeks

I reckon that I am being taken for a ride on the axle dropping thing so I would appreciate any advice from someone who has done the pump please

Thanks

Peter

 

Hey Pete,

I just call the local MB dealer pump is $314.00 take 3-4 days have to order it.
let me know if I can be any assistant. Just offering help that's all

 

MB Australia couldn't get a fuel pump in Singapore and it ended up taking two weeks from Germany

$AUD800 + the same for labour

They said the rear axle had to come out which seems a bit adventurous but it's all back together and running beautifully again

Peter