Carcheologist

Hey gang,

I also posted this in the diesel forum, but I feel like this forum gets more traction...

We started noticing slightly longer starts recently. When cold it used to start after about 4 revolutions, now it's 5 or 6. Hot it's even worse.

This weekend we drove it to a gas station, filled it with diesel, drove across town, shut it off and 5 minutes later it wouldn't start. It timed out 3 times.

Our friend gave us a jump and it started again, so we drove it home and parked it.

I have been reading up on this for the past few days and have found a few possibilities:

Low battery - the battery is only a year old, but I am going to put it on a charger to top it up.

Weak starter. It sounds fine, but I saw someone else say they replaced the starter and solved this issue.

Porous fuel lines. I replaced the fuel filter 30k miles ago, so I just ordered a new one and a hose kit. The hose attached to the driver side of the filter is looking a little rough. I always like to start with the simple stuff.

Leaking injectors - no signs of a leaky injector at the moment. I did have a bad o-ring 5 years ago which I replaced and it hasn't leaked since.

I scanned it yesterday and got error code 118100 - "Relay F58kD Engine circuit 87 relay switches off too late." I swapped it for now and ordered a replacement with the fuel filter.

Low pressure fuel pump?

High pressure pump? It runs fine once running, so I'm guessing it's not that.

I do have a scanner and can watch the fuel pressure and crank speed. I'm seeing crank speed under 150 RPM (I need to download the data, so don't quote me on that) which would point to a starter.

Any tips on tests to run?

Other things I might have missed?

I do have a copy of the Mercedes EWA workshop manual, but find it incredibly difficult to navigate.

I'm hoping to get at least 200k miles out of this thing, thanks for your help!

Max Blast

with those low crank speeds and new battery and known good starter I’d be concerned about excessive friction inside the engine due to lack of lubrication. Go look for forbidden glitter in your oil filter or have the oil analyzed you may be experiencing the precursor of seizure.

vesiadog

Many auto shops that sell good batteries will do a load test on the battery for free.
Load test battery and starter.
Definitely get an oil analysis done ASAP .
Between those two you will have a much better picture of what’s going on and it will not cost very much.

clk55AMG/CL600

Carcheologist, I've been down this road and got the shirt. Mine had the same problem, in the winter months it was breakout the Ether and stand back. In the hot, it usually start only to crank and crank after you turned it off, usually by the 5th no start I'd hop out and hit it with a shot of Ether and it'd start. In the beginning I changed the fuel filter then battery, starter, control module, crank position sensor, ohmed the glow plugs, looked for the black death around the injectors and checked fuel pressure both high and low. Everything was within spec. During a live hot motor data stream one day, I noticed my injector values were fluctuating, so I broke down and had the dealer do a balance test. Turned out my injectors had issues, I had them change them all and now hot or cold the truck starts before you release the starter button. Good luck!

Carcheologist

Thanks! I ordered a new starter and will try that next. After that it’s looking into injectors or return lines etc. I’m not ready to spend thousands on it while it’s still burning oil, but I’m not putting it out to pasture just yet.

I’m also upgrading my scanner, my current Aurel only captures one frame per second. Way too slow. It’s fine for static info, not for chasing issues like this.