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Hello hive mind, I have inherited a nightmare job on a friend's 350 GLE. 2016 60k
Starts and drives lovely up until it goes into limp mode, reset and it again goes spot on, accelerates well.
Fault logged is low pressure on rail. Every time you put foot down.
see photos of various tests performed.
It's had a new pump from merc, flow and press reg, temp sensor(came with pump), recent filters.
Press sensor new.
Low pressure is 4.5bar solid while driving.
Few wierd results on the tests but star seems happy with it.
Pressure test goes to 1400 ish bar and passes but isn't it supposed to go to 1800?
No leakage through pressure reg.
Holds 800 bar for duration of leak test so unlikely leaky injectors?
I've had a scope on reg pwm signals and all good.
Not a lot of leakoff from injectors although I'll do them individually today to be sure.
Thoughts? Injector leaking?
Any help very much apreciated as its getting on my **** now.
Thankyou. Assume the end is just reg wide open(technially closed as its a relief).
Just noticed the photos have uploaded at odd orientations, sorry.
Ok so problem solved.
The culprit was the pressure reg/relief valve sealing into rail, it came as one piece as merc don't sell individually due to exactly this reason, it was very tight but still leaked a tiny bit, I had to do it up to silly tight and work it in to bed the seating surfaces in, like snapping kind of tight.
It didn't leak at all untill it got to 1400bar so passed all the tests.
Head scratcher.
Last edited by SpareWheel; Jan 3, 2025 at 10:43 AM.
350 GLE rail pressure issue
