2.7 CRD (WG) Glow plug voltage (cold start issues)

[MartyVayne]

Originally Posted by bodgie

From memory there are two circuits, I think 1-3 are on one and 4-5 are on the other, if one circuit is down this may create an issue.

Also have you checked for codes to see if there is an error report by the ECU?

Jason

Found out GP's 1-3-5 are on relay no. 1 and 2+4 are on relay no.2. See attached detailed pic of ECM schematic diagram.

Marty

[MartyVayne]

Ok been a while, but finally found time to do overhaul on fuel line system.

Changed (using MB fuel lines):
- fuel line from filter to LP pump
- fuel line from LP pump to HP pump (including bleed valve)
- return fuel line from fuel rail to HP pump
- all black o-rings on fuel lines (although new) for green MB ones
- o-rings on fuel pressure regulator (had to remove fuel rail for that), this comes as a MB kit
- fuel filter for Mann filter
- old glow plugs for 5 new Bosch ones (old ones were all carbon tipped)
- air filter

When bleeding air with handpump, bubbles in fuel wouldn't stop coming.
Finally tried to start it. After about 30 sec crank it started but very rough. Died after about 1 minute. Fuel in fuel lines was foam instead of clear fuel, so obviously still a vaccuum leak somewhere.

In the end turned out to be the only o-ring that I had not changed was the culprit (of course): the o-ring on the water sensor in the fuel filter. I reused that one. Big mistake .
So draining and removing fuel filter again. Changed o-ring with slightly thicker one. A green HNBR o-ring from my o-ring box. Snug fit using some petroleum jelly.

Succes! After few bleeding pumps: clear fuel. Started after 10 second crank.
Today's tip: always change water sensor o-ring at every fuel filter change.

So what about the hard starting in the morning?
This morning about 3 degrees C. About 3 second crank. So not entirely happy with that and still rough idle / hunting.

Whats next anyone? Injector testing?

All hints appreciated!

Marty

[bodgie]

Given the cost of glow plugs I'd be inclined to replace them, it isn't an every difficult job to do.

It can be quite easy to strip the threads (aluminium binds to glow plug) in the head when you are extracting the glow plugs, even if you do everything correctly.

It is also a pretty easy fix with a timesert.

http://www.timesert.com

I'd also be inclined to do an injector leak back test to see if all is goo there, the other low cost thing to try is some Luqi-Moli diesel purge.

Jason

[Adrian D]

Originally Posted by MartyVayne

So what about the hard starting in the morning?
This morning about 3 degrees C. About 3 second crank. So not entirely happy with that and still rough idle / hunting.

Whats next anyone? Injector testing?

All hints appreciated!

Marty

Hunting idle after start-up could be:
Air in fuel lines (had that happen to me)
Glow plugs
Injectors
Fuel pressure regulator

Test the injectors and ditch the fuel filter for one without the drain plug and water sensor.

Fuel filters:
Jeep, with drain hole and water sensor: Mahle KL 188
Sprinter 901, with drain hole and water sensor: Mahle KL 195
Sprinter 901, without drain hole and water sensor: Mahle KL 100/2

I'm now using the Mann equivalent of the Mahle KL 100/2. Two less potential problems because if doesn't have those holes.

[MartyVayne]

Originally Posted by Adrian D

Hunting idle after start-up could be:
Air in fuel lines (had that happen to me)
Glow plugs
Injectors
Fuel pressure regulator

Fuel lines replaced including o-rings (used green MB ones)
Glow plugs replaced with new Bosch
Injectors unsure
Fuel pressure regulator serviced with MB o-ring kit

Test the injectors and ditch the fuel filter for one without the drain plug and water sensor.

Last week it was -8 degrees C and she wouldn't start. No matter what. Now temperatures are above freezing again, so was able to start the car.
This evening dropped car off at Bosch Car Service. Tomorrow they will test injectors and HP pump.
If it's injector(s) let's hope it's not no. 4 or/and 5.

Fuel filters:
Jeep, with drain hole and water sensor: Mahle KL 188
Sprinter 901, with drain hole and water sensor: Mahle KL 195
Sprinter 901, without drain hole and water sensor: Mahle KL 100/2

I'm now using the Mann equivalent of the Mahle KL 100/2. Two less potential problems because if doesn't have those holes.

I took your advice and went one step further. I used the MANN WK822/1 which has only two connections. 1 in (for normal 10mm inside diam fuel hose) and one out (MB clip connection).
For this I had to reroute the return hose from the fuel rail directly to the tank. By ditching the return valve on the filter, I went from 6 holes in the filter (return valve, drain screw, bleed screw, tank in, filter out, water sensor) back to 2 holes (tank in, filter out). So 4 potential leaks I can do without.

Here's a picture before:



And here's one in the new setup, the WK822/1 is a few mm smaller in diam, so I used old rubber bicycle inner tube to fill up the "looseness" in fuel filter bracket.



This is the MANN filter I used:



I also changed small piece of rubber fuel hose (10mm inside diam) from tank to filter. It was a bit stiff and after removal I found it had started to crack.



Will keep you posted what the guys at Bosch diagnosed.

Marty

[Adrian D]

Good work. I wouldn't have ditched the return valve, it's supposed to open at a certain temperature and ensures the warmer fuel on the return warms up the filter.

Mine has had a nice hole cut above injectors 4 and 5, later covered with some sheet metal.

[bodgie]

Originally Posted by Adrian D

Mine has had a nice hole cut above injectors 4 and 5, later covered with some sheet metal.

I cut 2 50mm holes above 4/5 and these are plugged with a couple of rubber plugs. Works well and is an easy way to extract/replace 4/5 injectors.