2.5 TDI (AEL) Volvo 850: Starting Problems

Hello everyone,

Our recently purchased Volvo 850 TDI is driving me crazy.
"If the car has been standing for several hours, it's an incredible feat to get the engine started. After the glow plugs have warmed up, I have to crank it for what feels like an eternity. Sometimes the engine seems like it's about to start, but then it just falls back into cranking again, spewing out a massive amount of unburned diesel in a white cloud... until, after what feels like an eternity, it finally starts with great effort. Once it's running, everything is perfect: full power is available, the engine runs incredibly smoothly, and for a diesel, it's almost silky. The fuel consumption is low (usually under 7 liters per 100 kilometers)."

Completed so far:
- Spark plugs replaced (4 out of 5 were defective).
- Bulb fuse/relay/power rail, etc. checked (it actually lights up).
- Starter motor replaced (the old one was turning very slowly).

Result: No change.

So, I wanted to go to the Bosch service center to have the fuel injection timing, the ESP, and the injectors checked... but then I remembered this forum (my T4 runs way too smoothly, which is why I'm obviously not here often enough ).



Now, searching in this forum has drawn my attention to the topic of "air in the fuel lines."
Unfortunately, I have two problems with that.

1. In Volvos, all the hoses are black, which makes them opaque and extremely difficult to diagnose. Is there perhaps another method to determine the presence of air in the system?

2. I have a feeling that - if the diesel line is emptying towards the tank due to air entering it - there shouldn't actually be any white smoke during the starting attempts... because there wouldn't be any diesel in the line yet. Or could even smaller air bubbles (e.g., in the return lines) be enough to trigger the phenomenon described above?


Best regards,

- the undisputed king of particulate matter -

Yes, to detect air leaks, you need a clear path or connection.
If it's running that smoothly, I'd mark the EP position with a pin and try advancing the timing a bit. It should at least start firing cold. Then, test if it starts cold.

teileklaus wrote:

if it runs that smoothly and silkily

Well... when it's cold, it does make some noise... but once it's warmed up and running, you'd hardly suspect that there's a diesel engine working at the front.

Regarding tinkering with the engine control unit (ECU), I'd rather leave that to the professionals. With my luck, I'd probably completely wreck it (or at least mess it up so badly that the car won't run and has to be towed to the workshop).

Question: Am I correct in understanding that a diagnostic device is needed to adjust the start of injection with AEL? This seems to be the case with ACV...

Hi.
What does "some hours" mean?
How does Sprint behave if it has been left unattended overnight?
The start of the funding should still be adjustable with a clock; it doesn't take long to set.
Best regards,
Dirk

Good morning, Mr. Fine Dust King.

Take a look at the fuel lines. That was the solution for my starting problems.

SG Christian.

Good morning, everyone!


@ Christian: Are you referring to the "oil leak lines" as the return lines from the injectors?

"@ Held: It's happening over a period of several hours, for example, overnight. However, yesterday it already started acting up after just under 3 hours (I had him on the lift to change the starter motor... so cold weather probably isn't the cause, because it was warm in the workshop), and he's also started up without any problems in the cold in the mornings before - so there are exceptions to that."

Hello,

Yes, exactly, mine looked completely normal.
I then replaced it as a precaution (after checking all the other cables), and that solved the problem.

SG Christian.

So, I went to the parts dealer today and bought a diesel filter, a check valve, and a meter of fuel line.

During the installation of the aforementioned parts, I noticed the following:
- The installed return lines were quite stiff and showed some slight cracking at the ends (although any major damage was not immediately visible).
- The check valve located on the filter appeared to be the original one, which meant it was probably about 14 years old.
- and as a "highlight," I noticed that the inner seal was missing from the diesel filter when it was installed (see attached image) ..... could this alone have caused the problems?

I was amazed by the fact that the car started immediately and without any problems after assembling all the parts: It has never started so smoothly since we've owned it. Although I had filled the filter completely with diesel, I had assumed that I would still have to wait a long time for all the lines to fill up.

Well... let's see what this Wednesday morning brings...

Hello, fine particulate matter!

Feinstaubkönig wrote:

... - and as a "highlight," I noticed that the inner seal was missing from the installed diesel filter (see attached image) ..... could that alone have caused the problems? ...

Are you absolutely sure that the "missing" gasket isn't stuck to the bottom of the DiFi holder? Did you check that before installing the new DiFi (with the mirror)?
I can't imagine anyone installing a filter with a missing inner sealing ring. On the other hand, it happens very often that the old sealing ring remains stuck to the holder!

Best regards from Munich!

Very often, the filters don't actually have a seal.

DieselBär30x wrote:

Are you absolutely sure that the "missing" gasket hasn't gotten stuck to the DiFi holder BELOW??

Yes indeed, I am absolutely certain!

My first thought was actually the same as what you wrote... but there was definitely nothing left there.

Held467 wrote:

very often, the filters don't actually seal

.
It's strange, I only know it with a , but that doesn't mean much to me, considering I only hold something like that in my hand a maximum of 5 times a year.
For internal pressure (or vacuum), the inner seal is irrelevant.

Best regards from Munich!

DieselBär30x wrote:

For (sub-)pressure applications, the internal seal is irrelevant.

So, then that probably wasn't the problem...

But never mind: I have to stay put now and wait to see what happens tomorrow morning.

DieselBär30x wrote:

Held467 wrote: very often, the filters didn't seal properly . It's strange, I only know it with a , but that doesn't mean anything to me, especially since I only hold something like that in my hand a maximum of 5 times a year

.
For internal pressure (or vacuum), the inner seal is irrelevant.

Best regards from Munich!}
I don't know anyone off the top of my head who has one.

Hey there, here he is again .

There should definitely be a transparent hose on the fuel injection pump so that you can see if there's any air in it!

Furthermore, have the pump settings checked, as you already mentioned.

Sure, here is the translation of the text from German to English:

"Hello"

roorback wrote:

Hi, there he is again

Moin Moin... well yes, the internet is small, isn't it?


@ Topic:
Unfortunately, even replacing the hydraulic lines, the filter, and the check valve didn't help --- this morning, I had to wait almost 2 minutes before anything happened.

When the engine didn't show any signs of starting on the second attempt, I filled the diesel filter completely to test if it would start that way (thus, I would have been sure that the fuel would flow back into the tank overnight). But even this action didn't work: As mentioned above, I had to crank the engine for almost 2 minutes before it finally started, emitting a huge white cloud of diesel smoke...

The local Bosch service won't have any available appointments until 2037, and even then, the prices are outrageous (removing the ES injectors is supposed to cost around 170 euros) ... the colleague on the phone didn't have any other suggestions --- it seems to me that this approach is completely unrealistic.