Audi 80 1.6 TD (Motorcode SB) - Significant Power Loss

Hi everyone,

Since my trusted local repair shop can only focus on the fuel pump, I need to ask around here, because I'm not spending so many Euros on this old vehicle (manufactured in 1990, 270,000 km) anymore. On the other hand, it would be a shame, because there was just a new crankshaft and a new cylinder head gasket after the connecting rod failure...

Here is the path of suffering:
The first symptom was slight shuddering in the full load range, with a maximum speed of 30 km/h being too low. Subsequently, I replaced the diesel filter and also performed an oil change (approximately 1500 km after the head gasket). However, nothing changed. When I tried to drive a slightly longer distance the next day, the engine stopped at 120 km/h, and it could only manage 80 km/h uphill. Engine temperature was normal, and fuel consumption was approximately 40% higher than usual, according to the fuel gauge. Since I had only managed 50 km of the planned 350 km, I turned around and eventually limped home with the engine completely dead, reaching a maximum speed of 60 km/h after repeatedly engaging and disengaging the clutch. "Initially, I installed the nozzles that I had been sitting around for ages (these were replaced by a friendly VAG mechanic about 200,000 km ago, supposedly on suspicion, and then it turned out they were okay), but that didn't bring about any noticeable improvement." Again, the same problem: after about half an hour of normal operation, there is again this extreme loss of power.

What next

I've read quite a bit about the LMM here, but does my "oldie" have it?
Could something with the diesel supply (besides the ESP) be wrong if I have air bubbles in the line from the filter to the pump? Why am I then consuming significantly more?

Otherwise - who wants to buy a well-maintained Audi 80, 1.6 TD 59kW (LLK), manufactured in 1990, with 270,000 km and slight performance issues?

Hello,

So, if you have air bubbles between the filter and the ESP, that could be exactly the problem. This issue has been discussed several times in this forum. Use the search function!!!
Since your engine's performance starts to decrease significantly after about half an hour and air bubbles form, it's certainly due to the low pressure in your diesel tank. This means that the tank's ventilation system is not working properly. To verify this, you can test by driving around with the tank open.

Before I start working on the ESP, I would first check everything else.
The bubbles in your fuel system certainly don't belong there.

Good luck!

mahk wrote:

I've read quite a bit about the LMM here, but does my "oldie" have it?

No.

Okay, I'm going to try leaving the tank lid open. It's also much more cost-effective than buying a new ESP. But can this really noticeably reduce consumption?

Another issue that also causes problems: The "glow plug" function doesn't always work, sometimes it glows for a few seconds while driving. (I already disconnected the temperature sensor at the top of the cylinder head about 150,000 km ago: depending on the engine temperature, I leave the ignition key on "Ignition" and then start the engine.) When I went to VW to get a new relay: 129 euros . If it really is the relay, the part has to be removed, and I determine the glow time by holding two wires together . On the other hand, I wonder if the relay is so expensive because it controls more than just the glow time... the engine still runs perfectly without the relay.

The relay sticks before and after the RA/SB. (JP, and JR only stick BEFORE)

When you disconnect the temperature sensor, it feels like the deepest winter, almost eternally.

I don't know how long it will take, because the {PREPARATION} process is stopped by {CLOSURE}.

m;

mahk wrote:

Okay, I'll try that with the open tank lid. It's also much more cost-effective than a new ESP. But can this really noticeably reduce consumption?

Only in left-hand turns


In your fuel injection pump, the injection start is adjusted in a speed-dependent manner based on fuel pressure (hydraulically).
Does your pump, for whatever reason, only suck up foam? In most cases, the injection timing is usually too late because then there isn't enough internal pressure that can be built up.
Follow-up: reduced performance, higher fuel consumption, turbocharger can overheat.

Hello, Rainer

Quote:

The turbocharger can get too hot.

Because injecting fuel into the exhaust manifold increases the exhaust temperature?

But the foreman has one with a water-cooled turbo

m;

So, since I'm currently driving my mom's Polo and my Audi is with my parents (200km away), I yesterday drove my dad around with the fuel tank cap open. But that didn't work . I also tried attaching the transparent hose from the filter to the ESP while the engine was running to observe: There were still really big bubbles. I'll be over again tonight to take a look myself - where do you think the air is most likely getting in?

at the filter (or at the connection on top) or at the back of the tank (pump and/or valves that should be located there)?

The control unit must also have the filter with the preheating valve (i.e., 4 instead of 2 connections).

This valve is only secured with a clamp that often doesn't press down hard enough.

That would be my first approach.

m;

Quote:

The SB should also have the filter with the pre-heating valve (i.e., 4 instead of 2 connections)

That's probably it... if I press on them, the bubbles will definitely be significantly less. I took them out and cleaned them yesterday, and guess what: I was able to get home 200km. However, it still jerks up occasionally in the full load range. I'll just replace the valve, it can't be that expensive.

Completely different: these hoses that connect the nozzles to each other - what are they actually for? And why is there always a little bit of diesel dripping onto the hot cylinder head? I have slightly modified the fitting for this hose on one of the nozzles because I didn't have any special tools. Could it be that it's now sealed and the diesel is leaking out at the weakest point?

Hello legal,

Glad you found the error.

'I've also had a situation where, during the diesel filter replacement, I damaged this return valve on the filter (or whatever it's called...). From the outside, you couldn't see anything, but it was clearly letting air in. There was a small crack that was the problem. I then went to VW and got a new one.' I can't say exactly how much it costs now, but it certainly doesn't cost the world.

The fact that the engine still vibrates a bit even under full load is probably due to the remaining air pockets.

The hoses that connect the nozzles are called fuel drain hoses. These are intended to drain excess fuel and must not be bent or blocked. Using the search function, you can find plenty of information about it.
If they are porous and leaky, you can't simply shorten them and put them back in place. In this case, you will need to install a new set of hoses. 'You can only use these oil leak seals, I read somewhere in this forum.'

These hoses shouldn't cost so much either.

According to http://www.heipro.de, approximately 1.5 meters are needed per vehicle at a cost of 3.20 euros.

So, as for the situation, you can also resolve your problems without a new ESP.

Best regards, Georg

Sorry,

should be 'oil leak line' and not 'oil leak line'.

Although I have gotten out of bed, I haven't actually woken up yet!!!

It was a tiring weekend, I probably need to make another pot of coffee...

"Oil leak lines" - okay... they definitely leak quite a bit. I'm really worried that one of the fittings on the third nozzle block is leaking because I've loosened it a bit. The hoses themselves, however, look very good; they don't seem to be leaking on their own. The problem is that the fluid is just being pushed back from the 4th nozzle block towards the pump (connected to the 1st), and with the 3rd, it just stops there. Then the fuel just finds its way (past the hose). If I position the leak lines so that this (blocked) fitting is the last one that's also fitted with a blind cap, then the excess fuel should return to the pump, and not drip out of any connection. Or is there something against connecting these cables in a slightly "unconventional" order?[/i]

mahk wrote:

"Oil leak pipes" - okay... they certainly leak quite a bit.

Very bad...

The order of the leak hoses doesn't matter, all the nozzle holders are simply connected together, and the 'Diesellecköl' is simply redirected back to the pump return.
Changing the order will not solve your problem

First, try to get all the lines and hoses sealed properly. Otherwise, you won't need to try anything else.

Hello, Rainer

I believe that a different order of things will actually solve the problem.

Currently, the excess diesel from cylinder 4 must pass through the third, second, and first cylinders, and then through all the nozzle holders, in order to return to the return line. However: Cylinder 3 is blocked because of a curved fitting. If I now change the order so that the curved end of the connector is the one "farthest away" from the pump (i.e., the one that is already closed with a blind cap), everything should flow smoothly again.

It's just awful, having to crawl from the office into the basement and get my fingers all cold and numb. Hopefully, something will be done about it tonight. But I'll keep you updated

oh, no: the lines themselves are not porous or cracked in any way. I have never had a diesel smell in the car either. Everything started suddenly after the fuel injector replacement. And that also fits with the somewhat clumsy solution with oddly shaped wrenches and so on... without a 27mm nut that fits over the entire nozzle holder, BUT is just long enough to reach under the ESP's arms, then you won't have any fun with the SB