Golf '95 Mk3 TDK @ 230000 km suddenly dies when idled and has lost power.

[$hitblast]

Yesterday, while on the freeway, the engine suddenly stopped as I dropped it to idle between two gears. I got it started again, but the engine wasn't behaving like before. It would seem to start, but then drop back to starter-engine-rpm. It would do this a few times before catching, and then had to be kept over 1600 rpm while under load, or it would stop.

After this, at first, there was no loss of power. Then, twenty minutes later, it became weaker. It was half an hour back home, but it went fine. I had to take the battery out and charge it, as it was town to 12,10 V after two more stops and lots of churning to get it going again.

I don't know much about this kind of failure, but I'd heard cars would go weak if the fuel filter clogged up. I've had a suspicion I've got the diesel bug, as I pumped up some diesel with small and somewhat bigger particles of yellow-brownish color from the bottom of the tank two years ago. I've added a special alcohol, for drawing out eventual moist, and diesel-bug poison ever since. The engine has been running fine up until now.

I changed the filter. I started pouring the contents, and saw that the top liquid was clear. Further down, it was brown-yellowish murky. I poured it into a clear bottle, and saw it split into two phases, the top one dissolving better than the bottom one. I suspect the bottom phase is water.

I tried starting it again today, from a cold engine. It would not start, but it wasn't quite unresponsive either. The engine would help with the churning, but would not sustain itself before I'd let it churn in intervals for two minutes or so. It would lose its rhythm under 2200 rpm. As it heated up, it could go smooth at 2000 rpm. If letting go of the accelerator, the engine would stop, if I didn't ease it down slowly.

I also noticed a rattling sound coming from somewhere around the main brake cylinder. This, I don't think I've heard before. It's quite distinctive.

I took it for a drive, but nothing had changed. It was still weak, and had to be kept over 1600 rpm under load to not stall.

What do you guys think?

[$hitblast]

The car had 10 liters put in it by my brother the morning the same day. He usually drives a gasser, but says he's sure he used the right grip. It's black here in Norway, with a bigger nozzle. Gasoline is green. I called down to the gast-station, to hear if they've had other cases, but the kid on the other and said there were none.

Gasoline-poisoning would explain these symptoms quite well, however. I asked him to check his credit card receipt data, to calculate type of fuel from price and volume. I'll add some engine oil to fatten up the mixture if these numbers come back indicating gasoline.

[$hitblast]

Today I put the mechanic's stethoscope to use, and listened in on the injectors. They're all alive and clickin' regularly. This would mean everything up to the pump works, I assume. There could still be some dirt in the injectors, however. I suspect this is the case, as it seems to irregularly miss beats on idle, and regularly when revving; i.e. it doesn't rev smoothly either.

Am I fumbling here? What do you guys think?

[h100vw]

I don't drive diesels but I'd be draining that tank out and flushing it if there's any doubt. Replace the fuel filter and see what happens then.

Also make sure there's no manifold leaks, likely accompanied by black smoke due to incorrect mixture.

Gavin

[sparkie]

I had a similar thing happen to mine, and it ended up being very hard to start. The first mechanic said the injector had stuffed, and the second diagnosed algae in the tank and got it going, cautioning that I clean the tank out, which I have done and 500km later it is still running fine. One way to try and force the fuel into the car is to find the fuel retrun line which goes back to the tank from the fuel filter, and 'push' compressed air in there (you'll probably hear the tank 'pop' as the air pushes the plastic out slightly), once there is some pressure in there, try and start the car, it worked a treat for me! I suspect in your climate water in the fuel is more common - do dodgy fuel servos cut with thinners or veggie oil?

[$hitblast]

h100VW: Hello. I already changed the filter. No difference whatsoever. I haven't checked the manifolds, other than listening for exhaust-leaks, intake-wheezing and sniffing for exhaust in the engine-compartment. I suppose a broken intake-manifold could disrupt the workings of the valves by alterating their operating pressures, but this I don't know much about this at all.

sparkie: So, you mean to use a large syringe, or similar, to blow through the fuel return and increase pressure in the tank, for the pressure to supply more fuel to the injection pump through a possibly clogged system? It seems to make sense. Would this fix the problem, or merely be diagnostic? And how did you clean your tank?

[$hitblast]

Today I started it up, and to my surprise, it started normally. The engine-sound was much more noticeable than usual, however. It sounded like a tractor. I drove about twenty kilometers in it, and apart from the noise and bumpy acceleration from 1600 to 2000 rpm i second gear, it behaved normally. I have no clue as to why this happened.

Just before this, I had taken a look at the timing belt. I don't know so much about timing belts, but I assume the markings on the camshaft and the pump shaft are supposed to align. They just about align for the pump, but not the cam; see pictures. I'm not sure how much weight I should put on this, as I haven't made any of these markings myself. The belt itself was changed about 10k kilometers ago, and doesn't have any noticeable wear yet, as far as I can see.

[kaanage]

I'll add some engine oil to fatten up the mixture if these numbers come back indicating gasoline.

Use 2 stroke oil rather than engine oil since it is designed to be burned (it can help clean out carbon deposits in the head and injectors as well)

[sparkie]

My suggestion merely diagnostic, but also if you blow all the lines through (I used an air compressor), and as you have changed the filter, you know the delivery is good.

I put the rear of the car on ramps, drained the tank, unbolted the fuel tank, after I'd removed the fuel gauge sender from under the boot floor, dropped the fuel tank off, blasted it inside really well with a high pressure water blaster, and then I dried the inside as best I could with towels, and left it in the hot sun for hours, before putting it all back together! You may not have these options in winter in Oslo, not sure what to suggest, a hairdryer? It is really important to get all the water out, obviously

[$hitblast]

@Sparkie Could you describe in more detail how it was more difficult to start? Mine would seem to almost start from the first turn, the engine giving slight bursts constantly, before catching on after about two minutes of churning. From its uneven rhytm and low power, it seemed to be not firing on all cylinders. Now, not having done much else than running it idle for about an hour, it for some reason has regained power and rhytm, but makes much more noise than before.

[$hitblast]

I took it for another 20 km spin. Apart from the tractorish noise, it worked just like before for the first 5 km. Then, over a four second interval or so, power and rpm faded, and it died. Churning it for thirty seconds started back up in a weird way; it would only rev if I kept the ignition key at starter-engine position. If I let the key go to normal position, it would fall from 2000 rpm to zero over a three second interval. This lasted only abruptly, and it would idle normally, but was quite weak, and died again right after on a slight inclination, fading from 2500 rpm in first gear. Churning it now again for twenty seconds, it came back online at normal strength, but now the engine had changed its sound. Every other beat was extra loud.

[sparkie]

When I ran my tank really low, it simply wouldn't start. At times it sounded like it would, but after lots of turning it over, it simply wouldn't catch. The engine sounded just as it always did, but there was simply no fuel getting to the injector (on Tdis the injector sucks the fuel into itself there is no separate lifter (fuel pump). I gave up and it was the second mobile mechanic who managed to start it by pressurising the fuel tank to assist the injector with sucking the fuel up. (This model is notorious at being difficult to start once out of fuel) Once he had started it, it ran fine, but he cautioned me to clean out the tank (which actually wasn't too dirty, maybe the algae was all in the fuel I threw away). He suggested that the car might work for a while, and then when algae was sucked up the line, it would stop again. I don't remember anything else in terms of noises or rattles being any different to normal

[gldgti]

I took it for another 20 km spin. Apart from the tractorish noise, it worked just like before for the first 5 km. Then, over a four second interval or so, power and rpm faded, and it died. Churning it for thirty seconds started back up in a weird way; it would only rev if I kept the ignition key at starter-engine position. If I let the key go to normal position, it would fall from 2000 rpm to zero over a three second interval. This lasted only abruptly, and it would idle normally, but was quite weak, and died again right after on a slight inclination, fading from 2500 rpm in first gear. Churning it now again for twenty seconds, it came back online at normal strength, but now the engine had changed its sound. Every other beat was extra loud.

air in the fuel lines. you have an air leak for sure

[Ryeman]

air in the fuel lines. you have an air leak for sure

Where to start with that then?

[gldgti]

well the fuel lines are typically hard (e.g. plastic or steel) until they get to the engine bay, so rarely any problems from the tank end of the delivery line until you come to all of the engine bay connections - between the hardlines and the fuel filter, and between the filter and hte Injector pump. Air can be sucked into the system anywhere between the tank and the pump, but I would try all of the hoseclamps and rubber lines first. The filter itself can also sometimes get a pinhole from corrosion and if that is coupled with a partially blocked filter the pump will suck air into the system thorugh the pinhole when the engine is running, and when it stops the fuel will weep out aswell.

Always remember that on rotary pump diesels, the injector pump is nearly always the only pump in the system, so there is suction in the fuel delivery lines all the way from the tank, and hence any leak point at all will allow air into the system which will cause rough running, hard starting (cold or hot), lowe power, timing problems (timing is dynamically controlled by internal pump pressure which gets screwed up when air is in the pump, as the air is compressible).

If you dont have at least some clear fuel hose going to the pump, you should install some (7mm clear PVC is just fine) and you will be able to see the air bubbles travelling into the pump.