Major engine failure caused by seizing oil pump?
Hi,
a while ago, my 2002 ALH Mk4 Golf had a major engine failure on the german Autobahn.
At the time, it looked/felt like a turbo failure - but it quickly became apparent that piston #1 had melted, leading to zero compression and a controlled runaway (only that cylinder was running on oil), which was easily manageable. The engine did not reduce rpm on its own (in gear), but it also did not accelerate on its own. Engine braking in gear was easy, near idle rpm it shut off on its own when I turned off the key even with the clutch depressed and without a SUV (racepipe installed).
We had lots of ideas about the culprit, some seemed pretty plausible, but it all just didn't add up. The injectors were working fine before and almost new Bosio nozzles (pop-tested and evenly set up at 220/300 bar) were mounted, and damage was limited to cylinder #1 - everything else was in perfect running order (about 200k km/125k miles, why shouldn't it be), and a few weeks before the smooth idle regulation said all cylinders were within spec when I checked with VCDS. Head gasket was fine.
The turbo itself wasn't it, either - it did sustain damage from the molten piston remains, but the seal was still intact and it didn't bleed oil out into the intake.
Valvetrain also looked fine except for one valve that had a molten piece of piston stuck under the lip so it was protruding minimally further into the cylinder - followers looked like there was no hard contact.
So we scratched our heads - oil pressure warning light did not come on at any point, ever. I can only guess that the first time you'll see that light come on is when you have no oil circulating at all anymore...pff. Sure had a CEL right away when I forgot to connect the switch one time, though...
I decided to have the engine rebuilt with a stronger bottom end (ARL pistons, PD conrods, uprated bearings and bolts etc), new oil pump (hadn't checked it at that point yet), nozzles, downpipe and the works.
Well, when the oil pump was removed to make way for the replacement, the real culprit was found - it was almost seized! Hardly possible to turn it over by hand, the insides were toast. Why the stupid oil pressure sensor did not trigger remains a mystery to me. The drive chain was still intact.
Now, I haven't read anything about the oil pump going south with mileage as low as this - what are your experiences?
The car did undergo some "Longlife" intervals when it wasn't remapped, but always ran VW-approved fully synthetic oils. After remapping, an oil change was performed every 6-10k miles/10-15k km.
Why the oil pump should fail at this stage remains strange.
In any case, a good reason to mount an oil pressure gauge...
Regards
Hi,
a while ago, my 2002 ALH Mk4 Golf had a major engine failure on the german Autobahn.
At the time, it looked/felt like a turbo failure - but it quickly became apparent that piston #1 had melted, leading to zero compression and a controlled runaway (only that cylinder was running on oil), which was easily manageable. The engine did not reduce rpm on its own (in gear), but it also did not accelerate on its own. Engine braking in gear was easy, near idle rpm it shut off on its own when I turned off the key even with the clutch depressed and without a SUV (racepipe installed).
We had lots of ideas about the culprit, some seemed pretty plausible, but it all just didn't add up. The injectors were working fine before and almost new Bosio nozzles (pop-tested and evenly set up at 220/300 bar) were mounted, and damage was limited to cylinder #1 - everything else was in perfect running order (about 200k km/125k miles, why shouldn't it be), and a few weeks before the smooth idle regulation said all cylinders were within spec when I checked with VCDS. Head gasket was fine.
The turbo itself wasn't it, either - it did sustain damage from the molten piston remains, but the seal was still intact and it didn't bleed oil out into the intake.
Valvetrain also looked fine except for one valve that had a molten piece of piston stuck under the lip so it was protruding minimally further into the cylinder - followers looked like there was no hard contact.
So we scratched our heads - oil pressure warning light did not come on at any point, ever. I can only guess that the first time you'll see that light come on is when you have no oil circulating at all anymore...pff. Sure had a CEL right away when I forgot to connect the switch one time, though...
I decided to have the engine rebuilt with a stronger bottom end (ARL pistons, PD conrods, uprated bearings and bolts etc), new oil pump (hadn't checked it at that point yet), nozzles, downpipe and the works.
Well, when the oil pump was removed to make way for the replacement, the real culprit was found - it was almost seized! Hardly possible to turn it over by hand, the insides were toast. Why the stupid oil pressure sensor did not trigger remains a mystery to me. The drive chain was still intact.
Now, I haven't read anything about the oil pump going south with mileage as low as this - what are your experiences?
The car did undergo some "Longlife" intervals when it wasn't remapped, but always ran VW-approved fully synthetic oils. After remapping, an oil change was performed every 6-10k miles/10-15k km.
Why the oil pump should fail at this stage remains strange.
In any case, a good reason to mount an oil pressure gauge...
Regards
