Timing Belt Failure: VW Golf V - Twice in 2 Years?

Vehicle: Volkswagen Golf V with BKC engine, purchased at approximately 123,000 km. The seller claimed the timing belt was replaced around 120,000 km in late 2012.

At approximately 200,000 km (November 2015), the belt lost 10 teeth and shifted by 2 teeth. A new belt was installed, and the car ran normally again.

At approximately 237,000 km (March 2018), the same issue occurred again. Both times it was a Contitech belt. This time, I also replaced the water pump; the old one looked okay, and otherwise, I couldn't visually detect any problems. So, I installed the new belt, put in a new water pump, and thankfully, it ran as expected again.

The driving conditions were the same both times. I was on the highway, maintaining a good speed for a while, then I took my foot off the accelerator to around 120 km/h, and then pressed the gas again. Suddenly, there was a loss of power, and then the engine cut out completely, leaving me stranded. The first time, I had to have it towed. The second time, it happened just before I got home, and I barely made it back with adjusted timing.

What could be the reason why it's eating through the teeth? The car had a different software installed at approximately 156,000 km. However, I don't see this as the main cause, as I haven't heard of this happening in conjunction with a performance increase before.

"Additionally, it occasionally needs a little water after being used. However, the cause of this has not been identified. Two years ago, the problem was more significant, and he had upgraded to heavier-duty head bolts from the ARL engine, which reduced fuel consumption. Three months later, using 'bar's leak' (added to a cleaned and flushed cooling system) provided a solution."

"Both belts appeared dry visually, with no oil visible on them. However, almost all of the teeth show uniform signs of wear."

Hi there!
Did you really just replace the belt?
The teeth on the idler pulley or tensioner may be so worn that the belt is subjected to excessive wear.
I once had a Passat where the timing belt only lasted about a month, luckily it was an interference-free engine.
After the third belt replacement, I replaced everything that had to do with gears, and then it was quiet.
Best regards, Frank.

Hi there,
The idler pulley and the tensioner pulley should ideally not have any teeth; the belt runs on them with its back side.
Of course, the impeller of the oil cooler, the impeller of the water pump, and the impeller of the power steering pump are all subject to inspection.
Was happened to the belt? Did it get damaged somehow, or was it a cheap part? Otherwise, the only possible causes are a blockage in the drain line (NW) or a problem with the pump itself.
hg
Herbert.

Hi. So, the tensioner and idler pulley were replaced each time. There wasn't anything obviously wrong with the crankshaft pulley or water pump pulley.
Can the pump seize up at full speed? Or is it more likely that the KV motor, with its smaller surface area, would be the one to strip its gears due to excessive force?
How can each of these be verified?
The belts were sourced from the local dealer who also supplied car dealerships.

I can't give you specific technical advice, but if this were my car, I would take a very close look at the gear on the crankshaft.
It seems to me that this wheel is made of a softer material than the one on the camshaft. (I might be wrong.)
It could potentially be worn out, although that is very rare and almost impossible.
I've encountered this issue before.
Or maybe someone replaced the wheel at some point, and it doesn't have the same tooth structure.
I think it's possible that something like that could block a water pump.
However, in my opinion, it is impossible for the system to continue functioning correctly and without errors after this.
Best regards, Frank.

Looking at the pictures of your timing belt again, the teeth appear worn out rather than blocked.
Best regards, Frank.

Several teeth were milled off side-by-side in this area, and the length matches the engagement length of the spur gear on the crankshaft.
It's hard to imagine from the picture that the camshaft didn't misalign in a way that caused the valves and pistons to make contact, especially considering that the engine continued running afterwards.
It's likely that this exact issue already occurred with the first damage, causing bent valves, and as a result, it repeatedly leads to jamming and excessive strain on the timing belt.
Nothing meaningful will come out of this without inspecting the cylinder head.
hg
Herbert.

Okay, now it's 2019...: Same car, BKC engine, now with approximately 161,000 kilometers on the clock. The timing belt that was installed in March 2018 (along with the water pump) and which had been put on at around 237,000 kilometers, has lost its teeth again. It happens when accelerating in 5th gear from 100 km/h upwards, especially going uphill.

My colleague who works on cars says it's dry (although there's a slight oil leak at the back of the engine), and that it's due to the power output; the car has just different software and around 135-140 horsepower with a maximum torque of 320 Nm. I can't really imagine that being the cause. Especially since every standard ARL already has more power, and I haven't heard of such problems before, and it uses the same belt.

Okay, I'm going to put a Gates belt on now... I'm tired of having to replace the belt every year or every 30,000 km, or getting stranded.

"I'll post more pictures of the belt in a few days after I replace it. The car has always had full power, and all the performance values are within range."
Can the nose wheel be locked during full speed? If so, how can it be checked? Should the pilot lower their head?

"With that many missing teeth, it's my opinion that it's impossible for the valves/pistons not to have made contact. Unless your engine is a free-running type, which I don't know about, but I would be surprised."
If the valves are misaligned, you should also have noticed a loss of power or increased fuel consumption. It's definitely not normal for a timing belt to only last 30,000 kilometers.

To inspect the valves, the cylinder head needs to be removed.

This is the third time this has happened in 3 years.

The first known use of dental floss dates back from approximately 120,000 to 200,000 years ago.
second of 200000 to 237000.
and the current mileage is between 237,000 and 261,000 kilometers.
All Conti belts.

"Recently, with normal driving, the fuel consumption was around 5 liters (as indicated by VCDS, adjusted to reflect actual consumption). Of course, it can be higher when demanding more power. However, over all these years, there has been no noticeable difference in either performance or fuel consumption. There may be a gradual, minimal loss due to general engine wear."

BKC is not a free rider.
I hope he didn't get hit this time either. But first, let's put the belt on and test it. If he did, just keep your head down .

I'm starting to suspect a problem with the camshaft drive.

Check if all the plugs are still in place on the camshaft's piezo elements. Oil pressure can leak out through there, which can make everything run more sluggishly.

I would never have simply installed a new belt without first investigating the cause of the problem.

Hello!
I've seen something similar before.
That was a long time ago, when the Volkswagen Golf 2 was still current.
"Once, someone came to me with a car that had the 1.6-liter gasoline engine, the version with electronic fuel injection and a lambda sensor, producing 72 horsepower."

The engine is making strange noises; I should take a look.

I've heard that it's related to the belt drive system.

Removed the timing belt cover, and then came the shock:
Not a single tooth left on the belt.
The strap was pulled incredibly tight.
The engine was still running, and the valve timing hadn't changed.

I've only seen timing belt teeth that have sheared off in cars where nobody had taken care of the timing belt for a long time, back in the old days, when there were no automatic tensioners.
"You know, you drive something for 15 years and never bother to check the timing belt. Then, suddenly, 10 teeth are missing, the valves hit, and the ride is over."

In this case:
I am not familiar with the quirks and problems of these engines.

Assuming the tensioner was installed and tightened correctly according to the instructions, which I believe is the case...
It's quite understandable that something might be running slowly or prone to getting stuck.

Hello.

Hopefully, the idler pulleys and water pump were replaced before the timing belt failed again?
Does the impeller of the water pump show any marks or signs that might indicate the presence of foreign objects?

Best regards, Rainer.

I've seen teeth that have broken off or been worn down more than once, including on my own car where the ContiTech belt only lasted 30,000 km... it has nothing to do with the age of the vehicle.

Without investigating the root cause, it will likely continue like this. I would suggest examining the valves, possibly using a camera in the first step.

Hi, so, the belt and all the associated pulleys were always replaced together, with the water pump being last changed in March 2018.

The engine is running again as if nothing happened. However, the mechanic (I really didn't have time) who installed the new one mentioned that it felt stiff when rotating (with the belt attached).

Next, I'll take a look at the "Nocke" (cam) and other components. They should be visible only after disassembling the valve head.

I've already got a cheap replacement engine with all the necessary parts on hand, just in case something goes wrong, so that the car doesn't have to be out of commission for too long.