**solved** 2015 Golf TDI - white smoke from the front of engine, but no overheating and no trouble codes

[Helluvadeal]

I've got a 2015 VW Golf TDI with white smoke coming from the engine, but I'm not getting any codes and the engine is not overheating. Car only has 53K miles on it.

This smoke only shows up after I've started the car and driven 3-4 miles. I've never had this issue until just a week or so ago.

EDIT: The smoke doesn't smell like electrical, rubber, or anything like that. It just smells "hot"

This is my first Golf, and I'm a very casual mechanic (I watch Youtube tutorials lol). I've been doing a lot of looking online but I can't figure out what could be causing this.

One article said that smoke from under the hood with these engines is a possible sign of timing belt tensioner failure and recommends I buy a whole kit that includes the whole tensioner assembly plus the coolant pump.

Many other articles and posts offer diagnoses all over the spectrum from catastrophic to needing an oil change, but nothing quite matches what I've got (white smoke only from the hood, no over temps or trouble codes).

As I'm not very experienced in troubleshooting, I'm struggling to try to figure this out.

Any ideas?

 

[AverageAndy]

Does it smell sweet? My guess would be a coolant leak, only showing up when car is warmed up. I think your car has an electronically controlled shroud around the coolant pump which limits coolant flow until engine is up to operating temp. If it is a coolant leak, eventually you will get a low coolant light. If you can pinpoint it to a hose or fitting, that would be good -replace as needed. If it is leaking on the timing belt then you should replace it, along with associated parts.

 

[Mike_04GolfTDI]

What does the smoke smell like?

For example, is it burning rubber, burning oil, or more like steam from leaking coolant?

 

[Helluvadeal]

What does the smoke smell like?

For example, is it burning rubber, burning oil, or more like steam from leaking coolant?

It doesn't smell like burning rubber, plastic, or anything electrical.

It just smells "hot", like you know something is cooking but can't quite put your finger on it.

Ugh, worst description of a smell ever lol

 

[Helluvadeal]

Does it smell sweet? My guess would be a coolant leak, only showing up when car is warmed up. I think your car has an electronically controlled shroud around the coolant pump which limits coolant flow until engine is up to operating temp. If it is a coolant leak, eventually you will get a low coolant light. If you can pinpoint it to a hose or fitting, that would be good -replace as needed. If it is leaking on the timing belt then you should replace it, along with associated parts.

Nope, not sweet. I can't think of a better way to describe it other than just that it smells "hot".

There's no distinct smell that I can recognize like electrical, rubber, etc.

Thanks for the input, I'll start pulling things off to see what I can see.

 

[740GLE]

has the coolant dropped any?

 

[oilhammer]

Take the accessory belt off, see if it still does it, as well as inspect the belt and pulleys and such. If I were to guess, I'd say the tensioner roller locked up.

 

[hjp]

What did this end up being?

Same thing happened to me today, 121K MI. Smoke started pouring out of the hood at the light and was audibly louder. Opened the hood with the motor off and it was clearly coming from the timing cover, especially if you take the tab on the front side of the motor and pop the plastic cover back a bit.

I am assuming this is covered under pg 10 of this doc, calling out:

Additionally, the engine long block warranty shall cover the engine
sub-assembly that consists of the assembled block, crankshaft, cylinder
head, camshaft, and valve train
.
The extended emissions warranty includes parts, labor, and applicable
taxes. The extended emissions warranty shall not void or supersede any
existing warranty. Conflicts concerning the warranty are to be resolved
in favor of the consumer

https://www.vwdiesellookup.com/pdf/VWCourtSettlement_Emissions_Disclosure_Gen3_Final.pdf

 

[Helluvadeal]

What did this end up being?

Same thing happened to me today, 121K MI. Smoke started pouring out of the hood at the light and was audibly louder. Opened the hood with the motor off and it was clearly coming from the timing cover, especially if you take the tab on the front side of the motor and pop the plastic cover back a bit.

I am assuming this is covered under pg 10 of this doc, calling out:

https://www.vwdiesellookup.com/pdf/VWCourtSettlement_Emissions_Disclosure_Gen3_Final.pdf

I Forgot to update this thread, my bad!

Your problem sounds a lot like mine.

I don't know the root cause or the order of failure but here's what was happening under the timing cover:

Seized tensioner pulley - When I removed it, the tensioner pulley was completely seized. It had blue scoring marks where it looked like the timing belt had been just dragged over it.

Partially seized pulley - One of the smaller pulleys was not completely seized, but not free-spinning either.

Black "dust" all over everything under the cover - It appears that the timing belt had been rubbing against the troublesome pulleys and blowing off bits of vulcanized rubber that covered everything.

Coolant leak - The coolant leak didn't happen immediately (or maybe just didn't completely fail right away) but after I rolled the dice and decided to drive it home from the parking lot where I'd pulled it into, a large leak developed and I saw it dripping and pooling under the car. The coolant had been tossed around by the belt and had mixed with the black rubber dust from the belt and made a nasty mess. Had to scrub it all out pretty well.

Timing Belt - The timing belt had obvious wear and tear on it when I removed it, particularly apparent around the edges.

______________________________

My Theory -

The coolant pump was probably slowly leaking, not enough to cause over-temping or set off alarms.

Enough coolant got onto the pulleys and caused them to start to seize.

The friction of the timing belt being dragged over the seizing pulleys was causing the coolant to cook and causing the white smoke I was seeing.

Eventually enough bad stuff was happening that a more complete failure of the coolant pump happened causing the coolant dump.

_______________________________

Solution -

The solution that I followed was to order one of the timing belt and coolant pump kits and swap everything out.

The coolant pump / timing belt kit I ordered was this kit from DieselGeek. Cost: $449

I also ordered this engine timing kit from Amazon. FYI, the cam and high-pressure-fuel-pump lockers with the silver handles didn't fit into the slots, so I used the ones with the round black handles from the kit instead. Cost: $26.

The DieselGeek kit came with a free tutorial video, but I followed this video on Youtube instead. This is probably one of the best Youtube tutorials on any mechanical task that I've seen. He's a hardworking dude handicapped with a British accent, so give the guy some love if you end up doing this.

______________________

Summary -

I'm not a mechanic by any means, but with the help of the step-by-step Youtube video and a complete parts kit, I got it done easily enough.

I've probably driven 300-400 miles since, have not had a problem.

Definitely dodged a bullet by catching this in time. I'd probably be buying a new engine if the timing belt had failed.

Gotta say though, I'm a tad paranoid now. I'll be driving down the road with the windows down and I'll smell something burning and start getting all freaked out but then I realize it's just someone's BBQ grill lol.

 

[hjp]

I Forgot to update this thread, my bad!

Your problem sounds a lot like mine.

I don't know the root cause or the order of failure but here's what was happening under the timing cover:

Seized tensioner pulley - When I removed it, the tensioner pulley was completely seized. It had blue scoring marks where it looked like the timing belt had been just dragged over it.

Partially seized pulley - One of the smaller pulleys was not completely seized, but not free-spinning either.

Black "dust" all over everything under the cover - It appears that the timing belt had been rubbing against the troublesome pulleys and blowing off bits of vulcanized rubber that covered everything.

Coolant leak - The coolant leak didn't happen immediately (or maybe just didn't completely fail right away) but after I rolled the dice and decided to drive it home from the parking lot where I'd pulled it into, a large leak developed and I saw it dripping and pooling under the car. The coolant had been tossed around by the pulley and had mixed with the black rubber dust from the belt and made a nasty mess. Had to scrub it all out pretty well.

Timing Belt - The timing belt had obvious wear and tear on it when I removed it, particularly apparent around the edges.

______________________________

My Theory -

The coolant pump was probably slowly leaking, not enough to cause over-temping or set off alarms.

Enough coolant got onto the pulleys and caused them to start to seize.

The friction of the timing belt being dragged over the seizing pulleys was causing the coolant to cook and causing the white smoke I was seeing.

Eventually enough bad stuff was happening that a more complete failure of the coolant pump happened causing the coolant dump.

_______________________________

Solution -

The solution that I followed was to order one of the timing belt and coolant pump kits and swap everything out.

The coolant pump / timing belt kit I ordered was this kit from DieselGeek. Cost: $449

I also ordered this engine timing kit from Amazon. FYI, the cam and high-pressure-fuel-pump lockers with the silver handles didn't fit into the slots, so I used the ones with the round black handles from the kit instead. Cost: $26.

The DieselGeek kit came with a free tutorial video, but I followed this video on Youtube instead. This is probably one of the best Youtube tutorials on any mechanical task that I've seen. He's a hardworking dude handicapped with a British accent, so give the guy some love if you end up doing this.

______________________

Summary -

I'm not a mechanic by any means, but with the help of the step-by-step Youtube video and a complete parts kit, I got it done easily enough.

I've probably driven 300-400 miles since, have not had a problem.

Definitely dodged a bullet by catching this in time. I'd probably be buying a new engine if the timing belt had failed.

Gotta say though, I'm a tad paranoid now. I'll be driving down the road with the windows down and I'll smell something burning and start getting all freaked out but then I realize it's just someone's BBQ grill lol.

Legendary write up, thank you! I will follow the same path you did and handle this on my own. Thanks for the links also.

It seems we both had a serious stroke of luck considering the belt survived. I have a feeling my vehicle had a similar failure mode, I have been adding coolant for the last year or so, was very minor and slow loss until recently where I lost a reservoirs worth overnight. I was due for TB service in 10k MI anyways, so this just scheduled itself a bit early

 

[whizznbyu]

This is scary. Unless you looked under the hood this would have gone unnoticed.

 

[Helluvadeal]

This is scary. Unless you looked under the hood this would have gone unnoticed.

I actually saw a wisp of white smoke come out from under the hood when I stopped at a traffic light. But yeah, you're right. Never would have noticed if I'd kept driving

 

[oilhammer]

I wonder if some of these newer cars' bearings in certain items are coming from the PRC. Because we've seen a spike in the last few years of failed sealed bearings in all kinds of things we never used to see. Denso alternators for one, the INA alternator pulleys place on Mexican-assembled Valeo alternators on North-American assembled Hyundai-Kia stuff that clearly says CHINA on it, and so many other little things.

 

[whizznbyu]

I suppose nothing can be done as a preventative measure? Such as a grease spray to the bearings? Changing out the timing belt and bearings way before the factory's recommended interval is the only solution.

 

[740GLE]

stick to 100k or if you notice the WP leaking.