TDI Turbos; Some Thoughts and Guidelines on Failures

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Will
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TDI Turbos; Some Thoughts and Guidelines on Failures

Post by Will » Mon Nov 14, 2005 10:51 pm

Hi
It is no secret that there are a significant number of failures on TDi turbos, particularly at Highveld levels and particularly on the Polo models. It is a known fact that VW replaces a lot of them, and that the reasons for their failures are often misrepresented. So here are some thoughts and suggestions for those who are either concerned or have had some experience with this problem.

First of all, let me clear something up which is a common misconception. The VNT15 turbo fitted to the PD motors is NOT a bad turbo, in fact the variable vane turbo fitted to the Polo is one of the best on the market. However, every part of a car is only as good as the conditions it works in, and there are a number of reasons which contribute to the failure of these units;
1.) Oil feed. The hoses that feed oil to and from the turbo are poor diameter and have limited thermal resistance to heat from the manifold, exhaust and turbo itself. These are often not replaced after turbo failure, even after a turbo repair, with the consequent result that the problem that caused the first turbo to go, may precipitate the same on another turbo. Heat causes the oil in the channels to carbonise, and often this carbon is drawn into the turbo bearings, ultimately causing wear & causing the shaft to break. Bearings are on their way out when you can hear a characteristic whine/whistle from the turbo.
2.) Although you will find precious little if anything in your owners manual, you should run your turbo down for 30 seconds around town and as much as 3 minutes after sustained high load running/ or long trip. This allows oil to circulate through the turbo. There is no auxilliary oil pump which operates after the engine runs down similar to that employed in the S3. Hot shutdowns may potentially precipitate 1.) above.
3.) Do not use poor quality oils or fuel. Make sure you see the right synthetic oil indiciated on your service invoice from VW. Also do not assume that all diesel is the same. There are currently only 2 low sulphur (Euro compliant) fuels on the market, and they DO make a difference.
4.) Tuning; Overboosting and overfuelling raises Exhaust Gas Temperatures in diesel cars, compounding the high ambient temps, less dense air (Highveld)and crappy fuels our modern generation high tech diesel engines have to cope with in SA. Make sure your tuner of choice addresses these questions before you commit to a chip. TDI's are very tuneable, but exercise caution. It is worth noting that turbos fail in both standard cars and modified cars, but a tuned car is more likely to make a weak link snap if it exists.
Running in decently is essential. Dont be tempted to over stress a new engine. It is tempting in an age when 1.9TDi's can embarass much larger performance cars, but respect the recommendations for running in and operation, and importantly do not over-rev a diesel, they do not like it.

If you are unfortunate enough to experience a failure on your TDI, check the following;
1.) ASk your dealer to assess the cause of failure, dont let him just swop the part with no explanation.
2.)Ensure that oil feed pipes are either replaced or thoroughly cleaned and inspected.
3.) Ensure that oil is changed along with the filter.
4.) Do not over-run the turbo for the first 1250km after replacement, use no more than 2/3 throttle.

They are great cars, properly cared for your TDI will respond well to the basic care outlines given above, even if your dealer doesnt advocate them all. Love your VW 8)
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Post by Shadow » Tue Nov 15, 2005 7:23 am

Thanks for the great post.

A few questions. My turbo tends to whine only when the car is cold, is that also an indication of bearing wear? (only 35k kms on clock)

Is there any way I can check the oil feed myself for dirt? a bit of preventative maintenance?
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Post by Will » Tue Nov 15, 2005 8:13 am

Shadow wrote:Thanks for the great post.

A few questions. My turbo tends to whine only when the car is cold, is that also an indication of bearing wear? (only 35k kms on clock)

Is there any way I can check the oil feed myself for dirt? a bit of preventative maintenance?
Hi
The whine should not be too prominent. But it may well be OK. If you start to notice smoke or the pitch of the whine increases, it is worth having it checked out.
Checking the oil channels is no small job as you will need to gain access to the hoses behind the block, loosen them from the turbo, and visually inspect the channels/ flush them out. Messy too, and you have to make sure that the copper washers on the banjo bolts do not get damaged with torquing or dirt infiltration when replacing.
On our Polo TDi race car we have actually upgraded the hoses to a larger diameter braided hose (available from International Race Supplies), a worthwhile upgrade, but maybe an overkill for a road car.
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Post by Iqbal » Tue Nov 15, 2005 8:27 am

Hi Will,

When you say smoke, are we talking out the exhaust, or in the engine bay. Don't know if it's my imagination, but the car seems to smoke more than she used to on pull off. The car has already done 12 000 km, and I've followed all the guidelines you've mentioned, from day 1, but I still worry about the turbo when i think of all the guys who've had problems with theirs.

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Post by Mk1-fan » Tue Nov 15, 2005 8:32 am

Very good post Will. On the GTI, is it also necessary to let the car idle after a hard drive? I used to do it in my C32, even though the manual also didn't mentioned it.
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Post by Will » Tue Nov 15, 2005 8:36 am

Iqbal wrote:Hi Will,

When you say smoke, are we talking out the exhaust, or in the engine bay. Don't know if it's my imagination, but the car seems to smoke more than she used to on pull off. The car has already done 12 000 km, and I've followed all the guidelines you've mentioned, from day 1, but I still worry about the turbo when i think of all the guys who've had problems with theirs.

Iqbal
Hi Iqbal
They all smoke to some degree under load, the degree to which it smoke is the question. It should not be billowing under load. You should not see ANY smoke in the engine bay.
I smoke 20 a day, especially under load :lol:
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Post by joggiep » Tue Nov 15, 2005 8:42 am

Hi .. Great post I'm going to move it to the Frequently asked questions and make it a sticky .

I'll sadow it in tech so it stays there as well. I think that it's an essential read to all TDi owners .
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Post by Rabbit222 » Tue Nov 15, 2005 8:48 am

Hat off to you Glibbery, an awesome and very informative post :D
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Post by RoadHaWg » Tue Nov 15, 2005 9:01 am

THAnks Will. Cool post.

I found a lot of really interesting Diesel info in the www.TDIclub.com FAQ.

I was wondering what turbo was in the polo...thanks for clearing that up.

My turbo whistles like a biatch, from the day i rolled her out the dealership but u say we should listen for a change in pitch? Also how much would a change to better oil feed lines cost? VW would prob **** about the waranty even tho its helping....aish....

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Post by Fanatix » Wed Nov 16, 2005 12:30 pm

Thanx For the fantastic post !! :wink:

I will hopefully be getting me another polo sportline in the next week or so ..

As for the braided hoses , what would an upgred like that set us back & who would be able to do it ?

Would it affect the warrant tho ? :arrow:
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Post by VAUGHAN » Sat Nov 19, 2005 5:37 pm

hi REVO_GTI132

Can an aftermarket aux oil be fitted to these these turbos? What oil do you recommend and should it be changed more often than stipulated? What in your opinion are the chances of it happening to any car owned by a fairly enthusitic driver, and besides observing your precaution with the 30 second idle for normal etc, what else can be done. Is this a car to be recommeded or should normally aspirated cars rather be considered (ST's and Renault sport). What can be expected fuel consumption wise? I have heard of new owners experiences 8.9 - 9.6 urban cycle, is this likely to improve as it runs in and what would it improve to. Is it a safe buy. Upsolute have indicated 120kw and 395nm, Revo 128 and 400, subjectively which of the two would contribute to more a reliable egine life?
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Post by Will » Tue Nov 22, 2005 3:34 pm

VAUGHAN wrote:hi REVO_GTI132

Can an aftermarket aux oil be fitted to these these turbos? What oil do you recommend and should it be changed more often than stipulated? What in your opinion are the chances of it happening to any car owned by a fairly enthusitic driver, and besides observing your precaution with the 30 second idle for normal etc, what else can be done. Is this a car to be recommeded or should normally aspirated cars rather be considered (ST's and Renault sport). What can be expected fuel consumption wise? I have heard of new owners experiences 8.9 - 9.6 urban cycle, is this likely to improve as it runs in and what would it improve to. Is it a safe buy. Upsolute have indicated 120kw and 395nm, Revo 128 and 400, subjectively which of the two would contribute to more a reliable egine life?
Hi Vaughan
Are you referring to an auxilliary pump for an oil feed after shut down? Not recommended, unless you are prepared to pay upwards of R3K for a compatible application of an afterfeeder pump. A Turbotimer is technically illegal but a far more viable solution. OTherwise run the idle time!!! That in my mind cannot be emphasised enough!!!
Oils; Stick with the OE oils recommended by VW, very important that the right SAE ratings are adhered to, and try and stick to one brands between services. 7500km is sufficient interval. Once the fuels have been homologated udner the new 0.08 Sulphur content, Diesel will have a lower acid content and I wont be surprised if service intervals are revisited for diesels by manufacturers. I wouldnt want to give any manufacturer a punt on the brand, but I will make a passing mention that wear rate when using Caltex Delo on our Production Class entry Polo TDi have been reduced since we switched.
I dont want to compare our tuning to Upsolute here, but we are happy with our PD tuning and the results we achieve within an acceptable margin of engine safety, which we do not compromise on.
Consumption will go down because torque delivery is earlier than before and simply put, therefore throttle use reduced.

Lastly enthusiastic driving is acceptable, the engines are strong, but they do not take kindly to abuse, so;
1.) Do not over rev, EVER!!!
2.) The temp gauge may say water temp is 90 degrees, that doesnt imply your oil is up to temp, take it easy from a cold start.
3.) After giving it horns, run the engine down, the more the better!

Internation Race Supplies (Mike Bond) do excellent quality braided hoses that will do the job. You will pay but his stuff is the best. I dont think warranty will notice to be quite frank, they are often gormless even with the stock stuff
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Post by shoves » Wed Nov 23, 2005 12:46 pm

I bought my 2000 VW golf tdi in feb this year. The car's only got like 119000 on the clock (had 108k when i bought her). Anyways, she still seems to be going strong and i only hear the turbo spooling between 1750-2100 rpm and that's echoing off a pavement or wall. Otherwise she goes like a dream. Clocking like 700+ km/tank urban driving. But most of all, I let her cool down no matter how far I drive. She's been serviced twice since I bought her (every 5000kms @ Ferroli performance centre and also stipulated by MBi warranty).

She only smokes under heavy load, but i generally dont over-rev her. I have respect for my TDi. Do you recon I'm on the right track by taking care of my baby? Oh yes, the cambelt was also changed a while back. So the majors have been sorted.

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Post by Super Stu » Wed Nov 23, 2005 4:01 pm

Mk1-fan wrote:Very good post Will. On the GTI, is it also necessary to let the car idle after a hard drive? I used to do it in my C32, even though the manual also didn't mentioned it.
All turbo cars should be idled after running. No need on the C32 as its supercharged.
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Post by Super Stu » Wed Nov 23, 2005 4:06 pm

Mk1-fan wrote:Very good post Will. On the GTI, is it also necessary to let the car idle after a hard drive? I used to do it in my C32, even though the manual also didn't mentioned it.
All turbo cars should be idled after running. No need on the C32 as its supercharged.
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Post by VAUGHAN » Thu Nov 24, 2005 6:10 am

Hi Will

Thank you for the quality and informative reply - your'e setting a standard! By what do you mean over rev, is it going past 4 or 4.5K. I am not not sure if there is a limiter in place, - although I am sure there is, now when reaching this is this considered over rev'ing. What kind of damage takes place and is this achieved with continued over rev'ing or even in a single occurance. I guess I don't understand why they don't like to be over rev'ed. When driving the car quickly (racing) where have you found the most optimal shift points. Do you take advantage of the torque or do you use the full rev range.

Is the engine oil temp (that lags behind water temp) vicosity not correct and therefore not effective enough or is there other reasons to bring the engine up to temp (apart from the obvious reason like correct tolerances expansion of materials etc)



On another note, do you dyno before and after on the cars you chip or is it a known outcome. How long do you take. ;)
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Post by Will » Thu Nov 24, 2005 9:10 pm

You should not go beyond 4500rpm. In any event, beyond that you simply arent making power, as you are outside the torque curve and efficiency range of the turbocharger.
Any easy way to test this is with an accelerometer, simple ones like the G-Tech illustrate this quite well. Whilst you may THINK that you are making more power because of the engine noise, the rate of change of acceleration (on the G-Tech this is show with a shift light) decreases, and you are only really wheezing :lol:
Dont get me wrong, the TDI is tough, but does not enjoy sustained abuse. Load is not eh problem, operating the engine outside of its efficiency range is. Leave revving to the 16v petrol engines. We change up @ 4500 max in the TDI racecar, and it is always in the torque range.
BTW, the 1.8T engines also have an efficiency range which peaks out @ about 5500 rpm when the K03 family turbo runs out of puff. I didnt believe this until I found out I was losing acceleration changing beyond 6000 rpm in my 132kw GTI.
In terms of the oil, I am not a lubricant boffin by any stretch, but although synthetics have excellent adhesion properties even when cold, their full efficiency and protection range will only come with temperature.
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Post by Will » Thu Nov 24, 2005 9:14 pm

VAUGHAN wrote:Hi Will

On another note, do you dyno before and after on the cars you chip or is it a known outcome. How long do you take. ;)
Tuning pretty predictable on the PD100 and PD130 cars, we rarely dyno, unless the customer wants to see the proof of the pudding. If the car is sound (we check the vitals before tuning) the outcome is pretty consistent.
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Post by JayWegs » Thu Oct 19, 2006 4:04 pm

Hi All.
Im with everyone else, thanks for all the informative and helpful info.
I recently purchased and have come to love my 2006 1.9TDI.
When I spoke to the Sales guy at VW about the turbo and the cooling down of the turbo, he said there was no need as the turbo only kicks in between 2000 and 3000 reves, and is not always active, is this true?

Whats the best way to drive to get the best peformance out of your turbo while getting the most life out of it?

Thanks again for all the tips.
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Post by Quinton » Wed Nov 08, 2006 3:00 pm

I think the Salesman should stop selling Cars....
the turbo spins off exhaust gasses exiting the head via the exhaust ..
so to answer your question , the turbo is always spinning when the engine is on.

maybe only getting full boost at a certain rev, but thats a whole different stroy ...

... just my 2c ...
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Post by majikins » Thu Jan 04, 2007 10:53 am

Hi

Thanks for the tips - you mention there are 2 low sulfur fueling companies to get fuel from. I currently only fill at Sasol stations which says low sulfur. Could you list the ones you talk about?

Thanks
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Post by [email protected] » Wed Jan 16, 2008 9:22 pm

HI

thanks for the awesome information

is there any reason why we suppose to Run-in the turbo ?
i thought the polo has a VNT turbo which doesnt have any bearings so there wont be any friction ? does this make any sense ?
MikeH

Turbo replacement

Post by MikeH » Thu Jun 19, 2008 10:48 pm

I love my 2007 96kW Polo and (as an old turbo driver) I always
1. use the best fuel (50ppm low-sulphur only in the Polo)
2. wait till the car is warm before playing the power band
3. let it idle for at least 3 minutes before switching off
4. have intermediate oil+filter-changes done by the dealer

Being over 50, I now have an excuse to drive properly (most of the time)

However….while driving in 20km/h morning traffic last week, my turbo blew.

The dealership (Hatfield, Bryanston on William Nicol Dr), was absolutely terrific and my car was fixed in a jiffy. They tell me the new turbo is an upgraded model and should not give me any more hassles. They replaced the map as well.

BUT…even though they assure me it still produces the same power as before (with a new 2bar boost), it feels VERY sedate.

I am NOT complaining so far because the old jerky ride has been replaced with a very nice, smooth ride.

Is it true about power still being the same? – But what about performance? (I don’t want to stress the new turbo in order to find out for myself).

P.S. Thanks for the techie info
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Excellent Thread !

Post by Dee - GTi 16V » Mon Jun 23, 2008 1:19 pm

I'm loving this thread !

In the process of getting a 1.9 TDi Sportline (96 kw ) and want this just gets me so excited !!!

Thanks again !
D
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