Turbo, EGR and Intercooler maintenance

[Marco34]

I've been reading from various resources (such as TDI forums) about the maintenance with the intercooler. Many people suggest flushing it with detergant, others say that a film of oil will soon return so unless you clean the intercooler frequently it isn't worth doing.

Are the turbos on a 1.9TDI variable vane or do they have a wastegate?

Also, the EGR becomes blocked with fumes from the PVC. I took the hose off mine whilst running and noticed vapour was coming out. I assume this to be normal. What are peoples views on the above particularly the following:-

1. Is it worth flushing the intercooler?

2. Is it worth disconnecting the PVC pipe to prevent contaminated fumes going back through the turbo. (reason for so much gunk in the intercooler)? or does the MAF expect this blow by to be pushed back in thus causing issues.

3. EGR - I assume this is the metal piece on top of the intake. I am pretty proficient with maintenance but the diesel engine is new to me along with Turbo's etc. Anyone have any pics per chance? Is it worth cleaning!?

If anyone has done the above have you found information on what to do? I'm a bit stumped as to how all that pressured air returns back to the inlet from the intercooler. The pipe running from the back engine to the intercooler does not seem able to cope with high pressure. The join from upper pipe to the lower one seems to be a large C clip and doesn't seem a mega seal to withstand pressure. Am I missing something?

Any gurus on the subject or you know of any good literature regarding the above please let me know. The more I've read the more cloudy it seems.

Many Thanks.

[Col]

At lot of that info applies to US TDI's where the diesel is really bad quality wise.

Whilst here in the UK we do suffer from the egr sooting up, it is not as bad. Cleaning is a good idea though if you suspect / know it is clogged.

As for washing out the IC and turbo maintenance.... a damned good thrashing at least once a week under all load conditions will keep everything free'd off and working nice !

If you drive like a sunday driver all the time, you are asking for trouble, the TDI's need to be excercised !

[Marco34]

BigCol thanks for your repsonse. Just one thing. I can appreciate that hard run will help but what does driving hard do? Does it simply increase pressures so high that the crud is blown out and burned by the engine. I thought this would be good for internals but does this also work for the turbo, egr and intercooler?

Cheers

[ini]

A good long run is good for VNT turbo engines (110+bhp and PD engines)

On your car the intercooler and egr will get fouled with oil, as the turbo oil seals tend to seep and the oil collects in the bottom boost pipe and blows up to the egr.

It may be worthwhile reducing egr operation slightly too.

[Col]

BigCol thanks for your repsonse. Just one thing. I can appreciate that hard run will help but what does driving hard do? Does it simply increase pressures so high that the crud is blown out and burned by the engine. I thought this would be good for internals but does this also work for the turbo, egr and intercooler?

Cheers

A good thrash ensures that the vnt mechanism works throughout its entire operating angles. The increased airflow will also help blow things through on the exhaust side. Note that the inlet side should have nothing to blow through other than a bit of oil mist, which leads me on to...

The oil that sits in the IC is mainly from the crankcase breathing system and will quickly return therefore in my opinion, cleaning out the IC is pointless.

[Dave Avant]

1. I've thought about this, but as said it will oil up again.
2. What is the PVC?
3. Disconnect the EGR, it really only works for the first few thousand miles when the engine is clean and new. After a while it cokes up and the engine can smoke a bit. I've disconected mine and it doesn't smoke. EGRs are the main cause of MOT smoke test failures as they put all cack in the inlet. I proved this by disconnecting an EGR on a car that kept failling, after it was disconnected it passed. Granted it effects cars more which do short journies and ones which don't see 4Krpm much. (yes it is the silver flying saucer looking thing which pokes through the engine cover.)

The passage of air;
Air enters air box, thru filter, then Maf which measures the volume of air, then it enters turbo which it is compressed and pressurised which in turn heats the air. It is now pushed through the intercooler to cool it back down as cooler air is denser giving a better ignition and more power. Then its up and round the back of the engine where it passes the EGR and into the inlet and finally the engine. The turbo is driven by exhaust gases which turn the propellor which on the other end of the shaft is another which does the compressing of the air for the inlet side of things. The EGR basically allows some exhaust gas to instead of going down the exhaust goes into the inlet manifold to be reburnt by the engine. The EGR is shut when under load or accellerating as otherwise the pressurised air from the turbo via intercooler will be lost into the exhaust rather than going into the engine. The idea is the emissions are reduced due to recycling, but instead it put dirty exhaust gas back into the engine which eventually cokes the inlet to the engine actually increasing emissions!!!

BMW had a similar idea on petrols where they used a hairdrier type thing to inject fresh air into the exhaust to reduce emissions, but it was more a cheat than actually reducing emissions!!

[Vdubba]

[quote=Dave Avant;48587]1.
Disconnect the EGR, it really only works for the first few thousand miles when the engine is clean and new. After a while it cokes up and the engine can smoke a bit. I've disconected mine and it doesn't smoke. EGRs are the main cause of MOT smoke test failures as they put all cack in the inlet. I proved this by disconnecting an EGR on a car that kept failling, after it was disconnected it passed. Granted it effects cars more which do short journies and ones which don't see 4Krpm much. (yes it is the silver flying saucer looking thing which pokes through the engine cover.)

The passage of air;

hey thats a good explanation of how the system works thanks!


by disconnecting the egr:
1.will it do any damage?
2.do you just need to disconnect the vacuum pipe and block it?

cheers

[onzarob]

this link is great in understanding the vnt turbo action.

http://www.technologie-entwicklung.d...t15-turbo.html

so a good thrash will burnt allot of the crud of and help it move freely.

[Dave Avant]

[
hey thats a good explanation of how the system works thanks!


by disconnecting the egr:
1.will it do any damage?
2.do you just need to disconnect the vacuum pipe and block it?

cheers

1. No, think of it as an add on and not an integral part of the engine or inlet parts.
2. Yes this is what I have done. I did remove it at first and gave it a bit of a clean, really to make sure its working properly, but then decided to 'blank' it off. It does needs to be kept in the closed position. It could get stuck open, but I would think there would be performance issues if it had.

you won't see any performance gains, unless it has stuck open. But I did notice before I did blank it off after a good accelleration, it produced a haze of smoke when I looked in the rear view mirror, more noticable at night in following car headlights, but now I must say I can't see any.

[Dave Avant]

this link is great in understanding the vnt turbo action.

http://www.technologie-entwicklung.d...t15-turbo.html

so a good thrash will burnt allot of the crud of and help it move freely.

Always wondered how the variable vane turbo worked. I thought it was 2 impellors that worked together with one being smaller for the 'light' boost and a bigger vaned impellor for the higher boost.