taken from the VW T4 Library originally posted by 'T4Trick'
on the 19th April 2007
There a quite a few images and so the page loading will be slow.
The Definitive EGR cleaning how to
This is everything that you need to know about the EGR. Why we have it, what it is, and how to gain better performance by cleaning it - yes cleaning it makes you go better!
This is also an absolute must if Project Powering
. I needs to be done before the injectors and the remap - or you may not gain the full potential of your outlay. (Speaking from experience)
The following is a guide, and only that. Please read the whole article before undergoing any work. It is your own decision and responsibility to carry out any work and the outcome of such work. Please bear in mind that there may be slight variations in models and years.
Apparently, the black gunk is carcinogenic - so protect yourself. You've been warned! Latex gloves are cheap as chips.
Right here we go:
Intake Manifold and EGR Cleaning
This vehicle is equipped with a CCV (crankcase vent) system and an EGR (exhaust gas recirculation) system. Oily fumes from the CCV system can combine with carbon particles from the EGR system to form a black sticky tar in the intake system (pics below). This build up eventually starts restricting the amount of airflow allowed into the engine through the EGR, resulting in gradual power loss as the vehicle ages and the intake clogging becomes worse.
Operating conditions, fuel quality, oil quality, driving habits, and general condition of the engine will all have some effect on how long the intake system survives before clogging up.
So, why do we have it?
The EGR is simply an emissions reducing measure. When the engine heats up excessively, nitrous oxide is produced and this is one of the worst emissions. To reduce this production, the engine temperature needs to be reduced and the EGR allows recirculated exhaust gas back into the inlet side of the engine. This is a continuous process happens more when the engine temp rises and help to reduce the operating temperature.
It does however, to differing degrees, make the engine less efficient and also curbs the maximum performance.
Some EGR applications can have the mapping of the valve changed to reduce the actuation, and others simply choose to block it off. You will see the latter below.
Blocking off is not possible on a petrol engine because of the MOT checks. But this is not the case on diesels and it certainly stops the gunge creation, as long as you are aware that the engine is producing more 'naughty' gasses than it was originally intended to.
OK, here's some idiot guide pics:
Take the inter-cooler (4 nuts) off and associated pipes (spring clips). Also the sensor clips. You may also unbolt the coolant reservoir (two screws) for easier access to the inter-cooler to EGR pipe.
The EGR is the aluminium inlet on top of the engine inlet manifold. The bronze coloured pipe, on top in the pic, is the exhaust inlet into the EGR pipe. Unbolt this (2 bolts) and undo the EGR (4 bolts). There are also vacum hoses to unconnect. Simply pull these off.
The pipes have a slight coating of oil from the CCV which is normal, but look at the EGR internals. They are where the gasses meet. You can see in the second pic, the deposits are far heavier on the outlet side.
Now have a look at the opening to the inlet manifold. Do not try and clean the deposits inside the manifold as you will allow solids to enter the engine. If you want to clean the inlet manifold, then that requires you to fully remove it and go through the cleaning procedure off car. A far bigger job.
To clean the EGR use something that you'll want to throw away. I used an old toothbrush and a stick (you know, the found from a tree type), and a full can of injection and carb cleaner (if you've never used this before, it will surprise you how good it is). Look at what one scrap produced.
And here is the finished article - clean. Looking at the pic, The diaphragm on the left is the EGR which moves by vacum the needle running left to right. This opens the inlet on the right hand wall - letting the exhaust gasses in.
If you want to go down the route of blocking off the EGR port, you need to make a plate to sit between the EGR and the exhaust pipe inlet. Below you can see one made from an old hand saw blade (left), as it is strong and thin. I used two new gaskets on either side of the blanking plate for a good seal.
Now its a case of rebuilding.
Buy new gaskets before you start the job (3). They will cost less than £10. Make sure the mating surfaces are clean, dry and grease free. Be very gentle when cleaning them as the alloy faces are easily marked and this would compromise the sealing ability.
Replacing all of the screws, bolts, nuts and spring clips. Inspect the pipes and be as careful replacing them as you were when taking them off. As they may be weakened in the engine bay heat. Remember to reconnect the sensors. Do not over tighten, as your threading into alloy. You could use a small amount of thread lock also.
The engine may stumble starting for the first time, but should be fine thereafter.
Now, if you blocked off the exhaust recirculatory inlet, enjoy the increased performance. With the miles done after the engine it will self clean the deposits in the inlet manifold and this means that the engine can only get better.
I was 15-20bhp less than others that had Project Powered at the Rolling Road, and this is one of the attributing reasons. That's 10% + of your engine power, not to mention the loss of driving sensation.
I hope this has helped.
In the original thread other folk posted links to other relevent threads:
More supporting posts regarding EGR and inlet manifold clean.
Originally Posted by Brooksie
It looks a straight forward mod to have a try at.
Will it make much difference then? Would be interested to hear what result people have notice that have done this to their T4's
Brookie - since I posted that thread, many T4ers have added their own info, both on their T4 experiences or from other walks of life, such as commercial garage/fleet mechanics and so on.
Every person had positive additions to the thread. It ran some 10 pages if I remember correctly and most of it was thanks about thier own vehicle. Its a messy job that lasts for the rest of the engine life. Mot's are fine, etc...
All the best, T4trick