Hmmm..., not sure this is a feasible explanation for the symptoms described. Once the engine starts to run on its own oil, the process is likely to be irreversible, ie the oil will continue to feed the combustion process and the engine speed will continue to increase rapidly until the engine suffers catastrophic mechnical failure.

 

Also, there will generally be evidence of oil in the intake system because the crankcase vents into it. 

 

Kita- a thin film of oil coating the inside of the hoses is normal, puddles are not.  Otherwise you need to get a diagnostic check.  Look out for Throttle pedal position sensor faults and coolant temp sensor faults. 

 

It sounds as though your van is a similar spec to mine as far as engine and wheels are concerned and I can easily (and often do 'cos I live near Germany and visit there fairly often) cruise at 100. It also has no problem keeping up with the average family saloon when pulling away from traffic lights or building up speed to join a motorway, etc. 

 

How many miles has the van done and why did the coolant needed to be topped up when the turbo pipe was replaced? There shouldn't have been any need to touch the coolant circuit to work on the turbo pipework.

 

 

My van would easily cruise at 90 or 100mph if I wanted to.  And yours should be the same. 

 

Only when its in gear and you release the clutch

 

or

 

All the time (doesnt have to be in gear)?

 

 

 

I`ve had one myself http://www.brick-yard.co.uk/forum/air-filter-busted-driveshaft_topic49371.html?KW=driveshaft - here

 

 

 

Good advice

 

 

 

In my opinion the guys "out back" with a spanner in their hand usually arent, its the suave, economical with the truth suits "out front" who wouldnt know the difference between a cam shaft and a calm day that like to try out the Dick Turpin routine 

 

 

 

Re the light clutch, check the brake fluid, the clutch uses the same resovoir.  It sounds like air in the system which means a leak somewhere.  Unfortunately (and stupidly) the clutch slave cylinder is inside the bell housing of the gearbox.  This means the gearbox has to come out to replace it.  The master cylinder would be cheaper to replace if it was that but check the fluid level first.

Lots of people believe the early build T5s had way more than their fair share of problems, and that the later builds were significantly more (but still not totally) reliable as VW started to get their act together (particularly for the 2.5l 5 cyl engine).

There is a proper VW dealer tool for testing the air intake system for leaks, or you could ask to buy T5 TDIs clever boost-hose-with-a-tyre-valve-stuck-in-it from his turbo squeal thread.

HOWEVER, from experience of driving 5 miles without the turbo connected to the intercooler (like an extreme intercooler leak), and not because the connectors are crap, but because i didn't put it back on properly, I can safely say the engine shouldn't feel rough, just gutless and black smoke.

A rough feeling, IMO, would tie in more with the EGR being stuck open and causing an unstable combustion or smothering it completely.

A cracked manifold will loose you some power, but obviously it depends how big the crack is. You're right in that if the hole is big enough, you will loose the pressure which drives the turbo. Most of these cracks are fairly small though, and while i did notice an improvement in fuel economy and performance while it was temporarily fixed with gun gum, I could still beat any other van at the lights now it is leaking again.

I don't think it could be the turbo causing the vibrations, if you think the most minuscule of imbalances and a turbo spinning at 200,000rpm would destroy itself pretty quickly, its not going to keep on causing vibrations you can feel, it would be just bang, and its gone.

 

 

 

VCDS = VAG COM

 

This is a cable which connects your van to any laptop and enables you to view the operation of sensors etc and read/diagnose fault codes

 

Cheap old versions are available on Ebay, the proper registered Ross Tech version costs around £250 but that includes free updates and support for life

 

 

 

 

The fact that you don't have black smoke out of the exhaust when running does kind of kill the leaky intercooler idea, as it should be smoking under acceleration because once again, too much fuel and too little air because it is leaking out, means black smoke. However the thread that i am still searching for definitely had a vibration as the turbo spooled up which was cured with an intercooler, I'm not really sure why it did that.

Normally you should also also get more black smoke with a stuck open egr too, because it is replacing the oxygen with exhaust gas, and so would again leave unburned fuel.

The MAF is definately worth checking properly, although when mine went it also caused more black smoke, its possibly it could be telling the ECU there isn't very much air coming in, so it doesnt inject much fuel and you get low power with no smoke. Doesn't explain the vibrations though?

The other possibility is worn cam lobes? A known issue on earlier T5s, could certainly cause vibration, not sure if it would make it smoke or not though, potentially its possible if it stops the injectors from injecting enough fuel.

Yes that's right, the fact that you can see black smoke confirms you have a hole, nothing more, nothing less.

I actually diagnosed my cracked manifold by running the engine when it is dark and shining a torch around the manifold. You can see the smoke rising in the torch light quite clearly as the engine is idling. It might be worth you doing this so you can gauge how much it is leaking. I had whisps of smoke rising from near the airbox which was from very fine cracks, if you get a lot of smoke from there it could be a lot worse.

I've never heard of runaway happening to any t5 (in terms of engine revs going up with no accelerator pedal). its very rare on a modern diesel engine and the very fact that its happening means you have a very expensive repair bill anyway, being able to stop it just prevents an even bigger repair bill!

 

Just out of interest I don't think the flap is used to actually stop the engine.  I think it is there only to limit that shuddering as you switch off.  The flap opens again after about a second after you turn the key off so I don't think it would help in a runnaway situation unless you could open the bonnet quickly enough to hold it closed by hand. 

 

Having driven mine more now I reckon it does feel crisper and more responsive and it certainly is doing better on fuel since I cured the exhaust leak.  The test with the flap is as Dave says just to cause some extra smoke which will be puffed out of the nearest hole thereby showing up an exhaust leak nothing else.  It's not even an official VW test, it's just yet another great Brick-yard T5 discovery.