Dumb ass question on 300tdi turbo

[ninjagreg]

A simple question but one I would like to know the answer to.

How does the turbo work on my 300tdi? Does it take oil from the sump to propel the turbine to create the boost?

Only reason I'm asking is that I've recently let my oil level get low and I've noticed a drop in turbo performance, especially uphill, it seems ok on flats. Is this because when I am going uphill the oil in the sump is not being picked up by the turbo as the engine is pointing uphill (remember my oil level is low)?

Thanks.

BTW. I'm putting more oil in her tonight!!

[Steve King]

How_turbos_work

[Gromit]

It uses exhaust gases to spin a turbine which compress the intake air.

The turbine rotates on an oil fed bearing. The turbo does not use oil but if worn, oil can leak past the bearing and be consumed by the engine. In extreme cases, the engine can run away just on this source of oil.

How do you know it's the turbo that is not performing?

[disco_al]

turbo's work using exhaust gas to power the blades, which then compresses air from the intake and forces it into the inlet manifold.

the oil supply comes in through the top of the turbo, and creates a "bearing" of sorts for the turbine to spin in - essentially a thin film of oil, rather than a proper bearing.

first thing to check would be the turbo hoses, as they can delaminate internally, causing a drop in performance. take the intercooler out, and give it a clean - usually involves removing it and filling it with brake cleaner, or some similar solvent, and leaving it to soak for a few hours.

[ninjagreg]

Thanks folks, I'm always amazed at how quick it is to get a response on here! I believe it's the turbo because I took the turbo off the other day to investigate an oil leak on the chassis underneath that region. And since I've put her back on there's been a noticeable loss in power going uphill.

If I'm looking at the turbo and the wastegate actuator (name?!! the thing with the arm) is on the right, what position should the wastegate lever be at when at rest? mine is pulled all the way to the right, towards the actuator.

I've also noticed oil on the casing, could the seal be leaking? and is this an easy fix?

All help is gratefully received!

[Gromit]

An oil leak would either be the oil supply (top) or return (bottom) on the turbo. If you clean it up it should be easy to spot where it's leaking.

I can't remember what position the actuator should be in, but possibly you've disturbed the waste-gate and it is now opening at under 1 bar. Is the boost pipe from the turbo to the injection pump connected and intact?

A boost gauge would tell you if the turbo & plumbing is performing correctly.

[ninjagreg]

Thanks, I think I need to do a bit more playing this weekend, get a gauge on her to see what pressure there is. The pipe from the injector pump looked intact. Can the oil come through the actual housing itself? Is there a seal?

I also found these folks http://www.gpopshop.com/garrettt2kits.html

looks interesting...

[Bush65]

Thanks, I think I need to do a bit more playing this weekend, get a gauge on her to see what pressure there is. The pipe from the injector pump looked intact. Can the oil come through the actual housing itself? Is there a seal?

I also found these folks http://www.gpopshop....rettt2kits.html

looks interesting...

The fuel injection pump has a compensator that adjusts fuel delivery as turbo boost pressure changes. A pneumatic line from the turbo compressor provides the boost pressure to the compensator. Oil can't come from this line, but if it is not connected, or is leaking, the performance will be poor.

Another pneumatic line from the compressor is connected to the waste gate actuator mounted on the turbo. The actuator holds the waste gate closed until the boost pressure in the line and actuator reaches the set pressure. If this line is not fitted or is leaking the waste gate won't open at the set pressure and the turbo will over speed (or over boost).

If the rod from the actuator was not connected to the lever on the waste gate, the performance will be poor - you would have had to pull against the spring in the actuator to get the rod back onto the lever. The length of the rod and thus how much the spring is pre-loaded adjusts the boost pressure.

The oil lubricates and cools the bearing in the centre housing of the turbo. When the bearing and seals wear, oil can leak from the centre housing - usually detected in the hose from the compressor to intercooler.

Check for radial and axial play between the rotating part of the turbo and its bearing - you can reach the end of the compressor shaft (remove inlet hose) to check. Play should be imperceptible this way.

The 1st kit at that link is what you need. Note: you must mark the position of the compressor wheel and retaining nut and ensure that they go back in the same position relative to the turbine impeller, so as not to upset the balance. If not you will have to get the rotating assembly re-balanced. Also make sure the compressor wheel has not been rubbing in the compressor cover due to excessive bearing wear - if it has you may have more problems that the kit alone won't fix. Do a search there are some good threads for DIY turbo overhaul - post if you can't find something useful and I will find a couple.

Edit: here is a link to a tutorial - it is a mitsu turbo, not garrett but useful just the same.

[ninjagreg]

Thank you for the detailed explanation Bush65. Very much appreciated. I will let you know how I get on. Greg

[Phils truck]

Here is a link that helped me rebuild by Garrett T25 turbo. Piece of cake.

http://www.sr20-forum.com/forced-induction-turbo/21597-how-rebuild-t25-t28-turbo-pic-heavy.html

Regards Phil...

[ninjagreg]

Here is a link that helped me rebuild by Garrett T25 turbo. Piece of cake.

http://www.sr20-forum.com/forced-induction-turbo/21597-how-rebuild-t25-t28-turbo-pic-heavy.html

Regards Phil...

Thanks Phil, much appreciated.