How freely should a turbo turbine spin when you push it with your finger?

jaybee · 12 May 2012 at 18:21

I think the turbo has gone on my diesel Zafira, but I am not sure.

Symptoms are, complete loss of boost aka none at all, ever. It idles fine, no smoke or other symptoms apart from no power and more loud/tractor like as the engine is stressed more without boost.

What have I checked? Codes = none, vac hoses look ok, air intake path not blocked, no massive oil build up in any pipes. Haven't cleaned/checked EGR valve yet but......

I took the side hose off the turbo to inspect it and when I rotate the turbine blade / impellor with my finger it is not easy to rotate. I cannot flick it and make it spin even one rotation. It just stops dead. It's not REALLY hard to move, and not clunky/notchy, but given that air should be able to move it under pressure, I'm not sure it can. Should it spin freely enough so you can just blow on it and it spins? I know some ball bearing type ones probably would on performance cars, but this is a Diesel Zafira. I can not see any scoring to the internal housing and there (to me) does not feel like there is massive play in blade. The fit is quite tight to the housing.

Can I start the car up to see if it spins? I am assuming this is a bad idea with it exposed as it could suck anything into it with no filter etc.

What do you think guys?

Kei · 12 May 2012 at 18:54

It should have some resistance given its a journal bearing turbo, so blowing on it won't move it. From what i remember of my spare turbo you should get about 1 rotation before it stops when flicked. (don't forget that the bearings are flooded with oil that will be thicker when cold) It should be quite easy to turn with your finger though. An exhaust blockage can cause similar problems to what you are experiencing. On petrol cars a collapsed cat is a common cause, don't know about a diesel.

Virdi · 12 May 2012 at 19:17

You should be able to turn the compressor wheel with your fingers.....

troops · 12 May 2012 at 19:56

Had similar symptoms on an Astra diesel a few years ago, it was the turbo actuator i think.

Matt82 · 12 May 2012 at 20:37

All the ones ive felt have had almost no resistance at all

tigerstyle · 13 May 2012 at 02:25

Running it for a few moments won't hurt it to check if it moves freely.
Unless you're in a swarm of bees.

ShakenNstirred · 13 May 2012 at 05:08

Virdi said:
You should be able to turn the compressor wheel with your fingers.....

^^^^

Dogbreath · 13 May 2012 at 05:34

Sounds like it's new turbo time, it should offer virtually no resistance.

*Moangroan* · 13 May 2012 at 13:31

Agree with above the bearing in oil will offer some resistance so about one revolution is all you will get.

Is there any play in the shaft,

Try looking for other causes.....as above actuator...vacuum leak if the actuator runs off the vacuum.

I remember when i accidently knocked off the map sensor connector if felt like I had no boost until plugged back in.

If you have no play in shaft....it spins relatively freely like its in custard. It does not leak oil or use any....or make any noise...they are the common signs of turbo probs.....

Dogbreath · 13 May 2012 at 13:45

*Moangroan* said:
Agree with above the bearing in oil will offer some resistance so about one revolution is all you will get.

Even journal bearing turbos should have very low friction. If you ever seen a turbo running after an engine has shut down then they can continue spinning for a good 5-6 seconds (ball bearing turbo can spin for ages). If it's so tight that you can't easily make it spin but there is little play in the bearings then it might be that the bearings are choked up with carbonised oil.