2CT Engine.

Turbo seems to be broken or maybe just the seals. There is oil coming out of where the Turbo charger meets the exhaust.

The 2CT Manual Fault diag says Turbo charger Oil seals will cause smoke (Which I have in abundance) and I suppose the green turbo light won't come on maybe because not enough pressure if the seal is broken (Although I don't know this as I am new to Turbo charging, I am guessing)

This may not be related but the car idles like an injector is not working but other times it idles fine.
Idle speed is 750 and I have tried it higher and not much difference. Sounds like it is missing occasionally.

Always idles rubbish when cold though.

I have changed fuel filter. Injectors are all re-conned and tested so I am pretty sure it is not them.

Fuel pump has recently been re-conned also.

As I mentioned above, lots of white smoke when reved in neutral (Not steam as it smells of fuel as far as I can tell).

Any help/ suggestions would be appreciated.
- (#1589) Andy, 1 Jun 05 12:46

A little oil in the exhaust housing is normal. If you aren't using a lot of oil, that's unlikely to be the issue.
Now a rough smoky idle is more of a concern. I'd consider having a compression test done, as a low cylinder will be smoky and rough. Valve clearances OK? Is there much blowby if you disconnect the crankcase breather hose? It'll spray a bit of vapour, but if you find that the smoke is reduced when you do so, then you need to look at rings or the possibility of a cracked piston...

- (#1589) David Miller, 1 Jun 05 14:51

Pipe had come off the turbo that goes to the back of the Air in take and now the green light comes on when it should.

Still seems like a lot of oil to me as it is running down to the bottom of the exhaust and dripping off there onto the road and it has never done that before.

It does not smoke that much at idle, it just idles rough. When I rev it, it is smokey.

Also it does not idle rough all the time. I can switch it on and it idles rough then it idles fine when it warms up. Then it idles rough whilst it is warm and then it idles fine again while it is still warm.

Valve clearances should be ok on as they were two weeks ago.

New rings not more than 2 months or so ago so I hope it is not them.

I will try the crank case breather and thanks for the help.

If you have any other ideas in the meantime then fire away.

- (#1589) Andy, 1 Jun 05 16:03

Well, to confuse you further, remember that diesels run on oil. If you're getting *enough* oil into the combustion chambers, the engine will run on it and not diesel. In this situation, the pump's governor will reduce fuelling to zero in an attempt to control idle speed. The rpm's might be unstable whilst it's trying to do this.

OK, it certainly sounds now like your turbo is expelling too much oil into the exhaust. This must be either because of a sealing problem (new turbo time) or... pressurisation of the crankcase by blowby. Back to that breather again. When you fitted the new rings, did you hone or otherwise deglaze the bores, and can you confirm that you did not fill with a synthetic oil during the breakin period?

- (#1589) David Miller, 2 Jun 05 02:03

Thanks for the Reply David.

I re-checked the valve clearances and found that one intake is now out of spec .33 but less than .35. (My Guages don't have .34 on them)

It should be no more than .3 according to the manual. A new shim is on it's way and I managed to get it out without removing the cam as you said before with a screw driver and a magnet and a pin to break the seal of oil.

Funnily enough when i untightened the Injector fuel pipe previously (To check injectors as manual states) this injector was the one that seemed to have the least effect on the idling. That seems to make sense as it is the same one that has the valve clearance wrong.

We did de-glaze the bores but I did use Semi-synthetic oil.

I have read up on Synthetic oils for "break in periods" (Now you have brought it to my attention) and there are conflicting views on it(What a suprise). Most say that it should not make any difference. I have no opinion apart from "I hope they are right". Perhaps because I have semi-Synthetic I should be half ok.

One thing that was mentioned is that Synthetic oil seems to find broken seals quicker.

Lets hope it is Turbo seals as that is easier to do than taking the engine apart for the third time, deglazing yet again and then running normal oil if thats possible or maybe there is an easier way.

How much crank case (Top of engine you are refering to I hope where you put the oil in and not the sump) pressure should there be. There is oil vapour coming out of the pipe but I was under the impression that this is normal. How much is normal?

I am not a mechanic but I am however learning a lot so bear with me if I am a but slow on the uptake.

I will do a compression test as well when I can get one (Can this be used to check for blowby).

Thanks for all the help, it is appreciated.

- (#1589) Andy, 3 Jun 05 08:34

Found more info on breaking in and they recommend no Synthetics (So I could be stripping it down again).

Also found diagrams on what breaking in is trying to achieve which is interesting.

Here is the link if anyone is interested.

http://www.ntnoa.org/enginebreakin.htm

- (#1589) Andy, 3 Jun 05 09:15

Valve clearances are OK, I woudn't have bothered ordering a shim.

Crankcase pressure? as little as possible. Does exhaust smoke decrease when you disconnect the hose? If so, you've too much blowby. However, duff turbo seals would be more sensitive to backpressure.

- (#1589) David Miller, 3 Jun 05 12:12

It depends if you are talking about the Rocker Cover hose or the Sump hose.

If it's the rocker cover hose then no the smoke does not decrease. If it's the sump hose then I have not tried that yet as I misunderstood.

Regarding the oil, it seems that there is loads of oil on the Bottom Gasket where the Turbo meets the exhaust. Also there is oil on the Exhaust Manifold gasket that sits on the top of the turbo.

Where would the oil be coming from? Perhaps the exhaust manifold and down into the turbo or does it work the other way?

- (#1589) Andy, 3 Jun 05 15:30

Disconnecting the top breather hose should reduce crankcase pressure, especially if the hose is clogged or kinked. If not, you might try or removing the oil filler cap, but you'd need to put a cloth over the hole to stop splashes...
Why would this affect the turbo tho?
Simple. The turbo relies on pressure differentials to make it's oilseals work. The seal is not unlike a piston ring, and pressure (exhaust or boost, depending on which side of the turbo...)presses the ring along it's bore so that it seals against the side of the groove it's fitted into. Now if for any reason the pressure in the turbo's centre bearing housing exceeds that on the other side of the seal, then the seal won't be pushed into contact with it's sealing face. Crankcase pressure caused by blowby will "back up" the oil in the return hose- that's the thick one under the turbo- causing this exact problem.

At idle there's no boost and only very minimal exhaust manifold pressure. Under load there's 10psi boost, and perhaps 40-60 psi in the manifold.

And when this happens, you will have raw oil making it's way through the intake or exhaust side of the turbo causing either runaway if enough oil gets through the intake, or oil running down the exhaust in the case of the turbine side.

So, chicken and egg time to an extent. Are the turbo's seals actually starting to leak, with a degree of blowby forcing even more through, or are the seals really still acceptable and the leak is purely caused by the effect of blowby?

- (#1589) David Miller, 4 Jun 05 04:07

So what is my best course of action?

I have taken the Oil cap off. There are some splashes of oil and also oil vapour and it sort of blows the cap around in it's thread whilst taking it off.

I am thinking of taking the turbo off cause it is easier than stripping it all down again but how will I know if the seals are shot? Will it be obvious?

Would a compression test determine blowby?

I probably need to check the Turbo seals anyway now and putting the Exhaust manifold on without the turbo there would be easier ( if I strip it all down and deglaze it).

Thanks For your help.

- (#1589) Andy, 4 Jun 05 16:36

Unfortunately a compression test verifies the condition of the compression rings, not the oil control rings. You could conceivably have good compression yet be passing oil.

Turbo is external and therefore easiest to deal with. Yet nothing short of stripping it (which is difficult, plus you have the problem of rebalancing it on reassembly) will inform you of the condition of the seals.

How many miles on the new rings? It might be worth persevering, thrashing it for a thousand miles yet to see whether the rings will bed in before panicing too much.

I trust your engine oil isn't restricting the running-in process? (see the other current thread on the subject...)

- (#1589) David Miller, 4 Jun 05 17:29

I can't really drive it with that much smoke coming out the back.

Perhaps if I put thicker oil in it (As you are implying I hope) like the other thread then that will stop the smoke and let the rings bed in a bit.

I had better change the filter as well otherwise I may get contamination in the oil.

Thanks for your help.

Andy

- (#1589) Andy, 5 Jun 05 07:38

After taking the turbo off I decided to get the exhaust manifold off as well to see where the oil was coming from.

As it looked like it was coming from the manifold and not the turbo I took the head off(I can do it in my sleep now).

Just as well really as one of the inlet Valves was covered in oil where all the others looked fine.

I took the valve out and then found that the valve guide bushing had a big split all the way down and had actually broke off where it meets the aluminium, the spring was keeping it in.

Some of this must have happened when the cam shaft broke previously and although it seemed ok at the time it obviously must have got worse (As it would).

This inlet valve previously had been bent badly.

If I had known then what I know now I would have spotted it.

So now I am mostly learning how to take a valve guide bushing out.

Aparently you have to heat it in water to about 90 degrees and then tap the bushing out.

I am toying with the idea of doing it myself but I will probably take it to a specialist as I probably need it pressure tested also. If it can break a valve Guide (made of Steel/cast) then it may have cracked the head or something else.

Thanks for the help and any suggestions (Clean) would be appreciated.


- (#1589) Andy, 8 Jun 05 07:43

Phew. That should be an easy one then. As long as the head isn't cracked, the guides aren't that tight a fit. Once head that I had actually had a couple of guides that came out by hand... You've got the old head still?

- (#1589) David Miller, 8 Jun 05 09:33

I do have the old head still, are you saying I should transfer a valve bushing from the old head? I was just going to get a new one and a new set of valve stem seals as I have taken all the valves out to check the others are not damaged. One of the other exhaust valves was sticking (because it was slighly bent) so I have thrown it away (So not to accidentally use it again) and I will use a good valve out of the old head.

I would like to have a go at a valve bushing but I am wondering if I am biting off more than i can chew (Is it hard) as it seems that you need a specialist tool to get the valve bushing out (Which I don't have) and it seems to take ages to get the tools. Also your supposed to heat the head up in a tank of water to 90' and then tap the Bushing out. I don't have a water tank that big.

We have a few head specialists local so I might just take it to them and see if they can do it. If not I will have a go.

Any ideas David on it would be appreciated as it seems like you have done this before a few times.

- (#1589) Andy, 8 Jun 05 14:23

As I said, they aren't generally in that tight; and if they aren't too badly worn why not reuse one?
Both ends of the guide are accessible, the special tool is nothing more than a shouldered drift.

If it were me (and I'm tighter than the average Yorkshireman...) I'd have a go at getting one of the guides out of the old head. If you have no hassles that far, you're halfway there. Any problems, pass it over the your local machine shop...

- (#1589) David Miller, 8 Jun 05 16:08

Ok then, I will give it a go and let you know how I get on.

- (#1589) Andy, 8 Jun 05 19:37

Oi, be careful about cracks about Yorkshiremen!

- (#1589) Ian Dunse (Derbs), 9 Jun 05 02:15