Timing failure and oil in intake

[Gaz]

Skoda Fabia Jan 2010 1.2 TSI SOHC 8v Direct Injection

Car came to us on the back of a recovery truck with a suspected fuel issue. Customer had said the battery light had been coming on randomly the past few days then the other morning wouldn't start. The oil indicator on the dash started beeping so they checked the level and put approximately 1.5 ltrs in. It was serviced by us in november and does around 20k a year, it's currently 64k at just over three years old. This car has always used oil but apparently this is normal for these kind of engines.

On cranking it was obvious there was little to no compression. There was also no spark and the oil level was slightly overfilled. Code read showed this,



All codes cleared and car started sparking but soon stopped as the cam position sensor code retuned.

Compression test showed zero compression in all 4 cylinders so it was decided that the head required removed. When removing the intake manifold it started pouring out oil, and I mean pouring,




No obvious signs of how all that got in there. Continued to strip the engine and found that (not to much of a surprise) the timing was out. The chain, tensioner etc. we're all still visually ok no apparent sign of any failure, still tensioned ok. Head came off and was met with this,




All four inlet valves bent. Another thing I noticed was that cylinder two had a lot more carbon on it compared to the rest,



This was also apparent on the no. 2 inlet valve.

I can sort the timing out and fix the bent valves out not a problem but what I'm struggling to understand is why the timing jumped in the first place? Also why no. 2 has so much more carbon than the rest and how all that oil got in the intake?

My best guess is that the tensioner failed due to the lack of oil. It is a simple plunger with a spring inside but is oil filled so I'm assuming the lack of oil caused a lack of pressure and caused the tensioner to slack off but that still doesn't explain all that oil in the intake.

Sorry for the long post but I wanted to get all as much info in as possible. Any help/advice from you guys is as always much appreciated. I know some of you have been playing with engines since I was in nappies!

[phaetonott]

I would agree with the tensioner hypothesis.

I also think the oil has entered the inlet via a breather, I can't actually place one on that engine, but if a breather has an oil separator inside, and that has become blocked, manifold suction will pull oil into the manifold. Does the sooty cylinder line up with a vacuum inlet on the manifold? I would not rebuild anything without cleaning or replacing the breather /separator.

Good luck

[Gaz]

Thanks phaetonott.

The breather was on the end of the cam housing at cylinder 4. I will double check the pipe work and for any blockage today.

[David]

Yes definitely looks like it's self siphoned and drank it's own oil.

Great help you provided phaetonott

[nitros44]

Ya I agree
The crown of a piston can can give a good indication of how the engine is running.i wouldent worry too much about the black carbon build up especially on number 2 cylinder.it does look like its been burning oil for some time .
A good clean out of the breather system,service the cylinder head(defiantly valve stem oil seals included in that) and what ever regards timing side should show a satisfactory end result.
We know why it was using oil !

[tim]

I am sure I read some where that they had a lot of trouble with pistons on that engine. Modifying them two or three times!!
So if you don't find a definitive reason for the oil in the manifold , such as a blocked PCV. Then it must be worth dropping the piston out to check before putting it all back together?

[Gaz]

Ok guys, thanks for all the help, little update. It seem these engines have a history of the timing chain stretching. Usually what happens is the camshaft position implausible fault code is stored and the EML comes on. Also as with most stretched chains you get a rattle on start up. Apparently this was not the case. The customer denies any EML or rattling (which I believe).

The head has been rebuilt (8 new valves and oil seals) and back on the block along with the cam cover. Just waiting on the replacement chain coming tomorrow and will check the length compared to the old one. Still none the wiser to the oil in the intake which is worrying me.

[Gaz]

New chain finally came today. It seems to have been updated as the links are different. Wonder why...?

[castrolrob]

Feb 21, 2014 22:06:52 GMT 1 Gaz said:

New chain finally came today. It seems to have been updated as the links are different. Wonder why...?

i would most certainly be changing the crankcase breather valve on this....

[carlos]

Hi every one, this is Carlos from Spain.
Gaz, could please indicate how the story ended? I'm really interested in the reason for the oil in the intake manifold.

I own a SEAT with an 1.2TSI engine with 53000 km and have the same problem. Car runs fine but uses 1 liter oil/5000 kms. Yesterday I was trying to find the reason for oil consumption and found the intake manifold full of oil, but not only walls impregnated, I mean it was like a little pool in the bottom of the intake.

I thought it should be the crankcase breather valve, but this valve is conected to the compressor, and the compressor outlet to the intake manifold was clean. so I'm a little worried about so much oil in the intake and not knowing from where it is coming.

[Gaz]

I can't remember the exact numbers but according to the owners manual up to 1.2ltrs every 1000mls (1600km?) was normal oil consumption.

Never got to the bottom of why the oil was in the intake but all the valve stem seals were replaced with the valves, head gasket and full timing kit. Had the car in for a couple follow up checks at 1k miles and 5k miles. No oil was found in the intake and the customer noted tha the oil comsumption had dropped slightly.

[carlos]

thank you for your answer. I also have some issue with timing, car runs really fine except for loud rattle at cold start up coming from timing chain. Loud noise lasts few seconds but enough to know timing chain is loose till chain tensioner gets oil pressure. I'm gona change full timing kit in short time, though I find no relationship with oil in intake.

If valve stem seals where the cause I think the oil would go directly to cylinder instead of going backwards and stay at bottom of intake manifold.

[Gaz]

I agree. I'm still unsure as to how the oil got where it did. All I know is that it's not returned and the only parts that were changed were the ones that I mentioned. A fault in the breather system as mentioned by others is a likley cause.

[nitros44]

The oil in the intake manifold is the oil vapour that has come into contact with the cooler part of the inlet manifold and cooled down then retuned to a liquid, it all comes down to the volitility of the oil,when oil hits parts such as pistons and valves some of it turns to vapour which the breather system takes care of and dumps it back through the intake.
Nothing to worry about as a small bit of oil is found on most engines these days,providing the internals of the engine are ok
The chances are in both of the engines mentioned and no other faults are present then it would come down to the incorrect or cheap oil being used ,in other words too much oil is tuning to vapour and ending up in the intake,it would be like putting ford fe oil into seat engine it will just burn off

[carlos]

Thanks for the answer. Interesting information I have not thoght about. This gives a little bit of light to me. This could explain why all intake from charger to throttle body are very clean and all appears in the bottom of intake manifold which cointains the air cooler inside.

Oil used is CASTROL EDGE FST 5W30, as per manufacturers recomendation.

Some pics to illustrate

Outlet of the charger



Throttle body, inlet part


After throttle body, bottom of intake manifold


Detail of the pool of oil

[carlos]

Also tried some investigation on breather valve.

Breather valve taken apart:




Breather valve has an oil cap at the end




Disassembled. It is fairly simple. Only has membrane inside and nothing more. A non-return valve which seems in good shape.




Only thing I found it is maybe an oil leak through o-ring in the oil cap. Next picture shows all o-ring seat clean except on point.


O-ring is not in perfect shape (difficult to show in camera)

[nitros44]

Looking at the oil in the intake the engine must do short journeys and never gets up to full operating temp ,?(not a blown head gasket as many would say)

If that's the only oil evident I would not worry
Maybe change the oil more often may help

Oil quality deteriorates with short journeys where the engine don't reach full operating temperature, the colour of your oil tells me thus may be the case.

Without having the opportunity to inspect the engine bear in mind these are my assumptions and should be taken as a guide

[carlos]

I also thing this issue has nothing to do with head gasket or other critical internal components. Car runs really fine with a very smooth engine behavior since new.

This engine drives every day two journeys of 35 kms. 30 minuts each. Besides these two journeys, 4 days per week it is driven for only 2 minuts (cold engine). I do not thing driving conditions are so bad.

In fact, my first assumption when I first detected the problem was oil quality, as you are pointing. So I also have in mind to change to another brand of oil in next oil change. But, as I'm using CASTROL Edge FST 5w30 (which should be good oil), I thought maybe I try to find if there was any other reason while waiting for next oil change. And searching in Google I found these forum.

Oil is changed every 15.000 kms or 1 year maximum.

[nitros44]

Like I said :
Looking at the amount of oil in the intake is nothing to be too concerned about at this time,