Megane Engine F4R776 165BHP mounted on Megane 2 CC 2006

[DanCVA]

Hello All,
After 3 years ago I sold my R19 16V from 1991, this year I bought from UK a Megane 2 CC 2.0T - 165BHP.
Unfortunately it was not in a good shape since its turbocharger was not working and a lot of oil was pushed through the exhaust.
My oppinion is that the turbogharger was damaged because the oil was not exchanged in time and was transformed into asphalt inside the engine.
I brought the car to a garage to be repaired and the following operations were made:
- compression test per each cylinder - result was good 13 bar each;
- turbocharger was dismantled, sent to be repaired by a dedicated workshop and brought back and fitted;
- intercooler was cleaned;
- timing belt and accessories were changed (including water pump and antifreeze - there are no antifreeze leaks);
- the oil and the oil filter were removed and oil pan was cleaned;
- new filter and 10W40 oil were introduced together with a motor flush for cleaning the oil circuit; after 10 minutes running the oil and the filter were removed and another new filter and 5W40 oil were placed.
Once the engine was started a cloud of smoke came out on the exhaust pipe and I thought that it was due to the fact that a lot of oil was still on the exhaust system. I've made around 200km with the car in this state and I've saw that the smoke was thicker on start-up and on idle.
I thought that there is a problem with the turbocharger and I went to the workshop that repaired it. These guys said that there is no problem with the tubo because the smoke was not present when the engine is reved'up and they advised me to change the oil seals of the valves.
That being said I've also changed those seals and the exhaust is not smoking burned oil during idle, but still is doing so at cold start-up.
Actually the smoke comes out after about 1 minute from the moment when engine is started cold and it stops after the engine temperature goes above 80-90 degree Celsius.
I've went to do the emmissions tests in two different places and both times it passed, so there is not a problem when the engine is normal working temperature.
Please note that the catalyzer is almost clogged and sometimes gives messages "Check Emmissions", messages that can be erased after reving up the engine and using an OBD interface.

My request to you is to help me with ideas to troubleshoot this smoking problem when the engine is cold.
Thank you in advace,

Dan

 

[Red21]

First, what is the OBD code and the description your code reader gives.

 

[DanCVA]

Actually it was used Clip Interface and i do not remember exactly the name, but I think that was something like cat filter element damaged or low element eficiency. First lambda sensor was showing a steady value, but the second one was jumping very much and frequent. Since the turbo was damaged I belive that the cat was afected a lot and now while the engine is cold, the smoke does not do well for the catalyzer.

Initially I also thought that the catalyzer is to blaim because it still has oil inside, but in 500km since the turbo was exchanged the car still smokes when engine is cold. I think that the oil should have been burned by now and if it is still oil to be burned, to burn also when the engine is normal temperature.

 

[Red21]

From that description the cat is beyond retrieval and has to be replaced.
It also seems that the upstream O2 sensor has also failed as it has a steady reading were it normally should fluctuate between 0.06v & 1.1v with the down stream holding steady around 0.5v.
The fluctuations of the downstream sensor indicate that both the cat & upstream senor are faulty and the ECU is trying to control emissions just by the downstream information and calculating the best fuel mixture which is generally on the richer side of 14:1 fuel mix.

 

[DanCVA]

So I was told that the cat has to be replaced.
Seeing your explanation about O2 sensors, could be that I've mixed in my mind the 2 sensors upstream and downstream and after seeing your explanation I am 95% sure that they are working like you described that they should work.

My question still remains:
Why there is pretty thick smoke with oil that comes out after 1 minute of starting the engine and that stops when the engine has the nominal temperature?

My hypotheses are:
1. piston rings damaged - oil leak stops when the temperature is normal by heat expansion;
2. oil into air intake from the cylinder head breather that is connected to the air intake pipes;
3. oil into air intake from the blow-off system.

 

[DanCVA]

After a hard winter and a rainy spring season. I went to a guy that repaired some F4R for Clio 2RS, Clio 3RS and Megane 2RS. We tested the compresion which is perfect and we opened the intake into the turbocharger to see if the turbo is wabling inside the its case. Turbo seems fine, but still is sending oil into the intercooler. This guy said to me that the oil comes from the cylinder head from the tube (breather) that is connected to the intake. His verdict was that the valves guides are too weared and that the oil goes both into the cylinder and top the rockers' cover. So the engine needs a repair of the cylinder head. The cat seems fine, but it has to deal with oil sent on the exhaust.

 

[andybond]

At least you have found the issue !

 

[DanCVA]

I came back. The problem of my engine was actually the turbocharger that was not refurbished correcty. I've changed the turbocharger and the car works fine now, but I want more power from it.
I bought another turbocharger, this one is a TD04 from RS225.

Is there anyone who compared by opening the 2 engines F4R 776 165BHP and F4R 774 225BHP?
The pistons are for sure different, but the rods are the same or not?

 

[Adey]

I did go through the differences recently compression ratio is higher for sure. I will try and find the info again i think it was pistons, cams and turbo as the main physical differences, possibly the rods too.