I am needing some urgent advice.
I own a a 2004 Nissan Presage 2.5l (QR25de motor) Auto.
Four weeks ago, I noticed it was running poorly. It has been running perfectly for the 3 years I owned it. it has 164k on the clock.
I took it to the mechanics and they looked into what was the issue. They found that I had a blocked Catalytic Converter and took it out. There is no need to have one in for NZ.
I brought the car home, and noticed that is was a little smokey, i rung and they said that it was ok, it was normal as it was burning stuff from the exhaust. I asked for it to go back, and have an oil change.
I brought it home after the oil change, and they had passed comment that the oil was sludgy, and that was probably the cause of the blocked converter. I drove 600kms in the car, and noticed that the smoke had not lessened, and also that the oil that they had put in, had disappeared. I rung and asked if they did put oil in, and they said yes, it was Castrol Magnatech 10w40. My specs ask that we use 15w30 and they said that it wasn't going to make a difference. I topped up the oil, with the 15w40 that I had, and continued to drive it. It wouldn't go one morning, and I had to call an Auto sparky, who plugged in a computer, and found the error code for a CPS sensor. This was replaced, and he passed comment that the CPS sensor was sludgy again.
After some research, I found that a PCV valve, plays a very important part, and that this being faulty can cause the oil to be sludgy. I took it back to the mechanic and asked for them to replace this part.
They rung to say, that yes, the mechanic has taken the valve out and you are correct that this part needs to be replaced. They would order one in. at this stage around 1000kms had been done, and around 6 litres of oil had gone missing in the car - assumed burnt)
Hopefully you have all kept up with me to here:
Now, the mechanic rings yesterday and says, that they have replaced the PCV valve in the car but when the started the motor up, the oil came out through the dipstick tube, and the air house/filter. they wore quite a bit of it and said they think they found the missing oil.
They also run a compression test and some stage, and it was even. slightly low, but it was even. They didn't give me the figures, (but research shows that I supposed to have a result of 9.5:1) and also they have put the bore scope down the pistons, and they seem to all look fine.
They took off a cover, and rung to say, that they want to look into it further now, and look at valve guides, and valve seals, and we could be looking at a replacement head, (10hrs of labour) or an engine conversion (10hours and $2500). We asked them to stop work on the car till we get some more information.
My biggest question is:
That with the history that I have written above and the series of events, the PCV valve was the issue in the very first place. It should have been replaced immediately. It was probably the cause of the converter blocking and sludgy oil from the start.
Now, my understanding is, that the PCV valve release pressure and the gas? that builds up, out of the crankcase. If this isn't working than that builds up. Wouldn't it be normal that with the installation of a new PCV valve, that the oil and pressure was released, and now that that has been done, give the engine a really good flush to remove as much sludge as possible, and change oil filter and put in clean fresh oil, and it shouldn't blow back again because the PCV will now work efficently?
We have also replaced all spark plugs, and two coils in the last 3 weeks of this all going on?
I just feel that we can't have done so much damage since we were on to it pretty fast, and that if we did what we suggested that the car may just run again. The mechanic hasn't done this, he wants to pull it apart to the head and look into further damage, cos his assumption is that that the oil has been pushed through the motor and already caused excessive damage, and he needs to investigate. I want him to put it back together, with a complete flush, new oil and see how it runs. It was a perfect car before 3/4 weeks ago, and never missed a beat - can we really have done that and technically blown up the engine in such a short space of time?
I may be completely wrong and eat my hat if i do, but just feel that this is really excessive all of a sudden, and my total honest opinion is that they should be coping half the blame that they never picked up on the PCV valve to start with, from the blocked catalytic converter and never investigated into the sludgy oil. I basically told them to replace a part, that they didn't even consider. (I am quite pissy about that). My mechanic is no backstreet country hobo either, it goes to a Nissan Franchised mechanic where we pay over $100 per hour!!!
Please leave any information that can help my situation, and whether you agree or disagree with my situation. I think i know my car, and read a lot about this motor, but I don' t feel i know enough to now tell the mechanic to put it back together, with a full service and drive it. I am needing a second opinion or advice on what to do next.
(Mother of four children, living in the counrtyside dream, needing my family car very urgently)