NX GTi-R: Version 3
What Happened! And Start Collecting Parts!
There has been silence in my garage for almost a year. The NX GTi-R, when you last saw it, had rod knock and was parked until I had the time to work on it. Life intervened and many things have caused this project to get pushed to the background. Resulting in the car literally being pushed from one resting spot to another. When my NX first appeared on MotoIQ in 2009, it was as an 87 whp weakling. I have showcased the highlights and the challenges that the SR20DET engine swap led to – and not only did this swap highlight the weaknesses of the car but also my weaknesses as an automotive mechanic/engineer. No surprise there, because one thing I know is that I am neither an engineer nor a mechanic. I am simply a guy who bought an odd looking car in 1992 because it looked sporty and it had a T-Roof. And then I got hooked on it as you have been able to see through the articles that I have written over the years. However, rod knock literally knocked the enthusiasm out of me. Pun intended. I knew that it would be rebuilt, but when or how was all gray and foggy.
Upon tear down, there was more mayhem in the engine than I thought would be found, but there were answers to a lot of questions. First off, why did my engine fail? This was a huge concern not only to me but also to Dave Schlueter, my engine builder. What we found was that this was a problem that started about three years ago. Literally. Heading up the back straight at Mosport (now CTMP) I did a money shift. For readers not familiar with this term, picture red lined in fourth gear, trying to grab fifth, but finding third instead. That forces the engine well beyond the redline and, I don't care how fast your reflexes are, if the engine is an SR20DET then you are going to pop a rocker. At minimum. That happened to me. AKA the Money Shift – because it is going to cost money!
Opening the valve cover we found the rocker sitting between the two cams. Hauled the car home and went over everything including removing the lower oil pan, and rejoiced that this was a lucky one. No bent valves. No evidence of damage at all, in fact. After giving the engine a thorough going over, we turned it over by hand, and then finally started it. Oil pressure was very low for 15 seconds, then back to normal. Racing continued. Daily driving continued. The oil pressure continued to be low on start and then be normal. That was three years ago. I did not think there was any connection when the car developed rod knock in the spring of 2015. But there was.
With the engine out of the car and on the engine stand, we pulled the upper oil pan off and we saw that the oil pump – which was installed new in 2012 – was broken. Literally broken. Could not believe this. I have never seen it happen. As we pulled the timing cover off and looked closer Dave saw the tell tale marks of a chain hit, coupled with a missing protective tab, that indicated that during that money shift the timing chain had somehow bounced, hit and cracked part of the oil pump three years ago! The discoloration variations of the cracked aluminum verifying the time difference between the initial crack (thus the low oil pressure on start up) and the complete break and loss of all pressure, resulting in rod knock on the third cylinder. Obviously, three years ago if I had pulled the engine this would have been prevented. But if it was just a keeper blocking the oil pressure sensor, which I wondered if that was happening, then that would have been a lot of work for almost nothing. Regardless, in the future my engines will be pulled.