A bit of history (part 16) – Still searching…

So engine back in, nothing found to indicate the source of my mystery noise, and the noise remains…I now needed a new MOT, but wanted to go over the map on the ECU at idle with my brother since we swapped the wideband sensor setup…the initial set up we used was running a bit rich, and would probably give me issues on the emissions test.

But the world of motorsport being what it is, he was tied up for a while travelling backwards and forwards between the UK and China trying to commission a new engine for the Chinese GT series…fun fun fun!

So in the mean time I decided to continue playing, and installed water lines to cool the wastegate…there was always facility to do so, but we had elected not to on the initial build.

Finally I managed sometime with my brother, and we had to switch closed loop lambda control off as it was causing the engine to hunt as it alternated between lean and rich. We later worked out that we had the response time for the closed loop cycle way too short, so the ECU had no chance!

Anyhow, we dialled out some fuel at idle and shortly afterwards I was the proud owner of a new MOT, despite their comments about how loud the exhaust was- which is strange as I had one of the “quieter” exhausts on there (HKS Hi Power Silent), with an exhaust bung installed!

I was very tempted to now book another session with Dave to remap for the larger turbine housing, but I just couldn’t get passed my concerns over the mystery noise…so in the end I stopped, and decided to continue digging.

As a summary for where I was with the search:

• The noise was a whirring type sound, increasing in pitch with engine rpm, and most audible in the driver’s seat, behind the driver’s right hand side.

• Dropping the clutch in and out had no impact on the noise.

• Outside of the cabin the noise is loudest in the driver’s side rear arch, and loudest by the crank pulley- so bottom of the engine at the timing end.

• Running with no alternator belt made no difference (so not the alternator)

• Water pump inspected and was smooth and quiet.

• Oil pump inspected and in A1 condition.

• Cam pulleys confirmed to be fully tight (and the vernier’s in them correctly locked down).

• Crank pulley correctly seated and torqued up.

So as a first step I removed all the timing belt covers (upper and lower) and ran the engine without them, no difference to the noise- and there were no witness marks on the insides of the covers that could indicate the belt rubbing on them).

I also swapped in a new timing belt just to see if it made any difference, and nope…although I did note the original belt had started to ride towards the engine on the cam pulleys and was actually overhanging the pulleys by 1-2mm. The new belt then proceeded to do exactly the same thing straight away…

Normally this would lead you to suspect that one of the idler pulleys was out of alignment, but they were both new (so the bearings were solid and straight), and the spacing washer behind the belt tensioner pulley was in place (this missing would move the pulley in towards the engine, and could pull the belt that way as well).

On removing the replacement belt I then noted that both idler pulleys were now coated in rubber where the new belt had been running too tight across them…interesting, but on different edges…the top pulley had rubber on the outer half of it, and the lower on the inner half.

What the hell is going on here?!!

I reinstalled the original belt, swapped the tensioner pulley and washer, and swapped in a new idler pulley…then ran the engine again, and sure enough the same thing again, together with the now familiar mystery noise. I was getting pig sick of this view lying on my back under the car…

I had been chatting to Peter as I went through this process, really swapping ideas and potential causes back and forwards…like I said before, we share a similar drive for understanding these things- and Peter was kind enough to spend time talking things through with me. But I have to admit I was fed up now, and could really do with a second opinion- I was so close to the issue that I could easily have been missing something really obvious!

Peter agreed to take a look for me, I didn’t want anyone else to work on the car, but I also needed a fresh pair of eyes on the situation…so I trailered the car up to sunny Yorkshire and left it at Peter’s house, safely tucked away in his garage.

Unfortunately Peter (as he had warned me) was up against it with another project, so it took a while before he could spend any time on it for me…but eventually he started to investigate. The first thing he noted was that the exhaust cam pulley didn’t look to be running true…so he swapped both pulleys out, although the mystery noise remained.

He confirmed what I had worked out- the noise was coming from the bottom of the engine, and at the timing end.

At this point my attention was pulled away from cars for a while as my first daughter was born, she was fully breach and we had to go in for an elective c-section…one of the strangest, but best days of my life!

Whilst dealing with lack of sleep, and dirty nappies, I then received an update from Peter- he had pulled the sump off the engine and number 1 main bearing was showing extreme wear. It looked like the crank had been running directly on the metal of the bearing…insufficient clearance, or a dodgy shell? Another theory was crank flex, but the pattern of wear on the bearing shells didn’t really support this.

Nothing else for it- time to pull the engine and strip her down…

…again!

September 2013 sees me back in Dad’s workshop, following a brew I crack on, and it’s really not long before the engine is out (6 hours working solo compared to two days the last time) and ready to take up to Yorkshire…I had asked Peter to do a full investigation and strip down for me.

I did want to do all the work myself, but given the issues I had when I built my track day car engine, I’m really not confident enough in my abilities to keep things as clean as they need to be…and I cannot risk wrecking this engine, not after all the cash that it’s soaked up! I chose Peter to help me with this mainly cos we had built up a good working relationship by this time, and I believed he really understood how important getting this right was to me.

Peter was also happy to give the tear down the level of attention to detail that I wanted, even if it meant it took far longer than a normal build…I needed someone as anal as me to do this work, and I know Peter got this.

The only downside was that Peter was (as always) proper busy, and it would be a while before we saw any progress…but at least with the engine away I could start to focus on some other aspects of my plans for this project…