JZX100 Multiple Problems

[m989]

Hey,

Over the past month or so ive had a few problems with my JZX100. Things like:

Boost spiking
Possible leaking wastegate actuator
Extremely black oil thats barely 5000km old
Weird ticking/knocking noise that is getting worse

What ive done so far:

Removed boost controller and that has fixed 90% of the spiking problems - I think the wastegate actuator may just be worn out due to age and KMs of the car (bit over 250k).

Ran injector cleaner through engine and also did oil + filter change. Used valvoline 10w30 as I have always done since owning the car (except the time before when I could not source valvoline and used castrol 10w30).

Changed spark plugs - NGK BKR6EK twin electrode copper plugs - same as I have always used with no problems.

ECU Reset - didnt help at all.

Ive been thru a few threads on JZXworld and most are suggesting that the VVTi cam gear is to blame for the knock/ticking noise. I have removed the VVTi solenoid and tested it and from what I can see its operating perfectly fine. I have also checked for error codes in the ECU and found none. The ticking sound is the loudest at 2200rpm and is barely there at idle.

I have included a recording of the sound taken directly above the engine. I think the rattle is coming from somewhere near the ISCV but cannot be sure. I did wonder if there was something rattling inside the PCV valve that could be causing the noise too but again, not sure.

http://vocaroo.com/i/s0BT4wC7bYwq

My conclusion is that the engine is likely very tired and in need of a rebuild. I have owned it for the past 40,000km's and its been well looked after - I cannot be sure how the previous owners treated the car though.

Any help appreciated.

Cheers

[BlakeNZ]

do a compression test mate, and if you have an onto it garage, a leak down test. Let us know how your results.

[m989]

Compression test from the front of the motor to the back showed: 160,165,170,170,170,160

Mechanic had a quick look and said the noise is possibly in the valve train, but can't say for sure without further diagnosis.

[BlakeNZ]

those compression figures are fine , in fact i'd say pretty healthy for 250k Km. Change your oil more frequently to see if you can flush out the black oil. Pull the engine oil filler cap off at idle. How bad is the blow by, and does the noise get (much) louder? keep a sample from your next oil change, as you may wish to send it away for analysis, to determine if that noise is coming from the bottom end.(though i'm sure a mechanic would let you know to stop driving it if he did think it was bottom end)

[m989]

Not sure about blow-by. I have pulled the cam covers off and measured the clearances between camshaft and shim and a couple on the intake side are above 0.25mm - top of the spec (0.15-0.25mm) right where the noise was coming from. Exhaust side also has 3-4 above spec (0.25-0.35mm) Now in the process of pulling the camshafts to check the shims and buckets for cracks and abnormalities. Car has not been driven anywhere since the noise was discovered.

[m989]

Small update, quite a bit of wear on shims 9,10,11,12 on the intake side. Almost all of the gold coloured coating has worn off the top on these 4 compared to most of the others where there's a nice round dot in the center. There is also a shitload of carbon buildup in the oil galleries of the head, under the valve buckets and even the camshaft clamps have not missed out. So its very likely previous owners have not kept up regular maintenance.

[BlakeNZ]

there's a few tips on the net about how to de gunge the top end of the motor. (IMHO better to do it physically than put a engine oil flush through it) Will be great to get that all cleaned out. Get those shims replaced with ones to bring it into the correct tolerances, and you should be OK. you have done well to get as far as you have. Good on you.

[m989]

Cheers.

I wasn't keen on the idea of using some random engine flush. Head will be removed, cleaned up and put back together with all new valve springs, retainers etc and also stem seals as those have been on their way out for ages.

[BlakeNZ]

since you are spending the money, ask them how much extra it would cost to have the valves' "throats cut"? ONLY on the exhaust side, will give the biggest gain and save money. It gives 85% of the gain of porting the head, but is far quicker, so reduces cost.

[m989]

Was planning to clean it up myself but thought about possibly porting it so that its future proofed.
Are you meaning cutting into the valve seat? do you have recommendations on who could carry out this work? I don't really want any more than ~250rwkw given that it was enough trouble on the street at 196rwkw mostly standard