Strange whirring noise from engine...

[rossiz]

first off, i have to say it's really great to have such a committed (and knowledgeable) group of z enthusiasts to help out - thanks to all for the thoughtful replies.

second, a big thanks to philip (blue) for taking the time to come and lay hand to spanner for the afternoon!

turns out by some stroke of great fortune, he was in seattle on business and had a free afternoon (go figure!) so he came by yesterday and we tore into the z. it was so great to have someone so completely familiar with these cars - he really knows his way around the engine bay.

interestingly the whirring has resolved itself - could it have been something on the clutch that re-seated/burned back in with a bit more use?

the world may never know...

there is now a light whistling noise that appears right around 3k rpms under load in first and second - not sure if it's tranny or exhaust leak, but it doesn't seem to be affecting operation and you really have to listen for it.

on friday i had done a bunch of compression tests (cold, hot, squirt of oil to help rings) and the results were quite disappointing:

cold: 150, 135, 125, 135, 130, 140

Hot: 150, 135, 130, 135, 138, 140

oil: 150, 140, 135, 135, 140, 150

philip walked me through a valve adjustment, which was shockingly easy. i can't believe how simple and robust the top end is on this engine. the whole thing was done in 20 min. and several valves were out of spec. i can see doing this regularly as it really is a no-brainer. i'm used to doing valves on a ducati desmo (bucket shims, dual lobes per valve, tiny, tight clearances, working upside down, etc.) and this is really a walk in the park. anyone with a pair of combi-wrenches, a feeler gauge and a crowsfoot for final torque can knock this out in a half hour on their first try.

the good news: after the valves were back in spec the new compression numbers were:

170, 161, 150, 160, 160, 160 :classic:

i believe #3 has an issue with rings or valve seal, but at 150 i'm not too worried for the time being. i'm going to pick up or make a spring compressor and then replace all the seals at some point.

we then sorted the distributor timing, revised some mis-matched vacuum lines, tuned the AFM, adjusted the BCDD setpoints, cleaned a few ground connections and did a few test runs. the z is running quite strong now, enough so that mr. blue left a couple of nice black stripes at the stop sign near my house

we then grabbed a celebratory bite to eat and geeked out about crazy mod ideas and all sorts of projects we have hatching in the background. all in all, an awesome weekend!

[madkaw]

An experienced Z guy and a good tune up does wonders. Sounds like a good day!

[Mark Maras]

Congratulations Geoff How many times did you pinch yourself just to make sure it wasn't a dream? Assuming your Z is now running great, as the burn-out would indicate, two questions remain #1 Is it going to be your daily driver? & #2 Will your daughter ever trust it or want to be seen in it again? Enjoy this next week, Temp. near 80 Wed. Perfect Z weather in the NW.

[siteunseen]

Blue's telecomm company's going to see the correlation of broken down systems and broken down Zs soon.

[Costjo]

Blue does it again! Its a pleasure having him around Z or not.

[Captain Obvious]

Blue's telecomm company's going to see the correlation of broken down systems and broken down Zs soon.

:laugh: Very nice. I can picture him packing:

"Let's see... Got directions to customer site, boarding pass, toothpaste, underwear, list of Z owners in the area..."

[conedodger]

Seen your neighbors cat lately?

[240260280z]

The pleasure was mine. Geoffrey is a mechanic and fabricator extraordinaire so it was e-z-p-z...I just had to show how to do one valve adjust then he did all the rest in a blink of an eye. Mr Obvious I hope you and Geoffrey get to talk as you two have similar genius-ous ways and ideas... knowing you both it would probably be telepathic mind meld .

Geoff's car sure looks nice. A great rich metallic green with shiny chrome spoke wheels and one of the nicest and quietest interiors with way-cool creature comforts that would make the car very desirable on Canadian winter mornings.

I was so used to working on 240s that it took a while to remember some of the classic 280z EFI snags but when we dug in, they popped up: corroded connections, AFM slightly off the mark, vacuum line re-routes, TVS a wee bit off, and timing a little advanced. Doing the checks then bringing everything into the sweet spots one at a time with enjoyable test drives to break up the wrenching was fun and a nice way to break up travel, work and hotel life. I was disappointed with myself on our next to last test drive as Geoff said it was still missing a little . Up to that point I did not bother with the timing apart from showing TDC to Geoff as he set the idle with an adjustable advance timing light to 17BTD. (as it seemed like it should have been ok, but, I did not want to leave with Geoff disappointed so I checked..... it was hitting 44 @ ~ 3000 rpm so I removed the vacuum advance and retarded it to ~ 13BTDC with full advance hitting ~ 36BTDC. Wow, Geoff took the wheel and said the car got its Mojo back. When I was not expecting it, he hit punched it in first and my legs lifted off the floor (torque + Washington slope effect Yup... mojo was back.

There was a whistling under-load ~ 3000rpm however Geoff's great detective skills found a hairline crack in the EGR pipe and also thought it could also be a bolt in the exhaust flow.

Pretty, peppy and comfortable car, nice owner, nice family, nice location nice day. BIG THANKS!

Edited April 29, 2014 by Blue

[240260280z]

BTW we discovered that there is a 10psi difference between using a compression tester with a rubber hose attachment vs. using the straight pipe attachment. This may be good news for those of us with lower readings and the rubber hose testers which seem to stretch. Geoff's even had steel braid but still a 10psi difference.

Edited April 29, 2014 by Blue

[Captain_Zeros]

Awesome, glad to hear it! I guess I know who in the Seattle area I need to bother if I need a pair of ears or whats between them!

[Captain Obvious]

My mind to your mind... my thoughts to your thoughts... :bulb:

Geoffrey and Blue, Can you guys picture today's hair brained projects?

Geoff's car sure looks nice. A great rich metallic green with shiny chrome spoke wheels and one of the nicest and quietest interiors with way-cool creature comforts that would make the car very desirable on Canadian winter mornings.

Forgot... How about some detail on those way-cool comforts?

And I've got a long history with green Zs. I wish my current one was a deep green...

Edited April 29, 2014 by Captain Obvious

[rossiz]

@ blue: aw shucks...

@ zeros: anytime.

@ obvious: i will be in philly for my nephew's graduation in a couple of weeks - coffee??

@ mark: DD for sure - and my daughter is coming around... the cool factor is slowly winning over the "adventure" aspect (read as: we may need to walk home)

@ cone: small children and woodland creatures beware - the z is on the prowl.

creature comforts are pretty basic - put in a set of seat heaters when i re-upholstered the seats, a ton of sound mat in the floor/roof + mass-back carpet to keep it quiet, and a decent little stereo. just trying to civilize the DD as much as possible to maximize the "jekyll & hyde" effect