Jump to content

Sign in to follow this  
rossiz

Strange whirring noise from engine...

Recommended Posts

monday afternoon i was fiddling with the AFM to lean out the mixture - my wife was driving behind me and said the car smelled very rich and was "making smoke" when i would accelerate. popped plugs - a little dark, some oil on a couple of them, leaned out the AFM via the spring wheel/gear by 4 teeth, took it up the street to a long gradual hill for a load test. from stop i punched it up to 5K in first, then second up to 5K then clutch in, turn off key, coast to stop, check plugs, lean out some more. did this twice - on the second time, i revved to 5,500 and the brake light came on (odd) right before i turned off the key. when i started her up, there was a strange whining/whirring sound - thought it might be the alternator. the charge gauge started acting a little erratic and a couple of my relays were buzzing (the one under the passenger seat, and one up under passenger footwell). i took out the crusty, 35 yr. old alt. and figured i'd take it apart to see if it needed some TLC - it basically disintegrated in my hands.

so, new alt. and belt went in last night and refreshed the connections. she started fine and charge gauge looks normal (all the way to right), but i still have that strange whirring/whining sound, almost seems like it's coming from my valve cover area... quick test drive and she feels down on power, a little breathless, and i hear a high-pitch almost whistling sound inside the cabin.

i'm worried i damaged something on the load tests... any thoughts? i'm afraid to take her to work this morning for fear it might be a tow truck home, and i certainly don't want to have a major catastrophe if i need to replace a part before it grenades inside the engine.

just when she was starting to run really well, go figure.

thanks in advance,

geoff

Share this post


Link to post
Share on other sites

Is it a whining noise? If so, it could be your water pump bearing. It sounds like your car might have been sitting for quite some time, so rusty bearings are always a possibility. Your water pump bearing might be whining because you have a different belt tension, and the noise might go away on its own. But it could be a forewarning of a water pump failure sometime down the road. Or you could have a bad alternator bearing, depending on the quality of the rebuild.

FAIW, you can buy a mechanic's stethoscope from your local Harbor Freight for a few bucks. You might even find one at your local auto parts store. You can use it to probe around your engine to find the source of the noise. Please DO NOT use the lauded "long screwdriver to your ear trick" when working around spinning pulleys and fan belts! And be careful when probing those areas even with a stethoscope.

Share this post


Link to post
Share on other sites

Do you have AC? Pretty common for the bearing in the tensioning idler pulley to go bad. It's easily replaced, and the bearing is a common one, readily available.

You can run the engine for a short while with no belts. The battery will power the EFI, and it won't overheat for the few seconds necessary to listen for noises, with no coolant pushed from the water pump.

Share this post


Link to post
Share on other sites

thanks for the replies - a little clarification:

- the whirring/whining sound started right after the second big "load test", accompanied by the alternator acting up (original belt tension)

- new alternator, new belt, (new tension) the sound is still there and i'm pretty sure it's NOT coming from the new alternator

- no AC, only belt is going around crank/fan/alt

- noise seems to be coming from mid-to-rear of engine, not up front

my big concern is how the power seems to have dropped - not sure what i may have done to my poor little z...

i will pick up a stethoscope from HF on the way home and run it w/out any belt (fan noise is distracting anyway) to try and better locate noise

Share this post


Link to post
Share on other sites

@ Blue: i live in magnolia - by discovery park, commute to the east side for work.

are you visiting? your avatar shows canada...

let me know if you have the time/inclination to meet up, as i'd be happy to buy you a cup of coffee and ask a few questions ;)

Edited by rossiz

Share this post


Link to post
Share on other sites
Is it a whining noise? If so, it could be your water pump bearing. It sounds like your car might have been sitting for quite some time, so rusty bearings are always a possibility. Your water pump bearing might be whining because you have a different belt tension, and the noise might go away on its own. But it could be a forewarning of a water pump failure sometime down the road. Or you could have a bad alternator bearing, depending on the quality of the rebuild.

FAIW, you can buy a mechanic's stethoscope from your local Harbor Freight for a few bucks. You might even find one at your local auto parts store. You can use it to probe around your engine to find the source of the noise. Please DO NOT use the lauded "long screwdriver to your ear trick" when working around spinning pulleys and fan belts! And be careful when probing those areas even with a stethoscope.

Yup, I experienced that water pump failure 75 km from home.. I'd recommend anyone who's Z has been in storage for a long time: replace the water pump !

Share this post


Link to post
Share on other sites
@ Blue: i live in magnolia - by discovery park, commute to the east side for work.

are you visiting? your avatar shows canada...

let me know if you have the time/inclination to meet up, as i'd be happy to buy you a cup of coffee and ask a few questions ;)

I'll try to arrange for fri or sat if i'm feeling better. Caught a darn cold and would not want to pass along. Pm me your number and we could at least talk, I'm working 2pm to midnight shifts but I should be off fri evening and all of saturday.

Share this post


Link to post
Share on other sites

Hey, John/Blue, why don't you get out of the damp NW and come down to AZ and visit the Desert Datsuns group, would love to meet you and share info/stories and adventures!

Share this post


Link to post
Share on other sites

so i ran it without the belt and it still makes the whirring sound - easier to pick it out with no fan noise.

the pitch of the sound follows revs and it's got me mighty worried.

the whole thing started after i did a high-rev shift from 1st to 2nd and i definitely felt an "event" in the engine - not any kind of horrific clunk or anything, but definitely something that made me think "wtf just happened??" then the alternator issues ensued, so i figured the alt blew up and that was that.

sounds to me like it's coming from the mid/back of the engine bay - could it be clutch related? oddly, the car seems to be down on power - kind of feels a little wheezy/breathless. doesn't really feel like the clutch is slipping though...

i took this video to capture the sound - don't watch, just listen (you'll get seasick as i move the phone all around the engine bay to try and pinpoint where it's coming from)

Edited by rossiz

Share this post


Link to post
Share on other sites

also - i tried using my handy-dandy new mechanic's stethoscope, and while it's cool to listen to the injectors clicking, the valve train and whatnot, i couldn't seem to get any reading on the whirring sound. tried all over the engine, front to back, including the clutch bell housing, nothing conclusive.

i have a new water pump coming ($30, easy job, prob. not a bad idea to do that anyways)

Share this post


Link to post
Share on other sites

Hmmmm... Very odd...

So I'm trying to think of what parts of the engine have either ball bearings or gears. I'm coming up with the timing chain assembly, the oil pump, and the distributor... and not much else. Maybe touch your stethoscope to the oil pump?

Or perhaps your water pump (yes, I know, front of engine) has some bent or broken vanes.

Share this post


Link to post
Share on other sites

not the distributor, can't be the water pump (no belt, it wasn't turning)

i found this exploded view and i'm just scratching my head about what could be making this happen - nothing LOOKS like it would do that.

post-30163-14150828301123_thumb.jpg

Share this post


Link to post
Share on other sites

Only revved up to 55K.

Popped the clutch a little hard between 1st & 2nd and something felt funny - like something let go... Then I turned off the key and coasted to a stop to read the plugs. When I started her back up the noise was there, and I figured it was the alt.

Share this post


Link to post
Share on other sites

Have you listened for the noise around the tranny? Maybe a throw out bearing noise?

I admit its a shot in the dark. Sounds like its a process of elimination now so.....

I just listened again and it seems as if it is louder near the firewall.

Edited by rcb280z

Share this post


Link to post
Share on other sites

Just something to try, push the clutch in while the engine is running in neutral and see if the noise changes. Maybe something with the TO bearing as mentioned or a transmission input shaft bearing.

--Justin

Edited by buysell

Share this post


Link to post
Share on other sites

i will put her up on jack stands so i can listen from underneath and try working the clutch to see if there's any change.

just out of curiosity - is there anything up top under the valve cover that could be injured and whining?

Share this post


Link to post
Share on other sites

Just another shot in the dark, could it be a lash pad that has slipped and stuck so the cam hits it?

Edited by mjr45

Share this post


Link to post
Share on other sites

That does sound like a lash pad has fallen off, mine has done that after a good romping. Pull the valve cover off and see, they're not hard to re-install. Sounds more "clickity" than whirring.

Edited by siteunseen

Share this post


Link to post
Share on other sites

Hi Geoff, While you're under the car, disconnect the clutch slave cylinder spring & see if you can move the clutch release arm for & aft. I adjust mine so there is about 1/4"-3/8" of movement. This will ensure the release bearing separates from the p-plate. If the r-bearing has been pushing on the p-plate, pushing on the clutch may not change the noise.

My first impression while "listening to the video" was serious valve train noise. Pull the valve cover take a look & a listen. I think you'll find it there. Then I listened for the whirring noise & heard it. I think you'll find it in the valve train but I'm going to listen to it a few more times to take a shot at that one. Give me a call if I can help. Meanwhile, Fawlty Towers, John Cleese screaming at his car. It will make you laugh. Guaranteed

Share this post


Link to post
Share on other sites

Throw out bearing or something in the clutch let go. It's hard to nail down noises since they like to travel around these cars. Try the above suggestions regarding the clutch.

Share this post


Link to post
Share on other sites

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 :cool:

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!

post-30163-14150828307804_thumb.jpg

post-30163-14150828306985_thumb.jpg

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.