grating noise from 1hz diesel

Submitted: Thursday, Apr 17, 2003 at 08:20
ThreadID: 4433 Views:1703 Replies:6 FollowUps:2
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At 2600 rpm i get an intermittent ( aprox. 1 sec. duration, 1 sec. interval )harsh "grating" noise from the motor. The noise ONLY occurrs when the engine is at running temp.(30-50 km.) is not load specific,will occur in any gear and always at 2600 rpm. The vehicle ( hzj 75 tray ) was bought new, well maintained with the noise commencing at about 75k.(now 105k.)
Toyota can't offer any explanation, drive belts ok (no A/C) my thoughts incline toward thermo. fan centre, or air intake system (factory snorkel fitted. Any help or comments appreciated.
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Reply By: Member - Cocka - Thursday, Apr 17, 2003 at 13:28

Thursday, Apr 17, 2003 at 13:28
You said not load specific but does it occur stationary and revs held at 2600. Also if not load specific I taker it it's occuring on down hill and up hill driving.
If it is not load specific it could relate to timing chain or belts, bearings/brackets in alternators. As you can only feel out of balance tyres at a certain # wheel revs. then something else similarly is throwing out of balance at specific revs. Sorry can't be more specific just trying to pin point and eliminate options. Carpe Diem
AnswerID: 17842

Reply By: haze - Thursday, Apr 17, 2003 at 13:54

Thursday, Apr 17, 2003 at 13:54
Thanks Cocka for your response. Yes, it occurrs up hill, down hill, and if revved whilst stationary. Problem with bonnet up is the general engine noise plus fan noise makes it most difficult to identify the b source. The one certainty is that it directly relates to 2600rpm,not under and not over. I dont work it too hard until properly warm, and even then it has never been over 3250 so I dont know if it recurrs at higher revs than this. Mystery remains!
AnswerID: 17845

Reply By: colin - Thursday, Apr 17, 2003 at 18:13

Thursday, Apr 17, 2003 at 18:13
if you think it might be thermo when engine hot stop motor and tie fan so it cant turn and take for drive but not for to long as overheating can occur on the fan clutch itself, if you can hear it in the cab when driving have you looked at the clutch throw out bearing as its closer and would be more audible than something at the front of the motor. Col
AnswerID: 17851

Reply By: Tony James - Thursday, Apr 17, 2003 at 20:56

Thursday, Apr 17, 2003 at 20:56
Just a thought but my 80 series (1HZ) has a strange little noise at about 1800rpm. It is some muffler putty in the muffler. Had a turbo fitted and eventually the clamp on the dump pipe came loose and some hardened putty used on the joint fell down the pipe and ended up in the muffler. Its quite annoying but not enough for me to pull the exhaust apart yet. Took quite some time to realise where the noise was coming from.
AnswerID: 17860

Reply By: gary - Thursday, Apr 17, 2003 at 21:00

Thursday, Apr 17, 2003 at 21:00
try removing all the belts, start and test ,if noise goes away it's got to be in the ancillary bits,add 1 belt at a time & test between adding belts.If it did'nt go with belts off,it might be a bit deeper.sorry can't help much more
AnswerID: 17861

Follow Up By: haze - Friday, Apr 18, 2003 at 07:14

Friday, Apr 18, 2003 at 07:14
Thanks for all your suggestions: my initial reaction was a loose baffle or some such in the muffler but this was eliminated. Iwill pull the belts off (only 2, driving alt./ waterpump fan ) and investigate there. The thought about the clutch I find interesting because when I stick my head out the window the noise seems to come from underneath (which is why I thought about the muffler first) Will be after Easter before I can test again but will post back. haze
FollowupID: 11211

Reply By: Member - Neil & Lynne(Bunbury) - Friday, Apr 18, 2003 at 10:20

Friday, Apr 18, 2003 at 10:20
Have you tried, whilst stationary and at the critical revs, operating the clutch? This should indicate if the problem is in that area.

Good luck

NeilLife's too short to say .. I can't do that
AnswerID: 17889

Follow Up By: haze - Thursday, Apr 24, 2003 at 21:21

Thursday, Apr 24, 2003 at 21:21
For anyone who has followed this,an old dog is having to learn new tricks ! Being the always conservative, and never wanting to "overload" I thought the fan/alternator belt would be ok "not over tight" So wrong! At 2600rpm I could see amazing whip in the belt on the slack side (between crankshaft pulley and alternator) corresponding to the noise. Tightening the belt (so B easy, end of problem) When all else fails, ask and get the grey matter to work!! Thanks for the ideas to get me on track. Cheers Haze
FollowupID: 11488

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