Author Topic: Strange noise at about 4800 RPM (Read 4078 times)

AJays · « **on:** October 13, 2007, 06:08:36 PM »

Hello!

I have an overhauled engine in my car and the break in is completed for a while now and today for the first time it did make a strange sound at about 4800 RPM.

Lets say i rev to 5500 RPM and let go off the gas completely and the engine revs drop and hit 4800 RPM there is some kind of a scratching noise but just at 4800 ... if i rev higher its okay and below also. Its just a short scratching or lets say scraping noise. Its also there when i rev up i think just not so easy to hear because i got a G-Power exhaust and removed some of the interior so its REALLY loud.

It was colder then usual today
but i let the engine warm up really carefully.

There are some other vibrating sounds sometimes because of some screws in the cockpit i think but this sounds more as if it comes from the engine itself.

i hope im wrong and its just some vibrating screws and parts in the cockpit at 4800 RPM but then again it wasnt there before

gearheadE30 · « **Reply #1 on:** October 14, 2007, 11:37:27 AM »

Funny, I'm having the exact same thing from 4800 to about 5500 rpm. This is the first time my area has gotten really cold. The car was warmed up as usual, so I doubt that was a problem. My noise also occurs under power and it almost sounds like a really noisy intake. Any ideas?

gearheadE30 · « **Reply #2 on:** October 15, 2007, 08:22:31 PM »

OK, my problem turned out to be a shot fan clutch. Looks like I'll be going electric soon.

EN318isPDX · « **Reply #3 on:** October 16, 2007, 11:21:23 AM »

Quote from: gearheadE30;35802

OK, my problem turned out to be a shot fan clutch. Looks like I'll be going electric soon.

I've had 2 fan clutches go out on me. Let me tell you when they completely run out of oil they sound like a jet engine under the hood.

dude8383 · « **Reply #4 on:** October 16, 2007, 12:24:03 PM »

Quote from: EN318isPDX;35826

I've had 2 fan clutches go out on me. Let me tell you when they completely run out of oil they sound like a jet engine under the hood.

how much hp do you think that gave you?

EN318isPDX · « **Reply #5 on:** October 16, 2007, 12:27:57 PM »

Quote from: dude8383;35833

how much hp do you think that gave you?

Haha probably like -10

gearheadE30 · « **Reply #6 on:** October 17, 2007, 03:04:16 PM »

Lol thats exactly what my clutch is doing. Oh well, I guess it can't break anything until I find a replacement.

EN318isPDX · « **Reply #7 on:** October 18, 2007, 11:55:15 AM »

Quote from: gearheadE30;35936

Lol thats exactly what my clutch is doing. Oh well, I guess it can't break anything until I find a replacement.

nice new sig pic gear, i think my new e30 is either having a fan clutch go out or its the timing chain.. ive never had a timing chain so i cant really tell what it suppose to sound like.. i can hear something.. it kinda sounds like a diesel, which makes me think its the timing chain guides.. guess ill get rid of the fan clutch now and do a timing chain job real soon

Febi Guibo · « **Reply #8 on:** October 18, 2007, 12:15:47 PM »

if yer engine is 'dieseling' its not a bad idea to pull the lower oil pan and see if you have lost some upper oil pan bolts...

EN318isPDX · « **Reply #9 on:** October 18, 2007, 12:39:42 PM »

Quote from: Febi Guibo;35985

if yer engine is 'dieseling' its not a bad idea to pull the lower oil pan and see if you have lost some upper oil pan bolts...

good point.. the gasket leaks anyway.. ill take it apart this weekend... what gaskets will i need if i find bolts in the pan.. the upper oil pan bolts are a common failure?

dude8383 · « **Reply #10 on:** October 18, 2007, 01:08:44 PM »

Quote from: EN318isPDX;35987

good point.. the gasket leaks anyway.. ill take it apart this weekend... what gaskets will i need if i find bolts in the pan.. the upper oil pan bolts are a common failure?

you'll just need a lower oil pan gasket.

it would also be a good idea to pull the valve cover and upper timing case cover's off to inspect the teeth on the sprockets. if they're sharp, chances are your guides need to be replaced.

get a new timing chain tensioner also!

EN318isPDX · « **Reply #11 on:** October 18, 2007, 03:29:28 PM »

Quote from: dude8383;35994

you'll just need a lower oil pan gasket.

it would also be a good idea to pull the valve cover and upper timing case cover's off to inspect the teeth on the sprockets. if they're sharp, chances are your guides need to be replaced.

get a new timing chain tensioner also!

Ok ordered myself a new tensioner.. Will I need upper and lower timing case gaskets?

gearheadE30 · « **Reply #12 on:** October 18, 2007, 05:52:40 PM »

yup. You need all the gaskets in this picture. They are availible on pelicanparts.com. There is a great deal of useful information on this site, and somewhere in here, there is a tutorial to rebuild the timing case.

denious · « **Reply #13 on:** October 23, 2007, 09:14:19 PM »

Funny, my 1993 Ford Festiva does that at around 2k... :p

[EDIT] Forgot to mention my cooling fan doesn't work though and it's a timing belt, not chain, so I have no clue what the hell's Festie's problem lol