PlaneDriver Posted June 6, 2009 Share Posted June 6, 2009 I bought a 1989 RX earlier this week with 73,000 miles. Everything's good except for a noise coming from the engine compartment above 3000rpm. Above 3000, I will hear it in various locations up to 6000rpm (the highest I've taken it). It will go away and come back seemingly at random in that range. If I hear it and then hold that rpm constant, it will go away. The noise happens regardless of turbo or air conditioning operation. Today I went out and made a video of the sound to hopefully get some answers as I would like to fix it. I also heard the sound sustained for the first time. It is at the end of the video when I am at about 5000 rpm. The first clip is windows up and the second clip is windows down. I've marked the video as to the locations of the sound. Some things I have reasoned: This sound does not occur between idle and 3000rpm. It only comes out at higher revs and then only temporarily (usually). I don't think it's the turbo because I have heard the turbo spool up completely without hearing this noise. I have noticed that the driver's side fan in the engine bay is cracked at various locations on the base between fan blades. Rotating the fan when the engine is off does not show any areas of rubbing. The fan isn't connected via belts to the engine either, so I doubt it's this, but I do plan on replacing it anyway. Anyone have a spare? Maybe it's a pump of some sort. I haven't noticed any problem with overheating. The longest I've had the engine running is 45 minutes in the city. The engine temperature gauge is always pegged in the middle. It never goes any higher than that. Any help as to what the sound is is greatly appreciated! Link to comment Share on other sites More sharing options...
TheLoyale Posted June 7, 2009 Share Posted June 7, 2009 Hmmm, Its hard to distinguish the noise thru the video. I hear the turbo wind up and I do hear another noise fantly (The noise ur talking about) Very hard to say, could it be a main bearing? and it only gets enough play in it at those RPMs? I'm sure GD will stop by (He'll prolly have a better guess then I) -Tom Link to comment Share on other sites More sharing options...
Turbone Posted June 7, 2009 Share Posted June 7, 2009 I cant hear anything but the engine :-\ Explain the sound. Ticking? Clicking? Whirring? What? Link to comment Share on other sites More sharing options...
TheLoyale Posted June 7, 2009 Share Posted June 7, 2009 I cant hear anything but the engine :-\Explain the sound. Ticking? Clicking? Whirring? What? I think he's hearing that Humming/Whirring sound at the end of the video (Other then the turbo, I do hear something) Love the sound of the motor though +1 Link to comment Share on other sites More sharing options...
PlaneDriver Posted June 7, 2009 Author Share Posted June 7, 2009 Listening with headphones may allow you to hear it better. At least for me it is due to crappy laptop speakers. The best I can do to explain the sound is a rubbing or grinding. Think of a bad skateboard wheel. You spin the wheel and instead of having a nice smooth sound, you can tell it has a bad bearing and slows down quickly. Very hard to say, could it be a main bearing? and it only gets enough play in it at those RPMs? But I don't feel any vibrations in the steering wheel. That's what makes me think it's an individual component. I've been thinking maybe water, oil pump, or alternator bearings. I wonder if it would be safe to put it in neutral and run it up carefully and have someone looking at the engine to pinpoint it more directly. This would also remove the wind noise component in a recording. Of course, if I didn't hear it, then it would narrow down to the drivetrain. Link to comment Share on other sites More sharing options...
4x4_Welder Posted June 7, 2009 Share Posted June 7, 2009 (edited) Heat shield rattle, resonating at different engine RPMs. Second guess would be boost leak, but that would depend on there being boost, plus the CEL would be on. What do you mean by "the fan isn't connected to the engine by belts"? The driver's side fan bolts to the waterpump, if there isn't a belt around that pulley, then the water pump isn't turning. Edited June 7, 2009 by 4x4_Welder Link to comment Share on other sites More sharing options...
Turbone Posted June 7, 2009 Share Posted June 7, 2009 Does this have a clutch type cooling fan? It fits onto the waterpump shaft. If not, it may have the accessory fan (electric), which would give it 2 fans. I would check out the fan that has the cracks. If that loses a blade, say goodbye radiator. Link to comment Share on other sites More sharing options...
TheLoyale Posted June 7, 2009 Share Posted June 7, 2009 Listening with headphones may allow you to hear it better. At least for me it is due to crappy laptop speakers. The best I can do to explain the sound is a rubbing or grinding. Think of a bad skateboard wheel. You spin the wheel and instead of having a nice smooth sound, you can tell it has a bad bearing and slows down quickly. But I don't feel any vibrations in the steering wheel. What I ment was, a main engine bearing (Could it have enough play/wear just to make noise at RPMs?) +100 Turbone, yes replace that fan ASAP! we had the fan shatter putting hugh holes in the rad and chunking off most of the shroud on a '99 Blazer when we were doing 75mph! Put a mean wobble on the Water pump (Alot of stress on the WP bearings) Just a thought. -Tom Link to comment Share on other sites More sharing options...
Niku-Sama Posted June 7, 2009 Share Posted June 7, 2009 that kinda sounds like mine, just alot louder. when its cold start it up and feel under the car arround the exhaust ports on the head and see if you feel any warm air, feel arround the heat sheilds down there too. just be sure not to touch because the heat up quick. i have a minor leak down there on the passengerside behind the heat sheild, i should take it to some place and have em weld it up, its a new pipe and i dont have the cash to replace Link to comment Share on other sites More sharing options...
Gloyale Posted June 7, 2009 Share Posted June 7, 2009 heat shield rattle, resonating at different engine rpms. +1 Link to comment Share on other sites More sharing options...
Frank B Posted June 7, 2009 Share Posted June 7, 2009 You can easily find other small problems to fix while figuring this one out. Get under the car after it's cool, and just tap and try to wiggle the exhaust shields, if you find a loose one, either tach weld it or wrap a large hose clamp around it to keep it still. Remove the belts on the engine and turn eash pulley by hand to see if any are rough, there's an idler in there that may have dries up. you may get away with just cleaning out the old grease and using new, but chances are the bearing is bad. Also turn the alternator. Try to see if there is any play in the ac clutch. When the ac clutch went on my Lumina, it sounded like an alrm clock going off! You also have two tensioners for the timing belts, same deal, bearings dry up over time. But save that for the last effort since you have to dig to get to them. Check your fans, turn them by hand or turn on the ac at idle to see if the electric fan makes noise. Remove the intake hose, exhaust or whatever you need to in order to access the shaft and see if there is any play. Can you replicate the sound revving up the engine, no load? Link to comment Share on other sites More sharing options...
The Beast I Drive Posted June 7, 2009 Share Posted June 7, 2009 Hpefully your noise isnt the same noise that ended like this -Bill Link to comment Share on other sites More sharing options...
PlaneDriver Posted June 7, 2009 Author Share Posted June 7, 2009 So I just got done spending some valuable time under the car. I added some foam to the engine bay where stuff vibrated. Doing that seemed to remove any sounds below 5000rpm. Just over 5000rpm, there is still a rattle. I ran it up in the driveway to try and find the source. Standing in front of the car with the hood open, it is impossible to hear anything but the engine at that rev range. That eliminated my bearing concerns. Standing to the side of the car though, you can easily hear a rattle. It's got to be a heat shield. I tried to move various pieces when I was under it but didn't notice anything. I'll check again later this week when I replace some of the CV boots. My dad and I also found evidence of a minor oil leak, which the previous owner had mentioned but said he never had to add extra oil. We also found an antifreeze leak. Just running it up 4-5 times in the driveway produced a noticeable amount of coolant on the ground. I plan on cleaning the bottom of the car to try and pinpoint the leak. Hpefully your noise isnt the same noise that ended like this I'm really sorry for your loss, Bill. That really sucks. I bought a fire extinguisher on my way home from work Friday. Turns out there was already one in the car, so now I have 2 2lb extinguishers. Hopefully I'll never need them. Link to comment Share on other sites More sharing options...
PlaneDriver Posted January 13, 2010 Author Share Posted January 13, 2010 I found the source of the noise when I was rebuilding the engine over the past week. The heat shield to the outside of the turbo under the spare tire holder had a few small cracks in it. I drilled a hole near them and put some washers and nut/bolt through it. This prevented the parts from moving together and now there is no noise at any point on the rev range. Link to comment Share on other sites More sharing options...
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