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Couple S14 Mechanical Noise Questions

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  • Couple S14 Mechanical Noise Questions

    Just figured I'd throw these out there as I've observed them since i've owned my car:

    1)Is it common for our motors to idle LOUDER once warm with respect to valve train noise etc? When I start my motor cold it's silent, but once it gets to full operating temp it gets far more tickety, which seems counter-intuitive. When the car is warm(and all valves are within spec!), I can hear valve noise just a little bit when at a stop light, and it is much more pronounced when I am near a curb or in a drivethrough ATM where it has a wall to echo off of. Sound familiar to anyone?

    Before you say it, I've driven 3500 miles since I got my car and the noise has been present since I've owned it. Rod bearings would be toasted if they were the culprit so they are ruled out.

    2)When driving, if I'm in 2+ gear at below 3k rpm, if I get past half throttle, my motor sounds noticably rougher up until 3k or so. It makes a noise that it very constant and 100% repeatable. It sounds like a cross between radio static with the grindy sound from a lightweight flywheel, except far more subtle. It is not intermittent like pinging. I have to be alone on the road to hear it as it's not audible over other cars. I could understand if it was say...1500 rpm as then I'd be bogging my motor(thats kind of what it sounds like) but 3k rpm seems high to be bogging. I might just be oversensitive.

    Just curious if these sound like normal occurences for other s14 people.

  • #2
    Adjust the valve clearances ASAP.
    The tapping should quiet down a bit but still be a little tappety....solid lifters.
    If on post valve adjustment test drive, the tapping does not quiet down noticeably and continues to get louder as the car warms up, then stop driving it until you can inspect the rod bearings.

    m

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    • #3
      Valves have less than 1k on a good adjustment.

      The rod bearings have 35k on them, always used mobil 1 synthetic, oil pan baffle, etc. Previous owner always warmed it up and drove easy until warm, I always do too. Car has seen one autoX since rebuild. If that was the case, I've driven 3500 miles with this sound with no noticable change...and the previous owner drove it like it is for a ways before that I'm sure. I feel like rod bearings would have been completely done for long before I got this far...
      Last edited by ShiftBMW; 12-03-2007, 07:53 PM.

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      • #4
        Just to clarify, I'm not looking for the answer to "What's my noise" I've searched and know most of the possible culprits for loud tickety idles etc.

        Just wondering if anybody has observed similar things to what I have for comparison sake...to this day I'm still not sure what an S14 is "supposed" to sound like so I guess I'm trying to figure it out :-)
        Last edited by ShiftBMW; 12-03-2007, 09:54 PM.

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        • #5
          I have to say that my engine's valve train is much louder after the engine warms up using Mobil1 10w-30 which may be too thin for this engine. The last time the valves have been adjusted is unkown. I don't drive the car very much just occasional weekends for about an hour. I plan to do a rebuild over the Winter not for that sound specifically but to freshen the engine for semi-daily use. I think that I will go with regular 20W-50 for the Summer after rebuild break-in and that may quiet the valve train.
          There'll be Spandex jackets one for everyone ...

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          • #6
            They are noisy at the top. They are a titch noisier than the 84 and older watercooled VW solid lifter engines which did not have a sound insulated hood..

            If you fiddle around with the valve lash, they can be quieted down quite a bit but the engine is definitely noisier than expected for a $35k plus new purchase.

            The electronic injectors are also a source of Tapping.

            m

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            • #7
              So I wanted to update this thread.

              I confident I found the solution to the second noise(high load, low rpm grinding). It is actually coming from my tranny/clutch area! It became a lot more audible with my shifter boot and rubber piece off. It is directly related to load, happens warm or cold, etc./ Sounds like some gearbox chatter...tranny still shifts alright so I'll keep driving it.

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              • #8
                As for noise number 1, I took it by a trusted mechanic(who has built more than a few s14's and s38's in his day) and he suggested that my "tickety idle" was perhaps coming from my bottom end(I suppose it's louder from under the car than above the hood). He also said that it didn't sound too bad and that he saw no problem continuing to drive it.

                I got to thinking, what could it possibly be? So far, I can't come up with a logical culprit. Again, the sound is far more noticable(almost silent when cold) when warm, exists only at idle and up to 1500 rpm, and distinctly "clacks." It doesn't strike me as being entirely rhythmic(aka it doesn't seem to always happen only once per rev or once per every two).

                I've played out as many scenarios in my head as I can think of and none of them add up. If I've missed something, I'd be interested to hear:

                Rod Bearings:
                Could be the case I suppose...although I feel like I would have grenaded my motor after 3500 miles of driving. Additionally, my oil temp is right at 210, water temp always straight up.I have an oil pressure gauge(although I don't trust the accuracy totally) but oil pressure at idle seems to be ~35psi or so. Also, it would seem a rod bearing would be audible right at cold start before oil pressure is built as well as upon lifting the throttle once warm, none of which happens.

                Piston Slap:
                This is what my s14 mechanic compared the sound to. I was under the impression this got quieter once warm(I know for a fact because my last s14 had a NASTY case hehe)! I have minimal if any upon startup(forged pistons). I do get a little bit of a deiselly sound if load the engine lightly at low rpm during the first minute. It doesn't seem like piston slap would APPEAR once warm.

                Exhaust leak:
                This is a viable option I suppose. Loose header studs or the like. I did have one back off and replaced it, as well as got a wrench on most of the others and all were ok. I also thought exhaust leaks of this nature got quieter at idle.

                Timing chain:
                S50 tensioner, chain has 40k on it, all new guides have 40k on them...doubtful? S50 tensioners don't really go bad do they? Maybe oil slips past the seal once it's thin enough and the tensioner doesn't tension totally(although I feel like this would produce the same problem above 1500rpm which I don't have).

                Waterpump, alternator, etc?
                Maybe??? Alt bushings replaced 40k ago...

                Valves:
                Done by dynospot, double checked...double checked. Valves are good.

                Feedback on any of my logic is appreciated. Feel free to contrast anything I've said or add anything I may have overlooked! I'm trying to eliminate the easy(and clean!) stuff before tearing down my oil pan and checking my bearings etc.
                Last edited by ShiftBMW; 12-21-2007, 04:10 PM.

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                • #9
                  Originally posted by ShiftBMW View Post
                  As for noise number 1, I took it by a trusted mechanic(who has built more than a few s14's and s38's in his day) and he suggested that my "tickety idle" was perhaps coming from my bottom end(I suppose it's louder from under the car than above the hood). He also said that it didn't sound too bad and that he saw no problem continuing to drive it.

                  I got to thinking, what could it possibly be? So far, I can't come up with a logical culprit. Again, the sound is far more noticable(almost silent when cold) when warm, exists only at idle and up to 1500 rpm, and distinctly "clacks." It doesn't strike me as being entirely rhythmic(aka it doesn't seem to always happen only once per rev or once per every two).

                  I've played out as many scenarios in my head as I can think of and none of them add up. If I've missed something, I'd be interested to hear:

                  Rod Bearings:
                  Could be the case I suppose...although I feel like I would have grenaded my motor after 3500 miles of driving. Additionally, my oil temp is right at 210, water temp always straight up.I have an oil pressure gauge(although I don't trust the accuracy totally) but oil pressure at idle seems to be ~35psi or so. Also, it would seem a rod bearing would be audible right at cold start before oil pressure is built as well as upon lifting the throttle once warm, none of which happens.

                  Piston Slap:
                  This is what my s14 mechanic compared the sound to. I was under the impression this got quieter once warm(I know for a fact because my last s14 had a NASTY case hehe)! I have minimal if any upon startup(forged pistons). I do get a little bit of a deiselly sound if load the engine lightly at low rpm during the first minute. It doesn't seem like piston slap would APPEAR once warm.

                  Exhaust leak:
                  This is a viable option I suppose. Loose header studs or the like. I did have one back off and replaced it, as well as got a wrench on most of the others and all were ok. I also thought exhaust leaks of this nature got quieter at idle.

                  Timing chain:
                  S50 tensioner, chain has 40k on it, all new guides have 40k on them...doubtful? S50 tensioners don't really go bad do they? Maybe oil slips past the seal once it's thin enough and the tensioner doesn't tension totally(although I feel like this would produce the same problem above 1500rpm which I don't have).

                  Waterpump, alternator, etc?
                  Maybe??? Alt bushings replaced 40k ago...

                  Valves:
                  Done by dynospot, double checked...double checked. Valves are good.

                  Feedback on any of my logic is appreciated. Feel free to contrast anything I've said or add anything I may have overlooked! I'm trying to eliminate the easy(and clean!) stuff before tearing down my oil pan and checking my bearings etc.
                  BOTH sounds are ABSOLUTELY normal (I get both specially as I've got an Evo II and they come w/LTW flywheel).

                  You're right the piston slap is present at cold and clears when warm. The top end noise (if valves are correctly adjusted) is due to the timing chain rattle. Check if you've got the upgraded E36 chain tensioner (if you don't , usind this will make the car sound like brand new), there are plenty of posts here with fotos so that you can check from the outside. If you do have it already and if the rattle is bothering you than save a few grand and replace the timig chain/tensioners/sprockets for a smooth hot idle again.

                  Mind you the exhaust leak can sometimes be confused with a knocking big end but then it would be more present under load, just like knackered shells do. Worn out shells on the s14 start knocking between 2000-3000revs under load.

                  The transmission grinding/moan is common just like the gearstick frenetic vibration around 4500revs, some cars are worst than others. This gearbox noise is believed to be coming from bearings and primary shaft when "looser" (a bit wornish).

                  P.S. I wouldn't trust a mechanic who can't figure out where the sound is coming and can't tell apart a top end chatter from a big end knocking specially if he calls himself a S14 specialist.
                  Last edited by kiko; 12-21-2007, 10:35 PM.

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                  • #10
                    I have 40k miles on the s50 tensioner, new timing chain, and new guides.

                    The noise I have is not loud valves...valves are quiet.

                    I wouldn't trust a mechanic who couldn't differentiate between bottom end and top end noise either. That's why I dropped by and had my s14 mech listen to my idle. He confirmed that it wasn't my valves. Maybe my wording the first time around left some doubt.

                    Can an exhaust leak get louder with engine heat? Also, can an S50 tensioner fail? Did I overlook any possible noisemakers?
                    Last edited by ShiftBMW; 12-22-2007, 09:18 AM.

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                    • #11
                      Originally posted by ShiftBMW View Post
                      Can an exhaust leak get louder with engine heat? Also, can an S50 tensioner fail? Did I overlook any possible noisemakers?
                      Yes. I'd check the bolt tightness as this is a usual culprit.

                      TO be positive about the noise the is an engine "esthtoscope" (spell?) and the cheap version is a flat head driver touching the parts you want to hears (ex valve cover) and and on the grip side you put you ear (making contact) vibration will travel to your middle ear and will match or not the noise you're hearing from the other ear, it's easier done than said.

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                      • #12
                        I actually have one. I have a hard time figuring out where to put it to isolate certain noises as it seems like sound can travel a bit. Can I check for exhaust leaks by placing the end of the stethoscope on each exhaust runner?

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                        • #13
                          No not really. The best way to check for leaks is to raise the car in a lift and hearing it. You need a lift to re-tighten them.
                          Last edited by kiko; 12-22-2007, 11:01 PM.

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                          • #14
                            Ah. I'll have to do that once I'm back with my car in a little over a week.

                            Out of curiosity, how likely of a candidate could wrist pins be?

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                            • #15
                              Slim to none.

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