Guest trofeo73 Posted July 1, 2003 Share Posted July 1, 2003 The riv started making a strange knocking sound down near the A/C compressor this evening......It goes away with rpm and the car does not vibrate when doing it either; My friends mark IIIV that had a bad wrist pin would shake the whole car violently when making a similar sound. His car had a deeper raspy sound too. Damn, I hope the bottom end or supercharger is not failing, I just bought it and it has treated me so kindly. It has always had a lifter-like tap when starting it up after sitting awhile though. But this sounds much different that that. What do you all think? Could the A/C compressor be failing or could it be a water pump about to say goodbye? I guess one way to find out would be to drive it till what ever does break breaks. The car only has 79K on it and it performed great on the road trip I took it on last weekend........ <img src="http://www.aaca.org/ubbthreads/images/graemlins/confused.gif" alt="" /> Link to comment Share on other sites More sharing options...
sahein Posted July 1, 2003 Share Posted July 1, 2003 Check your harmonic balancer! Remove the belt and try to rock the balancer back and forth. It shouldn't move significantly unless the rubber has seperated. Link to comment Share on other sites More sharing options...
harry yarnell Posted July 1, 2003 Share Posted July 1, 2003 Try turning the HVAC off (disengage the compressor)and see if the noise goes away or changes. Link to comment Share on other sites More sharing options...
padgett Posted July 1, 2003 Share Posted July 1, 2003 I'd go a step further - check the balancer with the engine cool and then before replacing the belt, start the engine. Since nothing else is spinning (including the water pump), any sounds will come from the engine (and with all the other noise missing will be easy to locate. I just would not run over 30 seconds. Make sure the a/c is off so the fan doesn't come on. Link to comment Share on other sites More sharing options...
Guest trofeo73 Posted July 1, 2003 Share Posted July 1, 2003 Thank you all very much,,I will give it a shot this evening. Thats a good idea about running it without any accesories hooked up, It would have to be the engine or harmonic balancer. Link to comment Share on other sites More sharing options...
Guest trofeo73 Posted July 1, 2003 Share Posted July 1, 2003 Well,, I took all the belts off and it STILL makes a wraping sound. I am afraid it is somthing of the expensive nature....Now the car experiences a loss of power too. Thats not good. Maybee a stuck valve?? Or to make my week worse than it already is.. a bad piston or what ever... Any way this is going to cost me some serious money, I just paid the $380 sales tax on it......Any ideas, are these engines hard to find or expensive to rebuild.........?????? Link to comment Share on other sites More sharing options...
Guest wally888 Posted July 1, 2003 Share Posted July 1, 2003 I use a short piece of Vac hose or something similar to find window leaks (air) or identify(locate) engine noises. Slip one end in your ear(not too far!) and place other end on suspect. Very efficient stetoscope. Link to comment Share on other sites More sharing options...
padgett Posted July 1, 2003 Share Posted July 1, 2003 Well the next step for me would probably be to drop the pan and have a look inside. Sometimes the problem is evident (such as the two cam bearings I found in my pan), other times not so. At least on a SBC if a rod is loose enough to knock, you can usually feel it by wiggling. Is hard to diagnose without hearing it (crank speed or cam speed).First might want to pull the plugs (not that bad on a cool engine) and see what a breaker bar on the balancer bolt feels like - I can usually tell the timing chain condition that way however if what you hear sounds like a knock with the belt off, it may just be.My (limited) experience with 3800s is that the bottom end is really pretty robust however if a rod bolt has come loose, you do not want to be around when it comes off.BTW a rod knock could be sufficient to trigger the knock retard on the ignition and could be the cause of the loss of power. Link to comment Share on other sites More sharing options...
Guest trofeo73 Posted July 2, 2003 Share Posted July 2, 2003 I figure I will spend about 1200 for one I found that has 70K on it. A guy is going to put it in for 800 bucks. I will be without the car a total of 2-3 days. The cars blue book is 7250, yet I only paid 5200 for it... So I guess I am not getting burned toooooo bad.. <img src="http://www.aaca.org/ubbthreads/images/graemlins/frown.gif" alt="" /> Link to comment Share on other sites More sharing options...
Guest trofeo73 Posted July 2, 2003 Share Posted July 2, 2003 One thing I forgot to mention is that the oil pan is heavily dented in from the previous owner. <img src="http://www.aaca.org/ubbthreads/images/graemlins/mad.gif" alt="" /> <img src="http://www.aaca.org/ubbthreads/images/graemlins/mad.gif" alt="" /> <img src="http://www.aaca.org/ubbthreads/images/graemlins/mad.gif" alt="" />(at least 1/2 to 1 inch deep!!! Could that have caused the oil pickup screen to be blocked thereby starving the engine the nessesary amount of oil??????????? Link to comment Share on other sites More sharing options...
Guest Greg Ross Posted July 2, 2003 Share Posted July 2, 2003 "Well,, I took all the belts off and it STILL makes a wraping sound."This seems distinctly different from a knock, at idle if the cam chain tensioner is worn out or if the chain has stretched you'll get the chain scuffing on the aluminum front cover. Can you further describe the term "wraping sound"?At 110,000 miles my original 3.8 was generating such a noise, replaced the chain/ sprokets/ tensioner complete and performance, such as it was, was restored. Link to comment Share on other sites More sharing options...
Guest DTerry Posted July 2, 2003 Share Posted July 2, 2003 <div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">One thing I forgot to mention is that the oil pan is heavily dented in from the previous owner. </div></div>I had a similar noise in a Ford 6 cyl engine. Had a dent in the oil pan deep enough to cause it to contact the crank shaft. Rapping noise, no vibration or other symptoms. Banged it on the side (oil pan, not car) to somewhat re-form it, and the noise went away. No loss of power, though. Link to comment Share on other sites More sharing options...
padgett Posted July 2, 2003 Share Posted July 2, 2003 To the knock sensor almost anything will seem like a knock (book recommends hitting the block with a hammer to check if it is working). When sensed it can retard the sprk by over 10 degrees, enough to notice the difference. Could explain the performance drop.I guess $1200 for a s/c engine is not too bad (does it include the blower ?), I paid under $500 for a n/a engine a few years ago (yard said it had 36,000 on it. They also said it was from a Pontiac but the s/n crossed to an Olds) but it was missing quite a few things & what was not missing was broke - then again all I wanted was a long block. Have put about 50,000 on it since so must not be too bad). AFAIR the s/c engine has a beefier bottom end and a 60 psi oil system.Hardest part of swap was the one backwards facing bolt on the transmission - took three feet of extensions to reach.First you need to find out what is causing the noise. If it is the crank hitting the pan you should be able to feel it but wouldn't (never say never) think it would go away at speed. What is the oil pressure reading when it does it and when the noise goes away ?Would check the "feel" of the chain with a breaker bar first - if bad tensioner should have slop - and if seems ok would pull pan next - is *much* easier than pulling timing chain cover, at least it was on the Bonne and any debris could be informative. Link to comment Share on other sites More sharing options...
Guest trofeo73 Posted July 3, 2003 Share Posted July 3, 2003 What do you mean check the slop on the chain with a bar?? Do I feel for some sort of play in the crank..??? The sound is a low-pitch knocking sound. It is more evident at idle than in drive. The idle on the car is very smooth; Just like it was when NOT knocking. I do not have an oil pressure gauge, but the oil light does NOT come on though. Link to comment Share on other sites More sharing options...
padgett Posted July 3, 2003 Share Posted July 3, 2003 Yes, is easiest to feel with the plugs out. Move in one direction until you feel the extra drag of the cam & balancer and then the other way. Shouldn't be much movement between. Harry might know how much is right for a 3800, not at home as usual.Am ->reasonably<- certain you can also check the chain tension by hand with the pan dropped.Idle can be very smooth with a rod or main knock. Am surprised a s/c riv would not have an oil pressure guage - think the light is set around 6 psi, is more of a "you have no oil" warning & why it has a fuel pump interlock. Could be that increased oil volume at higher rpm is quieting down.After the Bonne lost both center cam bearings (well, were not lost, were lying in the bottom of the pan) we drove over 1,000 miles at 70+ on 19 psi max after dealer said it was the guage and it ran perfectly smooth all the way.The real concern is that it might be a bearing cap coming loose & why you need to check it out before driving further. Link to comment Share on other sites More sharing options...
Guest trofeo73 Posted July 5, 2003 Share Posted July 5, 2003 I was wondering how far the oil pickup screen sits from the bottom of the oil-pan??? I took a closer look at it today it is dented in almost 1 inch.... Could that have slowly starved the engine of oil over time thereby causeing many internals to fail?? Link to comment Share on other sites More sharing options...
2seater Posted July 6, 2003 Share Posted July 6, 2003 It should be 1/4"-3/8" from the bottom, and pretty near the center if I remember correctly. Link to comment Share on other sites More sharing options...
padgett Posted July 6, 2003 Share Posted July 6, 2003 The way the pickup is shaped, even resting on the bottom of the pan is ok unless there is a lot of sludge. Have seen numerous cars with major dents in the pan that run fine. What does seem to happen sometimes is that the pickup tube will crack allowing air to suck in. The other factor is that with a pan dent you should never let the oil level get low since the dent usually pushes the pickup higher in the pan.That said these engines are remarkably tolerent as long as they are getting some oil - why the light goes off at about 6 psi. Link to comment Share on other sites More sharing options...
Guest trofeo73 Posted July 6, 2003 Share Posted July 6, 2003 This is a little off topic, but similar none the less. I think I inadvertantly turned the ignition on the trofeo with the idle air control plug off. Do I need to reset it somehow?? The car will start but will not idle unless you feather it several times. The idle count is in the upper eighties on my diagnostic display. No vacum leaks I know of too. Link to comment Share on other sites More sharing options...
2seater Posted July 7, 2003 Share Posted July 7, 2003 That shouldn't have made any difference to the IAC and with counts like that it should have a very high idle. It should be able to reset itself as it learns the proper position for the correct idle speed. You can go into the overide section of diagnostics and manually operate the IAC to see if the idle speed changes. If not, it is either defective, has a broken connection somewhere, or another problem exists. Link to comment Share on other sites More sharing options...
padgett Posted July 7, 2003 Share Posted July 7, 2003 Once the IAC has gotten confused, you need to drive over 38 mph in closed loop for the ECM to reset it. That said, unless it is way off it should be able to control the idle once you reconnected it unless it is gummed up (common). Link to comment Share on other sites More sharing options...
Guest trofeo73 Posted July 7, 2003 Share Posted July 7, 2003 I guess the IAC or somthing else has gone astray. The BLM reads in the 115-117 range too. I may have a vacum leak somewhere that needs to be tended to. Link to comment Share on other sites More sharing options...
2seater Posted July 8, 2003 Share Posted July 8, 2003 A vacuum leak will usually do just the opposite to the BLM, since there is more air flowing in than the MAF is seeing, the O2 sensor sees that as a lean condition for the cell it is in and cranks up the fuel to compensate. The low BLM is confusing me somewhat also, and mine is doing the same thing. My suspicion is the turbo is flowing more air than normal so we wind up with an air flow reading which is different than the computer is expecting in any particular cell. I would think that would indicate to the computer it needs to add fuel, but I now believe we are running in different cells than a non/boosted engine for the same throttle opening (something called LV8 which is the calculated load on the engine)so the correlation with the O2 sensor requires fuel be removed in that particular cell. Kinda confusing, but as long as the integrator is running around the 128 mark, the computer has adjusted correctly for the new conditions. With larger injectors, my BLM's are down around 100 in some cells. Link to comment Share on other sites More sharing options...
padgett Posted July 8, 2003 Share Posted July 8, 2003 Did you move the MAT sensor to read the same temp air as the MAF is seeing ? If the MAT is registering ambient rather than the much higher compressed air value (and if the throttle plate is downsteam of the turbo will just make matters worse) then the MAF value will be based on much cooler air than is actually flowing past it. The reduced wire cooling will then result in a lower airflow value than is actually happening.Need to check but I think the MAT table for a N/A engine only goes up to 33C so may not even be valid for a turbo but since the MAF on a S/C engine is in front of the boost, the MAT will still be rite. Link to comment Share on other sites More sharing options...
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