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Car Forum / Pontiac / Pontiac Fiero / March 2005V6 Problem: Driving me NUTS!
Guys, Ok, I gotta come to the group with this one. I cant figure out if Im looking at a clutch or engine problem, and could really use a second set of eyes on this one: History: I recently got a rebuilt engine put into my 87 V6 Fiero, along with a clutch rebuild because I was having issues with my clutch (couldnt shift). The guy replaced the slave & master cylinders as well as clutch plate and flywheel, not sure if any of them were brand new or used. Problem: Got car back and the clutch felt much different than it did for the 4 years I owned it prior. The guy who fixed it up for me did an excellent job with everything, but our two heads together just arent sure exactly what the issue could be. The clutch pedal, at least to me, feels much "softer" than it did before the fix. My old clutch had slightly less resistance than my brake, and I mean slightly. Now the clutch pedal feels really soft, and the sweet spot for shifting into gear is VERY small. My friend has had four manual tranny cars in the past three years and he even thinks it feels weird. Thats about the best way I can put it. The clutch pedal has no real resistance and the sweet spot is almost right on the floor, not nearly where it used to be, which was halfway between the clutch being to the floor and released. It went from the midpoint to the very bottom of the pedal. The clutch has been thoroughly bled, its not an air bubble issue. There is a second part, which I think might be related in some way. In any gear, once I hit 4000 rpm, the car just stops accelerating forward. It feels like a clutch slippage problem, but I was told that should be at lower RPMs, not at 4000. Say Im in 3rd, then I shift to 2nd to pass a car, if Im over 4000rpm the engine revs faster and the RPMs go up, but you feel like the car is just drifting. Its like NONE of the hosepower from the engine gets to the wheels at all. That was never like that. Forget about laying some rubber, if you max out the RPMs in 1st, drop the clutch, the wheels chirp and the car creeps forward while the engine revs away. Nothing at all. I lose all engine-to-wheel power over 4000rpm. Unexplored Issue: The only thing that I havent looked into is the Check Engine light. Its been popping on when Im doing 80 on the highway for 5 mins or more. Never comes on other than that. Im not sure if its related, but doing 80 in fourth gear is approximately the same RPM that my car goes into that "no acceleration" mode. Question: Any ideas with this problem? Is it potentially a bad O2 or throttle sensor or somekind of other sensor that leads to the check engine light? Id love for it to be something not clutch related as those repairs are pretty expensive. Anything I can do to test a theory? Im open to any ideas or suggestions, Ill definately try any proposed idea and get back to you. Is it potentially a defective master or slave cylinder? I have no idea what Im looking at here, but I assume it to be the clutch due to the lack of power transefered to the wheels from the engine. Please drop a line and give me and advice you got. Its all greatly appreciated! Thanks, Nate Your friend screwed up the clutch install. If he put in used parts, take them all out & do it right with new parts. Check the throwout arm; that could be an issue. You also may (probably do) still have air in the lines. Both your problems are clutch related (nothing to do with any sensors), usually it's one or the other I don't see how your friend could have screwed up on both ends but he did. ~ Paul aka "Tha Driver" Easy on the Giggle Cream! > Got car back and the clutch felt much different than it did for the 4 years > I owned it prior. The guy who fixed it up for me did an excellent job with [quoted text clipped - 9 lines] > released. It went from the midpoint to the very bottom of the pedal. The > clutch has been thoroughly bled, its not an air bubble issue. A characteristic of a diaphragm clutch is that as it wears, release force increases. This means that if you drive the clutch until it is slipping and then replace it the new one is going to feel like there is no pedal pressure at all. The release point on the Fiero is normally close to the floor until the clutch is almost completely worn out at which point it gets higher and higher and then the clutch starts to slip when you step on the gas in gear. This part all sounds normal. > There is a second part, which I think might be related in some way. In any > gear, once I hit 4000 rpm, the car just stops accelerating forward. It [quoted text clipped - 6 lines] > chirp and the car creeps forward while the engine revs away. Nothing at > all. I lose all engine-to-wheel power over 4000rpm. If you step on the gas at 4000 rpm and engine rpms shoot way up but the car doesn't speed up, then the clutch is slipping. This is usually accompanied by a distinctive smell of clutch lining burning. This usually is a problem at lower speeds because centrifugal forces increase the clamping pressure at higher engine speeds. If you step on the gas at 4000 rpm and the engine speed does not increase nor does the car speed, you have a problem in the engine, not the clutch. Unless of course you are in fifth gear at the time... there is a limit to what the engine can do.  SignatureRobert W. Hughes (Bob) BackYard Engineering 29:40.237N, 95:28.726W or perhaps 30:55.265N, 95:20.590W Houston, Texas "The city with too much Oxygen" rwhughe@oplink.net Unless you've got a defective tach and ear, the only way you can have more revs and no increase in forward motion is a slipping clutch. At higher revs, it could just be that you've entered the horsepower/torque curve where the clutch gives up. No bleed/master/slave issues should make it behave that way. Sorry to say, but it sounds like your clutch assembly is in trouble. I had one just like that on a Duke. Went just fine, then started to slip at higher revs. Quit running nearly at all, as the slippage started going lower and lower revs, just before a gas station that I was able to coast into to call the hook... L8R Skip, whose Fieros won't go on the boat (see URL below), so they're for sale in the Atlanta area 87 Duke Coupe "C'Ol' Blue" previously "New Blue" until I discovered it had Icy Air 86 GT "MsAmerica" formerly "Jack Armstrong, All-American, Red, White and Blue" Both can be seen in the members section of gafiero.org SignatureMorgan 461 #2 SV Flying Pig http://tinyurl.com/384p2 "Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover." - Mark Twain > Guys, > [quoted text clipped - 54 lines] > Thanks, > Nate Skip and everyone, Thanks for the replies. Ill take it into the tranny shop and see what they can come up with. Its good to have a few suggestions so that they dont hose me. I appreciate all the input and similar stories, Im glad I got something to go on with the problem. Thanks again, Nate > Unless you've got a defective tach and ear, the only way you can have more > revs and no increase in forward motion is a slipping clutch. [quoted text clipped - 104 lines] > > Thanks, > > Nate It's entirely possible to put a new master/slave cylinder set on the car and have it suck air if it's one of the rough sand-cast ones that are prevalent on store shelves today. Those are only good for paperweights. Best thing to do is stick with the smooth steel OEM ones and rebuild them as needed at whatever cost required. Also, make sure that the bleedscrew on the slave cylinder is seating properly - once I fought for an entire day tring to get my clutch hydraulics bled only to find out that the seat on the bleedscrew was corroded and was allowing air past on the return stroke. No matter how much air I managed to pump out of it, it would seep back in. Also, for your final pump on the slave cylinder, remove the bleedscrew completely, then slowly compress the rod and piston by hand - hold it tightly and reinstall (and tighten) the bleedscrew before releasing the rod and piston. This removes whatever air ma still be hiding in the bore of the slave cylinder. The clutch hydraulics are the most poorly-designed part of the whole Fiero - if I haven't loved my Fieros so very much, I'd have scrapped them all due to clutch hydraulic problems. Patrick W. Heinske -- LZeitgeist@aol.com 1988 Red Fiero Formula Convertible ( pics at http://members.aol.com/automodaformula ) I went through 3 of the cast master cylinders, each one would not stay bled for a shorter amount of time, last one only lasted until I backed out of driveway. Then I discovered a hairline crack (very small, needed a magnifying class to find it but I have old eyes) in the flare on the steel line. Cut the end of the line off and reconnected everything, which is not as simple as this makes it sound (1/4 comp-1/4 flare fitting, 12 inch #4 braided steel line, 1/4 flare - mastercylinder fitting) and everything worked fine, has been good for 3 years now. Might want to check your line. The flared end will show a blue/black line which is apparently the seam of the tubing and is normal but any other indication of a fine line is probably a crack and will let air in even if it does not squirt fluid out. SignatureRobert W. Hughes (Bob) BackYard Engineering 29:40.237N, 95:28.726W or perhaps 30:55.265N, 95:20.590W Houston, Texas "The city with too much Oxygen" rwhughe@oplink.net Wow - you must have really had to crush that compression fitting down hard! I assume they're the same all over, but.... that's 6mm hard line, not 1/4" (6.35mm)! > Cut the end of the line off and reconnected everything, which is not as > simple as this makes it sound (1/4 comp-1/4 flare fitting, 12 inch #4 > braided steel line, 1/4 flare - mastercylinder fitting) and everything > worked fine, has been good for 3 years now. > Wow - you must have really had to crush that compression fitting down hard! no, but it is 19 years old and had been removed several times > I assume they're the same all over, but.... that's 6mm hard line, not 1/4" > (6.35mm)! yes, but - 1/4 compression sleeve works, just an extra .010 crush. actually, could not find a #4 flare-1/4 compression adaptor, had to make it. >>Cut the end of the line off and reconnected everything, which is not as >>simple as this makes it sound (1/4 comp-1/4 flare fitting, 12 inch #4 >>braided steel line, 1/4 flare - mastercylinder fitting) and everything >>worked fine, has been good for 3 years now. SignatureRobert W. Hughes (Bob) BackYard Engineering 29:40.237N, 95:28.726W or perhaps 30:55.265N, 95:20.590W Houston, Texas "The city with too much Oxygen" rwhughe@oplink.net Hmph - I tried a 1/4" compression fitting, but couldn't get it to stop leaking (at which point I realized it was metric line!). Great if it worked for you though. As for adaptors - they do exist. I've been rigging up a 6mm -> 1/4NPT, then NPT -> AN adaptors, and a metric bubble -> AN up top, then slipping standard AN hose in-between. > yes, but - 1/4 compression sleeve works, just an extra .010 crush. > actually, could not find a #4 flare-1/4 compression adaptor, had to make > it. > It's entirely possible to put a new master/slave cylinder set on the > car and have it suck air if it's one of the rough sand-cast ones that [quoted text clipped - 9 lines] > corroded and was allowing air past on the return stroke. No matter how > much air I managed to pump out of it, it would seep back in. Seems pretty stable to me. I will try re-seating it to make totally sure. > Also, for your final pump on the slave cylinder, remove the bleedscrew > completely, then slowly compress the rod and piston by hand - hold it > tightly and reinstall (and tighten) the bleedscrew before releasing the > rod and piston. This removes whatever air ma still be hiding in the > bore of the slave cylinder. How exactly can I compress the rod and piston by hand with the bleedscrew off? Im not really a whiz with Fieros, but Im pretty handy when it comes to tools and whatnot. If you can just elaborate on the process that would be good. Im not sure where to look/how to compress it with the bleedscrew off. Do I need a second guy to help out? Id love to get some details on this. It might be good to try before heading to the tranny shop! > The clutch hydraulics are the most poorly-designed part of the whole > Fiero - if I haven't loved my Fieros so very much, I'd have scrapped [quoted text clipped - 3 lines] > 1988 Red Fiero Formula Convertible > ( pics at http://members.aol.com/automodaformula ) The problem with the corroded bleedscrew was revealed when I took the bleedscrew out completely - the seat had corrosion on it, so I cleaned that off with Emery cloth. By 'compress the rod and piston by hand', I'll clarify below. Loosen the slave cylinder bolts to move it away from the bracket and free the end of the rod from the cup on the clutch release arm. (It will take two people to accomplish the rest of this procedure.) Before we forget, top off the fluid in the master cylinder reservoir. Loosen and completely remove the bleedscrew from the slave cylinder. Keep it (and the wrench to reinstall it) nearby and handy. You may want to wear a leather glove on your left hand - you'll be holding pressure on the rod for possibly a couple minutes or so, and the tip of the rod can fatigue your hand quickly. Supporting the slave cylinder with your right hand, use your left hand/fingers to slowly push the rod and piston into the slave cylinder as far as it will go - be careful not to let yourself, your clothes or your paintjob get sprayed by the fluid squirting out of the bleedscrew mounting hole. (It is easy to compress the rod and piston manually since you're only working against the return spring in the cylinder, not against hydraulic pressure.) To reduce the spraying, you might ask your helper to use a rag to deflect the streams. Once the rod and piston are pressed completely into the slave cylinder, hold it steady (and keep it compressed *all the way*) while your helper screws the bleedscrew back in its hole and tightens it as much as can be achieved while being held by your hands and the loosened mounting bolts in the bracket. (Don't overcrank it - if you're able to get it completely properly tightened while in this position, then that's sufficient. We just want to make sure it's not going to allow air to seep back in.) Now, slowly release the pressure you've been manually holding on the rod and piston. Reseat the rod in the cup on the clutch release arm, and retighten the bolts holding the slave cylinder to the mounting bracket. Top off the fluid (again) in the master cylinder reservoir, close it up, and try the clutch pedal. By using this procedure, you achieve a few things - A.) By removing the bleedscrew completely, you give whatever air there might be trapped in the slave cylinder a less-restrictive exit, instead of taking a chance that it might just go right back up the hydraulic line as you manually compress the slave cylinder. B.) You are able to compress the piston deeper into the cylinder than it usually moves, providing the removal of more trapped air. C.) You remove any air that might be trapped within the slave cylinder itself, which may or may not be removed by the usual bleeding methods. I hope this helps... keeping the clutch hydraulics in good working order has been, by far, the largest headache I've experienced in all of my 15 years of driving Fieros daily. I'd love to invent some sort of 'push-cable' replacement mechanism to take the place of the hydraulics. I have a couple of questions, one of which will probably have to be answered by your friend. First, how many miles where on the old flywheel (is it the factory flywheel??). If it is the original flywheel, then there is a good chance that it is probably out of spec.(if it is a high mileage one). The flywheel has to maintain a certain thickness in order for the clutch to engage in the proper spot. This is crucial for hydraulic setups, but can be adjusted for in the older "linkage" setups. It can be compensated for during the new clutch installation by using shims between the flywheel and crankshaft. This "flywheel wear" is even more exharated if your friend had the flywheel turned in order to true it up. When reusing the factory flywheel on most clutch replacements it will be necessary to turn the flywheel anywhere from 10 to 15 thousandths to compensate for warpage and hotspots. If your friend did in fact have the flywheel turned, then you are going to want to make sure that everything was shimmed out, with additional shims used for high mileage replacements. The slippage sounds like it is due to proper break in periods not being adhered to. > Guys, > [quoted text clipped - 72 lines] > Thanks, > Nate Only had this happen once, but.... Guy replaced his clutch, his slave, everything. Problem is, he put the WRONG (too long) slave pushrod in! Clutch would slip all the time, because it was being partially disengaged all the time. >> Guys, >> >> Ok, I gotta come to the group with this one. I cant figure out if Im >> looking at a clutch or engine problem, and could really use a second set >> of >> eyes on this one: |
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