Hi there, I have an older small block chev 350cui V8 mated to a Toyota W55 trans with a Tilton twin plate ceramic 7.25" clutch with a hydraulic throw out bearing. The gearbox has been fully rebuilt and the clutch, flywheel (805 billet lightened flywheel with 0.100" step as needed for tilton clutch) P.plate and throwout are all brand new. The motor had a partial rebuild/freshen up about 9 months ago and has sat on the garage floor since then until it went back into the car about 4 weeks ago. The motor build included: new cam and crank bearings, New lifters, new push rods, new timing chain and gears. we left the pistons dangling in the motor and attached everything back onto them without removing or replacing the rings or connecting rods as they all looked to be good. For the first start the motor was in car but with no gearbox or clutch attached. I unplugged the leads and turned the starter to build oil pressure once I saw about 25PSI on the gauge I plugged them all in and fired it up, the timing was so wrong that a large fireball launched out the carb and it caught fire, I quickly killed power and extinguished the flames with a wet towel over the carb. I corrected the timing with a timing light and fired her up, she fired easily the first time and run OK I sat it on 2k RPM for 5mins and turned her off - ready for the shop to do final things. At the shop they installed the clutch, p.plate, throwout and gearbox, further corrected the timing (although it seems more out of time now) when I first went to collect the car after they said they were finished the clutch was overtravelling about 3 inches more foot travel then the tilton needed making it impossible to drive as the bearing was traveling so far into the p.plate forks it was bending them into the first clutch disc. - they hadn't set a floor stop. obviously I refused to take the car like that, the next week they called back saying its ready to collect, I jumped in and started it, the clutch pedal travel seemed good it started engaging about 1/4" from the pedal stop and pedal movement was about a thrid of what it was the week before. I drove it home, it seemed OK obviously I was nursing it home under 4k RPM, it seemed to want to start farting and sputtering up higher close to 4k so I cruised. I noticed quite a loud high pitch hissing/grinding noise coming from the gbox or clutch area during my drive home so once I got back I jacked up the car and noticed the throwout is not releasing off the clutch forks at all - its not pressing hard on them but is resting on them with no bearing clearance at all. I had the car running and thats when I noticed the knock, it has very loud valve noise which is constant and keeps up with the RPM of the motor tick tick tick... but then also a much deeper rumble less sharp not like a metal to metal clank but more of a rubber to metal thud but a spinning thud that comes on intermittently and then goes away for a bit. the strangest part is if its not making the noise and I press the clutch pedal even a slight bit in the deep rumbling noise comes and continues for a short or sometimes long time after the clutch is no longer being touched at all. after noticing it the engine has become much harder to start and doesnt stay at a consistent idle, I have to keep feathering the gas to keep it running.. The oil pressure is at about 60psi cold at 1k RPM and 45-50 at temp 1k RPM and goes as high as 85psi on rev once warm to 4k RPM. any advice?
Very much so, I am hoping somehow the motor is ok and its just the clutch making noises from being pushed in toward the flywheel to far maybe resulting in a cracked disc or something? but it does seem to be internal and I think Im just being hopeful..
I would check the crank end thrust. When the shop had the throw out bearing over traveling I wonder if they started it and operated the clutch numerous times trying to get it right. It might have wasted the thrust main and also tore up the thrust flange on the crank too.
If you are paying someone a shop rate to do stuff like this I would stick to proven formulas. EG...a Chevy engine with a GM 5 spd. A shop wouldn't be learning the ins and outs of new stuff on my dime... Gets costly...FAST.
Get someone to push in and out on the clutch pedal while the engine is running. Watch the front lower pulley and see how much movement it has back and forth. Many times it will be obvious that there is a thrust bearing problem by how much movement you see there.
Yup...and I've personally seen an engine (Ford V6) with over a 1/4" obvious movement when the clutch was pressed. Still ran...but obviously we have a problem!!!
Thanks for all the replies guys, it has been miserable rainy weather since I made the original post and I haven't made it out there, Im going to see if there is any obvious movement in the crank while operating the clutch and if there is not then I will pull the gearbox, remove the pressure plate and friction plates and start it up with just the flywheel to see if just maybe (fingers crossed) the noise is coming from the twin plate clutch ***embly...
When the motor was rebuilt I don't believe anything was balanced as the mechanic was sure balance was not an issue, since the build however I have removed the old clunky flywheel and installed a much lighter (about 1/3 weight if not 1/4 weight) 805 billet steel flywheel, could the reduced weight on flywheel side have caused a balance issue?
No, 350's are zero balance meaning they don't need counter weights on the flywheel or dampener. Are you sure it's a 350 and not a 400? 400's need special flywheels and dampeners. Also, I would have taken the pistons out while you were in there, just to know for sure they were OK. Look for flywheel and or pressure plate bolts that may be too long and hitting the back of the block somewhere. Something is fishy with that clutch. My 2 cents worth.
Based on your choice of words the p.plate forks it was bending them. Well they didn't get un bent - if they did bend and no one straightened them.
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