Forums/Z31P/z31-repairs-forums engine-mechanical/Harmonic Balancer Crank Pulley Gone Bad ? vibration at 3K
Imported from Z31Performance.com Forums{{#if:dbruce| — original post by dbruce}}{{#if:2018-08-01 15:14:07|, posted 2018-08-01 15:14:07}}{{#if:6| · 6 post{{#ifeq:6|1||s}}}}{{#if:/Z31performance_archive/forum/z31-repairs-forums/engine-mechanical/540458-harmonic-balancer-crank-pulley-gone-bad-vibration-at-3k.html|
Local archive: view archived thread on dev.z31library.com}}
dbruce: (2018-08-01 15:14:07)
I am wondering if the crank pulley can go bad … I get a vibration seemingly from the engine at about 3000-3200 rpm 1985 NA AT . that goes away above and below … Can I get vibration from the AT in park reving the engine ? This one car has had it since I bought it years ago … How do I get rid of it ?
any thoughts ?
albionwanderer86: (2018-08-02 00:14:07)
Crank pulleys can go bad, yes. Most have a layer of rubber in them that separates, though this typically results in the "rings" themselves coming off. Most Nissan engines are "internally balanced", so having a bad crank pulley shouldn't cause major carnage like it would on an "externally balanced" engine. Which also leads me to believe perhaps your crank pulley isn't your issue, as your engine won't be "out of balance" if your crank pulley separates.
albionwanderer86: (2018-08-02 02:03:56)
I've been doing some reading on this subject… and I haven't really come up with a definitive answer. Some suggest u-joints in the driveshaft, some same pinion angle and differential issues, others say engine / transmission mounts, and still even more even suggest misfires. The best option would be to take the car to a driveline shop and have it looked at. It might be worth whatever their inspection fee is to get either peace of mind, or find out exactly what is wrong and fix it.
Gem84Znt: (2018-08-02 13:00:36)
Put the car in neutral or park, check to see if vibration is still there. If it still has vibration it will not be u-joints/driveshaft.
dbruce: (2018-08-02 14:59:07)
Put the car in neutral or park, check to see if vibration is still there. If it still has vibration it will not be u-joints/driveshaft.
Yes this AT was rebuilt 22 years ago (before I bought it) and the car seems to have always had the 3K rpm vibration (in park/neutral) … So when it was rebuilt they might have missed something … It's definitely in the engine/trans area .
and I've read how the torque converter with age can deform and lose balance ( ie needs to be replaced) .
dbruce: (2018-08-04 00:03:08)
From what I've read , the TC Torque Converter may well become out of balance due to age It becomes deformed and friction particles accumulate inside … So it probably needs to be replaced …