Harmonic balancer????

[96qtrip]

I searched - but no V45 hits for this issue....... I have a repeatableengine vibration at 1800 to 2500 rpm - its very noticeable in first gear drive off, then masked more as the upshifts happen. during free rev (hood up)at this RPM the dampener seems to shake a little but appears to smooth out - Is there a history with the rubber failing? can't see much anyway if there are cracks -- BTW its tight and no real oil leaks - just replaced theleaky valve cover gaskets and inspected all other places as well.No codes to pull or MIL issues. Runs well at higher speeds and the freeway. Previuosly had crushed bearings in the drive shaft, but warranty fixed those at 75K...

Help!!

[Q45tech]

Many times the engine mounts and transmission mounts cause these type of vibrations, unfortunately the main cranshaft pulley is individually balanced to engine [$100k vibration analyser] so just swapping a pulley cannot achieve adequate results unless the oem unit is bent or broken.

Take a picture of oem pulley and note location if any of balance weights and try to duplicate on replacement.

Flywheel is also balanced to engine.

I would replace all 3 eng/transmission mounts as a first choice.

[goody90q45]

I agree with Tech. The rpm range that you're feeling vibrations sounds like it might be the mounts. Start by replacing the transmission mount and 2 exhaust hangers and if that doesn't get rid of it think about replacing the two engine mounts. Whether it's the source of the vibration or not you'll see a big improvement replacing the transmission mount and hangers. It's also a very simple repair as long as you don't mind laying on your back under the car for about an hour.

[captainluigi]

I totally agree with the previous answers you have gotten. However I will add my own personal observation based on my experience.

I replaced the trans mount & exhaust hangers(ez do)., Big difference. I too observed a wobbly crank pulley & decided to replace w/ new only to receive a defective unit. It happens. I then sent the original crank pulley/harmonic balancer off to a guy who will rebuilds them 1 at a time w/state of the art poly something meric. He will index the 2 pieces so as to go back together the same as before. I then re-installed the small weights & now is muy suave. costs $126 vs $222.

If yiu need to go thus route I will look thru reciepts for address.

Also you will need a few semi-special tools like a substantial chain wrench & a BIG *** torque wrench.

Search ''crank pulley'' & read all about it.
Modified by captainluigi at 7:21 PM 4/17/2008

[captainluigi]

Oh yeah, the idea that it disapears as rpm,s increase is the same as airplane propellers disapear as rpm,s increase. Think about it.

[96qtrip]

Wow - didn't think of the mounts...They are aged and the left one appears to be oil damaged from the aforementioned valve cover leaks. Sewell gets another order (Cody).

BTW I could sleep under the Q:-) I'll have to look for something else to do while under there...I've had it since '98 and the engineering is still niceto look at.

Thanks for all the responses.

[Q45man1]

Mike & Dennis... My G50 is closing in at 127K miles. Do you recommend replacing the transmission and engine mounts? There's no symptoms of vibrations, it's more of preventive maintenance.

Thanks,

[goody90q45]

It looks like I didn't read your post close enough to see that you can visually see your crank pulley out of balance. I was focusing on the rpm range and transmission mounts.

I've only got experience with my Q's but when I changed the transmission mount and exhaust hangers at 125K the transmission mount was flat and the rubber on both exhaust hangers was torn. I had vibration at around 2200 rpm in 2nd gear (45 mph) and in 3rd gear (60mph). I think it's like all the other rubber suspension components we replace- you don't realize that you have vibration until you replace the part. transmission mount, exhaust hangers, sway bar bushings, struts, bump stops, upper links, tension rods, engine mounts (haven't done those). At 127k miles you'll see improvement with every piece you replace.

Get your pulley taken care of and if money's not too tight go ahead and do the transmission mount and hangers. The parts are about $150-$175 and if I can do it in an hour laying on my back under the Q a shop shouldn't charge you more than that to change it on a lift. If you're a DIY'er it's a righty tighty, lefty loosey job. Very easy.

Since you're in La Jolla think about getting in touch with Jay (3Q Jay), Percy (Q45man?) and Tom. They get together (meet) every few months in the South Bay area for breakfast to talk Q's and would welcome another Q owner. They're meeting in the next week or two so the timing is right. For a benchmark, take a ride in Jay's Q to see what they felt like new.

[3Q Jay]

Mike is too kind.I try to keep my G50s at perfection, but of course I know every flaw....

to the original poster--i agree with all said. I'd also look at your alternator and even the idler pulleys. after replacing the alt on silver, i immediately noticed an improvement in vibration under load at low rpm. cause was 'rough' alternator bearings.

Percy- i'd at least do the transmount and the exhaust hangers. I've done it several times now, so would be an hour tops at my place.

[Q45man1]

Yeah Mike is a very nice person. Do you still have the idler pulleys?

Jay... Thanks for the offer and I'll contact Joe for the parts availability and I'll set it up next time. Maybe after out get together.

[96qtrip]

Hey it worked - replaced the transmission mount...presto!!! no vib or rumblethanks to those who have gone before... the pic shows the orignal was crushed so far the xmember bolts were rubbing on the frame for thetransmission side. it collasped almost 3/8"; see the overall height.

thx

[captainluigi]

Did the transmission mount also cure the crank pulley/harmonic balancer wobble????

[Q45tech]

The driverside motor mount will often be shot by 10 years or 150k whuch ever comes first.

Just because it's hard don't skip it!

For some reason few want to take these recommendations seriously even though T3 works on more old Q than any dealership in US.In ATL we probably work on more than all 5 local dealers combined............on any one day between our 3 locations there are 10-15 90-96 Q ---- that's every day 52 weeks per year.

I keep mentioning that ATL is the Elephant Graveyard for Q and until their final demise we keep them stumbling along.

[Infinitiguy19]

Is the harmonic balancer on the 1990-1996 Q45 one piece? Does it have a rubber isolator or is it a clutch type? I ask because everything can fail if not looked after.

Mine has not gone bad, I just want to learn...