Questions for past/present Q45a owners

[bgerner12]

First - I've tried doing all the searches that people have recommended and I didn'tfind what I needed so please only respond if you have personal experience withthese issues and know the cause and/or fix. These questions are in regard to my 95Q45a with 115,000 miles. I've replaced all nine accumulators two months ago (fromtexasoil), new suspension fluid and replaced the actsus computer, which seems towork fine and shows all-good (55) in self-diagnostics. Here goes:

- I have a loud creaking sound that comes from the driver side/rear suspension when that corner extends after a larger bump or dip. The humungus speed bumps at my daughters high school bring this out consistently. No amount of bleeding the suspension has diminished this noise. The active suspension seems to work alright otherwise.

- There is a constant whining sound coming from the engine compartment that seems to vary with rpm. Turning the steering to the locks has no impact so I'm guessing it's not the steering pump. It can get quite loud at times, then suddenly quiet down for no apparent reason. This change is most noticeable while going around a long sweeping off-ramp. My quess at this time is that the whine is the actsus pump.

- I get a fairly high-frequency vibration that starts at around 35mph and is gone at around 65mph. It comes back worse once I get above 80mph. This does not feel like a wheel/tire and placing the transmission in nuetral (rpms drop to idle) while at speed has no effect.

Anyone recognize these symptoms and know the cause?

[goody90q45]

- I get a fairly high-frequency vibration that starts at around 35mph and is gone at around 65mph. It comes back worse once I get above 80mph. This does not feel like a wheel/tire and placing the transmission in nuetral (rpms drop to idle) while at speed has no effect.

Anyone recognize these symptoms and know the cause?

This one sounds like a worn out transmission mount, aka 3rd engine mount. My vibration was at about 45-55mph and then again at 65-75mph and at around the 2250 rpm range. At 115k on your Q you're about due. Replacement takes about an hour and is very straightforward.

Do a search using Transmission Mount and you'll find lots of info.

[Q45tech]

There are dozens per side of rubber isolators in suspension metal arms that need to be replaced every 7-10 years. Isolators supporting differential.

By now [15 years] the rear subframe may begin to leak and need replacement.

[bgerner12]

Thanks, Mike!

I just took a look at my transmission mount and while it looks healthy enough, I willprobably follow your suggestion and try changing it as the vibration frequency feelslike it could be the driveshaft. I'll try the search you suggested also.

[goody90q45]

transmission mount is about $100 from IOS and I forgot to mention the "L" shaped exhaust hangers that are attached to it at $25-30/each. The rubber block tears on these. You'll need two. Look for a thread with pictures (mine if the pics are still linked) to see what each of these 3 "insulators" looks like when worn out. Good luck.

[bgerner12]

Hi Q45tech,

I checked the differential subframe mounts just now and they show no sign of everhaving leaked. I'll hold-off on those for now and try the transmission mount first to see ifthat helps the vibration issue.

The creaking is definitely the active suspension system. I can't make it happen byjouncing the rear (pulling up/pushing down on the body) unless the engine is running.I haven't been able to do it while lying under the car to locate the source though. Ican't quite bench press that much weight any more!

[bgerner12]

Hi Mike,

I read the thread you pointed me to and found the photos. The good thing is thatmy problem isn't unique so there's quite a bit of info on it.

[3Q Jay]

been there. know it well. multivalve unit.

[Dtrnql]

My 92a came with a whine that disappeared after the transmission was replaced and a bad front end vibration ended up being a bad bushing on the rack n pinion ???

[bgerner12]

Hi Q45tech,

You happen to know which consult II card covers the active suspension system?

BTW, I bought my wife's 97 Jag in Roswell, GA a year and a half ago. Left Boston6am the day after tornados hit Altanta. Went right to the dealer, picked up the Jagand drove it back to Pepperell, MA without a break. It rained like hell from Roswellall the way through half of NJ. That was a tough trip to do alone but the Jag hasbeen well worth the trouble.

[bgerner12]

Hi Jay,

Are you refering to the whine or the creaking (or both) ? Did you replace themultivalve unit (in the driver's side wheel well) to fix it?

[3Q Jay]

Bill- transmission mount may be separate issue. i'm referring to the 'drone' that peaks around 1700 rpm. i significantly reduced that by changing the MV (note that I bought a used one, and 4 years later the drone is starting to return although it is not nearly a loud as the original one).

the creak also has to do with the main pressure valve in the MV unit. It can be partially compensated for (Keith has a trick that involves the pressure control units--front and rear right side that he can tell you about, or with his consent i can also share it with you).

[bgerner12]

Thanks, Jay!

I'll start looking for a MV unit. I don't think Keith is talking to me, since I didn'tsend back my old accumulators for the core charge.

[Peterofdevon]

I'll jump in here with some ideas:

I had a whine that ended up to be a belt tensioner.The vibration on two of my Qs was the propeller combined with the tires. I switched to PS2s and Exaltos and replaced the drive shafts. Now... smooth as silk.

My bad transmission mounts were most noticable at idle.

250 plus pounds of rubber, argh!

Peter

[bgerner12]

Hi Peter,

Thanks for this info. Turns out my transmission mount is quite healthy so maybe it's thedriveshaft. This car sure does have it's quirks! I've never had to replace a driveshafton any other car I've owned (22 cars so far). What's even more strange is my wife's97 Jag is the lowest maintenance car in the fleet!

I'm still leaning towards the multivalve-unit for the whine, as suggested by 3qjay butI'll check out the belt tensioner also.

[Mint Q45A]

Multivalve...I have exactly the same issue since I replaced the accumulators. I went through the trouble of disassembling the MV, but everything looked ok. I haven't had the time (or the money) to look more into this. For some reason I believe the vibration is more some sort of resonance coming from the hose that goes between the reservoir for the Active fluid and the pump or multivalve.

[bgerner12]

I can't help but wonder if it's just a matter of air trapped in the system. Apparently,the Nissan Consult II tool has a mode for bleeding the actsus system. Too bad theyare so expensive. Also, nobody seems to know which function card is needed forthe active suspension.

I figure I'll just take my time and keep tinkering until I figure it out. I have been lookingfor a mv unit in the mean time though.

Thanks!

[bgerner12]

I may have stumbled across something useful with my tinkering. I won't betotally convinced until I drive to work and back tomorrow but it seems I mayhave found a cure for the loud creaking and other erratic behavior from mysuspension. Believe it or not, 3oz of Lubegard Red appears to have had adramatic effect!

I'll follow-up when I get home tomorrow.

[3Q Jay]

LGR does some good things....I have noticed an improvement with that as well.

[bgerner12]

I can confirm the improvement. Only the huge speed bumps at mydaughter's high school can get the slightest creak and I suspect that maygo away with time. All the other weird behavior of the suspension is gone.

Next will be to fix the (apparent) vibrating driveshaft. The transmission mountlooks real healthy so it seems less likely that it is the cause.

[goody90q45]

.....Only the huge speed bumps at mydaughter's high school can get the slightest creak and I suspect that maygo away with time. All the other weird behavior of the suspension is gone.

Lubeguard Red is great stuff. I've used it in a couple of hard shifting trannys with great success.

Just curious if you're able to drive over the bumps with any speed or do you have to slow down like the rest of us? I recall a video here of a Caddy with active suspension driving over a speed bump at about 45 mph and the chassis not moving an inch.

......The transmission mount looks real healthy so it seems less likely that it is the cause.

How did the rubber look in the exhaust hangers attached to the transmission mount? Still bonded to their bracket? Not torn?

[Infinitiguy19]

Mike is that still you? I would have kept the original NICO name.

But who would have though Lube Guard Red can make a differnce in the active suspension system too.

So 3 places Lube Guard Red is good on: Power steering, transmission and active suspension, No jokes please.

[bgerner12]

Hi goody90q45,

There are no cracks or separation in any of the three rubber pads attachedto the transmission mount. All of the rubber-metal bonds are solid also. That'sprobably unusual for the year/mileage but if you saw the condition of thecar as a whole, you wouldn't be surprised (as Paulwall can attest).

I'll be painfully honest regarding your other question, at the risk ofupsetting other members. My experience to-date is that the activesuspension doesn't live up to the hype. I would compare it to my wife's 97Jag XJ6 VDP as follows:

- Slightly less roll in turns.

- Slighlty less dive when braking.

- Small ripple/stutter bumps get absorbed better.

The Jag is noticeably superior in:

- Overall suspension smoothness and quietness.

- Steering and handling feel,

Please note that I drive both cars conservatively (like an old man in a luxurycar) as that's what I bought them for. My supercharged 98 A4 and RX-7powered 58 Austin Healey Sprite are for having fun at speed in the twisties.The few times I've pushed the Q45a in a turn it felt awkward. The steeringis too slow and there is way too much understeer. It does makeexceptional power and the auto transmission responds well. I don't push theJag. It puts a big smile on my face just crusing along at a pace thataggravates those behind me.

As for what speed I go over those bumps at my daughter's school, thereare four of them. Two ramp the tire smoothly up from the road level and I'llgo over those at about a fast jogging speed. The other two have no rampso the tire hits the bump sharply. Those, I come close to stopping for beforemaking contact.

[3Q Jay]

Multivalve...I have exactly the same issue since I replaced the accumulators. I went through the trouble of disassembling the MV, but everything looked ok. I haven't had the time (or the money) to look more into this. For some reason I believe the vibration is more some sort of resonance coming from the hose that goes between the reservoir for the Active fluid and the pump or multivalve.

Mint- I got your PM, but i can't reply to you (maybe you have disabled PMs?)
Yep, I still have 2 kouki actives.

[Infinitiguy19]

Multivalve...I have exactly the same issue since I replaced the accumulators. I went through the trouble of disassembling the MV, but everything looked ok. I haven't had the time (or the money) to look more into this. For some reason I believe the vibration is more some sort of resonance coming from the hose that goes between the reservoir for the Active fluid and the pump or multivalve.

Mint Q45A if you are still around...When you took apart the multivalve did it work as it did before you took it apart. I am trying to see if the Multivalve is fixable if broken or is it like a ABS Actuator.