Bad Motor Mount

[DougQ45]

Did the check for failed motor mounts Q45tech sugggested and have a 3 to 4 inch vertical movement on the drivers side. Bought the new mount, and climbed under to see what type of contortionist is required to replace it. The bottom 2 nuts are easy, but how do you access the top nut? ii) any special tools required?, and iii) does the exhaust manifold need to be removed to replace?? Thanks for any tips. :help

[maxnix]

Have you done a search? I think I remember Dennis saying the driveshaft and exhaust (among other parts) had to be decoupled to get enough play to replace a motor mount. If true, it would make sense to replace transmission mount also, for if it has not failed, it probably will soon. Might consider the other motor mount too for the same reason. The worn mount might permit a weird torsional harmonic when coupled with a firm new one.

[DougQ45]

Did try the seach before I posted, however couldn't find anything. Even searched back to the beginning. Very strange as I read one within the last 60 days posted by "Nardigholi??" that was answered by several users. That, of course, is how I was easily able to test my mount.

[nadirgholi]

I cannot find that post either. I posted it very recently. Within the last 4 weeks. Not earlier than that. Q45tech responded to it.

[Q45tech]

You just use 2-3 screw jacks [body on a lift] to almost rip the motor out of the car. The angle is such that taking the front of drive shaft off and releasing the transmission mounts makes it easier......like removing the oil pan not for amatuers or the faint of heart.

Something like changing the top mounted turbine sensor without dropping the transmission.Techs learn by breaking expensive things in trying to learn a faster way!

[DougQ45]

Looks like the best solution is to have all mounts replaced at a shop since I only have ramps and 2 floor jacks which doesn't look anywhere close to supporting all that weight/bulk. Also have a wife and 3 young kids that need me more than the fix to the motor mount. However, when reading Q45techs post about replacing the top mounted turbine sensor on the trans without actually dropping the transmission, a thought occurred to me. Dealer inspection from a few months ago cited"leaking speed sensor" on transmission with $800 estimate to repair. Is the turbine sensor synonamous with the speed sensor?? If so time to bite the bullet and kill 4 birds with one stone (2 motor mounts, trans mount, and speed sensor). Any help is appreciated.

[Q451990]

If I remember correctly, there are two externally mounted transmission sensors - the turbine revolution sensor (top of transmission, pain to get to, and a revolution sensor at the rear of the transmission - easy access. Given the $800 estimate, I'd say it's the turbine revolution sensor. I think the TCU monitors both sensors to determine how much slip is occuring in the transmission.

If they actually pull the transmission to get to it, have them replace the rear main seal too. I'd hold off on the sensor if you anticipate replacing the transmission in the next year or so... the new transmission doesn't come with a new sensor, but at least you won't pay for labor twice.

Heath

[maxnix]

But Heath, even if he has to replace the transmission, there is little extra labor to move the replaced turbine sensor over to the new transmission.

Maybe I overestimate the harm from a leaking turbine sensor seal.

[Professor_Mike]

A replacement trans should have the turbine revolution sensor, you have to swap the speed sensor. There isn't a lot of time overlap with motor mounts and sensor, usually the sensor leak is small enough that you can wait if you don't mind a few drops on the driveway.

[Q451990]

But Heath, even if he has to replace the transmission, there is little extra labor to move the replaced turbine sensor over to the new transmission.

Maybe I overestimate the harm from a leaking turbine sensor seal.

My point was that I wouldn't pay the R/R labor to pull the transmission just to replace the sensor if the transmission is on it's last leg. I'm not sure if a new sensor comes with a reman transmission or not... when mine went bad (electronic problem, not leaking) I was told it was one of the items that gets moved from the old unit to the new one...

Heath

[DougQ45]

OK, had both motor mounts and the transmission mount replaced. Enormous improvement in noise, feel, ride, smoothness etc... however the drivers side still moves vertically 1/2 inch or so. Passenger side does not move at all. Is movement permissble, or do I possibly have a bad mount?? Doug

[Q45tech]

Even 1" would be acceptable with this engine's torque at 2000 rpm stall in drive.

Just goes to show you that all rubber isolated parts/ arms/bushings are limited life.

[tangalora]

... The bottom 2 nuts are easy, but how do you access the top nut?...

I too am confused how to remove the top nut of the two 1990 Q45 motor mounts.

After supporting the 1990 Infiniti Q45 VH45DE engine from above and lowering the front engine crossmember (with the steering rack still attached), I can easily see each motor mount with the two lower bolts dangling (see photo below).

The diagram (SEM872C) on page EM-40 of the 1990 Infiniti Q45 factory shop manual shows only one bolt on the motor mount itself (holding the mount and a steel plate) but, that diagram on page EM-40 also shows four bolts holding the bracket which holds the top of the motor mount to the engine block.

It's difficult to see that top motor mount nut - let alone access it - even with the engine crossmember removed (by now, I don't blame Infiniti technicians for charging a lot for a motor mount R&R!). But, I'm already committed.

Forgive me if this is a dumb questions ... but ... It's just not intuitive to me what to do next to remove the motor mount:a) Do we just spin out the motor mount by hand?b) Or do we try to remove that top nut with a wrench?c) Or do we just remove the four bolts on the motor mount engine bracket?

[911/Q45]

If you can get at the top nut with a wrench, do that. Second choice would be to attempt to spin off the mount. If all else fails, remove the 4 bracket bolts and do it as an assembly.

[tangalora]

If you can get at the top nut with a wrench, do that

I haven't tried removing the 1990 Q45 motor mounts hard yet (working on the oil pan at the moment) ... but, when the time comes ...

Is there a special way (or tool) needed to access that top motor mount nut?

That top motor mount nut appears to be virtually surrounded by the engine mounting bracket (see photo below).

The reason I wonder out loud is that I can barely get my fingers on that nut, let alone a six-inch-long box or open-end wrench.

Even so, the angle to spin the nut seems severely limited by those engine bracket walls you see in the photo.

A socket & ratchet handle doesn't seem like it will fit at all.Is there a special motor-mount removal tool I need to buy?

My quesion, out of curiousity, is: Q: What tool is used to remove that top nut from the engine bracket?

[Aus94Q45]

Doug, do you mind sharing what the cost was for the replacement of the motor and transmission mounts?

[DougQ45]

IT was around $520, and worth it.

[Jesda]

Thats a LOT cheaper than I expected. What was the labor rate and number of hours?

[pito11213]

Did that $520 include parts and labor

[DougQ45]

I do not recall the labor rate but it was in at 8AM, and done by 5PM. This was for the labor only. Parts were bought from Joe.

[elwesso]

Thats a LOT cheaper than I expected. What was the labor rate and number of hours?

Obviously if you do the oil pan you have no reason to do this now

[tangalora]

For the record (to assist the next person), I tentatively concluded it is much easier (for me anyway) to remove the four 14mm motor mount bracket mounting bolts than it is to remove the one upper nut sandwiched between the pillars of hercules on top.

[tangalora]

To better assist the next person in doing a motor mount R&R in a fraction of the time it took me, here are the forward two 14mm bolts holding the passenger side motor mount bracket onto the engine block.

[tangalora]

For completeness, here are the rearward two 14mm bolts holding the motor mount bracket to the 1990 Q45 engine block.

[91QAZ]

So tangalora, did you successfully get the mounts replaced? Your last couple posts sound like you at least got very close. My mounts need to be replaced and I'd like to pick your brain further if you were indeed successful...

[elwesso]

She has not finished yet... She is in the process of replacing them...

I wonder if there might be a cheater method of doing it, just dropping the cross member a little so you dont have to do all that crap involved..

Tom there is a LOT (emphasis on LOT) of work involved to change hte mounts.. I might not recommend you do it at this time... at 91k they should be OKish... they wont be perfect but theyll be good enough.. my old ones at 130k still provided a smooth enough idle to satisfy most...

[91QAZ]

Wes, You may be right. I think I'll try the trans mount first and see if that makes it satisfactory for now.

[tangalora]

Wes is always right (so far anyway).

I ran a search a long time ago and just ran another for you to see if I could find a step-by-step Q45 motor mount R&R procedure on NICO. I may have missed stuff as there were plenty of hits but none I could find that explain the step-by-step howto (always correct me when I'm wrong):

Infiniti Online Mechanic » Bad Motor Mount Symptomshttp://www.nicoclub.com/zerothread?id=8936 (www.nicoclub.com/zerothread?id=8936)

Infiniti Online Mechanic » Q45 Vibration updatehttp://www.nicoclub.com/zerothread?id=44659 (www.nicoclub.com/zerothread?id=44659)

Infiniti Online Mechanic » 92 q45 timing chain setup helphttp://www.nicoclub.com/zerothread?id=48852 (www.nicoclub.com/zerothread?id=48852)

etc. (always correct me if I'm wrong as I don't wish to give bad advice).

The only method I know is the front engine crossmember method:- Purchase an eight-dollar driver-side front engine slinger & two bolts from Joe - Purchase a two-hundred-dollar engine-support-bar kit from OTC- Remove the air-intake from the air filter to the throttle valve thingey- Follow a ground strap bolted to the driver-side strut to the engine- Bolt front engine slinger to that ground bolt & the threaded boss next to it- Support Q45 engine from the two engine slingers (the rear slinger is stock)- Lift the Q45 as high as you dare & support the frame & transmission- Remove the two front wheels- Remove the black plastic engine undercover- Mark with whiteout (or similar) the lower steering shaft & lower u-joint position- Remove BOTH 12mm bolts on the driver-side steering lower u-joint- Disconnect the TWO steering rack snap electrical connectors - LOOSEN the four 22mm bolts holding steering rack to crossmember- Disconnect all hoses & metal brackets on the crossmember (six 10mm bolts)- Periodically remove grease chunks from your eye with TP & a mirror- Disconnect both torsion bars at the crossmember (four 17mm nuts)- Disconnect both transverse links at the crossmember (two 19mm nuts & bolts)- Remove four 14mm nuts holding motor mounts to the engine crossmember- Temporarily support the crossmember (an extra set of hands will do)- Remove six nuts holding the engine crossmember to the Q45 frame (17mm deep socket required)- Slowly lower the crossmember (it will likely hang on the drivers side)- Disentangle any steering components & hoses holding up the driver side- The two motor mounts should be tantalizingly dangling in your sight- Try to lock a wrench on the 14mm bolt at top of the motor mount- It's bounded on both sides so there is not much room to swivel- Once locked, if you can, spin the motor mount off with a strap wrench - Otherwise, remove the four 14mm bolts on each motormount bracket

DISCLAIMERs:a) I know nothing except what I've read & published on NICO web pages;b) I wrote the above based on a VERY MESSY set of grease-stained notes;c) Therefore I may be wrong in lots of ways (it will take hours to organize).

Please correct where I err as I think I read somewhere Dennis said you can get to the motor mount upper nuts WITHOUT removing the front engine crossmember (but I couldn't find that thread when I looked just now).

[elwesso]

Wes is always right (so far anyway).

Dont say that!

I bet if you were crafty enough you could detatch the motor mounts from the member, and hten hoist the engine up to replace... I bet it could be done...

[91QAZ]

Wow Tangalora, thanks for the play-by-play. I've been trying to diagnose a vibration problem, and was going to jump righti into the driveshaft, but have decided to take the systematic approach and do the following in order, stopping when the problem is fixed: rear transmission mount, engine mounts, center bearing, then driveshaft.

It sounds like the job is very involved, but not impossible. If I do need to go that far, I may try to leave the crossmember intact and jack the engine way up, but it's good to know there is a proven way if that does not work. Thanks again - good post.