iansanderson

I have been doing some work on my (new to me) 99 2.3 CL. I did a bunch of tune-up items, and wanted to rid this vibration at idle.

Problem: Vibration at idle

Solution: Failed engine mount(s)

The typical culprit for vibration at idle is a faulty front engine mount. (Your Acura or a Honda dealer should stock these as they fail quite often on 94-97 Accords and 97-99 CL 4 Cyl.) When the front mount has failed, it typically splits/cracks and allows for too much longitudinal engine movement.

Inspect the mount for cracks/tears in the rubber with a flashlight and/or mirror. Sometimes, cracks can be hard to find, but front mounts usually fail or become brittle after 100K miles.

Unfortunately, if the front mount wasn't replaced soon after initial failure, the additional movement of the engine could have damaged one or more of the other mounts. If this how-to doesn't cure your issue completely, you may need to replace your rear engine mount too. On AT models, the rear mount uses a vacuum-actuated fluid filled mount system that can also fail, so it should be checked before replacing any other mounts.

Here are the parts/tools you will need:

1 - Front engine mount Part No. 50840-SV4-980 (AT) or 50840-SV4-000 (MT) $41.00 Retail / $33.00 Wholesale

17 and 14 mm sockets

Socket wrench

Optional, but recommended:

1 - 12X95 Flange bolt Part No. 90176-SM4-010

Various extensions and a universal joint

Breaker bar

Note: You do not need a floor jack to perform this procedure. The engine does not actively rest on the front mount unless your car was in an accident or has been damaged underneath in some way.






First, let's locate the mount! It is situated between the engine and radiator bolted to the front cross member.









Allow the engine to cool if it has been running. You will be working around components that will burn you. That little hand that says HOT means business!




If you are impatient, turn the key to ON but do not start the engine. Adjust the blower to LOW, AC-ON to allow the cooling fans to run for a 10-15 minutes. They really move a lot of air, so it will cool the engine down quickly.




Now, (this is important) apply the parking brake fully then shift the car to Neutral. This is necessary to take all load off the engine mounts.




Now, remove the top 3 14mm bolts from the engine mount bracket.




Then remove the 17mm throughbolt from the mount. The nut is welded to the bracket on the opposite side.




Remove the mount bracket.




To make your life a lot easier, I recommend finding every extension bar you have in your toolbox. This allows you to turn the wrench above the radiator.




As you can see, the wrench has risen to a comfortable height.




My bolts were somewhat corroded, so a breaker bar was necessary.




Now, remove the mount.






As you can see, the old mount was definitely bad. The rubber has completely broken off from the attachment point.




Old Mount



Old Mount



New mount.

Note: Those are not cracks in the mount, it is cracked paint overspray from manufacturing. You can easily chip it off with your fingernail if it bothers you, but it has no effect on the mount's operation.




Now, install the new mount to the cross member and hand-thread the 3 bolts.

Important: Be sure to follow the order of the remaining instructions as they are written, or you will make this job 1000X more difficult.




Now, torque the 3 mount bolts each to 69 lb-ft. If you do not have a torque wrench, tighten them using a medium-high force, but do not overtighten or use the breaker bar for leverage.




Install the engine mount bracket over the mount and hand-thread the bolts into the engine block, but do not allow them to seat completely just yet. The bolt with the large-washer goes on the bottom.





Now, install the engine mount throughbolt and hand-thread it until the threads engage, then use a wrench to continue threading it until you see the bottom of the bolt peek out on the other side, but do not tighten it yet




Now, tighten the 3 bracket bolts to the engine block to 28 lb-ft. If you do not have a torque wrench, do not, under any circumstances overtighten these bolts. Tighten them snugly using light-medium force. The engine block is aluminum and the threads can be easily stripped.




Finally, tighten the engine mount throughbolt to 47 lb-ft.

Note: This is a self-locking bolt. The Acura service manual instructs you to replace this bolt whenever it is removed.




All done!




I recommend performing the idle learn procedure after performing this repair to ensure your idle is set correctly in the ECU. To do this, turn the ignition off and remove the 7.5 Amp
"Back-up" fuse from the underhood fuse box for 15-20 seconds then reinsert it. Make sure your climate control is set to OFF and headlights/defogger/radio is off and start the car. Allow it to idle until the cooling fans turn on twice. Then turn the car off.

After changing the bad mount and performing the idle learn procedure, my car is vibration free now!

bRunCL

iTrader: (1)

nice write up! Mods will prob move this thread to the DIY section.

WineRed2.2CL

sweet deal. Thanks for the pics.

CLMike98

That is Awsome*** My Cl vibrates at idle I did a 400 tune up including the front motor mount about two weeks ago but it didn't help. My battery died a while back bet that screwed up the idle. I didn't know about the Idle Learn Procedure Thanks Alot I'll try it tomorrow and see what happens.

One Q- If it don't help Can the back engine mount you speak of cause a vaccume leak and make it vibrate the dash when at idle? (AT)

iansanderson

Typically, if the front mount was let go for too long, it will ruin the rear mount from the added engine movement. The rear mount is the next place to look when fixing vibration at idle. You should also take a look at your transmission mount, just to make sure it is in good shape.

The rear mount uses a vacuum-actuated system on the AT. Around 700 RPM, the ECU activates a solenoid (located on your firewall) that begins drawing vacuum pressure from the manifold. It in turn pulls this little lever on the rear mount which directs fluid through a special chamber that is supposed to reduce vibration.

If any part of this system is bad, or the rubber itself is bad, it can vibrate everything like your dash and steering wheel. So, I would look at replacing it. It's not very easy and requires a lot of parts removal and wiggling around to get it out. But there's a 90% chance it will cure the problem, if the front mount didn't. Just make sure you are buying one for an AT, not an MT.

CLMike98

Thanks alot! Finally someone who understands the manualls LOL. I checked for vaccume leaks before but would never thought the back mount was vacuum-actuated thats crazy!

Also may be alittle off topic but what do you know about tranny interchanges? I got a 95 vtec accord tranny and want to replace mine (sometimes slams into 1st on downshift at a full stop, the accords don't do that but CL tranny's @ only 120K) they say its diff but bolt ups "look" the same and i got the TCM 4 it but am unsure if it will all fit together and work without changing the harness or making my engine light come on cause it came out a 95 but my 95v6 Accord is obd2 idk about the 4cly)

iansanderson

Is your CL a 4cyl? If it is, AFAIK a 95 Honda Auto will work in a 97-99. You may have to swap out some sensors if its coming from OBDI to OBDII, but that's easy work while the trans. is removed. I am not 100% sure, but do a search just to be 100% sure. There is no need to swap out the TCM from the 95. Yours will work fine.

azian_rain

You can also try window weld on the mount. They sell it at any hardware store and it will fix the broken mount while making it stiffer, but be aware that it will also make it a lot stiffer than it origanally was.

Yurhomieblaze

it'll be fine, i have a 95 accord trans in mine, it ran fine of the stock cl ecu, all harness connections where the same, no modifing plug and play

on my busted front mount i got a energy suspension insert, fixed.

MaxAlien

Thanks for an excellent write-up, it was a big help today as everything went smoothly. The only thing I would add, or modify, is to loosen the 17mm throughbolt before removing the top three 14mm bolts. If both rubber "stems" are broken inside the mount, like they were in my case, that makes it hard to loosen the throughbolt if the mount bracket is not held in place by the top three bolts.

Thanks again!

1997 Acura CL 2.2 Premium

This is great, my car idles like a bit@# and I could never figure out why. Nice job.

I am Hydrogen

My 98 2.3CL also has a rough idle in D4; although when I shift into Neutral the vibration lessens or goes away. I checked and my front mount is cracked in the same way as the photo above. It's been idling rough for about 8-9 months.

Before I replace the front, I want to check the sides and the rear. Can anyone instruct where to look? If the others are similarly damaged, would it be useless to replace the front?

I'm also wondering why the vibration would go away when it's in neutral?

iansanderson

You can make a visual check of the rear and transmission mount, but the left side engine mount is liquid filled and not very easy to determine if it's bad.

The rear engine mount usually fails if you have been driving for a long time with a bad front mount. This is due to the added movement of the drivetrain bc of the front mount not doing its part to support.

The reason the car does not vibrate when its in neutral is because the engine is in "neutral" position. When you put the car in drive, the engine turns toward the rear of the car in response to the torque produced and transmitted to the wheels. When a mount is bad, it allows for too much flex and then transmits vibrations to the sub-frame under the car. If you keep your hood up and put the car in Drive or Reverse, you can watch the engine move back and forth and understand why there is vibration. Bad mounts allow the engine to flex an extreme amount. With new or good mounts, the engine will still move some, but much less.

I am Hydrogen

Thanks for the quick reply, iansanderson. I'm going to go ahead today and replace the front mount, and hopefully that will alleviate some of the vibration. I'm hoping I didn't let it go too long that it damaged the other mounts. Thanks for the great write-up, that will be a big help today.

Since new mounts stabilize the engine, does that improve shifting at all, or no effect?

iansanderson

The new front mount should definitely improve it in your case. If you still have vibration, the rear mount is next in line. (I am saving that write-up for a warmer day) It is unlikely the left side or transmission mounts are damaged. They are the last to go.

Keep in mind, the rear mount is a vacuum-actuated system. You should make a visual inspection of that mount system. You might need a small inspection mirror to see it, but there is a little actuating rod attached to the left side of the mount that should move whenever the car goes to and from idle. If that has stopped working, it will cause vibration issues.

You may notice a slight improvement in shift quality such as firmer shifts.

I am Hydrogen

I just replaced the front mount, and there doesn't appear to be a real difference in vibration. Visually, I can see that a lot of the vibration is happening toward the rear, so I'm guessing my rear mount is also shot. I'm not sure exactly where it's located so I can't tell if it's broken.

I tried the ECU idle learn procedure, but since its in the 20s here, the cooling fans wouldn't turn on after about 10 minutes of idling. I'll have to save it for a warmer day.

Anyway, your write-up was very helpful and I look forward to seeing your walk-through for the rear mount.

juvenil3101

besides the engine mount theres a balance shaft belt around the timing belt..usually they tell you that you dont have to replace it..but that can cause rough idle too..

iansanderson

that sucks.. sometimes if the front mount was let go too long, the rear mount becomes over-stressed. I am devising a rear-mount write-up as we speak. I will be tackling it as soon as the weather breaks. It looks nasty and very involved. I know on my 93 accord, I removed it from the bottom.. and it was pure hell (no lift.. laying on my back) I don't think it will be as easy on the 99.

mbtech

so how hard is it to replace the balance shaft belt?

bRunCL

iTrader: (1)

just completed this job. if you follow the steps in this writeup exactly is it 100% diy-able. part was $60 from the dealer and reused my old thru-bolt. I would definitely suggest checking your front motor mount to see if its broken (until a few days ago i didn't know you could simply visually inspect it). Mine was worse than the OPs, it was completely broken into two pieces even though i didnt have any significant vibration at idle.

Gigolo

im not a mechanic but this is well put together
wish u added arrows to the location of the spots though...

i actually need to have this done as well...
how much is a good price for this work??
checking before i hear some crazy amount from a mechanic

thanx

Fredzep

Just a great write up! Even after I replaced the front mount today ($9 @ Rock Auto vs. $35 at Advanced), I still have the vibration issue. INot quite as bad as prior, so I am thinking the rear mount is the culprit as I drove many miles with the vibration. I can't seem to find any DIY's on the Rear Mount Repalcment. Are there any good writeups out there?