Question about 98 2.3L vacuum engine mount
 

Our recent addition to our family - 98 Honda Accord LX 2.3L A/T has a pair of engine mounts that need replacing, and I'll be doing it DIY as $624 is something I'm willing to take care of myself.

Question being: What exactly does the rear vacuum engine mount affect on this vehicle? I've worked on MANY vehicles over the years and never heard of a vacuum engine mount. I have a few trans related issues, and I'm wondering if the issues are related. Also, are there any other parts I need to be replacing or servicing with this mount?

I will be buying a factory service manual set for this vehicle, and I'm considering buying it on CD. Are these recommended and an actual Honda service manual set? It would be great to be able to print off the needed pages and get them dirty while working. I've always been slowed down cleaning my hands while handling service manual hard copies as I needed to.

Thanks in advance for your time!

1. The engine mount control system comes on Accords with automatic transmissions. It is used to control excessive vibration at low rpms (e.g. idle).

At low rpms, the PCM sends a ground signal (-) to the engine mount control solenoid valve, which opens the valve. There is one vacuum hose from the intake manifold and another vacuum hose that goes to the rear engine mount.

Aftermarket has both solid rear mounts and vacuum assisted rear mounts for replacement.

2. The factory service manual and factory electrical troubleshooting manual are good sets. The electrical troubleshooting manual is not much narratives; so, you need to know how to read circuit diagrams to get more benefits from the manual.

"automanualsource dot com" is a pretty good place to get a manual IMHO....last I looked it was ~$22 for a download and ~$27 for a CD shipped - I had to do the CD as my internet/computer would not download that big of a file....so I paid the ~$22 for the download and then when I couldn't because of internet/computer their customer service was great in helping me out.

Anyway, the rear mount is "vac controlled" - High level, when in gear the PCM will tell the solenoid to open and apply vac to the mount - this helps the mount "dampen" the load.

Not sure exactly the issues you are having - are there stored codes, note some codes do not "trip" the MIL/CEL. If the mounts are bad....well they are bad, don't worry about the vac part. There are tests you can do on the solenoid "system" for the rear vac controlled mount....test the solenoid, apply vac dirstly to the mount ect......testing will be ~ section 4, page 56 (each manual is a bit different).

EDIT: wow I'm way slow at typing.....when I hit send I now see RB posted....my bad.

Thanks for the info and help. I'll be hitting up your source for a CD copy, and luckily I've been an electrician and electrical tech for years - so the wiring diagrams won't be an issue. I "cut my teeth" as a mechanic working on dashboards and instrumentation back in the day - it paid great until my lower back starting throwing fits.

That said, I'll be going with an OEM vacuum mount, and testing the system per the manual. Thanks again for the input on this mounting system, I know Honda rarely designs something "just because they wanted to", and i was wondering if it was causing errant shifts due to being broken. Looks like I'll have to baby it for now, replace the mounts, and get further into it.

The issues I'm seeing are rough engagement into Drive (jerks), obviously less severe at low idle than cold idle (I've been letting her warm up whenever possible before driving), it will only downshift into 1st at a very low speed (2-3mph I would guess, and it takes a few seconds at that speed - which is concerning) causing a jerk, and it's delayed when slowing to make a turn, then occasionally gets "confused" and shudders in the shift (likely trying to ride it out on the clutch pack). I'm trying to "baby" the vehicle until I can get the rear mount sourced and installed, which I'll obviously need the service manual for. I've never seen an engine mount like this one before.... and I'm not willing to pay the local trans shop $472 to install a new OEM mount, knowing that I may need to spend some money with them soon to tear into it. After the mount, I'll be having them flush and completely replace the fluid, and see where that takes me. The front mount is cracking (spoking out), but not the worst I've seen, and not broken (yet) so it's further down the list. There are no stored codes regarding the trans, but it has a cat code showing - I may get to that once I get everything else taken care of.

And here's to hoping our "new addition" doesn't need a torque convertor and a clutch pack!

I was able to get that manual ordered on download+CD for $24 this afternoon, and reviewed the download copy. Although it doesn't discuss replacing the rear mount directly, it covers everything but attaching it to the chassis in the engine installation section. I'll just use standard torque specs per bolt size for the chassis bolts, as they are steel to steel. I'm still scratching my head as to the 4 hours the books call for that mount by itself, and I'm sure I'll find out firsthand just how much fun it is to change on the floor with a floor jack, a wood block, and jack stands.

One question, as odd as it may be - the manual flagged some bolts as "replace" - for example the "center pin" bolt in the front engine mount (and not others). Are there actual torque stressed ("stretch") bolts on these mounts that warrant replacing after use? I've run across cylinder head bolts that were disposable in the past, but nothing in this size, application and torque range.

They are not "torque to yield" and are generally reused. I suspect the threads are purposedly slightly interference threads as are some seat belt tie-down bolts to prevent accidental loosening. When installed/removed some of the interference is lost, hence the replacement warning. Use lock-tite, if you think it's an issue. I did not on mine.

There's a youtube video for 94-97 Accord which should be similar to your Accord.


good luck

Thanks for the info on the bolts, plenty of red and blue lock tite in my toolbox, and the video should help a ton!