'86 Accord vibrates aggressively when idling in Drive or Reverse (video)

[Shervin]

I'm really hoping this isn't a carburetor problem or something else tricky, but my '86 Accord LX shivers/shudders/vibrates/rattles aggressively whenever I put it into Drive. It has Parkinson's... or should I say "Drivinson's" since it only happens when the car is in gear. Maybe "Carkinson's". Ugh, sorry. Moving on...

Here's how a cold start usually goes:

I turn the key to the accessory position. I slowly give it four pumps of gas. I turn the key and start it. Sounds fine, like a normal older carbureted engine.

After waiting a couple of minutes for it to warm up, I put the car in Reverse (where it starts to shudder), then Neutral (the shuddering stops), then into Drive (where the really bad shuddering begins). The whole interior noticeably vibrates, unless I accelerate.

The shuddering comes back as soon as I come to a stop again or am sitting in traffic. And if I turn on the headlights and/or the A/C, the shuddering gets even worse. This happens regardless of whether the engine is cold or warm. And I live in California, so I know the car isn't shaking from the cold; it did this in September when I bought it, and it's still doing it now in March.

Here's a very short video: https://youtube.com/shorts/Cncw3Kadh10

I also took a picture of the tachometer at idle to show you where the needle sits (attached below).

Not only is this very annoying and makes for an unpleasant driving experience, but I'm also pretty sure it can't be good for the car. All that shaking probably puts a lot of unnecessary stress on the car and all its parts, and eventually something's going to break or come loose. The bezel of the clock on the dash has fallen off a few of times because of this, which is obviously an easy fix, but could be a sign of things to come.

The car has 125k miles, has always been garaged, and was with the original 95-year-old owner until I bought it from her last year. Since then, I have had all of the following done as preventative maintenance and care:

- New timing belt and tensioner
- New water pump
- New front engine mount
- New camshaft oil seal
- New crankshaft front seal
- New coolant
- New engine oil
- New oil filter
- New ceramic front brake pads and rotors
- New valve cover gasket and new grommets
- New rear sway bar and bushings
- New tires
- New headlights

None of these things have fixed the problem (some more obvious than others). Someone suggested I have the rear engine mount replaced too (I already have the genuine part from Honda), but I'm not sure if that will fix it. I'm hoping one of you has encountered this problem before and knows what to do.

Thanks in advance.

[Oldblueaccord]

I'm really hoping this isn't a carburetor problem or something else tricky, but my '86 Accord LX shivers/shudders/vibrates/rattles aggressively whenever I put it into Drive. It has Parkinson's... or should I say "Drivinson's" since it only happens when the car is in gear. Maybe "Carkinson's". Ugh, sorry. Moving on...

Here's how a cold start usually goes:

I turn the key to the accessory position. I slowly give it four pumps of gas. I turn the key and start it. Sounds fine, like a normal older carbureted engine.

After waiting a couple of minutes for it to warm up, I put the car in Reverse (where it starts to shudder), then Neutral (the shuddering stops), then into Drive (where the really bad shuddering begins). The whole interior noticeably vibrates, unless I accelerate.

The shuddering comes back as soon as I come to a stop again or am sitting in traffic. And if I turn on the headlights and/or the A/C, the shuddering gets even worse. This happens regardless of whether the engine is cold or warm. And I live in California, so I know the car isn't shaking from the cold; it did this in September when I bought it, and it's still doing it now in March.

Here's a very short video: https://youtube.com/shorts/Cncw3Kadh10

I also took a picture of the tachometer at idle to show you where the needle sits (attached below).

Not only is this very annoying and makes for an unpleasant driving experience, but I'm also pretty sure it can't be good for the car. All that shaking probably puts a lot of unnecessary stress on the car and all its parts, and eventually something's going to break or come loose. The bezel of the clock on the dash has fallen off a few of times because of this, which is obviously an easy fix, but could be a sign of things to come.

The car has 125k miles, has always been garaged, and was with the original 95-year-old owner until I bought it from her last year. Since then, I have had all of the following done as preventative maintenance and care:

- New timing belt and tensioner
- New water pump
- New front engine mount
- New camshaft oil seal
- New crankshaft front seal
- New coolant
- New engine oil
- New oil filter
- New ceramic front brake pads and rotors
- New valve cover gasket and new grommets
- New rear sway bar and bushings
- New tires
- New headlights

None of these things have fixed the problem (some more obvious than others). Someone suggested I have the rear engine mount replaced too (I already have the genuine part from Honda), but I'm not sure if that will fix it. I'm hoping one of you has encountered this problem before and knows what to do.

Thanks in advance.

All things being equal I would bump the idle up to about 1000 on your tach.

[RI86DX]

Rearmost motor mount. Absolute whore to do on non Weber swapped (or just non vac deleted with the stock carb) third gens. I swear I remember reading carbed accords are supposed to idle at a hair below 1k when warmed up.

[Shervin]

Do these motors only have a front and rear mount, or left and right too?

[RI86DX]

Four IIRC. Front, rear (worst to replace) left and right.

[Shervin]

Are there any shops/mechanics in the San Francisco Bay Area you can recommend who would know what they're doing when tackling a job like this?

I don't want to take it to just any young tech; I want it to be someone who is knowledgable about these cars. My longtime mechanic who did all the recent work fits that description, but even he said it's too risky and labor-intensive for him to take on. The Medusa spaghetti of vacuum hoses is his biggest fear.

[RI86DX]

Yeah do not let any mechanic who isn't older and used to working on pre OBDII cars touch it. One of many ways clean pre '96 stuff ends up in junkyards is letting the average joke of a modern "mechanic" touch it (they sabotage the car or just come up with a laundry list of lies and tell you to junk it) besides scumbag insurance companies, and scumbag "we buy cars"/donation companies.
I can't recommend any shops, I'm a very long way from there

[Shervin]

Fully agreed about the tragic owner-to-junkyard pipeline for these older cars. A few months ago, I saw an '87 Accord LX Sedan at Pick-N-Pull in San Jose in Sonic Blue Metallic (a one-year-only color for the Sedan), which is probably my favorite color on these. The car had 184k miles, but looked like it had 84k. Despite how dirty it was, I could tell it was a total diamond in the rough that had simply fallen into the wrong hands over the past few years. It didn't need to die an early death. Suffice to say, you won't need to worry about the same thing happening with my car.

[ShiRen]

There is no trans side engine mount, torque load is handled by the dog bone on top. Just front/rear and engine side

What is so hard about changing this mount? I haven't done it, but common sense would have me get at it from under the car with an engine support beam lifting it a few inches, just so the manifold doesn't have to come off

[Shervin]

Update: I had my mechanic replace the rear engine mount with a new genuine Honda one. The vibration is much, much less, but it's still there a little bit. I'm going to live with it unless it gets worse. At least it doesn't feel like I'm in an earthquake every time I put it into gear. It mostly drives like a regular car, except one that's almost 40 years old.