Vibration at idle (and a little above)

Maybe your engine has more compression now with the new pistons and rings, so it generates more power and the vibration is more violent than it was before.

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You know, someone else mentioned that too. I thought it sounded far-fetched, but the valves have nearly 200k on them and the pistons are brand new. I’ve read of others who had their pistons replaced per the Toyota TSB (not a complete rebuild) complain about the engine running differently too. I don’t remember mention of vibration, rather a lot of “louder” or “sounds like a diesel.” I’ll do a vacuum test and report back.

Were all the pistons replaced?
If not, is there a chance the new ones have a different weight than the previous pistons?

I too am suspect that something isn’t right with the balance shafts, but I’m trying to think of other possibilities.

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Yes all 4 Pistons were replaced. If only I had a lift the balance shaft job wouldn’t be bad at all. I just dread having to lie on my back for a couple hours to do it lol

You have stated that the one spark plug has a white tip as compared to the others. That could be caused by any one of a number of reasons.

Why not just replace that plug and see what happens. If the problem goes away then it needs to be figured out what is causing that tip to become white.
Keep in mind that it is entirely possible to have a plug issue to some degree without triggering the CEL or setting a DTC.

Reason I mentioned a vacuum gauge test is in the event that the white tip is caused by an air leak around the intake or who knows where else; and an intake leak can cause a rough idle and off idle situation. Not so much at elevated RPMs. Best of luck.

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Sounds like a head gasket problem though I did not read all the previous posts.

Here are the post-rebuild plugs after 10k miles.

The crusty one:

Vacuum test: Steady 21 psi at idle. Gauge was twitching and shaking between 20 and 22 psi like crazy from the vibration, but the middle of the blur was right at 21 psi. The engine shakes quite a lot below 700 rpm too apparently, I just can’t feel it in the car. I’m thinking the vibration isn’t rpm dependent, I just feel it the most around 900.

I still can’t shake that brief moment when the car was perfectly smooth right after I installed the new passenger side mount the first time. I’ve replaced that mount 3 more times since and it barely made any difference. It’s possible my engine being slightly crooked and/or the excessive vibration from misaligned balance shafts are causing that mount to fail quickly or even immediately. The mount in question is different from the others in that it is fluid and/or air-filled and the the other three mounts are just rubber and metal. I can’t think of anything else to rule out, so I suppose I’ll check the balance shafts. It will be extremely awkward and maybe impossible to do from underneath while lying on the ground, but I have to try. The vibration is that bad. I’ve ridden in/driven several cars with 4 cylinder engines (including two Toyotas I’ve owned in the past) that were smooth, quiet, and solid-never one that was janky like a shorted out massage chair. Pre-rebuild, the car was a dream to drive.

Sounds like it may be a couple of different problems bunching up on you making it difficult to diagnose. I’m going to throw my two cents in and add the VVT into the pile as a possible maybe.

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Your brother in law worked on car and not you? Why? Skills? Time? Work space? How are you going to inspect balance shafts?

A twitching vacuum gauge needle means ignition miss, valve spring or valve problem, and things of that nature.

That white tipped plug is absolutely horrible at 10k miles so there is something going on in that cylinder. Air leak, valve issue, or something along that line.
Is there any coolant loss?

With the plugs out I know that I would run a compression test; just to make 100% sure that there is not a serious mechanical issue lurking and which could make anything else a moot point.


He replaced the pistons and catalytic converter for me. He had access to a shop with a lift and an old beater car to loan me while he worked on it. He also picked the car out for me and assured me it was a good car even though I told him it was an oil burner so that may be part of it too.
The balance shafts are in a housing right above the oil pan. Pull the pan off, pull the oil pickup, and there’s a “cover” held on by 8 bolts that encases the balance shafts. Pop it off and the shafts will fall right out since they are just sitting on a gear and not chain-driven. My hunch is that the shafts aren’t timed properly because it’s a common mistake with this engine for them to be 180 degrees out and still look right with the timing marks. My symptoms strongly suggest a balance issue due to the fast, intense nature of the vibration (shafts spin at double the rpm) that is present in specific rpm ranges and is not affected by load.

Good to know. I thought the gauge was just twitching from the vibration, but yeah it was averaging 21 psi (good) but quickly bouncing from 19-22 like a blur. Pretty sure there is no coolant loss. The overflow tank needed to be topped of a couple of ounces but I think it’s just because it got colder here and I had removed the tank a few times to replace a mount.The radiator is always full when I look.
I did a compression test too about a month ago. The engine had been off for about 2 hours, so not hot or cold. The readings were (cyl 1-4) ~185, 175, 175, <175.
The vibration is very bad on cold start as it idles down. As rpms slowly decrease, the vibration is most intense as it comes down around 1000 and is loud and resonant like a sub-woofer.
Come to think of it, the vibration seems more noticeable when decelerating than just holding the rpms in the trouble range. That’s how I demonstrate it to other people-I rev the engine to above 1500 and point it out as the rpms go down. If that means anything to you, I’d love to hear about it. Thanks :slight_smile:

Sorry to be the bearer of bad news, but I do not think the balance shafts being “out of time” is the cause of your problem. I do not see this causing a rough idle, which smooths out at higher RPMs.

I think there is a problem with one cylinder, or perhaps two adjacent cylinders, which will show up on a compression test and leak-down test. I had this exact problem on my car, and it ended up being a head gasket leak between two adjacent cylinders.

Good call. It’s naive to assume it’s just one thing.

Hi Jon:
After you pull off the oil pan pickup, aren’t the timing marks visible on the outside of the balance shafts? If so, then you wouldn’t need to remove the 8-bolt cover that encases the balance shafts.

I had a balance shaft off one tooth once on a different engine. It vibrated at low rpms and seemed to smooth out as the rpms increased.

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Yes, the 8 bolt cover is what meant by “case.” Wow, one tooth? Was it a Toyota engine with the gear-driven shafts?

It was a Hyundai 4-cyl engine.

On a related note, given your vacuum gauge fluctuated a bit, if it were me, I may first consider the tips OK4550 provided.

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Thanks. I should reiterate that these symptoms are almost certainly related to the rebuild since the car was smooth prior and only vibrated a little under load due to worn mounts.
My BIL did tell me he drove the car very hard after the rebuild. He said he got it up to 100 mph. I’m not sure why. It was also about a quart low on oil when he gave it back to me. That was troubling.