Thud when pressing accelerator

[prwood]

2001 V70 FWD 2.4T.

When I push the accelerator pedal with anything more than a feather touch, I hear and feel a "thud" coming from the front of the car. We've been working on fixing this for a while, and I wanted to get some input. Our primary suspect has been engine mounts based on advice found here and elsewhere.

Early last year we installed a new top engine mount (the one attached to the strut tower crossmember). This seemed to address the issue briefly, but it returned within a few months.

Last month we installed a new torque rod (mounted to the transmission and subframe), as the old one has one bushing that was completely worn out. This didn't solve the issue.

Just yesterday I had paid [user=jonesg] a visit to make use of his VIDA DICE laptop to check out some messages on the DIM, and while there we were comparing notes on the top engine mount. His V70 has the older style round bushing while mine has the newer style square bushing. His top engine mount bushing seemed very solidly connected to the mount and there was little to no play. The bushing on mine moves around quite a bit inside the mount. I also noticed that the strut tower crossmember has a fair amount of play.

I made a video to show the play for this mount on my car:

https://photos.smugmug.com/Cars/2001-Vo ... 73-640.mp4

Is this amount of play in the engine mount normal, and if not, could this be the source of the thud? I am wondering if I should replace this mount again with something of better quality (I am pretty sure this one is an off-brand from eBay)?

Also wondering how much play the crossmember is supposed to allow. I'm assuming it has to allow some but don't know how much.

I appreciate any input. Thanks!

[Georgeandkira]

Both the mount insert and the brace itself seem to have a lot of play in them. If that was my car in that video I'd replace the bushings both ends of brace with the poly ones offered mainly because I've never seen non-poly ones offered.

The top mount's rubber insert in the video seems quite loose. I'd take it off, center the bolt hole and squirt silicone rubber into it and let it dry before reassembly. The main reason for that is because I've always wanted to do that. It interests me and I could always buy a new mount if it didn't work.

The same mount was replaced by the O.O. of my '07 at only 60K. They must not be made well.

NOTE: The same rubber perished in my '99. I bought the poly top from IPD and it shook HORRIBLY.
The Volvo rubber insert part (cylindrical version) was only $16 from dealer.
Those slid out and back in effortlessly.

Did you inspect the front mount by the crank pulley? Remove FR tire, 2 10mm nuts, fold back flap of inner liner to see it. The rubber of that one tears / collapses and you get what might be your noise.

[soulvoid21]

I have this same issue with my MY07 S60 AWD, and my mounts do the same thing. I just replaced the top mount, trans torque mount, and the side mount by the passengers tire. The main bottom mounts are completely solid, but not dry rotted solid. But the top mount and the cross member bushing seem to have a lot of play forward and back.

I used Hutchinson mounts from FCP for all of the ones I replaced. Thinking of replacing the cross member mounts with poly. I also get a clunk from my drivers side that sounds like it's the strut tower. But I just changed the strut assembly with ProPartsSweden quick struts, and didn't have this clunk from the suspension before hand.

I saw your other post about having issues getting the car into alignment. I'm having the same issue, only it's showing dead on with an alignment rack. Nothing is loose, but it always pulls to the right.

Tapping the cross member bolt that connects to the mount by the strut with a rubber mallet creates the same clunk that I hear while driving. You may want to try this and see what it sounds like.

I think the cross member mounts could be the culprit, and wouldn't hurt to replace/upgrade at this age if they seem worn. But would love some input from other members.

[prwood]

I was going to post a new thread, but when I searched for "thud," I found my own old post! Amazingly, the "thud" is still happening two years later. Clearly it's not preventing me from driving the car, but it does make city driving unpleasant since it happens when accelerating from a stop.

Current mileage is 248,426. I've done the following to try and fix the "thud," in order:

* Replaced torque rod
* Replaced upper engine mount
* Replaced right subframe mount
* Replaced lower engine mounts

In other words, I ended up replacing everything shown in this photo (using Hutchinson parts):


Every time I replace one of the mounts, the "thud" seems to get better for a short period of time (from a couple of weeks to a month), but then comes back.

Things I haven't replaced yet which may be possible culprits:

* Suspension strut brace mounts
* Subframe mounts/bushings

Do you think I should try going for one of the above, or pursue other avenues?

[EngineeringBloke]

I recall instructions to have the car in drive (brake on, two people or e-brake?) when tightening the bolts for the upper engine mount so that it is 'pre-stressed'. This is supposed to reduce vibration through the mount and might help you. I am really surprised by the amount of movement in your mount.

[prwood]

I recall instructions to have the car in drive (brake on, two people or e-brake?) when tightening the bolts for the upper engine mount so that it is 'pre-stressed'. This is supposed to reduce vibration through the mount and might help you. I am really surprised by the amount of movement in your mount.

Since my original post, that mount has been replaced, but yes, it did have quite a lot of movement.

I have read about the tightening procedure you mentioned, but only from one place: this 4-year-old blog entry at FCP Euro: https://blog.fcpeuro.com/how-to-replace ... e-mount-99

If the torque arm is not fastened in the correct position, excess vibration may occur. Have an assistant place the car into drive with their foot firmly on the brake before tightening the torque arm pinch bolt. This will pull the engine back into the correct position and locate the bushing properly in the torque arm's adjustable slot. Then, torque appropriately before relieving your assistant of their duties.

However, NO other source I have seen, including VIDA, makes any mention of this procedure. In fact I had asked FCP's customer service about this and they said it was not necessary and that they'd remove it from that blog entry (they haven't).

That being said, I did actually try the procedure once, back in 2017, and I seem to remember it helping... but the engine mount itself was pretty shot at that point, so I ended up replacing it shortly thereafter. That was the point where I double checked with FCP before installing the replacement, and they said it wasn't necessary, so I haven't done it since then.

I guess I could give it another try.

[prwood]

I went out and shot this video today to show the amount of movement in the top engine mount. This motion is coming from me pushing against the front bumper with the engine off, transmission in park, and handbrake set. It's more than I had realized. This is with all five engine mounts replaced within the last two years.

[youtube][/youtube]

[MDK]

Hey all..MDK here. Has anyone considered " sway bar bushings?

[prwood]

Hey all..MDK here. Has anyone considered " sway bar bushings?

I had not considered that. I replaced the sway bar end links about 10,000 miles ago, and while I had the car up I took a look at the bushings. They didn't seem to be in bad shape or loose. I could check them again.

Given the video I posted yesterday, does that seem to be a normal amount of movement for the bushing within the top engine mount?

[93SCMax]

Given the video I posted yesterday, does that seem to be a normal amount of movement for the bushing within the top engine mount?

No...abnormal. Way too much play. I'd bet the bushing/rubber is completely torn from the housing.