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Thud when pressing accelerator

Help, Advice, Owners' Discussion and DIY Tutorials on Volvo's stylish, distinctive P2 platform cars sold as model years 2001-2007 (North American market year designations).

2001 - 2007 V70
2001 - 2004 V70 XC (Cross Country)
2004 - 2007 XC70 (Cross Country)
2001 - 2009 S60
2003 - 2007 S60 R
2004 - 2007 V70 R

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prwood
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Re: Thud when pressing accelerator

Post by prwood »

93SCMax wrote: 01 May 2019, 09:06
prwood wrote: 01 May 2019, 07:27 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.
Is the bushing actually supposed to be bonded to the housing? I ask because I've replaced the top engine mount twice, once with an aftermarket and once with an OE Hutchinson mount, and both times there was at least a small amount of play of the bushing within the housing, but not nearly as much as it's showing now.

I also know there are two designs for this mount; one with a circular bushing and one with a square bushing. The circular was used on 1999-2004 models and the square was used from 2005-onward. The square bushing has flanges that protrude onto the surface of the mount, which I assumed was what was supposed to keep it in line, but also allow it to move.

1999-2004 Style:

Image

2005-onward Style:

Image

The original when I bought the car was circular, which makes sense since it's a 2001 model, but both of the replacements I've installed have been the square type. I had interpreted the bold text in this note on IPD's site to mean that I could use either style mount in my 2001 model (if the dealer could use it as a replacement, so could I...):
Most 2005 and later 5 cylinder models use a square style upper engine mount. If you have the square style mount, you can replace it with either style. Please note that some 1999-2004 models have the square mount installed by dealerships as a replacement.
But now I'm wondering if that's not the case, especially if the dealer made other modifications than just swapping out the mount (e.g. modifications to the torque arm or mounting nut/bolt). In fact, I now see that if I were to go strictly by Volvo's parts site, the specified mount for my chassis and factory code would be the circular type:
Two Types
Two Types
Screen Shot 2019-05-01 at 12.12.30 PM.png (49.18 KiB) Viewed 782 times
My car is factory code 2, chassis number 077411. 30680770 is the square type and 8649597 is the circular type.

I'm wondering if I wouldn't have better luck with the circular type. Or if there are additional modifications I could make that would make the square type work better.
Cars I've owned:
- 2015 to current: 2001 Volvo V70 2.4T; 2004 Honda Odyssey
- 2007 to 2015: 2002 Subaru Legacy L Wagon
- 2003 to 2016: 2001 Toyota Corolla LE
- 1999 to 2003: 1994 Toyota Camry LE

93SCMax
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Post by 93SCMax »

prwood wrote: 01 May 2019, 10:23

Is the bushing actually supposed to be bonded to the housing?

Yes, the bushing is bonded to the housing. When it is torn, there is too much movement and it doesn't meet it's design intent. You are getting the "thud" because there is too much movement of the engine when shifting gears. The bushing softens the torsion when the transmission changes gears. This is also why the solid poly mounts drive vibration into the steering wheel...you feel the vibration of the engine. I'm pretty confident that your rubber bushing is shot and not attached to the housing.

Unbolt it and see.

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prwood
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Post by prwood »

I did an exam of the upper engine mount last night. The bushing is definitely loose within the mount, but I don't see any clear evidence that it was ever bonded. Not sure if I got a defective part, or if the bonding is such that it was broken cleanly and easily. I posted a video of my exam here:

[youtube][/youtube]

The part I examined is "Volvo Torque Rod Mount - Hutchinson 30680770", ordered from FCP Euro in October 2017 and placed into service at ~230,000 miles. Current mileage is ~248,000 miles, for a total of 18,000 miles of wear.

The next question is, if this was originally bonded, how did it become un-bonded? Defect, chemical contamination, out-of-spec mechanical stresses? If I replace the part, how do I prevent it from happening again in less than 18,000 miles?

I ran through and made a quick timeline of the engine mounts I've replaced and when I replaced them. Not sure if this could give any clues as to why the upper mount failed so quickly.

Volvo Engine Mounts
  • Hutchinson 30680750 (lower transmission torque rod); installed 7/2017 @ 213,415 miles
  • Hutchinson 30680770 (upper engine mount); installed 10/2017 @ 229,173 miles
  • Hutchinson 30748811 (right side engine mount); installed 5/2018 @ 232,651 miles
  • Hutchinson 30778951 (front and rear hydraulic mounts); installed 10/2018 @ 242,035 miles
Cars I've owned:
- 2015 to current: 2001 Volvo V70 2.4T; 2004 Honda Odyssey
- 2007 to 2015: 2002 Subaru Legacy L Wagon
- 2003 to 2016: 2001 Toyota Corolla LE
- 1999 to 2003: 1994 Toyota Camry LE

93SCMax
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Post by 93SCMax »

Good video. Contact FCP Euro and share your video. They have lifetime warranty replacement.

The original upper engine mount (in 2001) was the circular version with rubber bonded to the housing. Everyone has experienced at least one failure of their original mount. The square version was a replacement (improvement?) around 2004/2005. I can't believe the rubber floats around in the housing...it has to be attached. I now have a square version on my 2001 T5. I have a third of the movement/play that you have. My car is a 5 speed and the upper mount was replaced about 40k miles ago, so they can last a decent length of time.

I've also submitted a question to IPD concerning whether the square Hutchinson mount has the rubber bonded to the housing. I'll share their response when I get it.

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prwood
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Post by prwood »

93SCMax wrote: 02 May 2019, 11:44 Good video. Contact FCP Euro and share your video. They have lifetime warranty replacement.

The original upper engine mount (in 2001) was the circular version with rubber bonded to the housing. Everyone has experienced at least one failure of their original mount. The square version was a replacement (improvement?) around 2004/2005. I can't believe the rubber floats around in the housing...it has to be attached. I now have a square version on my 2001 T5. I have a third of the movement/play that you have. My car is a 5 speed and the upper mount was replaced about 40k miles ago, so they can last a decent length of time.

I've also submitted a question to IPD concerning whether the square Hutchinson mount has the rubber bonded to the housing. I'll share their response when I get it.
I had actually asked this question of FCP via email back in 2017:
I'm wondering how much play is normal with the bushing inside the
mount? On my car it seems like the bushing has a lot of room to
move around. Just trying to determine if it needs to be replaced.
Their response was:
Our products manger says they're designed to have a small amount of play, but if it's excessive, replace it.
I could contact them again and this time send a link to the video to see if they can comment.
Cars I've owned:
- 2015 to current: 2001 Volvo V70 2.4T; 2004 Honda Odyssey
- 2007 to 2015: 2002 Subaru Legacy L Wagon
- 2003 to 2016: 2001 Toyota Corolla LE
- 1999 to 2003: 1994 Toyota Camry LE

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Post by DrDan »

93SCMax wrote: 02 May 2019, 11:44
The square version was a replacement (improvement?) around 2004/2005.
I'm not convinced it's an improvement. With the circular mount you can replace just the bushing, which is quite a bit cheaper. Tools needed are just a saw and a vice.

93SCMax
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Post by 93SCMax »

I don't disagree. I think they had so many failures with the original circular version, that they needed to do something different. I personally don't like the square mount.

Agreed, that with the original it was easy to replace just the bushing...hence the poly filled that became available. Only issue with the poly insert is increased vibration to the steering wheel. That's what you get when you have a stiffer mount. The square mount has more play, and prwoods mount has so much play that it isn't doing it's job.

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DeadEric
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Post by DeadEric »

I would think, only replacing one mount at a time would over stress the replaced mount causing early failure. Ie clunk goes away for a month then returns.

The break stand tightening procedure doesn't make any sense to me as you want bushings tight in their resting state so you don't stress them constantly.

While the play does look excessive from the video, I'd be interested in seeing movement of the engine while running, brakes held firm, shifting from reverse to drive, then drive with a bit of gas.

Does that produce the clunk? What exactly do you need to do to make it clunk? Have you had someone listen and feel for what is clunking while it happens? I'd hate for you to be chasing a clunk and have it be something else than where you're looking.

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prwood
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Post by prwood »

I just got a reply from FCP Euro. According to them, the amount of movement seen in both videos is normal:
Based on the videos it seems normal. The updated design moves more than the original which would explain the movement!
So, if this is normal, then it seems like I'll need to do some further diagnosis as DeadEric suggested to find out what the clunk is actually coming from.
Cars I've owned:
- 2015 to current: 2001 Volvo V70 2.4T; 2004 Honda Odyssey
- 2007 to 2015: 2002 Subaru Legacy L Wagon
- 2003 to 2016: 2001 Toyota Corolla LE
- 1999 to 2003: 1994 Toyota Camry LE

93SCMax
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Joined: 11 February 2012
Year and Model: 2001 V70 T5 mt
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Post by 93SCMax »

I respectfully disagree with FCP Euro. That much movement is not normal. I even have the square version, and mine doesn't move anywhere near that much. You talked to someone who knows nothing about an engine mount design and is basing their opinion on other videos. I'd love to see the videos they made their determination on.

Also, please check your front lower mount, as it will impact how much the upper mount moves.

Why would the original design be circular and bonded to the housing (practically solid), and the replacement loose and bouncing around in the housing? Makes no design sense. You are getting a "clunk" because the engine in moving excessively during acceleration, deceleration, and when transmission gears are changing. You won't get rid of the clunk until the upper mount movement is decreased or eliminated.

Do yourself a favor to save time and money. Order another upper mount from FCP Euro. When it arrives, take a video of both new and old mount, highlight the excessive play on the old one. I'll bet there is minimal play on the new one. Install the new one, send the old one back to FCP Euro for a refund (defective so apply lifetime warranty.) You get refunded, and the best part will be that your clunk is gone.

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