Front end shaking hard under acceleration

Post by **jtp** » 09 Mar 2018, 18:29

This was supposed to be the weekend where all the coolant hoses get swapped out so of course the car is going to throw me for a loop.

Just started today: under hard acceleration but eventually under more gradual acceleration too the whole front end shutters. Reading up it seems like the most likely culprits are either:

A) A front axle

B) A failed motor mount causing the engine to rock back and bind up the axles under load.

There is a definite loss of power when the shuttering kicks in. No CEL and plugs and three coils are newish or Id be thinking it’s misfiring.

Questions: I’m quite familiar with checking for play in run of the mill suspension parts like tie rod ends and hubs. I’m not familiar with checking for play in axles. What do I do and what am I looking for?

Post by **abscate** » 10 Mar 2018, 04:41

Does your code reader check pending codes? If you have a bad miss the ECU might not store a P03xx for a while. With a loss of power, get all the coils and plugs out to evaluate

Did you jump start or been jump started recently? That can finish a coil near its end of life

Post by **wizechatmgr** » 10 Mar 2018, 05:42

abscate wrote: ↑10 Mar 2018, 04:41 Does your code reader check pending codes? If you have a bad miss the ECU might not store a P03xx for a while. With a loss of power, get all the coils and plugs out to evaluate

Did you jump start or been jump started recently? That can finish a coil near its end of life

That or a bad/going alternator... I blew all my lights out (headlights and fog lights were on at the time) when mine went.

Also check for low/bad tranny fluid. It being low can cause weird shuddering if it slips. If overfilled it could foam...

Post by **jtp** » 10 Mar 2018, 15:49

Just looked at it and front lower motor mount is trashed. There’s so much movement on the motor when I accelerate or shift gears I should probably do some other motor mounts too.

On the drive to work today everything was basically fine as long as I drive like a little old lady and am real gradual on the throttle and braking.

I’ll get that motor mount in and then take it from there I think.

Post by **sleddriver** » 12 Mar 2018, 12:52

jtp wrote: ↑10 Mar 2018, 15:49 Just looked at it and front lower motor mount is trashed. There’s so much movement on the motor when I accelerate or shift gears I should probably do some other motor mounts too.

Are they original, now 19yrs old? If so, the hydraulic mounts have collapsed allowing the motor to sink down quite a bit. I was amazed at just how far mine dropped when both were replaced. Makes a world of difference when new.

Post by **jtp** » 12 Mar 2018, 19:24

sleddriver wrote: ↑12 Mar 2018, 12:52
jtp wrote: ↑10 Mar 2018, 15:49 Just looked at it and front lower motor mount is trashed. There’s so much movement on the motor when I accelerate or shift gears I should probably do some other motor mounts too.
Are they original, now 19yrs old? If so, the hydraulic mounts have collapsed allowing the motor to sink down quite a bit. I was amazed at just how far mine dropped when both were replaced. Makes a world of difference when new.

The hydraulic mounts are original and I was thinking about this as I’m researching stuff. I haven’t seen a source for the rear hydraulic mount yet, will look harder and it’s probably out there.

There’s also a mount I keep seeing that is apparently unique to the AWD p80s that looks like an angled piece piece of rubber with one really long bolt sticking out. Volvo p/n 9161101 I think. OEM it’s like 100ish. Where does this go on the car?

Post by **j-dawg** » 12 Mar 2018, 19:58

Check your CV joints while you're down there. Give em a wiggle. Play in and out is fine if it's springy but you shouldn't have any radial movement or hear any rattling.

Post by **jtp** » 12 Mar 2018, 22:31

j-dawg wrote: ↑12 Mar 2018, 19:58 Check your CV joints while you're down there. Give em a wiggle. Play in and out is fine if it's springy but you shouldn't have any radial movement or hear any rattling.

Im going to have it on a lift tomorrow for a Rotation and rear diff top off and I’ll check them.

The motor mounts are just so gone. I’m usually working on my car by myself so it wasn’t until I was able to see the engine rock while someone shifted and put it under load that I realized how bad they are.

It’s driving fine as long as I keep things driving miss Daisy level smooth and conservative, and it is noticeably harder to reproduce the shuttering when the car and outside temp is ice cold. Which kind of makes sense as far as the relative stiffness of a cold rubber mount.

It’s intermittently cut off/dimmed the lights when shifting, now it all makes sense with the motor mount issues. Who knows what all is getting stretched when it’s been shifting.

I have figured this out: for AWD P80s there is a single hydraulic motor mount in the front, it’s not available (of course) but you can supposedly use the FWD version so we’ll see. PN 9161101 basically takes the place of the rear hydraulic mount and it is still easy to get.

Im also going to try and use the bushing for the FWD torque arm. I did the torque mount on top of the car a month or so back and the slop in that bushing was bad.

Post by **scot850** » 12 Mar 2018, 22:58

Which front mount are you talking about? The hydraulic mount (the cone shaped one) is the same as the FWD one part # 6801722

The AWD lower torque mount on the other hand is NOT available. The FWD one is different. The bushes are different especially the smaller rear one. Also the rear mount 'arm' with the smaller bush has a different shape. I haven't had time to look further into this, but had planned to try to find poly-bush inserts from a FWD option and seeing if they will fit, especially the rear bush.

Neil.

Post by **jtp** » 13 Mar 2018, 22:29

scot850 wrote: ↑12 Mar 2018, 22:58 Which front mount are you talking about? The hydraulic mount (the cone shaped one) is the same as the FWD one part # 6801722

The AWD lower torque mount on the other hand is NOT available. The FWD one is different. The bushes are different especially the smaller rear one. Also the rear mount 'arm' with the smaller bush has a different shape. I haven't had time to look further into this, but had planned to try to find poly-bush inserts from a FWD option and seeing if they will fit, especially the rear bush.

Neil.

My torque mount looks good. Definitely not original. The rear mount I’m talk By about looks like a V with a huge skinny bolt sticking out of it.

Nobody has documented and explained P80 AWD part issues and availability issues better than you Neil. I have learned so much from reading all your posts since I got this car so thank you. If you’re ever in the Baltimore area I owe you a beer.

I’m not sure if this is an axle issue or a motor mount issue the more I look at my car and read old forum posts. Maybe it’s both, with the failed mounts stressing the RF axle to the point that it’s failing at the inner CV joint.

Bottom line for now is I’ve got the RF mount on the way, the AT-205 I added is still keeping my cam cover dry but I saw today with the car on a lift that the exhaust cam seal leak is back in full force and will soak this new mount if I don’t man up and replace the cam seals.

I can live with the current driveability issues for a little while so I’m going to do the mount and cam seals ASAP.

Then if the issue remains I have found a very well reputed local axle rebuilder called A-1 Driveshaft and I’ll take both front axles to them for rebuilding.