Ls Engine mounts

Has anyone had issues with motor mounts breaking or coming loose? What type of symptoms might occur? I have come across driveability issues where the vehicle will vibrate the steering wheel, and even firewall. One part is the ps pump -an hose clanging against the frame, another is the pass steel control arm contacts the exhaust header flange. These just start to get worse as time rolls forward lol. Now I am converting to manual steering and back to aluminum arms to get clearance.

I would try re-torquing everything. Crossmember, motor mounts, torque tube etc. I have my car up on stands for a full suspension rebuild and while at it, decided to check all the fasteners, from the motor back to the trans. After a couple thousand miles on the swap, found a few loose bolts including the mounts.

Loosening could be a problem but I have heard some other people having problems with breakage or the round urethane in the center of the mount crumbling. I believe the newest style mounts are the best. I have early mounts in my car and so far they have worked well. No vibrations in the vehicle from contact with anything. They should hold the engine very stationary. The engine should not move very much under load. One of my ignition coils is about 4mm from one of the brake lines but it has never hit it.

If your engine is moving around that much, something is wrong.

Something is definitely loose upfront. The noise starts just over 46mph @3500rpm clacking right around the drivers side mount area. There is a lot of stuff crammed there, steering, oil filter remote. The ps pump is just touching the frame in same spot. I will go through everything to tighten. It is hard to not seriously beat on this vehicle it is definitely my fault it brings the driver out.

Wow it's been fun driving this year but this rattle issue loomed until finding it today. Yeah I found the rattle.. thought it was necessary to strap a tech to engine bay while driving.Attaching a photo. To the right of the serial number back under master cylinder on my ls3 there is a bolt 1mm away from the brake cylinder mount. I can't remember what this bolt is needed for but as the hotcam rolls under high rpms it contacts the brake master cylinder brace and vibrates. You can slip a 1mm piece of cardboard between the brake ms mount and the head bolt in the block but can see obvious metal marring. Is this bolt even needed or can I cut it to gain 4mm or more flush? I cannot remember what it's need for.
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I don't have LS3 heads but I checked my LS1 241 heads and both have this threaded bolt hole in the exact same location that is apparently for accessory mount hardware.  Mine is 30 mm deep for an M10-1.50 bolt.
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Clearly you will need to lower the engine to remove the bolt unless you can get a cutting wheel in that tight space.

I hope this helps a little...

From the pic, that looks like a bolt in the back of your cylinder head. Typically, there would be a ground strap attached there or the bolt can be used as an attachment point to hoist the engine. You can ditch that bolt, just make sure there is no ground there. If there is, you can move it to one of the other holes on the head.

Thank you sir for the photo! Looks like non essential. I will try an air filer tool to widen the space. Really a small pneumatic hack saw is all I can think of to get into the space it's possible. Yes, you can see the ground strap under the bolt, that was a mistake. I have 2 other grounds on the head and block to the frame so this one can be cut. Looking at where grounds go on ls you tie heads together on ground on back then split battery ground to body and block head. That has fixed starter issue.

Found this it's small and you can get to the bolt from underneath to cut it off.

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Nice... might have to get me one of those!

If you have room, you might also consider a plunge saw with a carbide tooth blade.

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Funny I just ordered 10 new blades for that tool.. nice dewalt. And a mini die grinder which is ridiculous small impressive for 22 bux. I love harbor freight throwaways.

This tool is to carve a dent in the pass side steel control arm to keep the exhaust flange from hitting it. Lol, It's affecting castor and does not have the gap like aluminum control arms. Cheaper test option for troubleshooting for now.

I'd strongly recommend not cutting into the control arm. Losing a wheel at speed sucks.

This is what that looks like. Exhaust chipped about 4mm on the top edge already. This set is my templates so they can be boxed up. If I still can't get castor adjustment with steel arms the aluminum will go back on.

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Plucky...

If this notch provides the control arm clearance you need and you decide to continue using them, I suggest you grind/cut the remaining support flange in a smooth fashion that does not have a defined "notch."  A notch in any stress path creates what we call in engineering a "stress riser" and will lead to premature fatigue related material failure.

Grind the surface as smooth as you can with grind marks in the direction of the flange...that is, parallel with the flange edge.

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Straight (or slightly curved) blue line is the desirable cut surface.

Thank you Raymond! That is exactly the plan. That little pen die grinder is awesome it will do just that. Then primer paint and try to set castor correctly again. Once these 2 rattling annoyances are resolved the last one is the ps pump AN hose fitting hitting the frame below where the expansion tank is. Bending a 90 degree AN fitting will be a task as nothing else fits but I may squeeze a layer piece of tire sidewall there or dump ps steering for my manual 944 sport rack.

Got the bolt cut out. Yayyyy... About 2 hours with the pen die grinder. Had to use Dremel 1.5" cut off wheel n stone grinder. Just need a little paint touch-up on the master cylinder.

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Congratulations!!!

It never ceases to amaze me how many details must be addressed in these conversions.

Does it ever end???

Raymond-P wrote:Congratulations!!!

It never ceases to amaze me how many details must be addressed in these conversions.  

Does it ever end???

Yep I plan my week around how much time I have to perfect the beast 948. It's only been 20 years, 3rd engine, 3rd Trans and the doors close like new, no rust. What a gem of a project! Hope all feel the same because this can easily beat you down so you switch to small wins.

Dave

"...you switch to small wins."

Dave, I like that perspective A LOT!!  Thanks for the encouragement...we all need that once in a while.  

I guess this is what hot rodding is all about anyway.  Continuous personalized customization as we pursue our "need for speed."