Replaced the OEM motor mounts with Energy Suspensions polyurethane motor mounts on my Sons 98 S10 ZR2 with 4.3L. Problem I am having is I can't get the bottom bolt to thread on the drivers side, the two top bolts are in just fine of the three bolts that thread into the block I had no issue getting the bottom bolt to thread on the passenger side.

Is it acceptable to leave the bottom bolt out of the polyurethane motor mount on the drivers side of a 4.3L S10?

i think i would try the bolt with nothing in the way, if the threads are fine, open up that one hole a little, if its a thread issue have to find a threader, dont know anything about the engine bolt size but dont think i would try leaving it out

I guess that would be which way the torque is applied on the engine. If the engine torques(pushes) to that side of the mount, then I would say it would probably be ok. But if the engine is going to PULL on that mount, then I say no.

If you can, throw a jack under the oil pan, take the stress off that bracket, remove the top 2 bolts, then install the bottom one, but not tight. Then install the top 2. I've found with brackets and such that require proper alignment when installing bolts is to install them ALL before torquing them down.

They over engineer things all the time, a few extra bolts aren't really needed are they? Just kidding, I would make sure all three bolts are in the block. Like Justin said, you might need to get the drill out and open up the hole a little, aftermarket parts aren't always perfect fit.

Gentlemen,

Thanks. Bolt is now in. When installing this aftermarket motor mount I learned that loosing up the trans mount is the key. After doing that, bolt when it pretty easy. I spent 12 hours on this, once the solution was identified, 15 minutes.

interesting, never had to do that before

Be glad you weren't getting paid flat rate on that job.

I found the solution on a ZR2 forum, and also called the mount manufacturer who said the same thing. I was surprised I got someone at the manufacturer, many items like these are made out of small shops that make these part time.

The manufacture gave me some other warning/ tips. He said the OEM mounts may absorb a lot of driveline issues, with the poly mounts driveshaft, ujoint type issues will show that OEM mounts mask. He also told me it is ok to use poly motor mounts with the OEM trans mount, many people say if solid engine mount, than trans must be solid mount. He stated not true.

i never heard about using the same ones. i guess it depends how good the original design is. i have been using stock 350 rubber engine mounts for about 10-15 years, when ever i swapped it to the 305 that was in there before the 350, that was all they had at the parts store at the time. but i went with the poly trans mount for a th400 because they had it and its a member of the suspension on the f-bodies. the stock rubber engine mounts have seen alot of track passes, i thought they would give me a problem but not so far.