Stuck! Trying To Replace Motor Mounts 1990 Ls400

glenmore · January 14, 2006

Help!

Am stuck in the middle of changing out the engine mounts. I was following a writeup from a fellow member but there must be differences in the model year.

I have the lower 17mm nuts off. On the passenger side, the air intake is off and I got the PS holddown by the PS reservoir. Got the upper nut off the mount.

Driver's side: Removed hold downs on loom along the cross member. Removed holddownds for PS hose. Oil filter out. Unhooked oil pressure sender wire and one bracket to the block. Finally got the upper nut out. This was very difficult. Had the wife go to Sears and pick up a 17mm stubby wrench.

Here is the problem, when I go to lift the engine, the motor and everything else still rises. Something is still holding the engine to the chassis. After looking at it, an obvious problem are the two AC lines. There are some holddowns but I don't think removing them will help as the rigid lines seem fixed in the radiator area. Looks like you'd have to unhook the compressor from the block. Is this what needs to be done? Anything else that needs to be unhooked?

Thanks for any help.

glenmore

1990 LS400

hyperopt · January 16, 2006

No need to unhook the compressor, but you'll need to remove the return hose on the power steering pump reservior, otherwise, you'll break it when you fully jack the engine. You must lower the crossmember as low as it safely can go, otherwise, you won't have enough clearance to remove the mounts. I picked the jack points closest to the engine mounts to avoid having to lift up the whole engine.

Edited January 16, 2006 by hyperopt

glenmore · January 17, 2006

Well, finally got the mounts done. Not the prettiest of procedures but the results are fantastic. Nice solid start with no torquing of the engine. New car idle, whisper quiet. This is the procedure I used. Check out Bob's post on a 1995 MY also:

http://us.lexusownersclub.com/forums/index...=13030&hl=mount

Front of the car on jackstands. This is important! I initially had my car on ramps and ran into the problem in my first post. When I starting jacking up the engine and the entire car rose, I erroneously thought that I hadn't disconnected everything, when in actuality, I was just taking up the slack in the suspension. After I got past this point, only the engine continued to rise and I was able to continue with the repair. So have the car on jacks with the front suspension hangingand you can better gauge raising the engine.

This is for my 1990 LS400, about 145m:

Remove all the air cleaner stuff along the front of the car plus a couple of air intake holddowns on the left.

Remove holdown on PS return line by the reservoir .

Release fan belt on AC compressor pulley with 14mm socket on belt tensioner, counterclockwise. Same counterclockwise to reinstall.

Remove both lower 17mm nuts to mounts.

Release loom along the cross member. Release PS line along the oil pan. Remove oil filter. Release plug on oil sensor. There is also a ground to the block and a loom holddown to the block here, 12mm.

Release AC compressor, 2 bolts, nut, smaller bolt and ground wire. Release clip back of AC. AC compressor is hanging now.

On the easier passenger side, remove 17mm upper mount nut.

So far, everything routine, but now the upper mount nut on the drivers side is tricky. I used a 17mm stubby wrench with the box end on the nut and the 2 tines of the open end towards me. I got some extensions together and with the open end of the extension on one of the tines and a few bangs of a rubber mallet, I broke the nut free.

I was not able to raise the engine enough to get the mounts out so I tried lowering the cross member, 17mm deep socket. I got one nut loose but the 2nd held fast, even with a large come along. Not only do you need to raise engine /lower cross member enough to get the old mounts out, you need even more room to get the full size new mounts in. I remembered another post that suggested removing the submounts also. Both submounts are attached to the block with four 14mm bolts, the passenger side with an added ground. All looked easy to get to so I tried this way rather than the lower the cross member method, and I was finally able to get the old mounts out and the new mounts in. This takes a bit of juggling. You have the mount and a black metal heat shield that snap onto it, an aluminum heat shield and the sub mount. Start the top and bottom nuts, drop the engine and finish tightening. The only ones you can get at to torque would be the bottom ones, 43 ft. lbs. Submounts to the block are 27 ft. lbs.

Put everything back together and enjoy your new ride!

glenmore

1990 LS400

1991 MBZ 300CE

2000 C280

fisher972002 · January 27, 2008

Wow,

Just finished mounts on my 1991 LS 400 167,000 miles.. Both mounts were hard and torn at the top and separated about 1/3 or 1/2 the way through.. I noticed especially in winter more vibrations when the engine revs...

It's soo smooth now.. I think the engine mounts and the rear carrier arm bushings were 2 of the best fixes for this car, and the lower ball joints... Those 3 things wear out and greatly improve driveability of these cars!!

Thanks for all the info Glenmore, i printed your info out and followed to a T and I started at 9:00 A.m., finished with everything about 6 p.m. I had troubles getting the upper nuts off the mounts.. I have no idea how you took off the submounts, I couldn't get anything in there.....

Also Sears didn't have a stubby wrench in MM, just standard.. I bought a rachet stubby 17MM to try to fit in there, but the racheting end was too big and bulky and wouldn't fit on the nut.... I just used a regular wrench...

TO get more torque to undo the bolt I had to put the wrench closed end on, and do the trick where you put the closed end of another wrench on the tine and you can change the angle and pop it and it comes loose.. But wow.. Since I had to use the longer wrench, Seriously had to only move a few closed ent tines at a time.. Then hook again.. I swear it took 2 hours to undo those bolts..

But all the stuff you have to take off to get to the drivers side.. Wow... The PS lines and everything was a piece of cake.. I had to loosen the bolts on the compressor just to get it to push forward so I could fit in my wrench.....

I also had to lower my cross member to get the new mounts in.. The old ones were flattened and they poped out easily... But then I tried putting in new pass side and I had to lower the cross member to get it in, when you do that, plenty of room... In fact I had to raise it up to start the upper bolt, so maybe I could have put them in by raising the engine more, but I think it's easier to lower the cross member than further stress the angle..

I was pumping up with my jack and it started to get more and more resistance, it's not worth cracking a manifold or something, just lower the cross member and give yourself some more room... Just get a big mama breaker bar, one of those 3 foot ones 1/2 in drive so you can get torque and bust it out, once they loosten one turn they are easy....

Anyways.... Put everything back together, you have to keep double checking yourself because you don't want to forget a bolt ehre, a bolt there... Write everything down and reverse it..

Close to the end I had a brass nut left over.. Then I remembered it was for the PS return holddown unter the air filter...

Started he up and wow, it's soo smooth.. I think I had the original mounts....

Bravo.. Bravo..

Thanks Glenmore..

Now I just need to get my Timing belt changed and she's good for another 90K