i got a sc300 5speed today. it has about 160,000 miles. the motor on it runs good. but its not smooth. i had a 92 sc4 with 120k and it ran very smooth. what should i do to make the engine in my sc300 run smooth. i also have a 93 gs300 with 220,000 miles..and the motor on that car runs pretty smooth (smoother than the sc300 motor) im going to do new spark plugs, wires, rotors, caps, on monday. im also going to change oils. anything spacific i could do to help bring this motor to a smoother run.

 

I car with that many miles could use new engine mounts and tranny mount. I know that when I replaced those in my LS it ran MUCH smoother .

 

thanx. the car is also a little too loud. im going to put it on the lift and check the exhaust pipe. im not sure but the pipe might have a little hole in it. how much do the motor mounts cost. are they easy to replace.

 

This is from another post I did not too long ago in the LS forum:
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(for a 1991 LS400)
If you're going to change your engine mounts you might as well do the tranny mount at the same time. I had mine changed around June. RIGHT away I noticed how much smoother the car was . Changing them was a major improvement in my book. Anyway, here are the details:

12361-50100 = Engine mount (2 needed), list=$115.10, irontoad=$92.08....$184.16
12371-50010 = Tranny mount (1 needed), list=$64.50, irontoad=$51.60

labor = about 3 hours = I paid $210

Total = $445.76
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I can't speak for the SC, but these prices should give you an idea. To replace them you need to lift the engine up. I don't have the proper equipment for this so I had my mechanic do it. It will probably take longer than 3 hours to change them. Again, I'm talking about a LS and not a SC so I'm just trying to give you an idea .

 

thanx, im hoping the tone up and changing the mounts helps. the car is just too loud for a lexus in my opinion. it sounds more like a camaro or a transam. im going to check out the exhaust. and all. but i will keep everyone updated and thanx for all the help.

 

i think a bottle of fuel system cleaner like Techron and cleaning the TB may help

 

My GS3 had the same problem (too loud) but I discovered the problem. My driveway is really steep and the bottom of my car scratches if I don't go up on a shallow angle. I had a couple muffler shops look at my exhaust but they couldn't find out where it was leaking from...until another muffler shop opened up the heatshield in the exhaust piping right after the exhaust manifold. The occasional scraping put too much presure on the exhaust and caused the piping to split at a joint. This could not be seen without taking off the heatshield. The shop welded it back together and replaced the heatshield. Now my car is quiet again.

So check the exhaust system and if the shop can't find out where it is leaking from, have them remove the heatshielding (some shops were too lazy to take apart the exhaust to remove the shielding). Good luck!

 

if it kicks hard you might want to look at engine or tranny mount like stated above.

 

Do the usual system check culprit - plugs, plug wires, air filter, ac filter, change the oil, filter, fuel filter, etc.

Then upgrades to new mounts.

Then throw in a bottle of fuel system cleaner and don't forget to do engine flush when you do the oil change.

If all else fails, a ground kit might work. It seems to give better idling and smoother response on CL cars....