Someone out there know anything about loss of compression on a sc400....
My 2,4,6,8 cylinders r low on compression. any ideas.....so far i've heard timing belt can be off a tooth or two, rings r no good or even gaskets.

dont know which way to go w/ this?: uh:

 

First thing to do is to check timing on the cams to see if they are in time with the crank. Look for the timing marks on the cams and the crank pulley to see if they all match up. If they are in line then the second thing to do the next test: a leakdown. This applies pressure to the cylinder's that seem to be causing problems. If the valves are partially open then the pressure will leak out past the valves. You can hear this if it's coming out or even feel it if you put you hand over the intake/exhaust ports and feel them leaking. If it's rings, then the pressure will leak out the PCV valve or even the oil dipstick tube if you take the dipstick out. Gaskets would be the last thing on my mind, it might also be worn valves seats or even a damaged valve. How many miles does the car have?

 

i just had my starter replaced and to had replace my timing belt also, I was thinking when the belt was put on,it wasn't put on correctly, see, it all started when i replaced the starter, my buddy didnt put the fuel rail bolt on tight enough and it leak out fuel...started a fire, they threw water and kitty litter to put it out. some of it fell on the timing belt, it then tore. we put all together again, but it seemed a lil off, so i did a tune up while i was there.....still nothing... still rough idle, not as bad though....just seemed alil off. But when i would drive it would heisatate real bad, especially uphill, more like loss of power, thats when i checked my compression....mostsly read about 110 thru 115 all on the right side(2,4,6,8)....oh, i also put seafoam in my crank case...thinking that would help....no dice. So thats where im at now. Thanx.... i will double check on those things u mentioned

 

now that i've heard THIS (especially the timing belt replacment) i would definitly look into a timing issue with the cams. Do the leak down first to see where you need to start from and go from there.

 

cool, i'll go w/ that, just needed some more advice on this, its pretty simple when it comes to old trucks and domestic vehicles most of times....but as for imports and especially lexus...easy isnt even listed on the this baby.

thanx again.....