Martin54

I'm troubleshooting a 1993 SC300 which barely made it home after suddenly starting to run very rough. Upon stopping, it restarted once the following day and ran (still rough) for a short period, then died and cannot be re-started. Cranking sounds like about 1 out of 20 sparks might be trying to generate a hit.

Car's maintenance history is unknown, and it has 150K miles.

First thought was fuel pump, but starting fluid makes no difference in the behavior.

Battery is fully charged.

My next thought is that the timing belt may have jumped a tooth or two, then jumped more on the next day's re-start. I'm assuming that this engine has some convenient method for inspecting the crank and cam gears to see if punch marks are aligned, or something like that, but I don't have a manual. If the timing is jumped, I'll probably re-set it and drive it to a mechanic for belt replacement, unless the job is easy enough for an afternoon in the driveway.

Can someone help me with a description of how to check for proper cam/crank alignment?

Thanks,

Martin

brucelee1

iTrader: (2)

Well, for starters, the car is an inline 6, so if you really have a V6, it is one of a kind!

blk&blu*j

iTrader: (1)

This is not a V-6 engine it is a 2997 cc inline
86mm stroke 86mm bore 6 cylinder

Yes there is timing marks on the cam gears as well as the crank pulley.

Welcome to the disease

Martin54

OK, I fixed the typo, so how about some help? Such as: Cam mark 12:00 + crank mark 12:00, or whatever the correct answer may be.

Is there an online procedure for belt replacement? I didn't see it in the mega links sticky, but something with pictures would of course be great.

I'll be tearing into it on Sunday (weather permitting), so if anyone knows about this job, please reply.

best regards,

Martin

blk&blu*j

iTrader: (1)

Check your PM.

Martin54

Thanks, appreciate the phone help! I'll let you know how it works out.

Ali SC3

iTrader: (10)

wow, before you dive in that deep check the simple stuff.
what you are saying can be alot of things, like when I had a similar experience all of a sudden the car ran like junk and would run hardly sometimes, and not at all other times, it turned out to be the cap and rotor (inside the distributor) was not replaced in a long time.. one stop at the store and 15 minutes the car was good to go.
you will be surprised how many people change the plugs and wire and dont even think about the cap and rotor. at first I was down to 4 cylinders then it seemed like i was only hitting on 1 or 2. this happened to me around 135-140k JFYI

timing belts do not just jump teeth very often at all but thats the first thing people jump to.

get a socket on the crank and turn it over clockwise by hand until the crank reads 0.
take the cover off the timing belt, check where the 2 notches are on the cam gears, they should be pointing straight up at the 2 notches in the black timing plate behind the top of the cam gear.
If they are not even close at all, turn the crank around a full turn and back to 0 because you are probably out 1 revolution.
now see how they line up. If they still don't line up then clearly something has gone wrong like a bad tensioner then tear into it lol. if its lined up perfectly with the cover, then you know its still fine.

also you can learn alot from the condition of the belt, check it closely for cracks, you can turn via the crank so you can check the whole belt out. good luck. check your cap and rotor first though.