Dudes,


I attempted to smog my high-mileage, 230,000 miles, sc300 and it passed with 'clean' numbers except for visual/timing. The timing was up around 15 degrees BTDC. The engine runs just fine with nothing out of the ordinary. I found the distributor wouldn't go any lower. After verifying the distributor was stabbing correctly I concluded the distributor was worn out and I purchased a low-mileage used OEM distributor on eBay. The 'new' distributor helped but this time I couldn't set it below 11.3 degrees BTDC. I pulled the top cams cover off and verified TDC with the two camshaft pulleys marks aligning on the rear plate markings. That's when I saw this...






At this point I thought it could either be that the crankshaft is a tooth off or the harmonic balancer itself is bad and the timing mark shown in the photo is now in an incorrect position. I removed the harmonic balancer and have verified the timing belt is installed correctly; the crankshaft and camshafts are aligned/timed correctly. That leaves me with the possibility of the harmonic balancer showing an incorrect reading. It currently reads approximately 4 degrees ATDC per the photo. If the engine timing is correct and the harmonic balancer is 4 degrees off then it agrees with my newly installed distributor which currently cannot be adjusted lower than 11.3. 11.3 - 4 = 7.3 degrees which gives me the adjustment range I need to retard the timing up to 10 degrees BTDC. Can anyone think of another possibility?





Thanks in advance

 

if everything is TDC, the reading should read 0 in that pic. If it is not the harmonic balancer, the only other thing it can be is that plastic piece, the lower timing belt cover, with the degree markings may have also warped. Personally, I had to replace mines and as it did have some damage to the plastic.

 

a large movement n the crank wheel will be a small one on the cams, have you ever verified the timing marks before this to see they did in fact line up at some point after the last timing belt?? I would think even with it off that far you could hit 10 degrees.

so you saw that the key on the crankshaft is lined up with the dot on the cover, its not the most accurate but it would seem that it could be the balancer then as the next tooth would move it a good bit. was it off even just a little?

reason is the most likely explanation is that someone lined the belt up a tooth off on the cams before they put in the tensioner (with the tensioner out if you don't keep the slack all on the correct left side of the belt when facing it then when you put it in the tensioner the wheels move some). its pretty easy to do and at that point with the tensioner is in some people when its close will say good enough and thats that, cause its a pain to remove and then get back in since you just released the tension on it.

if the belt was originally lined up perfect, then you could have some issue with the balancer rubber section deteriorating, but maybe take a picture of the front of it and look for cracks etc.. it would have had to move significantly for this to happen, and then why would it stop moving at that point you know. also people say they make a squeaking sound before they "let loose".

Other thing could be that its close enough and your tps is out of adjustment.
believe it or not if the tps is set wrong the car wont enter "diagnostic mode" when you put the paperclip in the diagnostic port to check the timing, cause it wants to see from tps that the car is idling.
when it doesn't enter diagnostic mode you are seeing the real timing, not the base timing, and its usually 5-7 degrees higher than the base timing. this could be why you cant get it low enough.
how you tell if this is your issue is by using your ears. when you put the clip in the diagnostic port you should hear a very noticeable change in sound when the car is idling, if you don't hear any change then thats the problem and you need to adjust the tps.

the last option if all else fails or you dont want to reset the timing belt (assuming harmonic balancer checks out goot and timing is just off) is to simply set the distrbitutor back a tooth .
how did you verify that it is correct??
I usually have to turn it back a tooth before installation as it turns when inserting into the cam. how I know is if I can't get the timing below 10 which is your problem but my timing marks line up.
Also from the picture it seems that the crank is in the retarted position, so if anything your crank wheel would show a lower number on a timing light, not a higher number which would be to the left.
If anything right now the timing light is reading a lower number than it really is at if the balancer is the issue.
This really makes me think that you are just stabbing the distributor in with the marks lined up, you need to turn it a click or 2 back from that and then insert it from personal experience, it really depends what part of the cam its lined up on and how many grooves it hits on the way in, usually a click or 2 back gets you in the right range.

assuming harmonic balancer checks out good and timing is just off, the quickest way to fix the timing is to remove the top timing and valve covers, and then turn the crank till the harmonic balancer is reading 0 (cams will be a little off but pointing up-ish still), and then you pop out the belt tensioner, this releases the slack on that side. turn the cam's clockwise a hair and they will get some of the slack and then you can actually just slip the timing belt off the top of the cam gears, but have a plactic spring clamp ready to clamp the belt on itself so it doesn't fall down in the cover, basically pinching it against the lower cover. then you can turn both gears over so they line up while the crank is still at 0, and then slip the belt back on (you may need to slip it on a hair ahead of tdc and then turn it back due to how the slack works, its not rocket science as long as you are patient and double check) and then you pop the tensioner back in and see how well you did, turn it over a few times by hand and make sure the marks keep lining up. If you kept all the belt slack on the tensioner side it should work out perfect after turning it over twice, if you kept some slack on the other side the crank will look like it is in your picture.

it'll look like this except not vvti, you only have to remove top cover then and not having to undo crank pulley bolt and wheel etc.. (although you may want to inspect your at some point).


here is how it looks with the lower cover off you can see the tensioner at the very bottom (rusty long thing)

see how there is no slack from the top left gear to the top right gear to the crank? its like that cause the crank turns clockwise, so slack is on left side and removed by tensioner.
I actually use a monkey wrench on the cams to remove the slack myself after "lining it up" and before inserting the tensioner, I lightly turn them counter clockwise so that way I know that when I put the tensioner is, there is no slack on that right side to change the timing. like the 1uz has "T" marks on the cam covers which you line up when doing the belt and then turning back to the "L" mark, sort of makes it easier to diagram than saying "remove that slack".

 

Ali and Jadu dudes,


I've ordered a new OEM harmonic balancer. Whether or not the current harmonic balancer is accurate, it is old and high-mileage (230k miles), and it's time for replacement. Of course, I would like all of my problems to be solved with the new harmonic balancer, but I won't hold my breath. The cam cover with the timing marks is in very good condition with no signs of warpage; it is as accurate as it's going to be.

The TPS suggestion is interesting because when I use the paper clip, it does NOT affect the idle in any way; there is no change to the engine speed or sounds at all when I activate the diagnostic mode. So that would say there's a problem with the TPS. I will try to clean it over the next few days while I'm waiting for the new harmonic balancer to arrive.

I verified mechanical timing was correct by aligning the camshafts markings to the marks on the backing plate as well as the crankshaft key to the dot. The engine is mechanically timed correctly.

Here's the timing belt, camshaft pulleys, and crank sprocket.




Intake camshaft sprocket



Exhaust camshaft sprocket



Crankshaft sprocket





Those conditions shown result in the following reading from the current harmonic balancer...







.

 

^^^ no doubt that's at TDC. hope that the new harmonic balancer does it for you

 

Doesn't get more TDC than that.

 

yeah check the tps then, if its turned to far one way the IDL (idle) pin wont have continuity and the ecu will not enter diagnostic mode, which means you are looking at the actual timing not the base timing.

once you fix the tps adn hear the change in sound when putting the jumper in, you should be able to set it better, but yeah sounds like you have a bad balancer then also. even on top of all that you could have the distributor off a tooth there is really no good way to tell after its inserted if you got it right, its a bit of a guess and check as the rotor inside points to cyl 1 in a wide range of timing.