Thread: Which mark is TDC on this crank pulley? (2001 fwd SR20DE)

Hi, I have a 97 sentra with a 2001 roller rocker sr20de swapped in. I just bought JWT S3R camshafts and when attempting to install them I made a series of dumb mistakes that led to the timing chain jumping on one of the cam sprockets. I didn't notice which sprocket, or which direction it jumped, and didn't have the mating marks lined up with the marks on the sprockets but there's now too many links between the cam sprockets. It's my understanding that it's impossible for it to jump on the crank so I thought I could just turn the crank to cylinder 1 TDC then reinstall the cams at 10:00/12:00.

The problem I'm having now is when searching for information on how to find TDC with the crank pulley I'm generally finding people talking about a pulley with 6 marks. The pulley on this engine has only 3 marks. I've posted a picture with them highlighted to show their arrangement. It looks like there's space for 2 marks between the left most and the second mark on the pulley but there's no notch in the pulley or mark or anything there... Since that makes space for 5 I could only assume the left most mark on this pulley is 0 degrees but I haven't been able to find any pictures of the same marks on an SR20 and how to find TDC with it.

I don't want to remove the oil pans but I can if I really have to... Can you find it close enough by removing the crank pulley and lining up the keyway perpendicular to the oil pan line?

Thanks for any help with this

That looks too dirty to determine TDC.

I'd go with finding mechanical TDC instead. Remove Cyl1 sparkplug. Insert wooden stick. Rotate engine until true TDC is found.

It is so close when yo do it this way, so you can set timing trouble free at the cam side.

Usually the left most mark is the TDC mark. I say usually as some older engines have ATDC marks on their pullies.

OP - did you forget to zip tie the timing chain to the sprockets? That's usually what causes it to jump once you start removing the old cams. Sucks to hear

If you jumped a tooth and have no idea you need to remove the timing cover to verify that all the spots are lined up... nothing to do on the outside of the engine at this point. That sucks but this should be a hard lesson learned.

I did it all wrong haha... I thought it would be easier to remove the chain tensioner instead of making a chain block and just mark the chain where it met the sprockets instead of tieing them together, and remove the cams with the sprockets and take them off of the cams out of the engine. I then realized I didn't have it at TDC and thought maybe if it were that would help ensure everything went together right and I turned the engine by the exhaust cam bolt but forgot the tensioner was out... I would think it jumped on the intake sprocket because the slack was there but I don't know for sure

I work in a repair shop and was going back and forth between this and some other cars in the shop and then messed it all up from trying to do too many things at once

oh man. I hope you get it figured out.

I haven't been able to find any instructions regarding these kind of pulley marks but it's not gummed up or painted over or anything, there are only 3 marks. As far as I know it should be a factory 2001 pulley.

When I get back to the shop I'll see whereabouts I can determine tdc is by checking the piston, and if it's really close to that left mark I think I would trust that one.

Does anybody know, if I were confident enough to try and reset it without removing the timing cover, is there any margin of error as far as being 1 link off, 2, 3 etc links off before physical damage could occur from turning over? I'm thinking to get as close to TDC on the crank as possible, pull the chain tight to the exhaust cam at 12:00 then set the intake cam and reinstall the tensioner. Then turn it over by hand and if it feels ok do a compression test with the starter to verify

I know you can see the depth of the piston through the spark plug port but my boss always strongly discouraged this for finding TDC replacing any kind of timing belt or chain we've ever serviced because it's hard to tell exactly where 0 is and it'd be easy enough to be off a tooth or few degrees somewhere

Planning my day for tomorrow... If I did need to pull the timing cover are there any gaskets required for that or the oil pans? Does the head need to be removed?

Looks like this will be a PITA. I have a backup sr20 non-rr that I can swap the engine out for then work on this engine out of the car, if anyone thinks that would be a good solution with more priority given to getting the car out of the shop and keeping my engines safe than getting the JWT cams installed

The roller rocker engine has 120,000 miles on it, IF I did end up taking it out of the car to work on is there anything else that would be advisable to service at the same time, anybody?

Thanks for considering...

http://www.sr20-forum.com/naturally-aspirated-all-motor/43837-how-check-camshaft-timing.html

The OEM RR pulley has six notches. The leftmost notch is -5 ATDC. Second from the left is TDC.
I just looked at my OEM pully sitting in the garage.