1989 240SX Whats the position of sprockets cams during TDC.....

[amolao]

Im installing a new timing chain, and would like to verify the complete physical alignment of all respective parts involved with the timing....(pulley is not aligning properly during TDC...maybe due to prior chain installation...)Please verify the following statements:

At TDC, piston 1 should be in up position.At TDC, rotor should be pointing to cylinder 1.At TDC, crankshaft pulley should be on TDC marking.

Where should be top and bottom cam sprockets should be oriented towards during TDC????

Is there anything else I should verify after checking the sprockers to ensure that the timing is correct going by the marking on the pulley...

thanks and sorry if I confused you.....

[180fan]

The crank is set to 0 (second mark from the left) and the keyway for the cam sprocket is pointing up.

Yeah your "verify" statements seem pretty right. If you've an 89, you've only got one to worry about. The dot on the cam sprocket should be facing 3 o'clock if you're looking right at it. I forgot which way the crank's sprocket's supposed to face, but the keyway on the crank points up.

[s13sr20chris]

i cant remember but i will vouche for 180fan and his familiarity with the subject.

[180fan]

Yep verfied from the FSM baby! I knew I wouldn't forget that one hee hee hee (just line the keyways up and you'll be just fine)

[amolao]

thanks for the info, much easier to get a straight professional answer here than at the Technical forum, some of those kids just want to be funny sometimes...

Yeah, the reason I ask about the checks is that after I get everything on the right positions,(cams,rotor,etc) the pulley is like half an inch off from the TDC mark......any ideas in what to do to realign just the pulley..??

thanks

[180fan]

The cam sprocket? When you're putting the sprocket on, you can #1 use the same socket to kind of rotate it around when it's startging to get tighter or #2, when the bolt is fairly tight just stick someting into the cam sprocket and rotate it that way. I usually feel alot safer with the cam not tightened down but I don't think an inch in movement would do all that much

[amolao]

Oh no Im not replacing the sprockets, Im talking about just turning the pulley while is loose....will that be possible??? Or is the crankshaft keyway holding the pulley on a specific orientation???

[180fan]

The keyways will force the sprockets/pulley into a specific orientation. So if they need some adjusting, like the keyway for the crank pulley's not pointing right up, you could probably move it around once the crank pulley's on a bit to get it straightned out. Ditto with the cam, the dowel will force the sprocket in one way only. If your cam's not lined up pointing upwards, you can shift it about using the method I put above. hope that answers your question

[s13sr20chris]

if everything up top is lined up but your crank pulley is not...jumped time. that sucks. how far out of whack does the top go if you spin the pulley back to the tdc mark. there is some slack in the chain so small discrepancys are expectable.

[amolao]

Ok, guys here is a summary of past events:Finish the installation and the pulley sits on the 5+ mark( just like in the beggining)....that much..so whats out of whack?? Distributor?? or cam?.... R

Replace both sprockets and chain plus tensions.Put everything together and still cant get the pulley to align with the 0 TDC mark.......what can I do about this??? Will the rotor be off.... Again sprockets,chain are properly orien ted (3'o clock), so what can it be??? I started the car, and now also have a very loud ticking coming from the valves.....Arrghh!!!! and a leak....oil leak coming from the side timing cover, probably bad sealing job...Im going to take it apart again, so what can I do to check the pulley alignment issue, (will the ignition gear go in a specific position..?) and the issue with the loud valve ticking??? Should I stop here and take the car to a mechanic ....???Sorry about the long post...
Modified by amolao at 9:07 PM 9/23/2004

[amolao]

Im still not really sure about, the method explained by 180fan on the realignment of the pulley....I did replace also both gears. Another question (sorry!) Will the gear sprockets move/rotate if not tighted down......will the notch stop them from moving (rotating) on their shaft if they were loose??? how about the pulley?? does this apply also....??

Let me explain my question: When the gear sprocket sits on the camshaft the notch keeps it from turning , unless it slides off the notch.....right???

And the pulley is the same way ....right ???

Sorry I just want to make sure Im understood....

[JNM240]

I got your email and sent you a reply, but i will expunciate here for the forums sake.

The cam sprocket actually sits slightly below 3 oclock, an imaginary line from the center of the cam bolt to the cam dot will be parallel to the top of the cylinder head, which doesnt sit perfectly parallel to the ground. So if you are trying to get your 3 oclock with the ground, you might be off by that 5 degrees of timing, BUT THAT SHOULDNT MATTER because the crank sprocket would line up the same way AS LONG AS you have aligned the silver links of the chain with the dots on the crank and the cam sprockets. This would only cause a problem with the alignment of the oil pump to the distributor. And yes, the keyways keep the crank pulley on the crank only one possible way, same with the cam keyway (notch). You can move either the crank or the camshaft seperate of each other AS LONG AS you have loosened the rocker arm bolts, effectively closing all of the valves.

Let us know how it goes, ok?

[amolao]

can I move each cam indepently by disconnecting the chain???

[amolao]

Im mechanically incline but really a newbie when it comes to this.......sorry....

[amolao]

this thing is driving me crazy....one more question: If the crankshaft is notch pointing up, ??? Is the pulley automatically aligned to the 0 TDC mark......by virtue of this??? Is the keyway on the crank shaft designed to set the pulley on the 0 TDC marking???

thanks for the help....

[s13sr20chris]

i cant remember where the crank key points at tdc but i will tell you this. the crank and cams can point anywhere they want but if you line up the plated links on the chain then its all good. the sprockets are all a dynamic kind of balance thingy. what keeps it all together is the chain and the number of links between them.

[JNM240]

For arguements sake, we will say yes. The pulley is automatically aligned to 0 degrees timing at TDC by virtue of the keyway. The arguement is this: The chain keeps the sprockets moving together, the worm gear that drives the oil pump and distributor itself, have teeth (or gears) that mesh to synchronise. There is no way the oil pump and distributor can be off, because of the half moon design of the shaft (it fits in only one way). For the distributor shaft to be off, it would have to be off by one tooth on the gear, which would be OBVIOUS. Not like 5 degrees, but more like 20. Just like s13sr20chris said, make sure the shiny links match up with the dots on the sprockets, make sure the distributor and oil pump match, put it all together. 5 degrees of timing doesnt matter right now, you havent even started the motor yet. You cannot set ignition timing with the engine off.

Personally, i think you are thinking too much about it. Once you finish it, you will be amazed how easy it was. It all just falls together.

[s13sr20chris]

yeah, get your valve timing right on the money. then we can worry about ign timing. if you have to drop the oil pump and realingn it, that sucks but thats how you learn. you dont want to do the chain twice though.

[amolao]

thank you for your assistance guys, tomorrow i will take the timing cover off and recheck, the other issue that Im worried about is the loud ticking of the valves, it sounds kind like an engine is out of oil.....(yes I check oil level...) very loud at all times....you guys know what should I check if this continues??? maybe a bad valve?? how can I check the valves for right operation and serviceability???

thanks again.....

[JNM240]

Depending on how long the car has been sitting (especially with the rocker arms off lying on the side), they may be out of oil. If this is the case, it will have to run for a while to build up oil inside the rocker arms.

But lets get the chain back on correctly, then started, then worry about other things. One problem at a time. hehe

[amolao]

Finally got my car put together last nigh.....it was no fun.... Recheck everything, valve ticking gone after 20 minutes, yes JNM it was lack of oil. And no leaks, guys!!! so far.... this time I used a gasket material made by Toyota, expensive stuff, kind of a tar rubbery paste. Reccomended by a friend, will see if still holds. JNM thanks for the emails and understanding, s13sr20chris, appreciate you always stopping by in this part of the forum and reaching out to us,.......This was hard labor, guys,,,,,,,HEHEHEE!!!!!

[s13sr20chris]

yeah, it can be a bear. glad its all good in the hood bro.

[JNM240]

[amolao]

Oopsie, Im back.... the timing cover stills leaks , but not as bad as before. The cilynder block is missing the portion of gasket that goes around the top edge of the the timing cover, the guy that work on my chain last time made work with just RTV, but this time it just wants to leak...Rats!! What should I do???

Get cylinder head gasket replaced?? this time I will go with a mechanic, I just dont have the time and "knuckles" to do the work....How much will it run me???

thanks

Any other ideas other than redoing the complete process all over again including head gasket.....???

thanks

[JNM240]

Oh man that SUCKS! Yes, the cylinder head gasket seals the top of the timing cover to the head. If you are missing that part, and RTV sealant isnt working, you probably need to replace the head gasket.

Good news is you dont have to remove the front cover, and you only need to take the cam sprocket off the cam (as far as your chain goes). Bad news is you need to:

remove powersteering pump & high pressure lineremove upper and lower radiator hose from intake/water pumpremove heater hoses that go to heater core (thru firewall)remove all electrical connections to intake manifoldremove exhaust manifoldremove all beltsremove idler pulley and bracketremove rocker arm assembliesremove camshaft (leaving the sprocket and chain, wedge a block of wood down the front cover to prevent sprocket/chain from dropping into oil pan, or you WILL have to remove front cover)remove fuel lines, brake booster line, various vacuum lines that go to/from intake manifoldremove head bolts (and there are 2 bolts that hold the intake manifold to the support bracket right next to the oil filter) and lift head/intake manifold assy off

It is actually a lot easier, IMO, to do a head gasket than a timing chain on a SOHC. But, FYI, a shop will charge in the neighborhood of 8.6 hours of labor (at an average rate of $80 an hour) to replace the headgasket. This isnt including parts.

[amolao]

thanks man.....I will check with local shops and probably pay for it out of my pocket.....not feeling too motivated to work on this right now.....this sure has been a letdown and demoralizer for me....I will never work on my car from now on...

welll, maybe brake pads and stuff like that...

Hey bro, how much are the parts probaly going to run me??? And what will I need?? head gasket is a gimme, just wondering what else is required.....

[s13sr20chris]

prob reuse the exhaust gasketsnew intake gaskets(upper and lower)maybe reuse the valve cover gasket and plug hole gasketrtvmaybe if you clean off the old rtv from the timing cover and head gasket you could seal back up. if you want to do that.

[amolao]

s13sr20chris, that exactly what I did the second time I took everything apart....cleaned both areas and reseal with RTV with same results...leaking... Question(Im really considering doing this myself....change of mind..)when I pull the cylinder head off, after disconnecting exahust,ECSS,electrical,etc...does the cylinder head stays together as a whole??? does the camshaft needs to be taken apart? how about valves?? and after replacing the head gasket is there any RTV needed to be added to the areas of the timing cover and cylinder head that are making contact or is the gasket enough???/

thanks

[JNM240]

The cylinder head will still be attached to the intake manifold. There are two intake to head bolts that are below the intake that you cant get to unless the head is off the car. So just remove them as an assembly, then if u want to u can take the intake off the head.

You will need to take the cam out, but you will need to leave the chain with sprocket there. Get a block off wood, take the chain/sprocket off the cam, wedge the block of wood between the chain tensioner and the guide (with chain still on), and make sure the excess (where the sprocket is) doesnt fall through to the oil pan.

Valves can stay put (but obviously the rocker assemblies will have to come off). And no, you should not need any other RTV sealant.

[s13sr20chris]

i dont think you have to pull the cam. you do have to disconnect it from the sprocket. i dont remember. anything in the head is just to access the head bolts. do the wood block trick and slap some zip ties on there too to help hold it in place. i would use rtv but not on the block or head. just on the part around the t-cover.