Timing belt confusion.... help!
04-23-17, 01:29 PM
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Okay I lied. New (hopefully final) confusion.
I'm using this guide:
http://www.lextreme.com/timing.htm
He says, "when the crankshaft is pointing to zero make sure that marks on the camshaft pulleys are aligned with the marks on the engine."
And then his following photo is this:
I thought the LCAM and RCAM lines had to ALSO be lined up with the engine. Here's what I have:
The marks on the cam sprocket and the engine line up, but the lines on the timing belt itself do not. At all. Just like in the photo.
Am I good to run? Or am I facing certain death?
I'm using this guide:
http://www.lextreme.com/timing.htm
He says, "when the crankshaft is pointing to zero make sure that marks on the camshaft pulleys are aligned with the marks on the engine."
And then his following photo is this:
I thought the LCAM and RCAM lines had to ALSO be lined up with the engine. Here's what I have:
The marks on the cam sprocket and the engine line up, but the lines on the timing belt itself do not. At all. Just like in the photo.
Am I good to run? Or am I facing certain death?
04-23-17, 02:56 PM
#4
04-23-17, 04:13 PM
#5
Pole Position
As long as crankshaft mark is at 0 and the 2 camshaft marks line up with the marks on engine, you're good. The marks on the belt are there to make it easy on first line up. After the engine is spun once, or twice, to check all the marks again, the lines on the belt will never line up with the marks. There's no pic of your Right cam so we cant see if that one lines up.
04-23-17, 05:17 PM
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I haven't spun it over yet. The lines on the belt aren't lining up before I spin it over.
Right cam belt line doesn't line up either. It's just like the left - a few teeth off, but balancer is at 0.
Does it not matter as long as the crank and cam sprockets are all lined up? Or does the belt NEED to be in that orientation? Like you said - it'll never be the same after it's started.
Right cam belt line doesn't line up either. It's just like the left - a few teeth off, but balancer is at 0.
Does it not matter as long as the crank and cam sprockets are all lined up? Or does the belt NEED to be in that orientation? Like you said - it'll never be the same after it's started.
Last edited by Stingroo; 04-23-17 at 05:28 PM.
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04-23-17, 08:19 PM
#8
Stingroo, as mentioned by a few people above me, the marks on the belt are for ease of installation. But, they are very helpful. Someone said that the marks will never line up again. That's not true. However, the lines on the belt line back up with the corresponding timing marks many many many many revolutions apart. I don't feel like going out and counting the teeth on the sprocket and such or I could figure out exactly how often it happens. The jist of it is that the marks are used for installation and once the engine is barred over once they're useless after that.
In your photo the tension side of the belt looks a little slack. Timing belts have a tension side and a slack side. You can start the belt on either cam sprocket but I usually install the tensioner pulley first and route the belt backwards. The idler pulley is a little easier to install with one hand while holding the belt tight with the other than the tensioner pulley. You also need to use a little blue loctite on the tensioner pulley assembly bolt per Lexus. It doesn't matter which way you go to route the belt, the marks just need to be lined up when your done. The belt is nearly slip proof once the tensioner pulley and idler pulley's are installed even before the hydraulic tensioner is popped. There are many way's to make a mistake here and allow a tooth to jump. If you're going to save your attention to detail for anywhere in the job, it's here. The mark on the belt at the crank is probably a tooth or two off from the mark on the crank sprocket. Being that the belt wants to straighten out and the crank pulley is the smallest sprocket on the system you can skip a tooth here easy. I'm wondering if you even know that there is a mark on the crank sprocket that is supposed to line up with the crank mark on the belt. I say that because the mark is easily covered up by 20 years of dust. You'll need to clean the outer face of the crank sprocket with a tooth brush while it's off the engine. You will be able to see the mark then. When I do the timing belt jobs on these cars I leave the lower timing cover and harmonic balancer off until the hydraulic tensioner is installed and all marks are checked. It appears that you have already reinstalled the lower timing cover and harmonic balancer. I think you must have done that because you think the mark on the balancer to the lower timing cover is what you need to be checking against. Not really... Not when you have a belt with marks on it. That balancer mark should be verified after you've installed and tensioned the belt.
If I were you I would remove the balancer and lower timing cover. This may sound like a waste of time to you but you're better off doing it this way. Trust me. You don't want to put the entire thing back together and have it run like garbage. Then you're doing the entire thing all over again. Take it all back off, clean the sprocket, line the marks on the crank sprocket and belt then route it over the drivers side cam, under the water pump, around the passenger side cam, then install the tensioner pulley. Sometimes the cams like to spring a tooth or two one direction of the other that you need it so put a breaker bar and socket on the cam you're working on so you can rock it back and forth if need be. Once the belt is routed and the tensioner pulley is installed visually check all 3 of your belt marks to sprocket marks. Check it again, then check it again, and maybe again if you have time. Then install the hydraulic tensioner, pull the pin, and install the lower timing cover and balancer. Install the balancer bolt loosely. When the balancer bolt tightens just keep going and bar the engine over two full turns. Line the balancer mark up with the zero on the timing cover and get on a level plane with your cam sprockets and check your timing marks. The marks on the belt are useless at this point.
Questions? Check my tutorial that I created that dicer linked to. You may see some more pictures that are helpful to what you're trying to figure out.
In your photo the tension side of the belt looks a little slack. Timing belts have a tension side and a slack side. You can start the belt on either cam sprocket but I usually install the tensioner pulley first and route the belt backwards. The idler pulley is a little easier to install with one hand while holding the belt tight with the other than the tensioner pulley. You also need to use a little blue loctite on the tensioner pulley assembly bolt per Lexus. It doesn't matter which way you go to route the belt, the marks just need to be lined up when your done. The belt is nearly slip proof once the tensioner pulley and idler pulley's are installed even before the hydraulic tensioner is popped. There are many way's to make a mistake here and allow a tooth to jump. If you're going to save your attention to detail for anywhere in the job, it's here. The mark on the belt at the crank is probably a tooth or two off from the mark on the crank sprocket. Being that the belt wants to straighten out and the crank pulley is the smallest sprocket on the system you can skip a tooth here easy. I'm wondering if you even know that there is a mark on the crank sprocket that is supposed to line up with the crank mark on the belt. I say that because the mark is easily covered up by 20 years of dust. You'll need to clean the outer face of the crank sprocket with a tooth brush while it's off the engine. You will be able to see the mark then. When I do the timing belt jobs on these cars I leave the lower timing cover and harmonic balancer off until the hydraulic tensioner is installed and all marks are checked. It appears that you have already reinstalled the lower timing cover and harmonic balancer. I think you must have done that because you think the mark on the balancer to the lower timing cover is what you need to be checking against. Not really... Not when you have a belt with marks on it. That balancer mark should be verified after you've installed and tensioned the belt.
If I were you I would remove the balancer and lower timing cover. This may sound like a waste of time to you but you're better off doing it this way. Trust me. You don't want to put the entire thing back together and have it run like garbage. Then you're doing the entire thing all over again. Take it all back off, clean the sprocket, line the marks on the crank sprocket and belt then route it over the drivers side cam, under the water pump, around the passenger side cam, then install the tensioner pulley. Sometimes the cams like to spring a tooth or two one direction of the other that you need it so put a breaker bar and socket on the cam you're working on so you can rock it back and forth if need be. Once the belt is routed and the tensioner pulley is installed visually check all 3 of your belt marks to sprocket marks. Check it again, then check it again, and maybe again if you have time. Then install the hydraulic tensioner, pull the pin, and install the lower timing cover and balancer. Install the balancer bolt loosely. When the balancer bolt tightens just keep going and bar the engine over two full turns. Line the balancer mark up with the zero on the timing cover and get on a level plane with your cam sprockets and check your timing marks. The marks on the belt are useless at this point.
Questions? Check my tutorial that I created that dicer linked to. You may see some more pictures that are helpful to what you're trying to figure out.
Last edited by Banshee365; 04-23-17 at 08:28 PM.
04-24-17, 05:08 AM
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Okay, I will check the crank sprocket. I thought I saw a mark, but it wasn't very clear. Does it just pull off the crank, or will I need to use a puller of some sort to get it off and clean it?
If I can easily get it off, I will pull the crank pulley sprocket and paint a bright line on that tooth/dot.
Your tutorial is much better written. Much appreciated. I quite like this car and would be devastated to find out I destroyed it.
If I can easily get it off, I will pull the crank pulley sprocket and paint a bright line on that tooth/dot.
Your tutorial is much better written. Much appreciated. I quite like this car and would be devastated to find out I destroyed it.
04-24-17, 06:29 AM
#10
The crank sprocket slips right off with your hands. At most you may need a little coaxing from two flat head screwdrivers. Very light. Don't go nuts. I've never seen one stuck on there. It slips right on and off like the balancer.
04-24-17, 11:13 AM
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And it's keyed just like the balancer, then?
Okay. I will do that then.
So just to recap, one more time for the slow ones in the audience (I normally work on small block Chevys - this thing is a huge departure for me)
If I turn BOTH cams so those marks are in line on the sprocket and the engine itself, I can turn the crank to wherever I need and it won't damage the valves?
How do I know the difference between TDC on the intake stroke vs the exhaust stroke? I'm used to watching the rocker arms on a Chevy V8. How do I know this thing won't be 180 degrees out?
Okay. I will do that then.
So just to recap, one more time for the slow ones in the audience (I normally work on small block Chevys - this thing is a huge departure for me)
If I turn BOTH cams so those marks are in line on the sprocket and the engine itself, I can turn the crank to wherever I need and it won't damage the valves?
How do I know the difference between TDC on the intake stroke vs the exhaust stroke? I'm used to watching the rocker arms on a Chevy V8. How do I know this thing won't be 180 degrees out?
04-24-17, 12:15 PM
#12
I'm guessing either the wrong belt, or the crank pulley has spun or otherwise off... definately get to the bottom of it before firing it up. However I do believe 1994 and older engines are non-interference. 1995 and up is where things start grenading. Don't worry about 'stroke', you can't be 180 off with all marks lined up, just make sure everything is lined up belt marks and all - the marks not lining up are trying to tell you something.
Last edited by djamps; 04-24-17 at 01:18 PM.
04-24-17, 12:59 PM
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1995 and up are interference, and my car is a 1995. Sorry, I should have specified that somewhere in the post.
So if the marks are all lined up, it's for sure where it needs to be. I'm used to watching to know which valves are open. Never messed with OHC before - all new territory to me.
So if the marks are all lined up, it's for sure where it needs to be. I'm used to watching to know which valves are open. Never messed with OHC before - all new territory to me.
04-24-17, 01:22 PM
#14
1995 and up are interference, and my car is a 1995. Sorry, I should have specified that somewhere in the post.
So if the marks are all lined up, it's for sure where it needs to be. I'm used to watching to know which valves are open. Never messed with OHC before - all new territory to me.
So if the marks are all lined up, it's for sure where it needs to be. I'm used to watching to know which valves are open. Never messed with OHC before - all new territory to me.
I suppose you could find TDC manually by pulling the #1 spark plug and probing the cylinder, but it'll be a pain and possibly dangerous with the belt already off being an interference engine. My guess is the crank pully is spun, given there have been several threads depicting the pully actually falling apart.
04-24-17, 01:59 PM
#15
I will reply with the info you need tonight. Sorry, but I'm out with the wife and don't feel like typing that much on my phone. I've got your answers but just need the keyboard to put it into words.
I doubt you have any issues with your balancer. You're just off on the teeth. The balancer marks are used to check timing one last time, not set it.
I doubt you have any issues with your balancer. You're just off on the teeth. The balancer marks are used to check timing one last time, not set it.