When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
A few questions:
We replaced the timing belt on my son's '07 TL last night and now when it starts it sounds like the valves are making an enormous racket.
The old belt was extremely loose, as in we were able to pull it off without even messing with the tensioner! If someone had the valves adjusted while the belt was that loose, would it cause them to be that far of as to knock with a new belt?
We were extremely careful about making sure all of the marks were lined up, and after tearing the covers off again, they still are.
I noticed that when the crank is pointing correctly, the front cam gear can be at either 1 or 5. Is there some way to double check that cylinder ones valves are in the correct position? I used a plastic straw in the spark plug hole to make sure the cylinder was at TDC, but do not know how to check the valve positions without removing the valve covers.
Well, if you started it and it was at the wrong position to begin with, it's probably too late, sadly.
About the belt being loose...I'm not sure but that doesn't sound normal. I guess technically if you'd rotated rear cam forward you could have moved it enough to create the slack in the belt...
A few questions:
We replaced the timing belt on my son's '07 TL last night and now when it starts it sounds like the valves are making an enormous racket.
That doesn't sound good. You probably have something off.
Originally Posted by mising
The old belt was extremely loose, as in we were able to pull it off without even messing with the tensioner! If someone had the valves adjusted while the belt was that loose, would it cause them to be that far of as to knock with a new belt?
Not as long as all the timing marks still lined up. Did all the marks line up before you pulled the old belt off? It's really hard for me to believe that the engine even ran with a belt that loose. I would have thought it would be slipping teeth left and right.
Originally Posted by mising
I noticed that when the crank is pointing correctly, the front cam gear can be at either 1 or 5.
No, both front and rear cam sprockets should only be at TDC with the crank white mark next to the triangle (pointer).
That doesn't sound good. You probably have something off.
Not as long as all the timing marks still lined up. Did all the marks line up before you pulled the old belt off? It's really hard for me to believe that the engine even ran with a belt that loose. I would have thought it would be slipping teeth left and right.
No, both front and rear cam sprockets should only be at TDC with the crank white mark next to the triangle (pointer).
Thanks for the quick response!
The engine ran fine before but was well overdue for a belt change and had an odd squealing noise that we traced down to the front cam sprocket area. We had already replaced the accessory belt and tensioner.
The marks were off by maybe a 1/2 to a full tooth off with the old belt. The old belt had a good bit of play between the front cam sprocket and the water pump pulley.
We made sure to turn the engine over by hand several times (the recommended 6x plus a few more for good measure) before putting all of the covers back on to ensure that there there was no interference and that the markings remained lined up. If there was valve interference, wouldn't it be noticed while hand turning the engine?
Just really stressed right now.
I have done several timing belts and chains in the past, but have never run into anything like this where it actually runs worse afterwards.
I know if you were seeing 5 on the front cam sprocket when the crank was set at TDC, then you have the front crank off by 180 degrees.
Is there a way to check this?
The only thing I can think of is that we were both working on it and one of us may have turned the crank, extremely unlikely though.
I just noticed that as I was turning the engine over, the #5 would line up with the mark on the front cam sprocket, the crank would be lined up, but the rear was not lined up. When the cam sprocket #1 is lined up, all three are lined up perfectly.
I am getting the feeling that we are at least going to have to pull the valve covers so that I can see what the valve positions are during the cycle.
I will have to double check again tomorrow, but we checked the timing marks on the crank pulley after the initial start-up, and with both of the cam sprockets lined up, the timing marks were at about 11:00, or about an inch and a half before the arrow. Without turning the engine again, we removed the crank pulley and it's sprocket was still lined up with the arrow on the engine case. So everything is in line except the marks on the balancer. Not a good sign, I guess?
I will have to double check again tomorrow, but we checked the timing marks on the crank pulley after the initial start-up, and with both of the cam sprockets lined up, the timing marks were at about 11:00, or about an inch and a half before the arrow. Without turning the engine again, we removed the crank pulley and it's sprocket was still lined up with the arrow on the engine case. So everything is in line except the marks on the balancer. Not a good sign, I guess?
No.
And you may or may not have bent valves and/or piston strike damage now.
And you probably know this, but you didn't need to remove the crank pulley to verify if the crank sprocket was set at TDC. If the pulley marks line up, then the crank sprocket is lined up.
Did you follow the service manual procedure for installing the belt? e.g. idler pulley bolt installed loosely, belt installed starting at the crank sprocket and moving CCW?
Keep your fingers crossed. Good luck...
Last edited by nfnsquared; 01-10-2016 at 11:02 PM.
For 1 full turn of the crank gear, the cam gears only turn 180 degree. So you have to have 2 full turns of the crank before 1 full revolution of the cam gears happens. All 3 marks should line up on their perspective arrows after each full 2 turns of the crank. Did you make sure of this by turning the crank 6 times? Turning the crank 6 times clockwise, you should have all 3 marks line up 3 times. It is very easy to be 1 tooth off because the new belt is tight to put on. I did not touch the cam gears at all during the belt install. I don't agree with turning the cam gear forward a little bit with a wrench to get the belt on. Instead, I loosened the front idler pulley and water pump, routed the belt through the front cam gear, tightened the idler pulley, then routed the belt over the rear cam gear, then tightened the water pump all the way. You just have to loosen the water pump bolts a tad and the belt will go over the rear cam gear.
For 1 full turn of the crank gear, the cam gears only turn 180 degree. .....
Yeah, I guess that's right. Wonder why the service manual doesn't allude to that. The way it's written, it could make you think the belt was on wrong, e.g. "5" is at TDC on the front cam sprocket after one turn of the crank...
The SM pretty clearly says if you don't see a "1" at TDC on the front cam pulley when the crank marks are lined up, the belt is on wrong...
Thank you everyone for the help! I am going to try and get this checked out tonight. Since it seems like the crank and/or cam gears are out of spec, what is the best method to get them lined back up without further damage?
Thank you everyone for the help! I am going to try and get this checked out tonight. Since it seems like the crank and/or cam gears are out of spec, what is the best method to get them lined back up without further damage?
You might be able to get away with just removing the tensioner (you'll have to compress it in a vice and reset the pin before reinstalling) and loosening the idler pulley. (Set the crank pulley to it's mark first).
At that point, there might be enough slack in the belt to pull the belt off the cam gears one at a time (or both at the same time) and move the respective cam gear to TDC before putting the belt back on the cam gear. IIRC, you said both cam TDC marks were at 11 o'clock previously? Just put a wrench/socket on the cam gear bolt and turn the cam gear clockwise until the TDC mark lines up and then put the belt back on the gear.
Then tighten the idler pulley bolt and reinstall the tensioner and pull the pin.
I might be missing a step in here, but this procedure would allow you to fix the issue without having to remove the crank pulley again.
Last edited by nfnsquared; 01-12-2016 at 01:38 PM.
OK, I finally was able to go out and recheck and everything is lined up properly.
The issue I had with the crank alignment was user error.
What was causing my confusion was that I was looking at the wrong pointer on the cover I did not see that one when the accessory was on (thank you nfnsquared for the shop manual diagram of the cover), so it IS still lined up correctly- see pics below.
The belt hasn't been removed since we originally put it on a few nights ago.
I am really at a loss now as to what could have happened. I lined everything up, rotated it 6x and it is still lined up.
12-30-2015, 09:46 PM
