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carguy1, auto technician
Category: Toyota
Satisfied Customers: 25494
Experience:  25 Years experience all makes and models.Nissan factory trained,Certified Subaru Tech
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Might have a huge problem. Had a backyard mechanic change

Customer Question

Might have a huge problem. Had a backyard mechanic change the timing belt on my 2004 sienna and he let valve springs release on one side of the engine. I have little confidence he can get it right. Am I screwed?
Submitted: 2 years ago.
Category: Toyota
Expert:  carguy1 replied 2 years ago.

Hi there,

Do you mean the cam turned on him when trying to set up the belt?

Customer: replied 2 years ago.
I believe the valve springs were under tension and released when the belt was removed. He brought some other guy over and said the valves are bent and I need to replace the motor.
Expert:  carguy1 replied 2 years ago.


Usually you don't have to replace the engine when the cam spins out like this. I would need info on how they determined the valves were bent to be 100% on my answer, but personally when they aren't under load the engine is not damaged. By under load I mean running. This is a pretty common occurrence when doing a timing belt on a V 6 engine of any vehicle.

At the very least, I would put the belt on, start it and see how it runs. If it runs poorly then it is possible there is damage, but I find it unlikely to be honest.

Please let me know if there is any more I can do to help you from here.

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Customer: replied 2 years ago.
How do I get it back in place? I have seen a post for a 2006 sienna where they say move the crank 60-90 degrees, then reposition the cam. Which cam should be under load, the front or the back? Related post below...
Expert:  carguy1 replied 2 years ago.

I don't understand? You are trying to get the cam lined up now or the whole engine?

Customer: replied 2 years ago.
I would like to get the motor in a position so that the belt can be installed. To do this I would assume I would need to place one or both of the cams under tension, and place them at their correct marks. It might help if you call me.
Expert:  carguy1 replied 2 years ago.

I accepted your offer but for some reason your payment was declined.

What you need to do is set the crank at 60 btdc, this will prevent the valve from making contact with the pistons. Now, What you will do is rotate the engine clockwise until you feel it make contact with the valves, then back the cam off so the valves come back and rotate the engine, continue to do this until the engine is at the roughly 60 btdc. Next, you rotate the cams until their marks line up. Yes, one side will be loaded, sometimes its easier to get an assistant to hold this side in place with a wrench. Put the belt on the cams and line up the marks on the belt with the marks on the cams.

Now, once you get this far, rotate the crank until you are at #1 TDC, the mark on the cam sprocket should line up on the engine. Now you can slip the belt over the crank sprocket, put the tensioner on and once you have it all together, rotate the engine by hand 4 revolutions to make sure your valves are not making contact.

Customer: replied 2 years ago.
Cool, which cam should be under tension? The one closest to the firewall?
Expert:  carguy1 replied 2 years ago.

Not sure man, which ever one spun out on you when you took the belt off is the one that is loaded.

Customer: replied 2 years ago.
Really. Assume you don't know which one. How could one proceed from there?
Expert:  carguy1 replied 2 years ago.

I told you how to line up the engine for the timing belt. I am not sure what difference it makes as to which cam is under load or what you are even asking me to be honest. You are going to know which one is under load when you rotate the cam sprocket to line up the mark. One will have pressure on it, the other you will be able to move easily.

Customer: replied 2 years ago.
I will give it a try and get back to you.
Expert:  carguy1 replied 2 years ago.

Sounds good

Customer: replied 2 years ago.
Just to be clear is 60 btdc basically rotating from tdc mark right or left 60 degrees?
Expert:  carguy1 replied 2 years ago.

You want to go BTDC, so, if you are on the TDC mark, rotate the engine counterclockwise roughly 60 degrees.