I have a 2012 Honda Accord EX-L 3.5 V6. Timing belt tensioner went bad. Lost all 3 cylinders on the back head. Put it at TDC on the compression stroke and the rear head is binding up to the point that I can't turn it beyond about 15-20 degrees. Beyond that it doesn't want to move. Any advice would be appreciated. 💀

 

Pull both heads, have them reconditioned, and put them back on. Yes, I know you're saying only the rear cylinders have an issue, but it is an odds on bet at least one cylinder in the front has some damage as well.

 

That's what I figured. Happened while I was driving. Check engine light came on, lost all 3 back cylinders, back pressure was running through the intake, etc. I didn't hear a bang but the back pressure was pretty loud, had no power so I limped it back home. Timing belt was loose on both cams at the center of the engine when I took the covers off. 💀

 

I got my son to help me find TDC but I think he has me on the wrong stroke because he said he felt pressure but the rear cam feels like it is pushing on the piston. He has no mechanical experience and I can't be 2 places at once. I just want to make sure the crankshaft is at TDC on the compression stroke before I remove the heads. Any thoughts? Thought about ordering a compression whistle and turning the rear cam backwards so I don't do any more damage when I turn the crankshaft. If it's pushing on the piston and I turn the crankshaft it could crack the piston. I'm doing this all by hand, I know better than to turn the motor over by the starter. That would be catastrophic. 💀

 

I think I'm overthinking this situation because as long as the piston is at TDC, the stroke it's on doesn't matter because the camshafts and valves and rockers dignify what stroke it's on. Sorry, it's been over 20 years since I've done this and I'm a little rusty. Now I feel like an idiot. Sorry to waste anybody's time. 💀

 

You are correct on the cams dictating if you are on the compression stroke, so you can pull the heads.

When installing the heads, turn the cams to get the valves to TDC> You can set the pistons to TDC based on the crankshaft timing sprocket.

 

I'm a little rusty since it's been roughly 20 years. I'm guessing that is when the timing marks are lined up on the heads with the valves closed? Please correct me if I'm wrong because I can't remember. The crankshaft is at TDC right now. I used a wooden dowel to verify that the piston is at TDC. 💀

 

Sorry about not getting back to anybody on here. I broke both of my arms. Lol. Just left my God Daddy's shop. Intake and valve covers are off. Crankshaft is at TDC and neither camshaft will turn at TDC. Seems like it would be cheaper to find a used engine than to remove the heads and take them to a machine shop due to not knowing if the pistons are traumatized by the tensioner letting go. I know I'm traumatized due to the fact that I'm still paying payments on this car. Not sure which would be the cheapest route. Any advice would be appreciated. Thank y'all and God bless. 💀

 

As a general rule, valves bend way-WAY easier than pistons damage. While I'm sure it is possible, I've never yet read where a Honda motor suffered piston damage due to a timing belt issue.

My advice, pull the head and either replace it recondition it.

 

shipo I really appreciate the advice. I had to heal before I could work on the car. 2 broken arms ain't fun. Lol. I used to be a tech but these Honda engines are different than what I am used to especially these IVTEC engines since I have never worked on one or worked for Honda. I haven't worked for a dealership since about 08 so things have changed. I will pull the heads since I am healed now and check everything. Since neither cam will rotate at TDC I know there is a lot of damage. I will get back to you and anybody else on this forum with what I find after I get the heads off. I'm just worried about what it's going to cost me since I'm still paying for this car. I have no problem doing the work myself. I really appreciate it. 👍💀