2010 Head Gasket replacement - questions before reassembly

Was able to find time to replace the O-ring tonight... reset code but the P0016 was immediately present as a "pending" code after I started it up again.

Mr. F, I have been wondering that, and it seems to me that what you're saying could possibly be true. Highly unlikely but possibly true. I was hoping not to take the timing cover off again, since I have to drain the coolant, but I guess I gotta do what I gotta do. A new chain and the lower guides is $311 plus shipping from Lithia. Won't be the end of the world. I'm sure I can find the procedure to measure chain stretch in Mendel's signature but if you happen to know where it is, let me know

 

Yeah, I checked and it's not in there unfortunately

 

Is that from tech stream, @rjparker?

 

Where does one go to find the repair manual -- is it what you have to pay the subscription to Toyota for? I was unable to find it by searching but I didn't pay the subscription to Toyota to look there either.

 

Ok! So today I put the car in the air again and pulled the valve cover and crank pulley. I checked timing again and it was off a tooth on the crank pulley! I hadnt realized you could see the yellow link when the crank pulley was off. I had simply put the crank pulley to TDC and then checked the top two painted links. And it turns out, you CAN indeed have the bottom link off a tooth while at TDC and having the painted links in the correct positions on the cam sprockets. This is because without any marks on the head to line the cam sprocket marks up against (per our long and drawn out discussion), the painted links might be in the right place on the sprockets, while the crank is at TDC, but it doesn't mean the cam sprockets are in the right place. Verification of the painted link on the crank sprocket must also be made in order to time the engine correctly.

So - After this discovery, I unfortunately learned that there is enough room to move the chain one link on the exhaust cam sprocket, but not on the intake cam sprocket (and you certainly can't move it on the crank sprocket with the timing cover on). So I had to take the timing cover off again, drain the coolant, and lost about a quart of oil when taking the timing cover off too. Added a couple hours of work. But when I got it back together, no codes! And no pending codes either! (It had always had the P0016 as pending as soon as I reset it, previously.) I havent driven it yet but got it all buttoned up, with the wipers back on and ready to drive in the AM.

I am super happy I didn't need to buy a new timing chain. At least not yet. It's possible that I installed it wrong, or it's also possible that it skipped a tooth because it is worn out and if it's the latter, it would probably happen again. I'll find out shortly I suppose.

Looking forward to driving this baby a lot this week! And now I can move into my next project, a homemade battery reconditioner!

 

Yes, I removed the tensioner and then I even loosened the exhaust cam sprocket bolt, to get even more clearance. I worked at this for almost an hour before I gave up. I don't believe there is physically enough clearance between the intake cam sprocket and the timing cover to move the chain, even if you had it completely slack.

 

Just drove it around town for a bit, no codes, and it drives super smooth. It's definitely a little bit quieter. If I had driven a Prius for more than 10 minutes before I started it back up, I would have been able to tell, but I thought it was just a raspy motor. A bit quieter now!

 

Report after two weeks of driving: car runs great! Battery seems to hold a pretty good charge (Dr Prius says 59%), mileage on first 200 miles was 42.5, and this tank is looking more like 44 so far. The car drives really smooth, for something that has 263k miles now, it feels like a much newer car. No more check engine lights after I got the timing on straight. It's also quite fast for such an economical car. I'm really happy driving it and my kids like it too.

I need to repair the paint on the roof, because it has cracked pretty bad and if I didn't live in the desert it would probably be very rusty. And I am trying to fix the CD player, which won't load any CDs. But the nav and backup camera work great. And I am also collecting parts to build a homemade battery reconditioner.