Violent engine shaking at startup. Miss fire codes all cylinders

That's a good attitude, pace yourself.

Too: near insurmountable problems often get whittled down, just by walking away for a bit.

Almost without fail the head gasket failures are at cylinders 1 and 2. EGR feeds into intake manifold at cylinder 4 end. I think there's a connection, but don't have enough brain cells to understand it.

 

I also locked the camshaft using the method suggested in the video. But looking back, it really wasn’t necessary and doing so adds unnecessary risk of damaging the camshaft or the camshaft cap. There is a specific order in which those bolts are supposed to be removed in order to gradually release tension from the valve springs.

On your crankshaft gear/sprocket, what is the current position of the dot? IIRC it should be just past the 3 o’clock position if you are at cyl #1 TDC. In all honesty, it probably doesn’t matter too much as long as the tooth on the crank gear matches up with the corresponding link on the chain. At this point moving the crank gear a few millimeters clockwise will likely put you in the position shown in my picture.

When you have the engine mostly reassembled, leave the valve cover and the crank pulley off and rotate the engine until the colored links line-up again. Then install the crank pulley and make sure the mark on the pulley corresponds to “0” on the timing cover.

Good job with the cleaning. Your head gasket appears to have failed in the same place as mine. Did you purchase the overhaul gasket kit from Toyota or are you going a la carte?

 

Toyota FIPG 103 would be ideal, but in its absence, you can try Permatex Right Stuff:

Permatex® the Right Stuff® 1 Minute Gasket™ Maker - Permatex

The Ultra Black RTV will probably work but it has a long curing time and the instructions call for a re-torque.
https://441py33rout1ptjxn2lupv31-wpengine.netdna-ssl.com/wp-content/uploads/tech_docs/tds/82180.pdf

 

Here is what I can think of:

- Rotate the crankshaft to Cyl #1 TDC and confirm the piston for Cyl 1 and 4 are both at the same height. Do the same for Cyl #2 and #3. This is important to confirm that you do not have any bent connecting rods. It appears that bent connecting rods are not uncommon on these engines if there has been coolant intrusion. If the head is already back on I suppose you can use a depth gauge of some kind.

- Place the hydraulic lifters (valve lash adjuster) into an oil bath. I did not do this and my engine knocked/rattle for a few minutes during the initial start-up. I heard that air can get into the lifters as the oil leaks out, which may explain why the engine was noisy for several minutes.

- Clean all of the surfaces really well (no traces of prior RTV). The aluminum is very soft so I used CRC gasket remover and plastic razor blades.

- When installing the timing chain, it is similar to installing a timing belt where one side is the tension side and one side is the slack side. The right side (facing the front of the car) will always be tensioned even when the tensioner is removed.

- There are two bolts going thru the water pump which will benefit from having RTV.

- There are several o-rings which can get lost or displaced during disassembly. I also found these o-rings to be super hard so I highly recommend replacing of all of them. If you purchased the engine overhaul gasket kit from Toyota all of the o-rings are included. IIRC there are three o-rings behind the timing cover (1 large, 2 small), two o-rings on the outside of the timing cover for the oil filter housing, and two o-rings on the camshaft bearing assembly (1 very large one, and one tiny one that is probably stuck to the valve cover).

- Remove the oil pressure switch from the timing cover, clean and reinstall the switch with new thread sealant prior to reinstalling the timing cover.

Glad to hear that you were able to leave the exhaust manifold in place. To me it looked easier to remove the head and the manifold together, but I will keep this in mind if I get an opportunity to do another one.

 

Got it. Did you get the OE Toyota head gasket or a Fel-Pro?

You can take them to a shop to have them professionally cleaned and flow-tested, but since you are going the economy route, I would skip this step unless you are having issues.

 

I went ahead and looked up the critical o-rings I mentioned earlier. Please have your parts department double check fitment by your VIN, but I think these part numbers should be correct:

Camshaft Bearing Oil Hole Gasket (big one): 11159-37010 $5.34

Camshaft Bearing Cap Oil Hole Gasket (small o-ring): 90430-10024 or 90430-A0001 $1.72

Oil Filter Housing to Timing Cover O-Rings: 96723-24020 (need 2) $3.45/ea

Small O-Rings on the side of the Cylinder Head: 96721-24015 (need 2) $3.59/ea

Large O-Ring on the Engine Block: 96723-24020 $3.45

According to partsvoice.com, these are all normal stock items at my local dealer(s) so hopefully they will have them in-stock for you as well.

 

I have heard good things about Mahle on Euro cars, but I have no experience with them on Asian vehicles.

I used these diagrams:


CYLINDER HEAD. For 2011 Toyota Prius Hatchback HYBRID | Village Toyota Parts



CYLINDER BLOCK. For 2011 Toyota Prius Hatchback HYBRID | Village Toyota Parts



OIL FILTER. For 2011 Toyota Prius Hatchback HYBRID | Village Toyota Parts

 

Be sure to also replace the spark plugs. Coolant contamination fouls them and this will cause misfires.

There is increasing evidence that a failed or intermittently functioning electric engine water pump contributes to the head gasket failure. If yours is still original at 206k, it is a very good idea to replace it. RockAuto sells the Aisin WPT190 for $237 and it is the exact same pump as the one sold in a Toyota box. I know you are on a budget but a flaky water pump can/will cause a repeat head gasket failure.

 

Not sure on testing the pump. Perhaps @Raytheeagle may have some ideas.