2012 Prius - The Good Ol' P0301 Gremlin!!!

Yeah, it is an old trick. I did the same thing when I did the HG on my 2000 Ford Ranger. I have this hammer handy and it is one of the tools I have laid out for the job.

Thanks! Looks to be a pretty straight forward job. The hard parts appear to be the driver side with getting to the hoses. Hoses always tend to be a PITA. I have all the steps laid out and will adjust them as I go along and post them here.

I suppose I can list some best-practice-before-you-start things that I have thought of for a laymen. Mind you, a professional mechanic shouldn't/wouldn't need to do most of these things. This is for the laymen/DIY'er:

1. Buy paint pens in at least 3 bright assorted colors and label:
   • each ignition coil
   • fasteners of components that are known to be of different length than others and label the location they are to be re-installed into before going into remove them (if possible)
     
   • find ground wires to ICE, clean area where fastener is attached and number the fastener location, then use tape and label the corresponding wire
2. Buy painter's tape for labeling
3. Pre-label ziploc bags to contain fasteners for each component they are to be removed from
4. Print out torque specs and sequences. Have tape handy to hang them to underside of hood or where ever they need to be for reference
   
5. Itemize all electrical components that are to be disconnected in a spreadsheet, give them a unique numeric value. Print out that spreadsheet. As they are disconnected, use tape to label the connector what that unique value. Now you know where it needs to go in case you pull the harness back into position and things end up short
   
   • Do something similar with vacuum hoses and coolant hoses (probably won't need a spreadsheet. Tape should do
     • Use a different color paint pen for coolant hoses vs. vacuum hoses vs. fasteners
6. Ensure you've acquired replacement fluids and replacement parts: spark plugs, gasket kit (of course), RTV normally, but in this case the proper thing is to use FIPG, oil filter
7. Ensure you've acquired all specialty tools: i.e. head bolt socket, oil cartridge wrench, straight edge, pry bar/tool, mechanic's wire
   
8. Find a big sheet of cardboard for under-layment; the more the better in case of a nasty spill. An remnant sheet of linoleum works even better
   
9. Have wheel chocks ready. I'll be doing this on an inclined driveway
   
10. Have floor jack and jack stands ready, along with wood block handy as you will need to raise the engine up on re-assembly
    
11. Have all cleaning suppliers and tools handy: brake/carb cleaner (I bought 10 of them), razors for scraping gasket material, denatured alcohol, shop towels, rags
    
12. Charge all power tools
13. Have containers or boxes to hold parts removed in order
14. Have containers for fluid disposal
    
15. Lay out all tools for the job on bench/cart/in boxes/on a tray so you can get to them quickly instead of fumbling for them
16. Have gloves! When I removed the fan from my Ford Ranger, I scraped the top layer of skin off the back of my hand. Wasn't deep enough to bleed. But was deep enough to leave a huge scab and a scare that took a whole year to fade
17. Have requisite clothes ready. Long sleeves are preferable as you might get scraped up
18. Check your steps sheet and print them out
    
19. And most importantly, schedule time to do the job. Don't let this be a weeks or month long project. Get it done in one go.

I have this scoped for my skill level at being a 6 hour job of straight through work IF I was just replacing parts and given my skill level. But I am going to complete it over 3 days because I will have to clean parts myself and let them dry. Some parts are going to soak overnight for cleaning. The last day is dedicated for re-assembly.

 

I put this off for a while because of the holidays and because it was cold (low 40's/1st world California problems). Started back at it today, but hit an unexpected snag/red herring (explained here).

There is a coolant leak somewhere. Hope it is from the blown HG or a hose and not a cracked engine. The wire harness is off and I taped off the receptacles for the AC compressor and water pump so no coolant can spill into there causing permanent damage. Something I learned from one of the Youtube videos. That is all I'll do today as a result of the delay. Will set a goal to have the tear down done tomorrow, so the parts can come out to be cleaned. With the proper power tools, this job does not seem hard at all.

 

I mean to say, the coolant is leaking out of the engine to the pavement. The coolant tank has ran to empty. So obviously, there is a significant coolant leak. Hoping it is a hose or that it is coming out of the blown HG.

I don't have a pressure tester and am too far into the disassembly at this point to even use one if I did. I'll just have to keep an eye out for it during disassembly and cross my fingers that it is not a crack in the lower engine.

So this is where I am at. Also at this point, I feel I am on a suicide mission. My engine may just be kaput. A few things makes me think this:

1. I have significant coolant leak somewhere in the middle/back of my engine bay. There are no coolant hoses there. So the only repairable source would be through the HG out of the back of the engine. But it could very easily be a crack in the lower engine.
2. When I went to manually turn the engine to TDC, I felt some tension and some kickback right as I got to TDC
   1. Is this normal?

 

That makes sense. I guess I will find out pretty soon. The head is just about to come out.

 

I am getting ready to put this baby back together today. But I can't seem to find torque specs for the chain guides. Can anyone help?

 

Yeah, I can't find torque specs on these and the other chain guide anywhere.

 

No worries, It isn't sealing anything. Doesn't need to compress evenly I'd imagine. I just went for snug.



This is what my HG looked like. Clearly there was failure between cylinder 1 and 2. When the head came off, there was no coolant in the lower engine. Cylinder 1 and 4 were at TDC and were at the same height. Cylinder 2 and 3 were slightly off Is that expected? The engine never overheated and there was no warpage on the lower engine or the cylinder head.

Also, as you can see, there is no failure in the back of the HG. So the source of the coolant leak was not likely the HG, which is a relief (I think). There was some pooled coolant to the back driver side of the engine, under and a little bit back from where the EGR is. I don't remember when I removed the EGR coolant spilling out at all. So I don't know how the coolant got there, unless it came from a hose in the EGR system after I removed it when I wasn't looking. I did not see any evidence of coolant spilling out from the back of the engine, so likely no crack there. Wherever the coolant spill is, it came from somewhere above the transmission, to the driver side of the engine, and under the EGR. Inverter levels are good, so I suspect exhaust gas pressure in the coolant system caused a rupture in a hose or an eruption from the coolant connection. I saw no evidence of rupture on the hoses either. I'll leave the splash panel off for a few days to see if I can reproduce the coolant spill and look under the car to see where it is dripping from.

I cleaned the cam cover and the timing chain cover and am waiting for them to dry. The chain is wired up so that timing doesn't slip a tooth. I'll replace the gaskets in both of those systems tomorrow. Will replace the gasket for the timing tensioner. Then I'd imagine it is all downhill from there.

I learned tons. The biggest pain was removing the harness. I'll remember to sum up the experience once this is all done.

 

Yeah, at TDC with the head off, 2 and 3 looked off by eyeball test.

The head is back on now, so I'll rotate again after the timing cover is back on and measure the piston height on cylinders 2 and 3 when I rotate them to the top of the stroke. I should have done that when the head was off. Report back then.

 

What I meant was the source of the external coolant leak (coolant spilling onto the pavement) was not the head gasket. Clearly, the HG failed between the coolant passage and cylinder 1. Hence P0301.

But you can see, the outer back areas of the HG are in tact.



Coolant was observed to be pooled in the area encircled in purple. This leads me to suspect the source of the external coolant leak is a hose issue.

QUESTION: How many turns does it take for the engine to return to TDC from TDC? I will manually turn the engine half that amount so that cylinder 2 & 3 are at the top of the stroke to see if I have a bent rod in those cylinders.