2013 1.8l Prius cylinder head gasket replacement

https://photos.app.goo.gl/6PyDKP9dMibKP23z8 If I did this correctly, you can see the top of the old head gasket here which I believe is the factory item plus 145,000 miles. Note the gas blow-by, especially near cylinder 1. Also, original finish has flaked off in a number of places but none of the breaks common in more compressible gaskets. The burned areas touch a number of oil or coolant passages.

Thanks for the ideas. I'm not taking it apart until I pressure test the cooling system and do an engine compression test. Regardless of what the felpro guy told me, I keep thinking an excessively smooth cylinder head might not correctly mate with the gasket.Otherwise, it really makes no sense to have the lower end of the average roughness specified in the manual. I was also told that quite a few race teams use the 3 layer metal gaskets over and over again unless they develop defects.

On the subject of head bolts, I told him I had removed them since I failed to put oil on the threads initially. He said he wouldn't have worried about that at all. He said the initial torque (36 ft lbs if I recall correctly) is a baseline torque and oil either present or absent makes very little difference on clamping force at that torque level. The 90 and 45 degree turns are unaffected. He said they'd done quite a bit of testing relating to clamping force on gaskets and his guess is that my situation is not related to either a gasket or bolt problem. I hope a few more diagnostic tests, which I should have done in the first place, will help narrow things down.

 

I'm reading about oil coolers and that sometimes coolant can get into oil if the oil is cooled by engine coolant.

 

I'm thinking I can probably convince Felpro to give me new gasket and bolts. Felpro said however that the 3 layer metal gaskets don't have the compression issues that older gasket types do. I've changed numerous gaskets but this is the first three layer metal one I've seen. First Prius too.

 

So I'm planning to do a cooling system pressure test and an engine compression test to try to help pinpoint the Prius problem. Of course the plugs are the wrong size so my compression guage doesn't fit and the coolant cap is the wrong size so it won't fit the unit I rented from the auto parts store, even with the extra adapter I got. Oh, and the guy at the auto parts store says he only knows of one other car in the world that has this size spark plug thread!!!!!!

 

Now, there was a spark plug adapter in a 50 dollar compression test kit but the hex nut on it will never fit in the spark plug tube! I guess what's needed is a threaded male fitting on a 6 inch narrow tube with female threads on the top end.

 

Thanks.

Thanks. Wonder whether a little blue loctite on the threads would work? Also, any ideas on the coolant reservoir adapter? I really would like to get an idea on that leak possibility as well.

 

Yes, there is a little o ring so it doesn't need to be that tight to work. In fact, mine has a secondary o ring and a second set of threads on an adapter that fits to the rubber hose so that sometimes the first piece remains in the plug hole when the hose is removed. If that's what the other poster was talking about, then a littlw grease only on the first o ring is a solution. I would not suggest loctite on the first threads but maybe on others closer to the compression guage.

 

One more compression test question:

If the car is in test mode, can the start button be used to crank the motor in a compression test?

 

I got this procedure from manual for entering test mode. I'm guessing that if this procedure is followed with ignition and fuel delivery disabled, then the engine would crank but not start and if a compression guage was used in each cylinder separately, cylinder compression could be tested.

(1) Turn the power switch on (IG). (2) Fully depress the accelerator pedal twice with park (P) selected. (3) Fully depress the accelerator pedal twice with neutral (N) selected. (4) Fully depress the accelerator pedal twice with park (P) selected. (5) Check that "MAINTENANCE MODE" is displayed on the multiinformation display. (6) Press the ON switch with brake pedal depressed. (I don't have the Toyota ScanTool or the toyota software.)

 

So I'm getting ready to do the prius leakdown test. Got the kit 27138 from Autozone and neither of the adapters fits. The peeps at Harbor Freight have spark plug adapters in a kit as small as M8 so hopefully they'll have what's needed. Wow!!!!!!

 

Thanks for the additional info. I think my kit has a space for the smaller adapter but alas, it's missing. I did find the adapter in a kit from Harbor Freight which actually includes one even smaller than the one needed, for a total of 4 adapters. I didn't have a spec for the diameter of the bolts above the threads so will check that if I pull them out.

 

Leakdown test completed...sort of.

I hooked my compressor up to each individual cylinder separately with the cylinders at TDC on the compression stroke. I allowed the 3 gallon tank to fully fill with air, 110 psi. Then, after connecting the air line to a cylinder, I listened for air leaks while timing the air loss down to a reading of 90 psi. For cylinder 1, I couldn't hear any leaking air and it took 4 min 50 seconds to reach 90 psi. Cylinders 2, 3 and 4 took 1:30, 1:45 and :47 respectively and I was able to hear air leaking into the valve cover through the oil cap opening. After that, I hooked up the coolant pressure tester at 15 psi. This value decreased to 5 psi within 10 minutes. As I mentioned previously, in this situation, the coolant seems to be mixing with oil and coolant as well as broken down oil is present on the dipstick. Additionally, small bubbles are visible under the oil cap in the mixture of oil and coolant. It seems to me that there is a coolant leak AND a combustion leak or leaks.

Felpro told me that the bolts I used were within spec, at least for length and that re-installation of the 3 layer metal gasket was not going to cause a problem being installed for a second time. I'm not sure where to go at this point but guessing I might see the problem when the cylinder head is removed again.

 

The real danger is in the high voltage battery in the rear of the car, driver's side. Check owner's manual for safety information. I personally think you're fine by disconnecting the small 12v battery in the rear, passenger side. If you mess with the high voltage battery or any of the orange cables leading to the front under hood area, you could die. And whoever tries to pull your body away from the car could as well. There is a safety disconnect plug (orange) on the side of the high voltage hybrid battery if you're doing anything with that system or if you want to completely disable that but even removing that, it makes sense to wear high voltage insulated gloves. There is nothing wrong with rotating the crankshaft manually as it's part of a regular 1.8l DOHC Toyota Engine.

Your best clues to head gasket problems will be oil mixed with coolant, small bubbles in oil under the oil cap, overheating, rough running, especially on cold startup, etc. Look under oil cap, pull the dipstick. Oil that looks like a chocolate milkshake means coolant has mixed with the oil and that reduces lubrication properties in the oil which can lead to engine damage. If you see small bubbles under the oil cap, combustion gasses are leaking from the cylinders into the oil. If you see really dark oil on the end of the dipstick with lighter fluid up higher, there's coolant in that there oil.

In fact, all the problems that head gaskets cause in other types of cars can happen in the Prius. If you can put the car in test mode, you can do a compression test or you can do a leakdown test which can be even more helpful. Spark plug (and windshield wiper/cowl assembly too!) removal is required for both. If white exhaust smoke is present, the head gasket, or maybe the cylinder head itself has a problem as coolant is being burned in the combustion process.