Is my head gasket bad?

It sure sounds like it, but I'm not that knowledgeable, more mechanically inclined, like @danlatu will hopefully weigh in.

How many miles on it, and have you cleaned the EGR circuit? A clogged EGR will lead to higher engine temps I think, which doesn't help matters.

 

Watch @NutzAboutBolts videos, pinned at top of maintenance forum.

Still, sounds like HG is leaking, EGR clean is always good but won't reverse things.

Good luck.

 

If there’s a coffee and milk coloured stuff in the oil refilling cap present, its gonna b a head gasket issue. Getting worse in cold weather. Engine should deal with this, but expect higher mpg⛲️

 

Pull of windshield cowl and have everything ready to pull plugs. Run engine till engine is warm/195 degrees or so. Pull plugs immediately. You should see which cylinders are wet. The reason the engine is shaking is due to the increased compression and imbalance of combustion. Engine misfire is due to fowling plugs. It does sound like you have a blown head gasket. Continued use of motor with these symptons with bend/throw rods and pretty much destroy the engine. I would start looking for a used motor. Replacing the head gasket is cheap if you do it yourself 60$ for head bolts and a head gasket. The labor it takes to replace this is very very high. That is why the dealer charges so much. If you do it yourself, any mistakes can result in pulling the motor and doing it again. Did your car have new plugs changed @ 100k? changing them @ 180k is not good.

If an oil catch can was installed at lower miles, I believe you would have avoided a head gasket failure.

 

Well, I don't think anyone really wants to say yes, the HG is toast. I don't either but I'm thinking the chances are somewhere around 100-110%... The mileage, the symptoms, the zero EGR circuit cleaning... It's pretty textbook, aligning perfectly with what we've seen become a VERY common story over the past ~2 years. Plenty of miles (sweet spot, actually) for the EGR issue to have cooked the HG itself, but certainly the overheats could have pushed it over the edge. It certainly could be argued the overheats WERE the problem, too, but there is plenty of data around here to suggest it isn't water pumps that kill turd gen engines. You won't necessarily see coolant in the oil, either. I'm pretty sure coolant to crankcase is not typically noted.

I'm not sure I'd bother with the EGR circuit clean to run on the current engine unless you decide to keep and repair it. If you do a donor engine or buy another turd gen altogether, salvage the entire circuit from this engine to have for future swap-outs. Several of us here keep a spare EGR valve and cooler, then just clean the intake manifold and EGR pipe while performing the swap. You could have a spare intake manifold and EGR pipe, too, and lose zero time cleaning when you did a future swap. And if you do a donor engine, it would be a great idea to make sure the EGR circuit is cleaned before the engine goes in the car. Low-mileage (under 75k miles is my thought) is a good idea for the donor, so you don't end up putting another carbon choked EGR engine right back in.

 

Whoops, never mind...Dan said it while I was typing my reply..

 

I had same symptoms as you described. However, I never had overheat issue. Only noticed knocking during last summer when driving hard in hot weather for a while. After that misfires started after overnight and then more frequently after every stop longer than 15-20 minutes with loss of coolant. I removed the coolant seal on the coolant cap to not have any pressure in the cooling system and the misfires went away. Now that I fixed the head gasket, cleaned EGR cooler, and installed oil catch can, everything is running super smooth. One thing you can also do is look into the combustion chamber with one of those cheap USB borescope to see any water leaking to confirm.

 

@Joele3 has done this recently with some success .

Maybe he’ll share some insights .

 

Yes so far it seems to be working. I had gas engine water pump fail. Not long after knocking at start up. Check engine light on multiple misfires Cylinder 1 and 2. I replaced spark plugs, swapped coils from 1-3 2-4. Cleaned intake manifold, all of the EGR plumbing. Misfires stay away for around 900 miles. Knocking came back right away. My coolant level was still dropping, very minor. I was watching videos of the knocking, reading comments. One user said he had success with K seal and to let it sit for 24-48 hours. I poured contents into reservoir tank. I was concerned it would just sit in the tank and not circulate around cooling system. I then drove home from work (30min drive) spirited driving with the heater on full blast. Got home parked it. I let it sit for 27 hours drove it around and been driving it to work 6 days a week 75 miles a day. Not one knock at start up and the misfires cleared on its own. My coolant level seems stable. This was 2 weeks ago. Keeping my fingers crossed.

 

My sisters 2010 did the same thing at the same amount of miles that you have. Probably would have tried some liquid head repair if it wasn't for the engine drinking oil on top of the coolant.

We reaplaced the engine ourselves.

 

If the coolant tank is pressurized when you pop the top, then combustion gasses are leaking into the water and there is nothing your going to put in the water that will stop it. If the metal gasket cant keep the gasses in additives are not going to help you. I just finished reringing my engine today. Jump in, the waters fine Good times!

 

If the tank is pressurizing your going to need a lot of luck. I just finished putting the camshafts back on mine. This engine is assembled with goo for gaskets which makes it painful. Combine this with manuals that don't make a lot of sense and my happy scale is just pegged. Good luck!

 

Can you offer an update? How long did the half bottle of gasket seal last? Did you end up replacing the HG after all? I just had this happen and I used a half bottle. The car is running great for now, but internet advice seems to be that it’s time to unload the car and cut my losses. 2010 Prius with 196,000 miles. It had pretty textbook misfires, white smoke, etc.

 

this is why i always buy new.

 

Sell or get new lower mileage engine

 

i have a 2010 Prius with 198,000 miles. Coolant in oil stick. Adding Bar’s Leaks Head Gasket Sealer today.