[SOLVED for $0] -- 2010 misfire, stumbling, stuttering, coolant loss, head gasket, etc. symptoms

The only problem with this solution is that the coolant may boil. A 50/50 solution of antifreeze will not boil until 223F, but only if it is pressurized to 15 psi. By removing pressure from the system you are effectively lowering the boiling point to 212F.

The Prius normally runs at about 190F - 195F and the temp creeps up under certain conditions. 212F does not provide you with a very large margin.

 

LOL. He "invented" nothing.

Ever since the week after pressurized cooling systems were invented........about 100 years ago......mechanics quickly figured out that not allowing the system to come up to pressure would eliminate or minimize a coolant leak and allow you to still drive.......for a while.

 

You have the right idea but I think your numbers are off a bit.
I think 223 is the boiling point at one atmosphere (no added pressure) and with 15 PSI it goes up to about 240.

 

You’re right. That number should be a bit higher under 15 psi. I googled and 223F was the number I found, but it seemed a bit low for 50/50.

 

I would love to know if there was any side effects to this fix, I have 2012 PriusV I been notcing my coolant level has been dropping the car seems to struggle unless its in power mode can someone give definant answer to this problem everyone is facing it cant be just as simple as removing the orgin from the coolant resevoir

 

You are right. It isn't that simple.
Leaving the pressure cap ajar so that no pressure builds up is only an EMERGENCY measure to let you limp off of the highway and into a shop.
Doing that often results in a violent boil-over if you drive fairly hard and then slow down or stop.

There is no magic. If you have a coolant leak you need to find the leak and fix it right.
If coolant is leaking into your crankcase oil, and you continue to drive it like that........your engine eventually is likely to be damaged, beyond an inexpensive repair.

P.S. And not everybody has that kind of a problem. Far from it.

 

Just did that today using 1/2 of a 38 oz bottle of Bar’s Leaks Sealer with carbon fibers. Worked as described. No more engine shake or cylinder #1 misfires or radiator coolant disapearibg

 

drew, how is your bars leak seal holding up after a year and how many miles on it so far with the fix?

 

how did it go long term after removing the coolant o ring?
how often do you need to top off the coolant?
how did it perform in the summer?

 

What happens with one person's car has little to do with someone else's. There are lots of variables: ambient temperature, car use (flat or hills, traffic or highway, A/C or not, EGR condition, how "bad" the H/G leakage is, etc). So the short form is, it will last until it doesn't.

Posted via the PriusChat mobile app.

 

How long did this car last?

 

I only had strong misfires accelerating, when I got moving they went away. were getting real bad many misfire codes. changed plugs and coils (OEM Toyota coils) disconnected EGR, compression test. and several other things I cant remember right now. nada. when I remembered this post and tried it. stopped immediately misfires and I use torque to monitor coolant temp never letting it get above 200 F. one week late still running strong and only once a pending code 3001. this may be dangerous but shaking hard every acceleration and sometimes up to 65 misfires in cy 1 are much more dangerous. my coolant seems to be steady maybe going down a little (I bought 2 gallons of coolant just in case) by the way I bought coolant from local Toyota cheaper than ZEREX

 

Coolant leakage is a dangerous symptom.
Often, the engine head gasket will blow, coolant will leak, and damage the engine.
You should not only monitor the temperature, but also periodically inspect the engine cylinders from the inside with a flexible measuring device.

 

Do you mean P0301, misfire code for cylinder one? What’s the miles on it?

it’s patently obvious head gasket failure.

 

You have fired the parts cannon and spent almost as much as a basic hg repair. There is only a short window for that repair and that time has past when coolant is being consumed.

You will stop when you have a hole in the block. There are at least two short term hacks, with both equally damaging as the other, yours has a shorter grace period.

Shudder video
“Hey Walt… they want to wait and see if it gets worse…”

 

Long time reader of this forum, first time commenting.
For background, I have a 2010 Prius with 513k miles. I my head gasket blew in 2017 at 240k miles. I replaced with a 2015 engine that had around 60k miles. Around the same time, I replaced hybrid battery with one I bought off dude paring a 2015. I just replaced hybrid battery again from a 2013 someone was parting out.
Now to the point of my comment. About 4 months ago , right after I did the EGR/cooler cleaning, I noticed I was having misfires in cylinder 1 as I left to work in the morning. It would last only a few minutes and burn off. I replaced spark plugs, but misfires came back after a week. I suspected a small head gasket leak. I started removing coolant reservoir cap after each drive to release pressure. I figured this will buy me time to decide if I wanted to pay for head gasket replacement or swap engine again. It’s been four months and no misfires since I release pressure each drive. Decided to go will engine swap for $2500 with JDM motor when my head gasket finally blows. But I’ll just keep releasing coolant cap until that time. Why rush. Thanks for all the years of advice. Cheers!

 

Your experience and miles is the same as taxi drivers with these cars. Your current solution is better than using a sealer.

 

There's an accurate idea here, but the numbers aren't right. 212F is the boiling point of straight water at atmospheric pressure. 50/50 ethylene glycol has a higher booking point at atmospheric. That's the 223F figure. Then pressurize the system and it's even higher: around 270F, I think, at the 108 kPa pressure marked on the cap.

 

You can probably get away with that for a good long while; but when you have to smog the car - that may become an issue. I know some smog shop will let a pending code slide, but most will probably fail you.

Just be prepared for the worst - Sorry....

 

At what frequency are you doing that? A thorough cleaning, including intake manifold?