Coolant loss- any connection to a fuel injector

You could just go ahead and pre-empitvly change the head gasket now.
Then the rest is mute!

 

Preventing coolant pressure from pushing in coolant through a hg leak will eliminate start rattles for a while. It won't fix the problem and is likely to lull the driver into a false sense of satisfaction until the engine overheats.

You will only see plums of steam out of the exhaust when the coolant is going down fast and largely when the engine needs to be replaced. You need to watch at the exhaust as someone revs it up to observe it.

Cold start rattles will progress to anytime rattles when the engine restarts - such as at a traffic light.

Even at an advanced stage the severe rattling and shaking won't be every time but it will be much more frequent than the early stage once or twice a month rattle.

Losing a significant amount of coolant in a week is beyond early stage and entering risking the engine zone.

 

If that's the cooler, the coolant is in passages, like the radiator.
So unless it's cracked, you won't be loosing coolant through the cooler.
Exhaust won't pass through it as much as it's clogged.

Pressure test..... unless it's overheating, then it's getting blown out of the coolant tank....

 

That is one of the possibilities. I personally think it's a combo of things.
A blocked cooler will create more back pressure.

But since you have a coolant leak, a pressure test will tell you where coolant is leaking.
And if your head gasket has failed yet, or not....

 

Do not believe everything you read on the internet. Answer one question for me. Why would the engine run hotter if the EGR cooler is clogged (or the EGR valve is closed)? Do the following experiment. Monitor the engine coolant temperature and see if the engine runs hotter when the EGR electrical connector is disconnected (valve closed, no EGR flow) versus when the EGR valve is operational. You will not see any difference in the engine coolant temperature.

My theory is that many Gen 3 Prius head gaskets go bad because the engine coolant pump starts going bad, and no trouble code is triggered. The engine overheats and causes the head gasket to go bad. Then, coolant slowly leaks into cylinder #1 or #2. This causes the misfires and the death rattle at the damper located between the engine and transaxle.

 

Yep, coolant temp. lamp doesn't turn-on until 248+F, when normal operating temp. is 185F-210F. If the lamp is flashing on-off your right at the cusp of 248F, hot enough to start breaking things - considering all the plastic in newer engines.

 

Please explain by what you mean that a blocked EGR cooler will create more back pressure on what? The EGR is teed off of the exhaust system before the catalytic converter. What back pressure are you talking about?