Loud bang and the rattle highway speed

You want to take it to a mechanic. Driving it when it's making loud noises is a surefire way to throw a rod, bend valve stems, etc.

Is this the same car that you mentioned in your other thread? The one that threw a code?

 

how are the oil and coolant levels?

 

Not really enough to go on to make an informed diagnosis I’m afraid.
Does it make the noise freewheeling?
Any different noised decelerating?
Braking?
Pick the car up, spin each wheel up by hand?
List is not exhaustive but I’d do this sooner than leaving it imvho

 

Right, but how are the levels now?

 

A bent rod will primarily manifest as reduced compression in the associated cylinder which leads right into a rougher run from the weaker combustion and reduced overall power. You can detect it with a compression test. You can directly measure it on the car, with the plugs out by comparing TDC of the four pistons with a long wire probe indexed crossing a reference level set up on the valve cover.

Usually whatever bent the rod also damaged the bearing on the big end of it- it's just that much stress! So that bearing burns before long, often with souvenir ejecta.

I don't know what caused the noises on your car- near-hydrolock starts? Classic backfire or exhaust issue? Broken parking pawl getting chewed up in the gearbox? I'm just not close enough to do better than spitballing, sorry.

 

Sounds like you need to down the car for maintenance.

Used it for *what?* exactly.
history?
miles?
previous problems?

If you're on head-gasket 2.0:
Did you repair the underlying problem that led to the original failure?
Was it repaired "correctly?"

Bent connecting rod symptoms do not "come and go."
As mentioned above, the engine usually fails dramatically if operated in this condition.
The good news is that if this is the case you're going to be in the market for a short block pretty soon anyway.
Other than getting the car back in the barn, replacing the bottom end is no more difficult (if not less messy) than it would have been before it failed.

 

Post from your other thread:

Link:

Can code 361B indicate blown head gasket? | PriusChat

Starting a fresh thread is just muddying the waters, but anyway:

What test was done?

 

Oh....I see.
Well....it doesn't really matter.

Sounds like that engine is going to be coming out of the car pretty soon either way.

 

For a TDC height test? You'd crank the engine by hand for that. You'd want to rock the crank back and forth near TDC to make certain you were really there.

For a compression test there is a maintenance mode procedure to standardize the results.

 

????????? How in the world can you check for exhaust gasses at the radiator???
The exhaust manifold is behind the engine. Not even close to the radiator.

 

The exhaust gases begin life in the cylinder. There's nothing there but a head gasket to keep them out of the coolant passages.

 

To check the coolant for “Gases”.
Use of a 4 or 5 gas exhaust analyser sniffing the vapour/gas is to check for the presence of hydrocarbons. This gives an indication the the cylinder head gasket/hairline crack in the head or block (basically, leakage of combustible gases etc into the coolant)

 

??????
Do you mean "IN" the radiator??? Because outside the radiator does nothing, unless it's leaking.
Or the exhasust is leaking and your driving backward, or the wind is blowing under the car and up
over and around the engine.