LOUD bang, followed by temp dropping

[mikeylighter]

Well....I just went for a drive, was accelerating through 3rd, and out of nowhere, there is an extremely loud bang from what sounded to be the engine bay. I pulled over, nothing was leaking out, seemed to be running fine, but on my way home the temp gauge slowly dropped all the way down. It has always ran right in the middle of the temp gauge, If I let it sit and idle, it will warm up to normal temp, but when I get moving it drops. Does anyone have any idea what it could be? It sounded like a shotgun going off.

 

[Nekid]

Could be two separate things. The only time I have had the 'gunshot' under the hood is a coupler coming off at 30PSI. Check all your couplers. You may also got lucky enough that even though it popped, it managed to seal enough again to not show any affects down low. Do a boost leak test.

For the temperature, the way you describe it is your thermostat is not closing 100%, it can open to have the circulation while idle, but while you are moving and the air is chilling your rad, it isn't closing to get the temp back up.

If you aren't leaking anything and your coolant level hasn't changed, I would highly suspect that you ran into the rare instance that two different things have shown themselves instead of being related.

 

[eclipsyco]

every day I learn something new gotta love DSMs
Man try replacing the sensor it costs $25 brand new oem that's the only thing I can think of.

 

[ChrisMgst]

Shotgun? The temp issue could be a thermostat needing to be replaced.

 

[Afizzle]

maybe you ran over a pothole

 

[gusu]

Shotgun? The temp issue could be a thermostat needing to be replaced.

Eh, this could possibly be the case.

Sometimes with a sticky T-stat it will want to work all the sudden releasing cold coolant into a hot ass motor. This would almost always cause coolant to leak from the system as the pressure would be pretty damn high.

A coupler popping off does not make sense since it would be a huge boost leak and most likely you'd be running like shit at 25 mph tops.


As far as what I said first it might be that your coolant overflow caught all of the overflow, but with the pressure involved I would expect your freeze plug to pop out.

 

[91-GS]

On related note, were all caps where they are supposed to be? For example, if what gusu is describing was to hapend, chances are it will pop the top on the overflow tank.

 

[tstkl]

You probably blew a radiator hose. If there is no coolant in the system your temp gauge is reading the air temperature, which will be completely arbitrary relative to engine temperatures. By now your head is probably warped if that's the case.

 

[91-GS]

When radiator hose blows there is steam and water everywhere. He would have noticed that something it not right.

 

[project98dsm]

If my memory serves me correct, every time I've ever had a blown hose, or even a leak in one...my car has ran hot. Never enough to cause any catastrophic damage, but enough to make my needle go a needle thickness or two past the middle. And it wasn't due to low coolant...as I only had to add a cup or two of coolant to top it back off at the neck after it cooled down.

OP do you have any way to log coolant temp? If so, check and see if your coolant temp is displaying a logical number that it would see before starting it all the way to operating temp. If it's showing something like 20 or 30 and it's been 70* outside then it's probably time to replace your CTS. However if you had a bad CTS there would be other negative side effects to go along with it. Like mentioned before, a bad thermostat could be a reason for your low coolant temp. You're sure the sound came from your engine bay, and not a backfire or anything?

 

[delta448]

The bang was the cooling system relieving pressure somewhere.
If you can't find an external leak, check the pressure cap and the thermostat. If it cools with movement, then it is probably the thermostat.

 

[twicks69]

If you aren't leaking then it is probably thermostat or radiator cap. All the other loud pops are normally accompanied by leakage. Did you already confirm that your cooling system is filled and not leaking?