Coolant Temp Warning Question

The first thing I would suggest is removing the grille blocking altogether, then see if the problem replicates. If not, the temps and driving were probably a bit too warm for the grille block

My inverter coolant tank is near the top, slightly past the Full mark. The engine coolant tank is around 70% filled. It helps to check in a dark place - inside a garage or at night - by using a flashlight.

Put the flashlight directly onto the engine coolant tank the level should be at least 50%. If it's less, that could mean a leak or never properly filled

The cap on the engine coolant tank should have two hoses, one goes to the motor and rad, the other is a short overflow tube that goes alongside the tank. If the cap is damaged, it's possible the engine has been allowed to run with air in it.

Note, the actual rad cap is under the plastic trim pieces between the front cowl and rad. You have to take that crap off to see the cap itself

 

Rob, has the fan turned on? This is a situation where I would err on the side of caution. I would pull the insulation although I don't believe it is a factor and take the car to the dealer. If the fan is off and the light isn't on steady I don't think it's overheating but something isn't quite right.

For example, last week the low coolant light on my Intrigue stayed lit for a few minutes. The coolant in the recovery tank appears to be a bit low. The light hasn't lit since. I'm changing the coolant since it is due not because I believe the idiot light indicates a problem.

 

Rob,
Have you read this thread on grill blocking cautions?

http://priuschat.com/forums/prius-modifications/40206-grill-blocking-caution.html

 

Be careful there as it is hard on the block to have repeated heat spikes. You could damage the head gasket or worse. Plus with no gauge you don't know how spiking it's getting. If it was me I would check the water pump to see if the weep hole is leaking. The bearing could be going on the water pump. You don't mention you maintenance routine. When was the last time you changed the coolant? Whats it look like if you open the cap to the rad not the coolant recovery? Whats the miles? If the coolant recovery tank is repeatedly low you got a leak somewhere.Period. First culprit is weep hole. Do you smell coolant ? If no leak and your spiking one of the electric rad fans as mentioned earlier is probably bad. Easy to check that. One fan is cooling and the other is ac assist. Put on the ac on full blast after car is thoroughly warmed up and look under the hood and both fans should be running. But if a leak get that fixed asap.The one thing I dislike about our cars is no temp gauge. I would guess by the time the temp light comes on full time its done some damage.

 

Jim

There is a TSB out for some GM vehicles with the coolant level sensor in the overflow tank. The sensor can get gunked up and sometimes give a false low reading.

That said, it's also a good idea on GM vehicles to keep the overflow tank higher than the Min level. Otherwise air can get into the system and accelerate corrosion. Some reports indicate the early horror stories of Dex Cool - "Death Cool" - stemmed from this

jay

 

A 2005 shouldn't be ready for a coolant change unless over 100,000 miles. Do not continue driving the car with low coolant and/or a leak. Aluminum block/head motors are nowhere near as tolerant of low coolant or overheat spikes compared to old fashioned cast iron blocks/heads

The air bleed procedure can also be complicated, due to the thermos used in the Prius. This really isn't a Shadetree mechanic type of procedure. If you have access to a vacuum coolant bleeding system, that is best:

http://www.mityvac.com/info_sheets/MV4535_Info.pdf

I have one at my hobby farm, and the nice thing is you collapse any air trapped in the block or rad.

If you don't have hot air coming out the vents when set to Max Heat, you probably already have air trapped in the system. Continued operation could bugger up the motor, coolant transfer pump, etc.

Get it fixed ASAP

 

Dont get it!

wy wurry about overheating the prius?
the car sensors will tell you when its time to stop and before there is any damage! thats wat there for!

 

the car sensors ARE telling him somethings wrong. The question is why it is intermittent.

 

On the note of loosing fluid. make sure the small line from just below the radiator cap that goes to the bottom of the reseivour is connected. fluid goes back and forth threw this line as engine heats up and then cools down. Make sure the cap is tight also. That can stop the vaccum from forming and not let the coolling engine suck up needed fluid.

 

ok sorry
i was thinking the can scan only told the temp is high and the prius engine temp light dit not come on!

 

Just my .02. I've never used a grill blocking device, but I do have a scangage, and the highest temp I've seen is 206F (usually about 184F), while climbing a moderate grade in the summer. I didn't see a temp warning light come on, but was watching the temp on the scan gage. First, I would lose the grill block, and invest in a scangage (or similar) to monitor the actual temp, and not rely just on the light.

 

The Prius thermostat BEGINS to open ~185. It isn't fully open until~205f.

205 is NOT too hot. That begs the question of what is too hot. In my mind, if the fans are on full, and the temp doesn't go below ~220f then you might be getting a bit hot. Modern pressurized cooling systems won't boil until somethin in the 260f range. I wouldn't run all day at that temp, but your fine at 205f.

It would be nice if some engineering type could/would give us a definitive "never to exceed temp".

In my Subaru, with the scan gauge, the middle of the scale on the car temp gauge is 195, a long way from the "too hot" mark.

Icarus

 

My 2008 is very sensitive to low coolant flow and intermittently triggers the red triangle. Only takes about a pint or so to make the alarm go away. Car did have front end collision and shortly after repair, triangle went nuts. Called shop and they said oops, we thought we ran it long enough to get system hot and filled. That was over a year ago and only had same problem occur today. Again, just a little coolant stopped triangle.