Safe to drive without plastic cover UNDER engine?

Its safe to do. Just go thru deep water puddles very slowly as not to splash water on engine and short out electrical components. Its just to keep engine dry and contribute to the aerodynamics of vehicle.

 

I've cleaned my Prius engine with a garden hose plenty of times. The electrical connections aren't likely to be harmed by water. The danger is sucking water into the engine air intake. But in a Prius, air enters the engine through a long horizontal hose and then into the bottom of a large air cleaner box, so I think it would be almost impossible to suck water into the engine unless the car was under water.

But with the splash shield gone? I think there's no way you'll get water damage because of that. Just a dirtier engine from grime and dirt getting kicked up there.

 

And slightly lower mileage.

 

^ This.

I have pipe insulation sections pushed over the seams at junction between top of fender and hood. These plus the engine under-cover, besides improving engine warm-up, seem to be keeping the engine bay on ours near-new looking.

 

pictures?

 

Yeah, worth a thousand words.


(3rd gen pic)

 

ok, now I see. how high has the foam to be (meaning, what size did you buy?) that would probably help me to keep at least some of the dust out of my engine compartment. here in new mexico dust & sand is/goes EVERYWHERE....

BION
StarCaller

 

It's a common size, OD about 1.5". For 1/2" (nominal) copper plumbing pipe size. The groove along the top is from the hood, just snugs on it.

Guess you go through the air filters.

 

Mendal, I suspect sealing those gaps increases the underhood temps a bit. Not important here in Canada, but in the desert southwest....

 

Yeah faster warmup was my object. Then I noticed our engine bay staying quite clean so hey. I did monitor temps with ScanGauge for several years, and never saw overheating, but that's here. Good point, about desert climes.

Something like a sustained uphill mountain climb too, you might want to pull everything off.

 

you might be up to something here/
I didn't think about that/

 

FWIW, the only time I've seen temps "womp" right up to 90~95C, and stay there, is on our local ski hill. Dragging a ton or two of car up a steep grade for half an hour.

 

if I drive home from albuquerque it pretty much goes up all the way/
maybe it's better to leave at least some little gaps for the hot air to escape....?

 

I've left that insulation (per the pic) in year 'round, right through summer. I do regular grill block much more cautiously. It's debatable, less so if you have some way to monitor temps, for sure. ScanGaugeII?

 

yep, scangauge is there/
so I guess the only way to figure that, would be to put the insulation on & see if it makes a difference temperature wise/
might take me a few days to go to albuquerque to go to lowes or home depot to get some insulation/
but what I think is that there will be a heat soak under the hood, once the car is shut off/

 

Well, I wasn't wondering about the coolant temp, but rather the air temp under the hood. I think the coolant temp wouldn't be affected much by those tubes. It's fan controlled and the hot air vents under the car. But after shutoff I suspect -some- hot air normally vents out those slots, narrow though they are. You could be making a convection oven. Maybe I'll have to try them too. The hottest we see here is around 30C, but it's the coldest that's of concern - -40C sometimes. My lower grill is blocked all winter and even in the late fall and most of the spring, and I never see high temps or hear the fan roaring. In fact, in winter when it's below -10C I almost never see the temp rise to the thermostat opening temp (85-90C).

I wonder how many of you know that automotive temp gauges are designed to "lie". If the operator actually saw how much the temp varies and how quickly, they would (and have) panic! We don't have one, except for those of us with "Scangauge". I don't even know if we have a light. I'll have to check sometime.

 

Yeah I'm starting to think I should pull those upper tubes out in summer.

 

It's really the same thing. The coolant circulates to exchange the engine heat with the coolant, and the coolant in turn exchanges heat with the ambient air. So if the insulation increases air temps within the engine bay, it raises coolant temp and, in turn, engine temp. This would be particularly acute when the hot car is standing still, because there is no cooking airflow over the radiator.

I say all this because monitoring coolant temp is at least as good as monitoring engine compartment temp. In fact, it's probably better because it more closely measures engine temperature, which is what matters most.