Grill blocking w/o scangauge

I blocked mine for a couple days, but got cold feet and remove the blocking. I could not stand not knowing what was going on with the temps. Your probably OK blocking the bottom only without worry. H

 

With current East Coast temperatures (mid-30s for daytime highs in the mid-Atlantic), you're OK blocking everything. If it manages to get back above 50F, you might consider unblocking the lowermost slit of the lower grille. Above 70F, I would unblock the entire lower grille. See this (identically titled thread) for more.

 

Yes.....I was also afraid to block. But see that there is a high temp warning light. that gave me so confidence to go forward with the blocking. Looking for the advantages of it now.

 

I didn't block my Gen III till I got the scangauge. I have the lower grill blocked at 100% and it doesn't seem to be enough (of course it was -9F without the windchill this morning). Will try 1/2 of the upper this weekend.
I'd be too chicken to do it without the Scangauge.

 

I blocked all of lower grill and half of upper grill. I would have blocked it all but I had installed some led lights in the upper grill and i don't want to block them. it takes a lot less time for the engine to warm up and i haven't seen the temp go any higher than it usually does. The temp here is hitting -10C to -15C now.

 

Without instrumentation to measure inverter temperatures I would block the upper grill fully and the lower grill partially (leaving 0.5 ~ 1 slit opening). Good luck!

 

I don't think the size is that critical. As long as the pipe insulation fits snugly in the grill slots and doesn't fall out after a test drive you are good to go.

 

I have a 2005 and was pleased with mileage in mid 50's low 60's until this current big chill. It dropped as low as 23.3 but I have been nursing it back up with the advice of some of these posts. The dealer says wait for warmer weather ... The info re 'blocking' makes a great deal of sense without any other gizmos. In western Canada in the '70's my first car, a 61 Volvo had a grill blind on a chain that the driver operated from inside. I lowered the blind as the operating temp rose. All other wehicles had grille covers and flaps. Time to resort to engine block heaters and flaps!

 

Warmed Over,

:welcome: to PRIUSchat. :cheer2:

The unseasonable cold we've been seeing this last week is killing my
MPGs too... and that's with full blocking up and down with ScanGauge.
On my ~18 mi. one way commute, 70/30 urban streets/freeway, I get
up to 157 degF coolant temps only in the last 8 miles. In the summer I
get there in ~1.5 mi. Brrr...

On the pipe insulation, go for the cheaper, gray stuff, it lasts multi-years.
The dark black stuff tends to tear easily and goes sticky in a year.
The 3/4 in. is a lot easier to get between the grill bars. There are 5
openings. You may have to slit the insulation in half lengthwise to get it
to set tightly in the thin top and bottom openings.

I hesitated blocking until I was doing some barbecuing during the week
after Christmas two years ago. I was using twice the amount of
charcoal and thinking I needed some insulation for the Webber kettle.
Then I looked over at the Prius and instantly understood why grill
blocking could help with maintaining ICE heat... a no brainer.

+1 on what Tony said. Unless your pulling heavy loads or long up-hills,
in my experience you can full block the Gen II without concern up to 50
degF. Higher than that you better get a SG.