A belt on the engine??

partipilo · 10-12-2007, 04:48 AM

I thought this engine was beltless... The A/C is fully electric, the power steering is fully electric, MG1 is your starter/alternator, just about everything is electric. But I peeked under the hood for the first time today, and noticed that there is indeed a belt on the engine. I couldn't make out more then the main crankshaft pulley and an idler pulley... What in the world is it used for?

rigormortis · 10-12-2007, 05:20 AM

<div class='quotetop'>QUOTE(partipilo @ Oct 12 2007, 03:48 AM) [snapback]524487[/snapback]</div>

Quote:

I thought this engine was beltless... The A/C is fully electric, the power steering is fully electric, MG1 is your starter/alternator, just about everything is electric. But I peeked under the hood for the first time today, and noticed that there is indeed a belt on the engine. I couldn't make out more then the main crankshaft pulley and an idler pulley... What in the world is it used for?
[/b]

isnt that the serpentine belt for Water Pump, Compressor And Idler?

i thought the air conditioner pump was in front of the radiator, and you wouldnt be able to see it
unless you took that big plastic piece off

patsparks · 10-12-2007, 09:27 AM

That belt drives the water pump.
Because the AC is electric the idler is there to allow the belt to be adjusted.

tochatihu · 10-12-2007, 10:13 PM

Toyota has not yet concluded that it would be cost-effective to replace the (mechanical) engine coolant pump with an electrical one. Even though this would eliminate the thermostat and one crankshaft seal. I have long thought they should do it the other way, but my opinion in these matters does not count for much.

donee · 10-12-2007, 10:38 PM

Hi Toch...,

That pulley has a harmonic balancer in it. So, one probably could not get rid of the seal. The balancer is a device which damps vibrations in the crank shaft.

patsparks · 10-13-2007, 09:49 AM

There also needs to be a means to turn the crankshaft when performing some service and repair proceedures such as adjusting valve clearances. Therefore having the crankshaft coming out the end of the engine has it's advantages. Pitty about the power robbing belt. Shame Toyota couldn't run the pump off the timing chain and leave off the belt.

The water pump in modern engines moves water around the block even when the thermostat is closed to maintain even temperature through the engine. An electric pump would need to run almost all the time to achieve this anyway, unfortunately.

partipilo · 10-22-2007, 10:29 AM

<div class='quotetop'>QUOTE(patsparks @ Oct 12 2007, 09:27 AM) [snapback]524550[/snapback]</div>

Quote:

That belt drives the water pump.
Because the AC is electric the idler is there to allow the belt to be adjusted.
[/b]

This is rather unusual, methinks. At least with my last vehicle, a Jeep with the i6, the water pump was bolted directly to the crankshaft, so no belt was required. It would sure suck to have a belt break and seize the engine.

qbee42 · 10-22-2007, 01:57 PM

<div class='quotetop'>QUOTE(partipilo @ Oct 22 2007, 10:29 AM) [snapback]528805[/snapback]</div>

Quote:

This is rather unusual, methinks. At least with my last vehicle, a Jeep with the i6, the water pump was bolted directly to the crankshaft, so no belt was required. It would sure suck to have a belt break and seize the engine.
[/b]

Many modern engines power the water pump from the timing belt, so you still have a belt. It really sucks when you need to replace a timing belt driven pump.

Tom

seasalsa · 10-22-2007, 02:53 PM

<div class='quotetop'>QUOTE(patsparks @ Oct 13 2007, 06:49 AM) [snapback]525076[/snapback]</div>

Quote:

The water pump in modern engines moves water around the block even when the thermostat is closed to maintain even temperature through the engine. An electric pump would need to run almost all the time to achieve this anyway, unfortunately.
[/b]

Actually the Prius has 2 water pumps, ref.DENSO
"The Prius's main water pump loses its source of mechanical energy when the vehicle is running on battery power alone and the engine is off. So, we developed an auxiliary electric water pump for the car. Our electric water pump provides a constant flow of heat to the cabin even when the mechanical pump is stopped. The mechanical pump operates when the engine is running, which reduces the load on the battery. And a bypass function reroutes water flow to avoid resistance from whichever pump isn't running."

etyler88 · 10-22-2007, 03:59 PM

I wonder if they could make it an air cooled engine?

10-13-2007, 09:49 AM	#6
patsparks An Aussie perspective Join Date: Jul 2007 Location: Adelaide South Australia Posts: 9,265 My Car: 2004 Prius Model: N/A Package: Base Thanks: 128 Thanked 185 Times in 143 Posts Friends: 33	There also needs to be a means to turn the crankshaft when performing some service and repair proceedures such as adjusting valve clearances. Therefore having the crankshaft coming out the end of the engine has it's advantages. Pitty about the power robbing belt. Shame Toyota couldn't run the pump off the timing chain and leave off the belt. The water pump in modern engines moves water around the block even when the thermostat is closed to maintain even temperature through the engine. An electric pump would need to run almost all the time to achieve this anyway, unfortunately. __________________ All the warranty I need. Still averaging 4.4L/100km across town 2004 silver base model Prius Shark fin, genuine mudflaps, colour matched side mouldings, rear bumper scuff guard, sheepskin seats, BT Plate. I love it!

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10-12-2007, 04:48 AM	#1
partipilo Weirdo Join Date: Sep 2007 Location: West Palm Beach FL Posts: 76 My Car: 2008 Prius Model: Package: #2 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	I thought this engine was beltless... The A/C is fully electric, the power steering is fully electric, MG1 is your starter/alternator, just about everything is electric. But I peeked under the hood for the first time today, and noticed that there is indeed a belt on the engine. I couldn't make out more then the main crankshaft pulley and an idler pulley... What in the world is it used for?

10-12-2007, 09:27 AM	#3
patsparks An Aussie perspective Join Date: Jul 2007 Location: Adelaide South Australia Posts: 9,265 My Car: 2004 Prius Model: N/A Package: Base Thanks: 128 Thanked 185 Times in 143 Posts Friends: 33	That belt drives the water pump. Because the AC is electric the idler is there to allow the belt to be adjusted.

10-12-2007, 10:13 PM	#4
tochatihu Senior Member Join Date: Apr 2004 Location: Kunming Yunnan China Posts: 2,413 My Car: 2001 Prius Model: Package: Pioneer #1 Thanks: 1 Thanked 39 Times in 39 Posts Friends: 14	Toyota has not yet concluded that it would be cost-effective to replace the (mechanical) engine coolant pump with an electrical one. Even though this would eliminate the thermostat and one crankshaft seal. I have long thought they should do it the other way, but my opinion in these matters does not count for much.

10-12-2007, 10:38 PM	#5
donee Senior Member Join Date: Aug 2005 Location: Chicagoland Posts: 2,244 My Car: 2006 Prius Model: Package: #2 Thanks: 2 Thanked 54 Times in 47 Posts Friends: 0	Hi Toch..., That pulley has a harmonic balancer in it. So, one probably could not get rid of the seal. The balancer is a device which damps vibrations in the crank shaft.

10-22-2007, 03:59 PM	#10
etyler88 etyler88 Join Date: Mar 2005 Location: Dover, DE Posts: 450 My Car: 2005 Prius Model: Package: #3 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 1	I wonder if they could make it an air cooled engine?