Rattling noise from engine compartment

[fast_dave]

That was around 1.5 years ago. Unfortunately (or fortunately in this case) my A/C doesn't work, probably out of gas due to rotten pipes.
But how does A/C affects the water pump?

@Ghen,

When the A/C compressor engages, it draws approximately 20 - 25 horsepower from the engine.
Another way of saying A/C's a drag on the engine, which in turn raises the engine operating temperature.

 

[Deleted member 352605]

@fast_dave wow i never knew it lost that much, I knew it lost some, but never that much...

 

[fast_dave]

@fast_dave wow i never knew it lost that much, I knew it lost some, but never that much...

@ExplorerGuy2007

Yep.

Forgot to add that you are also having to energize the Electric Clutch on the A/C Compressor.
So there's ANOTHER component to create a drag on the engine, which is the increased load on the Alternator.

To wind up - FWIW - I have a habit of tracking my MPG every fill up the old school way = Miles Driven divided by Gallons Consumed.

During the summer months here in the PRK when I'm using the A/C I see a corresponding 20% - 25% drop in MPG.

 

[Deleted member 352605]

i never knew it sucked that much power, but i get 18 mpg on great days, and like 14 city... so mine doesn't vary that much, given i don't use my ac much even tho i live in SoCal, which is weird but now maybe i will with a drop in fuel prices...

 

[fast_dave]

@ExplorerGuy2007

The flip side of not regularly running A/C compressor is pretty bad...

You see, within the freon component is a few ounces of refrigerator oil.

The purpose of the refrigerator oil is to lubricate the o-rings & seals within compressor, as well as the hose to hose connections/o-rings lubricated, so the freon can't escape.

The oil also keeps the hoses somewhat "moist" and pliable on the inside, so that they don't get hard and crack from the under hood heat and vibrations.

To distribute the oil to all of the o-rings, seals and hoses, you should run your A/C at least 5 - 10 minutes every week during the summer, and the Defroster at least 5 - 10 minutes every week during the winter months.

The worst thing you can do to your A/C & Defroster system is not use it - at minimum you'll lose all of the freon.

At worst you'll dry out all the seals in the compressor, hose connections, and dry out the hoses.

This condition will also allow moisture/humidity into the A/C system which creates a whole 'nuther problem when you try to fix it...

 

[Deleted member 352605]

@ExplorerGuy2007

The flip side of not regularly running A/C compressor is pretty bad...

You see, within the freon component is a few ounces of refrigerator oil.

The purpose of the refrigerator oil is to lubricate the o-rings & seals within compressor, as well as the hose to hose connections/o-rings lubricated, so the freon can't escape.

The oil also keeps the hoses somewhat "moist" and pliable on the inside, so that they don't get hard and crack from the under hood heat and vibrations.

To distribute the oil to all of the o-rings, seals and hoses, you should run your A/C at least 5 - 10 minutes every week during the summer, and the Defroster at least 5 - 10 minutes every week during the winter months.

The worst thing you can do to your A/C & Defroster system is not use it - at minimum you'll lose all of the freon.

At worst you'll dry out all the seals in the compressor, hose connections, and dry out the hoses.

This condition will also allow moisture/humidity into the A/C system which creates a whole 'nuther problem when you try to fix it...

oops... i don't use it very often except when its sweltering hot... only during the summer months occasionally... like 3 times a month... :/ ill have to test my ca and check the hoses later today...

 

[C420sailor]

MPG with air conditioning vs windows down depends on vehicle speed. Around town, I usually just keep the windows down. Highway? Windows up, AC on. HP loss from the AC is static independent of vehicle speed. Parasitic drag, however, increases exponentially with vehicle speed. A brick with windows down at hwy speed creates a lot of drag.

Just my $.02

 

[E.T.]

You sure that it's the timing chain?

Timing chain guides:

Engine hoist: $200
Various wrenches/sockets: $50 (probably)
Timing kit: about $100
Replacement guides/chains/whatnot: $100+
Beer to calm your nerves: $50

so it's a $500 job if you have 2-3 days free, or about $1,000 if you have to buy a new engine and tools. On the plus side it drops to $200 every time you have to replace said guides..

I just started mine up for a listen earlier, and it was making subtle noises at the "I'm about to fail and die" frequency. I probably cursed it by reading this.. Took it apart:

and this was a VERY quiet rattle. The bolt had worked loose over 8 months, must have come out on last trip

 

[1998Exp]

@Ghen,

When the A/C compressor engages, it draws approximately 20 - 25 horsepower from the engine.
Another way of saying A/C's a drag on the engine, which in turn raises the engine operating temperature.

Where did you find this number? I have seen numbers ranging from 4 to 10 KW, or about 5 to 13 HP, depending on the size of the vehicle. Perhaps your number is the power draw when the compressor is running, but except for extreme heat, they cycle ON/OFF -- the hotter outside, the longer the ON time. As for your additional comment on the clutch, I don't know the exact number, but it's protected by a 10A fuse, so no more than 100W (about 0.15 HP) -- which is negligible.
Having said that, the impact of A/C on fuel economy is indeed significant. That's because most of the time the power needed to move the vehicle is just a fairly small fraction of the engine's peak available horsepower (about 200 HP for an Explorer). Much of the studies on the subject were done for electric cars, due to the obvious relationship between A/C load on range.

 

[donalds]

which is negligible

No such thing as negligible when looking for power Yeeyeee

 

[Spuddy]

To distribute the oil to all of the o-rings, seals and hoses, you should run your A/C at least 5 - 10 minutes every week during the summer, and the Defroster at least 5 - 10 minutes every week during the winter months.

^Spot on advise from fast_dave...

A/C compressor also runs on bi-level (floor and vent) setting - in other words, in all settings except heat, vent and off.

The moisture will accumulate in the dryer and rust it out. Ask me how I know.

The SOHC is well known for poorly engineered chain tensioners and therefore rattle ( AKA, timing chain death rattle), and it sounds to me as if, at least, one or both of your timing chain guides have broken and are now in your oil pan.

I wish you luck, my friend.

 

[jr230]

My water pump had intermittent leaks, losing around 1 liter per 1000km, I took a long trip to Calgary, 1000+ km, and it got fixed by itself!

possible rust clogged hole but are you sure the truck not running a little hot? and you dont fill the plastic resouver full when cold some will overflow when hot the ford combined the radiator tank and overflow container so it cannot be filled to brim. another dumb idea like the no trans dipstick.\
they can also leak from the thermostat housing its plastic. as fo ac yes does add drag to run but most reason the condensor is in frount of the radiador so the heat from cabin is pumped in frount of radiator so it cools and adds heat to airstream of radiator.
all ac loses freon and if low will rapidly clutch on and off and stop after enough leaks my 99 used 1 can r134a every 2 years when it was about 8 yrs ols
usinc ac or defrosters on cold to clear windshield keeps compressor lubed and longevity so try refill og freon unless you see bad hoses

 

[2000StreetRod]

As for your additional comment on the clutch, I don't know the exact number, but it's protected by a 10A fuse, so no more than 100W (about 0.15 HP) -- which is negligible.

The clutch is electromagnetic to engage the compressor. The compressor is the significant load on the engine when the clutch is energized. The compressor load on the engine increases with engine speed.

 

[Ghen]

possible rust clogged hole but are you sure the truck not running a little hot? and you dont fill the plastic resouver full when cold some will overflow when hot the ford combined the radiator tank and overflow container so it cannot be filled to brim. another dumb idea like the no trans dipstick.\
they can also leak from the thermostat housing its plastic. as fo ac yes does add drag to run but most reason the condensor is in frount of the radiador so the heat from cabin is pumped in frount of radiator so it cools and adds heat to airstream of radiator.
all ac loses freon and if low will rapidly clutch on and off and stop after enough leaks my 99 used 1 can r134a every 2 years when it was about 8 yrs ols
usinc ac or defrosters on cold to clear windshield keeps compressor lubed and longevity so try refill og freon unless you see bad hoses

No it's not running hot, the leak was intermittent, I never saw a drop under the vehicle, just found the reservoir empty. Until one morning I drove it to nearby shopping center and as soon as turned the engine off smoke and vapor came up the bonnet. and coolant was running under the vehicle. When I checked it was coming from the hole in the water pump body. Which was indicating a bad water pump seal.
Not sure if the long drive fixed it or the extreme cold in Calgary!

 

[Zeromarine]

Mine kinda sounds like that hot or cold. I only have 97,000 miles. There is no sound from the motor when I’m actually driving it tho. Only at idle can I hear mine. It’s not as loud as yours either. Been like that since I bought it a year ago. Not sure I’ll do anything as it hasn’t gotten any worse. Maybe one day I’ll take a peek.

 

[MrQ]

@Ghen,

When the A/C compressor engages, it draws approximately 20 - 25 horsepower from the engine.
Another way of saying A/C's a drag on the engine, which in turn raises the engine operating temperature.

Umm, I call BS. I'd say more like 5hp. This compressor is the size of a large window unit compressor and I bet dollars to donuts it doesn't pull more than 10 on a hot day (compressor has to overcome the higher head pressure from the heat buildup in the condenser) You also have to remember that the compressor is usually working the hardest and runs longer at low speed (less air flow through the condenser) so it will use more power (thus why your you see you RPM gauge drop so far at at idle). Also the HP an engine makes is on a curve not a straight line. At 800rpm your engine may only make about 20hp so you feel the drop in power more there than say 2000rpm when the engine is making around 100-120 HP. Granted this varies per engine, rpm ranges, and HP curves. But I doubt the compressor is taking 25hp at idle on this v6, if that were the case the engine would die every time the compressor kicked on at idle.

@2000StreetRod "The compressor load on the engine increases with engine speed. " How is this right? The faster the compressor runs the faster it compresses, the load reduces as the head pressure decreases from the extra cooling and the frequency of the engagement also changes. Longer engagement at low speed, shorter engagement at high speed, thus why its more efficient to run A/C at high speeds than low speeds.

 

[Mbrooks420]

20-25 seems mighty steep. I see no difference in MPG at all in my car. As I understand it the AC compressor runs in all settings except feet only. Even with heat, to save the compressors from dry seals.

 

[MrQ]

If he is running the A/C in town a lot (stop and go traffic) I still bet he wouldn't see that kind of drop, unless there is something else wrong with his system (clogged condenser, under or overfilled freon, compressor going bad, etc).

 

[1998Exp]

... At 800rpm your engine may only make about 20hp so you feel the drop in power more there than say 2000rpm when the engine is making around 100-120 HP. Granted this varies per engine, rpm ranges, and HP curves.
...

Seems to me an engine can turn fast and still make very little power. The power it delivers depends on both rpm and load. I bet you it doesn't deliver 100-120 HP when idling at 2000 rpm. In fact, when cruising at 60MPH on level ground in 4th gear, the engine turns at about 2000 rpm and probably delivers something around 30-40 HP -- unless you are towing a boat.

 

[MrQ]

Seems to me an engine can turn fast and still make very little power. The power it delivers depends on both rpm and load. I bet you it doesn't deliver 100-120 HP when idling at 2000 rpm. In fact, when cruising at 60MPH on level ground in 4th gear, the engine turns at about 2000 rpm and probably delivers something around 30-40 HP -- unless you are towing a boat.

In this you are correct. At a rated RPM the engine can produce up to the HP stated in the power band. However, there is more capacity for HP at a higher RPM than a lower one (on most engines). The engine CAN produce 100 HP at 2000 RPM, but it will only use what is needed to move the load at the required speed (HP is work over time). Thus, the engine under accessory load at 800 rpm will use a higher percentage of the available HP than at 2000 rpm as the power available is much lower.

The power band is a graph of the engine power under load based on RPM's and shows the max capability of the engine over an RPM range, but not what is actually utilized during normal operation.