Does coolant pressure depend on RPM?
03-20-11, 07:03 PM
#1
Does coolant pressure depend on RPM?
Might sound like a stupid question but i was wondering.
I had a coolant line burst on me today. AGAIN. Thankfully all the problems i have had with my car had been minor and 75% of them are coolant hose related lol. I should just replace every single coolant hose to prevent anymore future problems.
Anyway today i take my car out, nice sunday cruise like i always do. On the way home, it was time to have some real fun. I get on it in 4th gear, long pull, then i hear BEEPPPPPPPPPP.
Coolant buzzer goes off, water temp gauge shoots to 220F in a matter of seconds. I literally do a nascar pit stop brake onto the shoulder of the highway and shut her down and threw the fans on right away.
Hose burst right where the little red dot inside the red circle is.
My question is, is coolant pressure dependent on rpms? Because during my drive today, i wasnt getting on it initially, probably 30-40 minutes of driving and no problems. On the way home, i hammered it pretty good in 4th and coolant buzzer went off and hose burst where i put the red dot at.
Another question is, does it look like the "bend" of that AST hose a bit extreme? It looks like the water filler nipple is almost protruding the hose, like its about to rip through it by itself.
Funny story about this happening today, because it happened to me yesterday too!!!! LOL
Same exact spot of the AST hose, same incident. I was getting on it, come to a stop and i see steam rising out of my hood. Then coolant buzzer went off and i saw hose burst at that same exact spot i put the red dot, right where the nipple seems to be protruding the rubber hose.
There is no blockage but i think the "bend" might be almost kinking the hose, probably restricting proper coolant flow??
Can someone give me peace of mind and say its the bend of the hose. I already ordered a new 2PC AST hose set off rotaryperformance because i want extra insurance.
But in the meantime i need to hear some good news lol
Thanks
I had a coolant line burst on me today. AGAIN. Thankfully all the problems i have had with my car had been minor and 75% of them are coolant hose related lol. I should just replace every single coolant hose to prevent anymore future problems.
Anyway today i take my car out, nice sunday cruise like i always do. On the way home, it was time to have some real fun. I get on it in 4th gear, long pull, then i hear BEEPPPPPPPPPP.
Coolant buzzer goes off, water temp gauge shoots to 220F in a matter of seconds. I literally do a nascar pit stop brake onto the shoulder of the highway and shut her down and threw the fans on right away.
Hose burst right where the little red dot inside the red circle is.
My question is, is coolant pressure dependent on rpms? Because during my drive today, i wasnt getting on it initially, probably 30-40 minutes of driving and no problems. On the way home, i hammered it pretty good in 4th and coolant buzzer went off and hose burst where i put the red dot at.
Another question is, does it look like the "bend" of that AST hose a bit extreme? It looks like the water filler nipple is almost protruding the hose, like its about to rip through it by itself.
Funny story about this happening today, because it happened to me yesterday too!!!! LOL
Same exact spot of the AST hose, same incident. I was getting on it, come to a stop and i see steam rising out of my hood. Then coolant buzzer went off and i saw hose burst at that same exact spot i put the red dot, right where the nipple seems to be protruding the rubber hose.
There is no blockage but i think the "bend" might be almost kinking the hose, probably restricting proper coolant flow??
Can someone give me peace of mind and say its the bend of the hose. I already ordered a new 2PC AST hose set off rotaryperformance because i want extra insurance.
But in the meantime i need to hear some good news lol
Thanks
03-20-11, 07:20 PM
#2
Wolf Pack!
iTrader: (9)
Join Date: Jan 2011
Location: Fairfax Va
Posts: 150
Likes: 0
Received 0 Likes
on
0 Posts
There should be only enough pressure as the cap allows. But in theory if you are running 12psi at 180°(I don't know the pressure related to temp) and then you gun it and temps rise then pressure will rise.
From my understands of water pumps is they will produce some PSI in the system at higher rpm but they plateau at no where near red line.
If that was my hose I'd get a longer one just on the safe side. I think the issue was bent hose+ engine pulling away during acceleration+ just that time= Small rip.
From my understands of water pumps is they will produce some PSI in the system at higher rpm but they plateau at no where near red line.
If that was my hose I'd get a longer one just on the safe side. I think the issue was bent hose+ engine pulling away during acceleration+ just that time= Small rip.
03-20-11, 08:05 PM
#3
Yes. Water pump at high RPM will produce substantial pressure, especially when it's throttled by the thermostat and/or bypass restrictions. 30 to 60+ PSI pump outlet pressure can be achieved. Pump pressure will continue to rise with RPM until cavitation occurs. And this is on top of the cooling system cap pressure. Problem is worse if the pump has a high pressure impeller on it (e.g., certain aftermarket performance pumps). Hose failures are not uncommon (with weak pressure side hoses) during high rpm pulls.
03-20-11, 08:12 PM
#5
Yes. Water pump at high RPM will produce substantial pressure, especially when it's throttled by the thermostat and/or bypass restrictions. 30 to 60+ PSI pump outlet pressure can be achieved. Pump pressure will continue to rise with RPM until cavitation occurs. And this is on top of the cooling system cap pressure. Problem is worse if the pump has a high pressure impeller on it (e.g., certain aftermarket performance pumps). Hose failures are not uncommon (with weak pressure side hoses) during high rpm pulls.
So we're saying i was seeing past coolant cap pressure?? My AST has a 13LBS cap on it.
Could it also be i was at high rpms while the thermostat was closed that caused the hose to burst?
Cause i was around 170F at the time of me getting on it. (car did warm up properly but highway driving brought temps down)
I'm not wondering if i do actually have a pressure problem or was it just the damn hose and how its routed.
Because i have never had a pressure problem til yesterday when the hose burst. Then again today at the same exact spot.
03-20-11, 08:28 PM
#6
Wolf Pack!
iTrader: (9)
Join Date: Jan 2011
Location: Fairfax Va
Posts: 150
Likes: 0
Received 0 Likes
on
0 Posts
http://www.stewartcomponents.com/tec...ech_Tips_3.htm
"Years ago, cars used low pressure radiator caps with upright-style radiators. At high RPM, the water pump pressure would overcome the radiator cap's rating and force coolant out, resulting in an overheated engine. Many enthusiasts mistakenly believed that these situations were caused because the coolant was flowing through the radiator so quickly, that it did not have time to cool. Using restrictors or slowing water pump speed prevented the coolant from being forced out, and allowed the engine to run cooler. However, cars built in the past thirty years have used cross flow radiators that position the radiator cap on the low pressure (suction) side of the system. This type of system does not subject the radiator cap to pressure from the water pump, so it benefits from maximizing coolant flow, not restricting it."
"Years ago, cars used low pressure radiator caps with upright-style radiators. At high RPM, the water pump pressure would overcome the radiator cap's rating and force coolant out, resulting in an overheated engine. Many enthusiasts mistakenly believed that these situations were caused because the coolant was flowing through the radiator so quickly, that it did not have time to cool. Using restrictors or slowing water pump speed prevented the coolant from being forced out, and allowed the engine to run cooler. However, cars built in the past thirty years have used cross flow radiators that position the radiator cap on the low pressure (suction) side of the system. This type of system does not subject the radiator cap to pressure from the water pump, so it benefits from maximizing coolant flow, not restricting it."
03-20-11, 08:58 PM
#7
A new hose and you should be golden.
Trending Topics
03-21-11, 05:55 AM
#8
Speculating that the first failure was a result of time and heat...not even knowing it maybe you leaned on it while working under the hood, or accidently hit the hose against the nipple... weakening it further. After the first leak developed did you cut the hose behind the failure and re-attached it? If so, the second failure was probably just due to stressing the wall of the already old hose on the nipple because it was now even shorter.
A new hose and you should be golden.
A new hose and you should be golden.
Last time I had a coolant hose issue was in oct. 2008 where it actually burst an rx7 meet (how ironic lol). And I remember I should have replaced old looking hoses while the system was drained anyway. Well I didn't. I just fixed that coolant hose at the time, which was the TB coolant hose.
Overtime as I do my usual checks around the car, every other time I take it out, I noticed the AST hose looked old and corroded, turning almost white at the area where I put the red dot in the pic. But I paid no mind because if it ain't broke, don't fix it when it comes to my car. Especially since I hate downtime and I only see it on the weekends I just wanna drive it when I do see it.
So yeah sgtblue you're right over time I guess stress on the hose built up and finally let lose.
And right again. When it burst first time saturday, it burst at the knuckle of the filler nipple and I just pulled on the AST hose to reattach it to get home that day.
Then yesterday I guess was even more tension because there was no more slack on the hose, its barely hanging on via hose clamp. I think this in conjunction with the bend of the hose and coolant pressure made this thing go bye bye again lol.
I ordered a new hose kit though so I can't wait to put it in.
Out of curiosity, how many degrees are coolant hoses rated at? Like 250f?
03-21-11, 02:09 PM
#11
No, he's referring to the clamps requiring a screw-driver to tighten are tough on hoses. They're called "worm-gear" clamps because what your are turning is a "worm-gear".
The OEM hose clamps are the spring-metal ones that you pinch together to loosen and remove. They're alot better clamps for the hoses, just not friendly for skin and other soft tissue when your working around them.
The OEM hose clamps are the spring-metal ones that you pinch together to loosen and remove. They're alot better clamps for the hoses, just not friendly for skin and other soft tissue when your working around them.
03-21-11, 03:57 PM
#12
No, he's referring to the clamps requiring a screw-driver to tighten are tough on hoses. They're called "worm-gear" clamps because what your are turning is a "worm-gear".
The OEM hose clamps are the spring-metal ones that you pinch together to loosen and remove. They're alot better clamps for the hoses, just not friendly for skin and other soft tissue when your working around them.
The OEM hose clamps are the spring-metal ones that you pinch together to loosen and remove. They're alot better clamps for the hoses, just not friendly for skin and other soft tissue when your working around them.
I dont really trust pinch clamps though. Some of my misc lines are held by pinch clamps and i can literally twist the hose left to right, thats how weak the clamp is. I have a pinch clamp to my BC and i put a worm gear hose clamp right next to it for insurance lol.
Ill see what i can grab at the next run to the auto parts store. IM gonna start carrying coolant hose and a bunch of clamps with me now. Im getting paranoid again
03-21-11, 05:19 PM
#14
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,829
Received 2,597 Likes
on
1,845 Posts
also as pointed out the factory clamps are best, they stay at a constant tension, and they don't tear the hose. if a hose with a factory clamp on it leaks, the hose is bad.
on a stock turbo FD if you replace all the hoses, say with the engine it'll go another 60-80k without having to do more than inspect it at the normal service intervals.
03-22-11, 11:28 AM
#20
Original Gangster/Rotary!
iTrader: (213)
We replace all coolant lines (all, including the trio of short heater hoses under the ABS) on every build unless theyre already fresh. We also usually delete the AST on higher powered builds to minimize the number of failure points in the cooling system. We do have cars that retain the AST if the owner desires.
03-22-11, 07:05 PM
#22
The problem with those clamps is that you won't be able to reach the screw to tighten them in a lot of places - turbo coolant lines, TB coolant lines etc.
When you get new OEM clamps, they are held open with this small aluminum tab which makes install a breeze in tight spots. Just line up the clamp and then pull the tab off and it springs closed on the hose applying the correct amount of torque to seal the stock hose to the nipples/pipes. Makes it sooooo nice and easy.
When you get new OEM clamps, they are held open with this small aluminum tab which makes install a breeze in tight spots. Just line up the clamp and then pull the tab off and it springs closed on the hose applying the correct amount of torque to seal the stock hose to the nipples/pipes. Makes it sooooo nice and easy.
03-25-11, 10:02 PM
#25
Ill be clearing up the engine bay significantly if and when the motor goes
God forbid not anytime soon but why would i start touching things when car is running fine, except for that stupid AST hose.
Well i changed it, still feeling paranoid about driving the car but i have to get rid of that mentality. Things breaking while driving, especially in older cars like ours are the inevitable. I have to learn to deal with it.
Im keeping extra coolant hose, tools, water and hose clamps with me just in case though lol.
And i still have my tow truck assistance just in case major problems happen
God forbid not anytime soon but why would i start touching things when car is running fine, except for that stupid AST hose.
Well i changed it, still feeling paranoid about driving the car but i have to get rid of that mentality. Things breaking while driving, especially in older cars like ours are the inevitable. I have to learn to deal with it.
Im keeping extra coolant hose, tools, water and hose clamps with me just in case though lol.
And i still have my tow truck assistance just in case major problems happen