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Small Claims Case - Coolant Flush/Water Pressure Question

  1. Feb 8, 2007 #1

    I know that this is a auto mechanical issue but I hope this is a question that someone here can shed some light on for me. It involves water pressure.

    I recently had my coolant flushed at an Oil Changer shop in the bay area.

    The kid hooked up a "Coolant Changer" machine to my radiator. The machine vacuum sucks the old fluid out and then pumps the new fluid back in. When he did this, he wasn't paying attention and we were both surprised by a stream of coolant coming out of my radiator similar to puting your thumb on the end of a garden hose.

    According to the Manufacturer of this machine, the unit has a regulator built in to keep the pressure from exceeding 7 psi. (sounds awful low) They also claim that an average coolant flush, using this machine would take only 5 min.

    According to my car manufacturer, my coolant system on my car (98 subara legacy) can handle 12 psi maximum.

    I have attached an image of the machine to show you the rubber cone that they use to seal the hose to the radiator. I assume that when too much pressure is appied to the system that the seal can break causing it to stream out (like what happened to me).

    The reason I'm asking this is because I have a blown head gasket now. My car started over heating (which has never happened before) immediately after the flush and the splash incident (it covered my windshield)

    My theory is that the machine over pressurized my coolant system causing my head gasket to blow. Either that or running it hot in the shop for over an hour could have done it (which they did that too).

    Is it possible for 7 psi of water flow being pumped into an enclosed (sealed with cone) coolant system to exceed 12 psi if there isn't anywhere for the water to go?

    I am taking this company to small claims tomorrow. I have already won but they have appealed. In california, you are allowed to bring an attorney to small claims on an appeal. I feel that I will need as much evidence as possible.

    Being able to explain the water pressure build up, i feel, will better my case.

    Any help pointing in the right direction would be very helpful!


    Attached Files:

  2. jcsd
  3. Feb 8, 2007 #2


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    I approved the attachments and moved the thread to the Mechanical Engineering & Aerospace forum from General Physics. Seems like you'll get more ME views here.

    I'm of no help on your questions, however. Have you tried a google search with some of your keywords to see if there have been similar problems in the past? Either with that device, that method, or that company?
  4. Feb 8, 2007 #3


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    If the machine was functioning correctly (and as you describe) then there's no way your cooling system could have been pressurised to over 12 psi without something else going on. Running the car hot is far more likely to have blown the head gasket, but if the cooling system was working properly there's no reason why this should have happened.

    It's possible that your cooling system was damaged (rust, corrosion, perished gland etc) and that by clearing the system out they unlodged some goo or muck which was sealing a potential leak. Then your system was possibly run dry causing the head gasket failure?

    By the way, your second attachment is too small to make head nor tail of.
  5. Feb 8, 2007 #4
    Sorry about the second picture. These were taken from http://www.oilchangerinc.com/services/coolantservice.cfm" [Broken]

    If you would like to see the brochure from the manufacturers website (better pictures):

    and the Manual (7mb)

    I suppose your point of the possibilty that my car had some corrosion before the flush and that this could have disturbed a problem that was waiting to happen would be a pretty good argument for them. They didn't argue that the first case but I suppose they could claim that tomorrow.

    Mechanical things are very difficult to argue when your not very mechanical. Thanks for the input, I really appreciate it!

    BTW, It may seem like I'm exaggerating about the water spraying out a little bit but I'm not...and then immediately after that my car starts to overheat.
    I'm left thinking this had something to do with it.

    But either way, it sounds like it will be easier to convince the judge that this damage was caused by the overheating in the shop when flushing improperly.

    Thanks again.
    Last edited by a moderator: May 2, 2017
  6. Feb 8, 2007 #5


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    No way your head gasket will blow out from that machine, remember it seals the exploding exhaust gases at 100's of psi (or more?). "Blown" head gaskets are actually a misnomer; when the head overheats due to loss of coolant, it warps and the gasket is no longer compressed, giving you a leak.

    Perhaps you can explain your comment that they "ran it hot in the shop for over an hour"? Was the car idling the whole time?

    Also describe the radiator leak. Was it properly repaired by a radiator shop?

    Without more information than you've given so far, I'll describe the following possible scenario:
    Your radiator sprang a leak under the pressure of the flush operation. Either your radiator was rotten and ready to let loose anyway, or the machine operated at high overpressure (if the latter, why wouldn't the cork have popped out?). The attendant refilled your car with coolant, you drove away, it all dribbled out (maybe when it got hot?), and your head overheated. Or maybe he failed to fill your car, you drove away and overheated.

    In any case, I wonder if your car had some coolant system issue to start with (as Brewnog also asked). Sorry, I know that's not what you want to hear...
  7. Feb 8, 2007 #6

    The car was idling the whole time. My car has never overheated before or even indicated more than the 30% mark... The car ran for about an 1.5 hrs total. They may have turned off the car for no more than a minute. I was there for 2hrs. The reason it ran for so long is because they sent someone to the autoshop to buy a thermostat and that alone took over 45 minutes (after they flushed it 3 times). It would hold a temp for about 2 min and then the gauge would spike to the top and drop back down. Spike to the top and drop back down.

    A month later, it started doing this again. Spike to the top and drop back down... Took it straight to Subaru... Pressure test failed... Called Oil Changer they said they don't trust Subaru...They wanted their mechanic to look at it(diagnostic check)...I said you pay for it...They said no problem...Their mechanic does a chemical test...Says it's a blown head gastket....I never hear from oil changer again...

    I'm not sue happy one bit...This makes me quite pissed off that I even have to go through this over a trip to Oil Changer. BTW, I didn't ask for a coolant flush they sold me on it...They said that it would only take a minute.

    So, thanks for letting me throw my case out and spill my guts to you...That felt better right there...now I'll just have to drink a beer, get some rest, and win again tomorrow.


    I don't remember saying anything about a radiator leak. So, no, I didn't have a leak repaired... What happened was that the guy had the fill hose in the radiator (with the cone sealed) and filled it up so fast that it spurted out all over my car. And I thought that the water pressure built up high enough to blow the head gastket. Seriously it built up good .

    Also, I can still drive the car short distances (30-40 miles) without it overheating. I'm just waiting for it to die...The mechanic from Subaru says that he has customers drive to and from work for over six months before the car will start blowing smoke.

    I'm not sure exactly what won my case for me last time so I'm just making sure I cover all of my bases before I go back...

    So I guess we can all agree that the machine theory doesn't fly over well...
    I still want to argue it a little further though before I dismiss it completely...

    That machine smoked my car! the guy didn't turn off the air pressure(70psi) before he refilled the radiator! He over pressurized it until it popped a head gasket. It MIGHT have been weak and ready to go but would have lasted another 50,000 miles easy if the guy would have been paying attention...My car started overheating immediately, spiking to the top and droping back down...they flushed it three times and sent someone to the store to buy a replacement thermostat...no cost...I asked them if I should turn off my car...they said your car isn't really hot, it's just the gauge telling you that because your thermostat is broken...ok...1.5 hrs later they get the car to hold a temperature. I ask for some money back...they give me 20 bucks....I leave...1 month later it spikes to the top and drops back down...go figure..

    Judge asks Subaru Mechanic, how does the car stop over heating (with a blown head gasket) and then start back up a month later? The subaru mechanic says, they put water in it. She says huh? He says, they filled it up properly and it can now drive short distances before steam builds up and pushes water out of the reservoir...then the car loses water and starts to over heat again. If you keep the water level up correctly, these cars have been known to drive short distances (to and from work) over 6 months before blowing smoke.
  8. Feb 9, 2007 #7


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    I still don't see how the machine could provide enough pressure to damage your head gasket. The overheating (more correctly 'undercooling') is the probabe cause; you said yourself that the coolant pissed out. What caused the leak we don't know!

    I wasn't saying it's possible your head gasket was weak and ready to go, I was saying your cooling system might have been weak and ready to go. Without coolant, your head gasket wouldn't have lasted very long at all.
  9. Feb 9, 2007 #8


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    You seem to be approaching this completely the wrong way.

    The usual legal disclaimers apply to the rest of this post: I've no legal training, but I have sat on a jury, and been an expert witness (not both in the same trial of course!)

    IMO, if the company made an appeal and won it, the only thing that matters to you now is to show that the argument they made to win the appeal was wrong. The easiest way to do that is if somebody broke the rules of the court. If that didn't happen, you have to show that argument they made at the appeal, which was accepted by the judge, was wrong.

    Getting at the truth, and/or being fair and reasonable, isn't the name of the game. You have to play by a nonsensical and artifical set of rules called "legal procedures". Sorry if that sounds cynical, but it's the way it is.

    Going back and arguing about the original facts of the case has nothing much to do with it. If you didn't put the evidence at the first hearing that (from what you said in post #6) the guy who did the job was obviosuly an untrained moron who didn't even know how to fill a radiator properly, let alone use a complicated piece of machinery without proper supervision, and therefore he should be held personally liable for criminal damage to you car even if the company denies responsibility, you have probably lost your chance to do that now. If you do try it now, they will just turn round and ask "why didn't you mention all this before". If you don't have a good answer to that, the implication will be you made it up after the event because you lost the argument first time round.

    Yes I know most of the above may seem completely OTT - but once you decided to take it to court, you gave up the option of making a calm and rational decision based on facts and logic.
  10. Feb 9, 2007 #9


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    Aleph, the OP has already won the case. It's the repair shop who is appealing the court's decision.
  11. Feb 9, 2007 #10


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    So the problem shows up already here--your car overheated somehow and warped the head, either coincidentally before you arrived (unlikely) or from something they did. I still agree with Brewnog that no machine will generate enough pressure to "blow" a head gasket, but I'm not experienced enough to diagnose the cause.

    Best of luck in court, it sounds like they don't have much of a case!
  12. Feb 9, 2007 #11
    Thanks all for your feedback and advice.

    I won..

    The eruption that the kid did when filling up the radiator was enough to convince the judge that the chain of events started in their shop and not before I came in. I had 147,000 miles on my car when going in. If I had a lemon car, my car would have showed evidence or a sign that the head gasket was blown before I went to their shop. She was convinced that it started when the eruption happened. Not proving that the machine did it but proving that they did do their job improperly.

    Again thanks for the debate here about the machine because I still think that if the wrong guy operates this machine that they could send enough pressure in to blow a head gasket. I think he forgot to turn off the air pressure (perhaps) and with the cone sealed to the mouth of the radiator, filling up at high speed, will leave nowhere for the pressure build up to go except the weakest points...(the head gasket and the geyser spurting out of the radiator).

    Either way, I won.
  13. Feb 10, 2007 #12
    Similiar thing happened to me, but it was because I had an old/bad heater core. Did a flush on my system and the heater core blew a leak. It was just worn out..nobody was at fault besides the old car. I wouldn't take them to court over this. I would think just the compression from starting your engine is far more likely to blow the head gasket.
  14. Feb 10, 2007 #13


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    Sorry, I misread the OP, for some reason I thought he won the original hearing, the repair shop appealed and overturned that, and he was making a 2nd appeal.

    Anyway, I guess he's happy with the result :smile:
  15. Feb 10, 2007 #14


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    Glad that you won, sky1tech. However, I'm still sure that the pressure from the machine itself didn't blow your head gasket. There are probably 30 or so connections and components in your cooling system that would have failed due to high pressure before your head gasket did. As marcusl rightly pointed out, combustion pressures are hundreds of times higher than the pressure any flushing machine could develop.
  16. Feb 10, 2007 #15
    30 or so connections?
  17. Feb 10, 2007 #16


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    Top and bottom radiator hose, two expansion tank hoses, two heater hoses.

    Then there are the radiator and heater themselves, filler cap, drain tap, water pump, thermostat, temperature sensors, etc.

    And the head gasket... :uhh:

    Thats about 15 components and a similiar number of seals clips and gaskets, without trying too hard.
  18. Feb 10, 2007 #17


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    Yeah, hose clips either side of the radiator, hose clip on the thermostat housing, expansion tank, all the bosses and tappings for the sensors.... Aleph's got it!
  19. Feb 10, 2007 #18
    Point taken...

    They did finally change the thermostat after 3 flushes, so I suppose the geyser could have done a number on the thermostat and the overheating in the process blew the head gasket. Remember, I'm not a very mechanical, mechanical person. I just throw out what makes sense to me.

    Even the Subaru mechanic didn't bring up the points that you've brought up here. They were always more on the overheating being the cause of it. I guess I just thought the pressure was the cause but really it only initiated the chain of events.

    You guys have definately shed some light on this for me and now I have a better understanding of what really happened. It's funny that I was still able to win without understanding a thing about cars.

    This was an 9 month process...Now wish me luck trying to collect (could take 9 years).

    I love my car. One day we will take long trips to the snow once again! Subaru's rule the snow!
  20. Feb 20, 2007 #19
    Coolant system flush


    An auto repair shop did the same crap with my car. I brought the car just for changing oil and they recommended me to flush the coolant system. After flushing I could hear a gurgling sound under the dash, and the temp light came on several times and I filled the coolant tank with regular tap water (several times happened totally about 2 litters). after some days I brought the car to that shop again and they flushed it again and the sound again came back after several days! and I had problem with the alarm light of the coolant system again. The third time that I brought the car they flushed it twice and they said the problem is still there and you have a blown head gasket!!!
    And they refused to pay for the repair. I am an international student here and pretty new in States and this problem pissed me off, cuz I don't know how to prove it, what's the legal procedure for doing that, and my car was all of my saving:(
    BTW another mechanic which is affiliated to this shop told me that you can not prove it in court :(
    I am in Northern California too.
    Any help would be really appreciated.

    Thank you,
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