Water rushing sound (coolant leak, bad heater core?)
 

There was another thread about this just posted, but it didn't get a lot of exposure due to it's strange title.

When the car first starts and usually until it warms up I can hear what sounds like water rushing from the glove box area when I rev the engine . I also experience some of the minor symptoms associated with bad coolant seals, ie - small puff of white smoke in the AM (doesn't really smell like coolant), occasional rough idle for the first few seconds after starting, low coolant light that comes on when the car is first started but goes away as it warms up, coolant expelled from the overflow after shutdown, coolant bottle is always completely filled up. I have to top off the coolant every few days, it doesn't take much though.

Last time I had symptoms like this I had the coolant system pressure tested and it turned out to be a loose hose clamp on the coolant line that takes coolant to the TB. This time I haven't had it pressure tested yet, but I'm thinking it may be a combination of problems. One may be a pinhole leak in the line from the overflow bottle to the filler neck (AST has been deleted), and another might be a leak in or near the heater core.

Anyone care to speculate or comment? TIA.

I was getting that rushing sound too last week. I think it might have to do with the cold weather. I still have my stock AST (God Forbid) but I popped the hood after shutdown and listened to what sounded like a jacuzzi in the engine bay. I wasn't about to burp the system when it was hot, so I left it for a while and opened it later before I drove the car again. Didn't seem like any pressure was built up underneath the cap, but I haven't noticed the rushing sound anymore.

Keep topping off your coolant and it will go away.

That is EXACTLY what mine is doing. I know the coolant seals are going. Mine had got to the point it was nearly impossible to start, but ever since I used some coolant system leak sealer that has been mimimized. But it still over pressurizes the cooling system and forces the overflow to....over flow. What happens is you keep filling up with coolant in the filler neck, eventually the AST is full of coolant too, and then there is no place else for the coolant to go but out the overflow.

Like I posted once before, this is a strange death to watch on the part of the engine. Other than having to top off the coolant every now and then, and seeing the overflow soaking the right front wheel every now and then, the car runs fine.

What I have been doing is sucking the overflow nearly completely empty after filling and burping via the filler neck, and I make sure that AST is no more than half full.
This way I can go about a week without having the overflow spew coolant all over everything. I probably add about a half pint of coolant or so after every time I drive me car these days. But I always get that rushing sound in the heater core on start up.

i get it after to shut down, it really scared me, ive had my rx for about 4 months now and i never that before, at first i thought it was like some nosie coming from the rotary. i wasnt sure at all, but this thread helped me realize wut it was.

i dont have a coolant leak at all, and i never had to refill my coolant, so wut could be the possiable reason for my water making sound?plz help, it sounds like a stomach ache or somthing hehe :)
geoff

Pretty simple really: You have a coolant leak - somewhere...

1) If you have the engine "O ring" blues you can either try Block Weld or rebuild.

2) If it's as simple as a hose, replace. If your hoses have never been replaced do them ALL at once or you could end up chasing a leak for months.

:confused: there is no coolant loss in my car...why is there that nosie still?

Because you have air in the system.

If it just started making the sound after 4 months of ownership you have a leak OR a bad O ring seal in the engine. You can always fill it up, burp it, and hope for the best, but the odds are very strong you have a leak somewhere OR are burning coolant.

hmmm thanx for the help man

Thanks for the advice, I'm fairly certain all the hoses are original and are due to be replaced. Anyone have a commplete list of all the hoses and/or their part numbers. Here's what I came up with off the top of my head, feel free to add/correct me (keep in mind my AST is deleted):

2 large hoses in and out of radiator
1 small hose from filler neck to overflow bottle
2 small hoses in and out of throttle body
2 small hoses behind alternator feeding the lines to TB
2 medium hoses in and out of heater core

Any others?

1 small behind the air pump (very hard to replace, may need cutting)

You mean the 2 small hoses to and from the turbos? I forgot to mention those are new because I just had rebuilt turbos installed.

jr - these were the EXACT same symptoms I had before my coolant seal failure. I'd get another pressure test done and maybe replace the refill cap.

JR,

I have a vacation day scheduled on Friday December 27, 2002. If you want to drive out I, can pressure test your system for you? I am about 20 minutes further than 7 Speed (Washington County also). I went through the same problems that you described with my remaned motor (at 4K miles). My solution was three fold, leaking stock radiator (replaced), leaking lower radiator hose (also replaced all hoses), and stock spring clamps (again replaced all). I would suggest ordering your new hoses and in addition, buy new hose clamps for all you fittings. To trouble shoot further leaks I also added a packet of coolant dye. Therefore, in the future I will be able to spot leaks easier. Give me a call at my office (412) 967-8294 or cell (412) 805-7888 if you need any further assistance or want to come out on the 27th.

Tom Delegram

jr- went thru the exact problem you are experiencing about 2 yrs ago. Maybe you will luck out and it is not the coolant o-rings. (mine was) To get all the hoses needed, go to the Mazdatrix website and use their order form. I believe there are 14 hoses total. will cost you about $200 for all of them. Good luck.

Thanks for all the advice guys.

Tom - I'll call you as the 27th draws closer. I may be back in NYC for the holidays, but probably not. Either way I appreciate the offer and look forward to meeting you.

Jr,

If you get a chance, give me a call at my office today.

Tom

I don't know about the noise coming from the glovebox area, but if you pop the hood and it is coming from the front right side (I guess this could sound like the glovebox area if you are in the car), then it is possibly normal.

One possible cause is the radiator cap. When Mazda changed form the 1.1 to .9 bar cps, peopl started hearing the percolatng noise.

Also, people who have swapped out the stock AST for an aftermarket one like the Tri-Point said that this helped cure the problem. I think Tri-Point may ship their AST with the .9 cap.

For more info, see my site and go to: Upgrades --> Engine --> Cooling System and look at the Radiator Cap and AST sections.

If you are also etting white smoke, then it could be the O-rings. See How-to --> Cooling System and read the sections on O-ring Failure and Fixes.

Cheers,

Yep, I had that noise on a newly installed reman. After switching to the Pettit AST, it was gone.

jr, since your AST is gone, I would just try to keep burping the system.

ok, Im just about to do an AST swap, because I have those exact symptoms right now as well, the only thing is that I dont have trouble with start ups, and Im happy about that. :) But I do hear that noise that u guys are talking about, sounds like rushing water inside the glove box or underneath, but I can't seem to hear anything under the hood, and Im hoping that this new AST will cure the problem. Anyhow, I was wondering how to change out the AST. NE one have a good link or site that has install instructions? I found a couple sites that just tell you how to remove the AST, but none that show u how to replace it. Im sure it can't be that hard, but I think Im going to replace the connecting hoses that go with it as well, and was wondering if there is anything that I should look out for, i.e. drain coolant first, new clamps, etc. etc. Theres three of those hoses that run from the AST right? Oh, btw, I ordered an ASI tank, so if that makes it different somehow, let me know as well. And while we're on the ASI tank, does NE one have this tank and know what the pressure is on the cap?

Check this thread:

https://www.rx7club.com/forum/showth...hreadid=139120

my 2 cents

dont forget that you do NOT want to top off the overflow when the engine is cold, then you will 'over flow' the over flow when you shut down, I kept dumping coolant and then kept filling the overflow when it was cold, well, then it warmed up, I shut down and it had to put the coolant somewhere, and the overflow was full , so it dumped it out the overflow to the street :-)


my car had similar symptoms as described in this thread (coolant light going on at funny times, dumping coolant at shutdown, et) and it was just trapped air in the collant system, after a few times of topping off the coolant at the filler neck (not the overflow tank or ast tank), then it was fine.

a trapped air bubble by the filler neck will be very hot and trip the coolant light to go on.....if you eliminate this air and you still get the light...then you have serious issues :-(

I'm having a similar problem with my engine. I hear this water rushing sound near the glove box area when I revup the engine, I can only hear it inside the car, I can't hear it in the engine bay. I've elimiated the AST, all new coolant hoses, just had the engine rebuilt, new radiator. Any idea what this could be? I checked the carpet under the passenger glove box, doesn't seem like the heater core is leaking.

My car does the same thing, People never believe me when I tell them I can hear my coolant rushing around. Im not sure if my coolant seals are going and wont find out until I start driving it again this spring but I did have a little over heat episode last fall and have been weary about it every since because my motor only has 12k miles. I get smoke for a few seconds at startup but it doesnt smell like coolant at all, I always just assumed my turbos were going because sometimes at a stop it will smoke for a few seconds and then go away.

Anyways the more I think about maybe having blown coolant seals, Its like if the engine is still running I just consider it like free water injection... Haha