So, I've change my thermostat (twice), changed the rad and water pump, and changed the rad cap (all work except for thermostat and rad cap was done by Mazda in Delray FL) And all hoses were replaced less than a month ago while I was still in Pittsburgh.

The problem is all of my coolant is ending up in the overflow tank and I am now clueless as to what could be wrong. The car is going back in to Mazda on Monday and the guy that has been helping me said he wants to put it on a pressure test again (but he did that after they put the water pump in and it held pressure over night already). Does anyone have any suggestions as to what it could be? Is there something that I could look at myself to check? How does the coolant get from the overflow tank back to the engine?

Usually, the times that I have driven it since I got the work done, the car hasn't run hot..it just looses all the coolant and the only time the buzzer really comes on is when I'm stopped at a light, and if I blip the throtle it turns off. Although, when I was going to school today, the buzzer wouldn't shut off and then the car began to run hot (and when I got to school I oppened the hood and there was a really wierd noise coming from the engine compartment).

P.S. this may look famillar, I had a post in the lounge about this a couple of days ago, but that wasn't really about the techinical side of it.

 

so the overflow tank gets completely filled and the overflows itself? did the mazda dealer check you coolant for hydrocarbons/exhaust/etc.? they should have during diagnosis... or at least i would have. what were the results if they did?

how old is this engine? i'm leaning towards coolant seal failure personally...

 

Yes, the tank fills then overflows itself. No, they did not check for that (that I know of). The engine is original ('86 NA about 151,XXX miles).

Is coolant seal failure rebuild land?

 

take it to a radiator shop and get them to check it. if you're losing coolant and overheating and you've replaced everything else, then it's probably internal i would think. is your car smoking from the exhaust?

 

It's not smoking enough that I can see it from my rear view mirror while I'm driving and when I get out and check there is nothing at idel.

 

Sounds like you have a blown coolant seal.

 

Does that mean I need a rebuild?

 

yes, but get it confirmed at a radiator shop and be careful... if it is a coolant seal you may be able to salvage most of the block parts if you don't let it overheat and disassemble it with the quickness.

wait too long and you'll be pulling a solid ball of rust out of that car, you know... assuming it is your coolant seal.

you may also be able to buy a hydrocarbon detector kit... good luck.

 

I let my block set for 3 months with a blown coolants sea,l and when I tore it down there was water in the housings, but it did not rust AT ALL.

 

Here is a possiblity: The coolant expands and the extra goes into the overflow. When you shut down and cools down, the coolant contracts. If you have a leak that will not hold vacuum, air is drawn into the system from leak instead of drawing back the coolant from the overflow. Could be a leak that will hold pressure, but will not hold vacuum. Next time you drive the car, the process repeats, until there is not enough coolant to move the heat from the engine to the radiator. You then overheat the engine.

The reason the coolant buzzer quits buzzing when you rev or drive the car is that the air at the top of the radiator becomes mixed with the coolant and is circulated as a bubbly mixuture due to the increased flow when the water pump is turning faster. The low coolant buzzer has a timer (7 sec?) and as long as a bubbly glug of coolant makes the connection every couple of seconds, the buzzer does not go off. By the time you have buzzing while driving, you are in serious trouble.

First do the cold engine crank test. Crank the car with the radiator cap off. Coolant should not spew from the radiator opening. If your car passes this try the following proceedure.

For the time being, put a jug of 50/50 antifreeze/water in your car. Each time you drive, BEFORE you start the motor, top off the radiator. What you should find, is that the overflow tank gradually fills up. The tank will hold about a gallon of coolant. When your overflow tank is full, remove the two bolts holding it in and pour the contents back into your antifreeze bottle. If the volume of antifreeze returned to the bottle is very near to the amount you started with, then the engine is not consuming the antifreeze. You have a simple vacuum leak. Then you can keep looking for the problem, while keeping your engine safe.

If however, the volume returned to the bottle is significantly less than you started with, then you probably have a coolant seal issue.

 

The coolant seal retaining walls have a tendency to erode, causing the seal to pop into the water jacket. Strangely, this situation can stop coolant from flooding the combustion chamber, yet allows large amounts of exhaust gas into the coolant system. This in turn creates an overpressurized coolant system causing the coolant to be expelled into the overflow tank.

We have seen many cars that pass the coolant pressure test , but fail the hydrocarbon test.

 

because engine compression is a alot higher than the 13-16+PSI the cooling system generates, it's not all that strange.

 

i'm sorry but there is no way water can sit on the bare rotors and housings for 3 months and not rust anything... it's a horrible idea to do that and you got lucky as hell. there might have been water in there from disassembling it... but it wasn't in there the whole time.

no one should do this if they want to salvage and internal parts from their block.

 

ok well, um. i had this happen to me, and a guy who had a rx7 told me there is a little screw on the side off the radiator. plastic on the neck. he says run the car. and unscrew it. u will hear air comming out of it, when it stops. close it up and it should be good.

 

No. I have had them sit for over a year, on tear down nothing but rust on the rotor that just scrubs off. You will not encounter anything serious until the coolant turn to an acid base and eats into the nitrate coatings.

 

take your chances man...but i wouldn't trust an engine built from a core like that. are you actually saying it's not a bad idea? it obviously is... and that light coat of rust that sluffs off.. how did that affect the seal clearances when the seal grooves were cleaned out? i can safely say it didn't ADD material. what about the side seals and corner seals?

there are also different levels of contamination... that core may have had less. aside from that if an engine has been leaking coolant profusely it's very likely that plain tap water or poor/used coolant at best has been used to keep the car running in a pinch when nothing else was available... fresh coolant i wouldn't be worried about leaving in until i found time, but who knows what one has put in there.. for example on a freeway or at a friends house who doesn't work on cars.

so yes, sure let's tell this guy to wait as long as he wants to get his motor apart, which likely has a bad coolant leak, then we can wait for his wanted posts in the for sale sections or his post in here where to get a good core around pittsburg...

 

Stop puting words in peoples mouths!

I have stated that certain destruction of the motor from siting is false. I stated exsperiance on it as well. Take it as you want. No one told anyone to do crap. I simply told you that you were wrong

Do you want me to go photograph specs and clearances for you? Do you realy need that?

 

Going back to the original topic at hand...

My TII with about 4,000 miles on the rebuild is pushing coolant into the overflow tank.
The rebuild was done by BDC, so I am ruling out the combustion pressure into the coolant. (no HC test though)

I have a small leak between my water pump and the housing.

1)There is a chance you have another uncommon problem that is causing your coolant to overflow.

2)How is my coolant overflowing the reservior tank on the freshly rebuilt engine?

 

since when is being cautious wrong? stop while you're ahead... a 10 year old would probably warn against letting a motor sit with old scale and coolant and water in it.

i'm not putting words in anyone's mouth. your post insinuated that it was a good idea... at least it seemed to to me. take chances yourself, but don't tell someone who doesn't understand the risks to do something. that's my whole deal with these comments... you might have gotten away with it, but they give people the wrong idea.

of course there are instances where the motor was ok after sitting, stranger **** has happened, but to discount my advise to this guy and say i'm wrong? that's a little far.

"No one told anyone to do crap."

i did. i told him that if he wanted to salvage the engine then don't let it sit with a blown coolant seal... not everyone has the money or time to go find an entirely new core and would rather not take the chance of having to do so. now you're trying to debunk my advise.

..and no, i don't want the specs. rusty engines aren't a concern of mine (see above posts).

 

What I stated was there would be no long term damage to major parts until the coolant turned into an acid base. The time of this is unknown unless you keep up very well on the motor. I never suggested leaving in, I suggest tearing it down ASAP. I wanted to make known that the rust received will only be deposits and will brush off unless the coolant turned into acid.

I have housing and rotors and irons sitting in my shop that have been sitting with coolant seals from previous owners and some that just sat. I have one that is a fine example that must have sat for years where the coolant did go bad and eat a hole over 1in big in one of the housings. This was the only long term damage done at all.

It would be hard pressed for the coolant to reach up to the rotor bearings so what you will get is some water that may have gotten on the rotor faces and a puddle on the bottom or a little pocket trapped in a upper position of the rotor if the seal blew on the intake side "unlikely"

Davidov – The leaking water pump seal would lead me to suspect even more that a coolant seal would blow. With a leak you allow air bubbles into the system and the water pump can/will cavatate. This will no longer allow proper flow of coolant developing localized hot spots.

 

This can be a vacuum leak in the cooling system! Do the HC test. Fix the small leak at the waterpump. Your waterpump leak may be sucking air into the cooling system when cooling down, instead of letting the vacuum pull the overlow back into the cooling system. For now recycle the overflow tank per my earlier post in this thread. Don't just accept the 'you gotta rebuild it' theory without more investigation.

Good luck.