WillT

I have an RX8, and went and picked up an RX7 earlier this week. Everything seemed fine, so I purchased the car, but I have now found a leak (which seems to be getting worse!).

As you pour liquid into the coolant resoviour it leaks out the bottom of the tank. I have the 1994 twin turbo import, so its very hard to see or get to the coolant resoviour.

If I pour coolant directly into the system everything is fine.... car runs fine and no problems. Its only when the car is switched off, or at idle for 30-40 seconds, when the coolant is returned back into the resouviour that it starts to leak.

Has any one else had any issues with the resoviours? Are they prone to going? From what I can see the connection from the "downpipe" (where you pour the coolant) to the resouviour looks very weak and not fitting together properly... now this wouldn't make coolant come straight out, but i'm wondering if something at the bottom of the resoviour acts similar.

I am going to put the car on a ramp tomorrow, so should be able to get a better understanding as to whats going on, but just thought i'd see if this is a common problem. I'm hoping that I can fix this with a few tools and some glue, as the resoviour from my understanding doesn't undergo any pressure? As it is simply holding the coolant until the engine requires it. Tell me if i'm wrong!

grimple1

iTrader: (1)

the coolant tank will overflow onto the ground if it's too full. are you sure that's not what's happening?

if it's cracked then just buy another one. I wouldn't say they're common failures but they're not uncommon.

Mahjik

iTrader: (1)

Check my comments in this thread:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/q-about-coolant-overflow-tank-backup-779734/

Six Rotors

iTrader: (17)

The hose from the air separator tank to the overflow tank certainly leaks and in some cases the hose can separate.

WillT

Hey guys - ok so I took it up the a garage and stuck it on a ramp to see what the hell was going on. Any way, a "mechanic" there was trying to help but i'm not sure if he completely screwed it instead.

He firstly filled the overflow AND main unit (by passing the resoviour) until they were full. Then put the caps on, then after about 5 minutes of it being turned off, the main "downpipe" (as seen in the picture) started spurting coolant out of its seal.

Obviously this isn't good! but the question is what the hell is going on? Until then, the car was running well (other than this leak i described above).

How much pressure should there be in the coolant system? As there did seem to be a LOT! I assumed this was normal? Should the overflow ever be filled up? By the word "over flow" I sort of assumed it shouldn't have liquird poured into it?

What could the worst case scenario be here? Are we talking big bucks, or is there something more logical have gone wrong. Any help here would be much appreciated!

The car is now sat up at this garage as I can't really move it!

Six Rotors

iTrader: (17)

thats the level sensor---you need to replace it.

WillT

Doesn't come out of the nipple (if thats what you meant) it was coming out of the actual pipe where that slightly rusted connector is. If that makes sense?

Attached another quality image lol.

renedis

hmm.. thats the main output to the radiator..
can't you make it more solid with a screwdriver?
or replace the ring with a new one?

WillT

I can and will be doing that but i'm just wondering why the pressure would have been so much that it burst out there?

When a pressure gauge was put on the main filler neck, the gauge was dropping pretty quickly. Ie pumped up, and you could physically see it falling away slowly.

I assume this means the cooling system has a leak somewhere? Also I'm still wondering how much pressure the system should have? As when I was taking the filler cap off, it seemed pretty intense!

Mahjik

iTrader: (1)

What does happen to these motors is that the engine coolant seals can fail. This can allow coolant into the combustion chamber and also possibly combustion gases into the cooling system (i.e. adding too much pressure to the system).

If/when that happens, that means an engine rebuild.

Zoolander

iTrader: (8)

My coolant is low every month or so (or less even) at the overflow tank...and I have to fill it up (at the overflow tank...which is wrong I guess.) There's never a puddle underneath the car but I can actually hear bubbling (like boiling water) around the engine. Where could this coolant be going? Is it burning off? Could it be leaking while I'm driving only?

renedis

i don't know for sure but i thought it can hold 0.9 bar (13psi)

this could mayby a stupid question but did you pulled the filler cap off when the car was running? or pulled it off when it was still hot? OR did you pulled it off when the car was cold?

when the car it hot or running.. it's under pressure, so it's logical that the coolant comes out of the fillerspot.

RIX-7

iTrader: (2)

sounds like over filling, and your stat could be u/s,or the cap is not releasing pressure,change your stat n caps as its cheep and go from there

WillT

Ok guys this is good help.

Mahjik - i'm pretty sure this isn't the case. The oil has no moisture in it at all, and the exhaust isn't smelling sweet (as in coolant being in it). No white smoke, infact no smoke at all even at cold startup. Hopefully this isn't the case....

What type of caps should be on each of the fillers - ie the main filler and the overflow? I think I read somewhere that the main filler shouldn't be sprung? and the overflow should be? Is that correct. At present i'm pretty sure I have 2 standard sprung caps on each. I assume I can buy this from a normal autoparts store, and which type do I require?

So when pressure builds up in the system, does the cap(s) release the pressure? Sorry for sounding like a complete newbie here, just want to be 100% sure I know how this system works.

I am still slightly concerned that the coolant start spurting out the side of the downpipe (below the main filler).

Other than this (pretty major) issue, the car did run like a dream and really was the best car I have driven (kicked my rx8's *** ).

Mahjik

iTrader: (1)

Check this thread:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/big-fat-fd3s-cooling-thread-571088/

It should get you up to speed on the cooling system.

WillT

Thats a great thread. Thanks for that, pretty much how I already thought of it, so thats good!

Any other advise? Plan of action tomorrow is

- Buy 2 new caps (2 sprung 18psi ones for main filler + overflow?)
- Tighten the screw which was spurting water earlier
- Fill system via main filler and keep lid off to let all air out of the system
- hopefully it'll stop bubbling meaning air is out
- shut down car and put the main filler cap back on
- Start car up and see if everything is working correctly.

- Obviously at present my first problem is probably still present (ie the possible broken resoviour) - or theres a chance that this was down to the caps!

Sound a decent enough way to go?

renedis

yes, try your moves first. i don't think your resorvoir is broken or something. i had the same problem last week with my rx-7. after filling it in the AST and then in the main filler it was all good.

good luck!

RIX-7

iTrader: (2)

when filling with coolant take the small pipe of the back of the engine where it connects to the throttle body when coolant comes out push it back on.ensures no air in the system

WillT

incase i can't find this! Is it ok to run the engine with the main filler cap off, until all bubbles stop appearing? Or is this not a decent enough way of doing it.

Also, if there is air in the coolant system, is this bad in general?

Thanks.

renedis

you can try with the filler cap off, it just builds no pressure. but i suggest that you fill it like this:

1. fill it at the AST (right side next to the intercooler)
2. fill it at the main filler.
3. if needed, fill the rest at the resorvoir.

it could be that the system gives beeps.. wait for like 10 seconds and it should stop beeping. after running for like 5 or 10 minutes, let the car cool down because the system is under pressure. be sure that the car is cold before you open the caps (main filler cap and AST cap) to see if it's empty or full. if it's empty, re-fill it the same way.. if it's full, you're ok!

that's how i solved it with my rex.

and again, good luck

WillT

Ok just been down to the car!

I haven't got any new caps yet, but have found some and picking them up this afternoon.

I filled the coolant as someone said by taking the coolant line out of the throttle body till there was liquid. I then started the car with the main filler cap off, and watched for bubbles - as this was my main concern! No bubbles which is good!

Took about 10minutes for the car to get to temperature, and then the water start coming out relatively foamy - I assume this is because its boiled in the engine? Is this correct?

A few minutes later, all the water was sucked into the engine, and there was none left in the main filler area. Is it meant to do this? Or did it do this simply because there was no pressure on the cap.

At this point the car was running for about 15minutes.... main temperature gauge was dead centre as normal, and car seemed to be ok.

I then shut it down, and water was coming up and going down the main filler (again i assume because it cooling?)

lol, I like to assume! :p

Thanks!

renedis

just like oil.. the coolant expands if it gets hot. so your assuming was right.
how much coolant did you put in it? it should be around 6,5 litre

WillT

Yes it was around 5-6 litres - obviously it lost a lot as it was slowly overfilling from the main filler cap (as it wasn't on), so i probably lost another 3 litres.

Another question hah! Where abouts is the overflow pipe - where does it dump fuel? Is it on the drivers side under the light (right hand drive)?

KJL Designs

I hate to say this mate, but it does sound like the coolant seals are on the way out. Has this car had a rebuild? If not what sort of mileage is it on?

Whereabouts are you in the UK? There are pleanty of good rotary garages knocking about.

WillT

O bugger - car hasn't had a rebuild no, 62k on it.

Am based in Leeds.