Coolant probs sorted....

[wiggy]

Hi all

Update on the add coolant mystery I\'ve been having.

Looks now like its been the rad cap on the AST all this time. I have just been out to check it again (my daily ritual) and bleeding the system it still came on (Carl I followed the bleed instructions in the manual so didn\'t feel I had to bother you )

Well anyway, long story short the inner seal on the cap is flubbered. It must have always had a split in it which has been letting water get into the expansion bottle far too easy. This has given me the symptoms of loosing coolant as the boiling water is evaporating in the bottle. This explains the bubbling noise as well when I turn her off after a run.

So, I already have an Apexi cap on order and this new cap should solve the problem This also would x\'plain why the thing has been doing it intermittently. Because some days the split in the cap might have sealed better than other days.

Anyway, all those having this problem I suggest you examine you rad caps closely for splits or any signs of perrishing. Mines completely gone now as a chunk has come off the rubber.

Thanks for all your help and advice guys, you\'ve certainly helped me understand a bit more about how it works and what to look for

Now, anyone got a part number for the rad cap adaptor for the Gen II so I can get rid of the AST?

Cheers

[Carl]

That is great news,see they are not all terminal engines!!
Kind regards
Carl

[wiggy]

Cheers Carl, now this is looking to be sorted I can carry on with my plans.....Mwahahahaha (sinister laugh)

[Martiny]

Wiggy, I would keep the AST. A lot of us have upgraded it, though to a metal one. Mazda\'s plastic one is prone to splitting. The Ast has an important function, it removes air bubbles form the coolant, (air Seperation Tank).

Just because the Gen II doesnt have one, doesnt mean the Gen III doesnt need one.  200hp vs 280hp = obviously a different car!

Well done for sorting it, though :-)

[wiggy]

Hi Martin

I still can\'t see the point :confused: Most cars don\'t have this, even high powered ones.

Also there aren\'t many highly modded RX7\'s that still have the AST so its not a case of more power = more need for one?

My plans for the cooling are as follows

Fluidyne ally rad
Remove AST
1.3 Apexi rad cap on the Gen II filler neck
better fans (still deciding which) probably a pair of spals with better cfm than the std ones?
Possibly have a fan overide switch on the dash like I had on the 4 for track days and brisk driving.
New thermostat (lower temp one if you can get them) if not a std one with 2 x 4mm holes drilled in it for constant coolant flow

Cheers

[iaint]

Originally posted by wiggy
Also there aren\'t many highly modded RX7\'s that still have the AST so its not a case of more power = more need for one?

care to elaborate?  most of the guys i know running single tubbies seem to have them still (although usually an ally one).

Iain

[wiggy]

Just ones I have seen on my search to obtain info, seems to be a big thing in the states as most of the engine bay pics and specs I\'ve read include the AST going.

Also the pic I posted up on my other post about modding the coolant system. Clives car...

If someone could explain to me why the rex has it and not many other cars do it would be a big help whats different about the Rotary that means it needs an AST and how come the earlier version could do without?

My idea of a cooling system is for water to travel round the engine via a pump and through a cooling device (radiator) controlled by a thermostat of some sort to maintain a certain temp.

The Mk 1 Celica GT4 had something similar to this when they first introduced it in the late 80\'s, it was considered that bad Toyota did a recall on it and removed it all together, never to return on any of the future models. maybe this is why I\'m unsure about keeping it, seems like a headache in the making :confused:

Can anyone elaborate on the reason for it being there, apart from removing air?

[clive]

Apparently they are tiny air bubbles caused by hotspots in the engine due to heat, because of the alloy used in our Rotarys these bubbles can eat through the castings over a long period of time.

I have used a monster upright custom Rad and have trouble getting it up to temperature let alone be hot enough to \'eat the engine\'

[MillSpeed]

Wiggy, have you heard of Evans NPG+ waterless coolant? I\'m giving some serious thought to giving it a go if I could manage to find any. The bonus with evans is the fact that it\'s boiling point is way up around 370 degrees farenheit. It will never cavitate like conventional water/EG does and you\'ll never end up with hot spots like I described in that other thread. Also, because the coolant will never reach it\'s boiling point, you can run your cooling system at atmospheric pressure (i.e. a 0 psi system). Absolutely no strain on the cooling system. There\'s been masses of threads about it on rx7club.com, but they all seem to descend into slanging matches when two blokes decide they know more about thermodynamics than the other. Basically, because the NPG+ doen\'t conduct heat as quickly as water, the engine will run slightly hotter...but you will NOT get cavitation which is a much more serious threat to rotary health. And then there\'s the corrosion issue. The reason why the rotary suffers from pin-holing of the aluminium rotor housings is because the construction of the rotary engine (i.e aluminium sandwiched between iron) is basically a fricking corrosion cell! I won\'t go into the electrochemistry behind it, but essentiall you need 4 components for corrosion to occur: an anodic reaction (the dissolution of aluminium), a cathodic reaction (the reduction of water to hydroxide ions on the surface of the iron end plates) a flow of electrons between the two reactions and an aqueous electrolyte (your coolant). If you eliminate one of these components, corrosion simply cannot occur. Traditional coolants have inhibitors to try and slow one of the two reactions, but unless the coolant is mixed in the correct proportions and the inhibitors are at the correct concentration their effectiveness is compromised. By using a waterless coolant, the cathodic reaction is completely inhibited thus preventing the dissolution of aluminium (the actual visible signs of corrosion). Evans is bloody expensive, and you must flush your cooling system with evans sierra first to remove any trace of water, but once it\'s done you never have to change your coolant again.

[wiggy]

Sounds very interesting...

Where can you get the stuff then?? How much???

Gotta b worth a try I\'ll try anything once

[MillSpeed]

I\'m not sure...that\'s the problem. I haven\'t been able to find a UK supplier, might be worth checking out the Evans homepage. Hey, do you know rjropes from the GT4OC forum? I work in the same office as his girlfriend. As soo as my rex is finished me and rich are gonna have a little dice-up....apparently his GT4 packs quite a punch!

[wiggy]

I\'ll have a look, keep me posted if you find anywhere that sells it.

Yeah I know rjropes, He\'s been in the club for years, most of this time he has spent fitting and mapping his ECU. I think he only got it running again recently. I usually chat to him on Microsoft Messenger.

Plus he is now running an ST205 engine with forgies etc.

I expect his car is fairly nippy now

Tell him I said hello when you next see him  

[wiggy]

I\'ve sorted it

Found the dealing in the UK, I mailed them direct and they kindly sent me the details.

http://www.gearfox.co.uk/index.html

needless to say I\'m ordering some

[MillSpeed]

Nice work fella! What sort of money are we looking at? Did they mention flushing the system with anything before filling up with NPG+?

[wiggy]

The guy is ringing me today so I\'ll update you then.

I am going to flush the system with the stuff they sell to do it as you are only allowed 3% of water left in there and to do this simply by draining would be impossible unless you removed the heater matrix and all the pipes. I will blow through most of it with an air line as well to get as much out as possible.

My plan of action is:

Drain system via rad and engine drain plugs.
Fill with Evans Flush
Run engine up to temp, allow to cool and drain again
Remove pipes going to heater matrix and blow through lightly with an air lin
Leave plugs off for as long as possible to allow the remaining fluid to evaporate
Give the block and radiator a blow through with air
Fill with Evans NPG+
Run up to temp
Check levels and refil as required until full

Then see how it goes...

I am also going to be fitting a new thermostat at the same time and also check the water pump condtion while its off. I will also be drilling 2 x 4mm holes in the stat to allow constant flow of the system.

I believe doing all this will mean I no longer need to buy the new ally rad I was planning on getting so I\'ll save a few hundred quid there

I\'ll let you know when the guy rings me and what he says

Regards