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If the AST was removed, you should be able to get an aftermarket replacement and the proper hoses and hook it up. However, since the car has an aftermarket intercooler, you'd have to find a creative way to mount the replacement AST. And, if your radiator is also aftermarket, that might be a bigger problem if it doesn't have a nipple at the bottom for connecting the AST return hose. Here's a diagram of the stock coolant flow (the overflow tank is not shown, but is mentioned -- the AST's pressure relief cap nipple vents to it):
I think you are getting somewhere on this mystery .
First off I would do a proper AST elimination. You can either add a nipple to the thermostat housing you have (which is a little tricky) or get a good used thermostat housing that's 2-piece that will let you bolt on the fill neck that has the nipple. As stated you can use the Mazda part from the 2nd gen RX-7 or get the billet part from Banzai Racing. Stock part is plastic but really holds up fine.
There is a hose from the overflow tank that is supposed to go to that nipple on the radiator cap neck, I see the hose in the picture, it has nylon spiral tubing around it. The big question is where that hose is going.
Also, a few notes from your engine bay pictures -
- No belt to the power steering or AC pumps. I can't see if the AC compressor is still there, other AC parts are there (lines, drier, condenser). Not sure why they just took the belt off. If you do end up, for whatever reason, taking the AC off, FOR THE LOVE OF GOD take it off CAREFULLY and sell the parts. They are in demand and NLA from Mazda. But, you may want to get your AC working, it's worth putting the work in and working AC is wonderful in an FD. Taking it out won't make the car faster or save enough weight to be of notice.
- Brake booster hose from upper intake manifold to firewall is missing a hose clamp. This is a must, if that hose pops off under boost you will have no power brakes which functionally means you have NO BRAKES. I have experienced this once, it isn't just "push harder on the pedal", it's "you have no damn brakes and the pedal is doing nothing". A cheap hose clamp will prevent that from happening.
- You need to eventually figure out an actual filter for the turbo. Some screen door and a clamp isn't gonna cut it. No filter harms the turbo and the engine big time and will drastically shorten engine life.
- Again long term but that turbo can use some sort of heat blanket or something, you have a crazy hot turbo up high cooking everything around it.
We're here to help, you can get this all good, just take things step by step and ask questions and research and read.
If the AST was removed, you should be able to get an aftermarket replacement and the proper hoses and hook it up. However, since the car has an aftermarket intercooler, you'd have to find a creative way to mount the replacement AST. And, if your radiator is also aftermarket, that might be a bigger problem if it doesn't have a nipple at the bottom for connecting the AST return hose. Here's a diagram of the stock coolant flow (the overflow tank is not shown, but is mentioned -- the AST's pressure relief cap nipple vents to it):
Originally Posted by DaleClark
I think you are getting somewhere on this mystery .
First off I would do a proper AST elimination. You can either add a nipple to the thermostat housing you have (which is a little tricky) or get a good used thermostat housing that's 2-piece that will let you bolt on the fill neck that has the nipple. As stated you can use the Mazda part from the 2nd gen RX-7 or get the billet part from Banzai Racing. Stock part is plastic but really holds up fine.
There is a hose from the overflow tank that is supposed to go to that nipple on the radiator cap neck, I see the hose in the picture, it has nylon spiral tubing around it. The big question is where that hose is going.
Also, a few notes from your engine bay pictures -
- No belt to the power steering or AC pumps. I can't see if the AC compressor is still there, other AC parts are there (lines, drier, condenser). Not sure why they just took the belt off. If you do end up, for whatever reason, taking the AC off, FOR THE LOVE OF GOD take it off CAREFULLY and sell the parts. They are in demand and NLA from Mazda. But, you may want to get your AC working, it's worth putting the work in and working AC is wonderful in an FD. Taking it out won't make the car faster or save enough weight to be of notice.
- Brake booster hose from upper intake manifold to firewall is missing a hose clamp. This is a must, if that hose pops off under boost you will have no power brakes which functionally means you have NO BRAKES. I have experienced this once, it isn't just "push harder on the pedal", it's "you have no damn brakes and the pedal is doing nothing". A cheap hose clamp will prevent that from happening.
- You need to eventually figure out an actual filter for the turbo. Some screen door and a clamp isn't gonna cut it. No filter harms the turbo and the engine big time and will drastically shorten engine life.
- Again long term but that turbo can use some sort of heat blanket or something, you have a crazy hot turbo up high cooking everything around it.
We're here to help, you can get this all good, just take things step by step and ask questions and research and read.
Dale
Thank you very much, will definitely get there and I’ll keep asking questions hahah, so yeah he (po) did say the power steering parts are there but not working which I’m guessing is just missing the belt like you said, which he left in the trunk for me to hook up if I wanted to, that belt is for the AC AND the power steering or the AC is a diff belt? PO told me that the AC just needs to be charged but it works, not sure what he meant by that, I should’ve asked more questions.
Will definitely put a clamp on that brake booster hose, already felt that feeling of no brakes when I stalled on a hill when I drove it before, pretty scary, and I will find a proper filter once I get the coolant stuff out of the way, since I won’t be driving it anyways for a bit while I try to get everything together.
So I took the inter cooler off and found a few things, the overflow tank hose isn’t connected, just laying there, the filler neck hose is connected to a nipple on the radiator and the tank on the side next to the battery is connected to the radiator also, here are some pics . I also added a couple more pics of some wires that aren’t connected and I’m not sure If those are just extra connections and not needed
The white plastic tank next to the battery is for windshield washer fluid. Are your sure it is connected to the radiator?
The new pics confirm that the filler neck is stock and has not been properly modified for AST elimination.
It looks like the nipple on the radiator (that has the hose to the filler neck) is on what is functionally the top, not the bottom of the aftermarket radiator. If you reinstall an AST, you would need to run one of its hoses to a nipple at the bottom of the radiator. Can you post a photo of the radiator from underneath the car that shows where both of the big hoses from the engine connect to the radiator?
The white plastic tank next to the battery is for windshield washer fluid. Are your sure it is connected to the radiator?
The new pics confirm that the filler neck is stock and has not been properly modified for AST elimination.
It looks like the nipple on the radiator (that has the hose to the filler neck) is on what is functionally the top, not the bottom of the aftermarket radiator. If you reinstall an AST, you would need to run one of its hoses to a nipple at the bottom of the radiator. Can you post a photo of the radiator from underneath the car that shows where both of the big hoses from the engine connect to the radiator?
Oh I was talking about the metal looking tank that looks like an ast tank right below where the battery is, that one is definitely connected to the radiator on the same side.
I’ll take another photo tomorrow if the bottom one, the car is currently left at my friends house as I don’t have space at my current place.
Oh I was talking about the metal looking tank that looks like an ast tank right below where the battery is, that one is definitely connected to the radiator on the same side.
I’ll take another photo tomorrow if the bottom one, the car is currently left at my friends house as I don’t have space at my current place.
^The thing you're describing is part of the A/C system - that "metal looking tank" by the battery is the A/C receiver/dryer, and it's plumbed via metal lines to the outlet side of the A/C condenser (radiator looking thing IN FRONT OF the radiator), and the A/C evaporator core (inside the cabin).
^The thing you're describing is part of the A/C system - that "metal looking tank" by the battery is the A/C receiver/dryer, and it's plumbed via metal lines to the outlet side of the A/C condenser (radiator looking thing IN FRONT OF the radiator), and the A/C evaporator core (inside the cabin).
The white plastic tank next to the battery is for windshield washer fluid. Are your sure it is connected to the radiator?
The new pics confirm that the filler neck is stock and has not been properly modified for AST elimination.
It looks like the nipple on the radiator (that has the hose to the filler neck) is on what is functionally the top, not the bottom of the aftermarket radiator. If you reinstall an AST, you would need to run one of its hoses to a nipple at the bottom of the radiator. Can you post a photo of the radiator from underneath the car that shows where both of the big hoses from the engine connect to the radiator?
Here is the video of the bottom of the radiator: videos . The 2 big hoses connect from filler neck to the upper corners of the radiator, I don’t see a nipple at the bottom of the radiator only the top on that connects to the nipple on the filler neck. Would it still be possible to add an aftermarket AST or would I just have to do a proper ast delete? Not sure how to go on about it. I posted earlier but the post didn’t show up on the thread so just posting again thanks for all the help
In the stock configuration, some hot coolant from the filler neck nipple flowed to the AST and then from the AST to the nipple on the bottom of the radiator where it mixed with cooler coolant before the coolant was sucked back into the engine via the lower radiator hose. The functional equivalent of a "bottom" in a crossflow radiator would be the side that connects to the lower radiator hose where cooled coolant is returned to the engine. In your case that is the side nearest the battery. So, the nipple on your radiator is not on either the crossflow equivalent of the top (hot inlet) or the bottom (cooler outlet) side of the radiator.
However, some crossflow radiators are configured internally to route hot coolant back and forth from side to side before it leaves, giving longer residence time and better cooling. I don't know what the inside of yours looks like, but the nipple might be ok to connect to a replacement AST if it is functionally close enough to the radiator outlet to see enough suckage to pull enough coolant from the filler neck through the AST. If the radiator nipple is functionally too close to the radiator's inlet, the AST may not work as well, but I think it would still be a big improvement over what you have now, which doesn't work at all since you have no pressure relief.
In the stock configuration, some hot coolant from the filler neck nipple flowed to the AST and then from the AST to the nipple on the bottom of the radiator where it mixed with cooler coolant before the coolant was sucked back into the engine via the lower radiator hose. The functional equivalent of a "bottom" in a crossflow radiator would be the side that connects to the lower radiator hose where cooled coolant is returned to the engine. In your case that is the side nearest the battery. So, the nipple on your radiator is not on either the crossflow equivalent of the top (hot inlet) or the bottom (cooler outlet) side of the radiator.
However, some crossflow radiators are configured internally to route hot coolant back and forth from side to side before it leaves, giving longer residence time and better cooling. I don't know what the inside of yours looks like, but the nipple might be ok to connect to a replacement AST if it is functionally close enough to the radiator outlet to see enough suckage to pull enough coolant from the filler neck through the AST. If the radiator nipple is functionally too close to the radiator's inlet, the AST may not work as well, but I think it would still be a big improvement over what you have now, which doesn't work at all since you have no pressure relief.
Originally Posted by DaleClark
You would have a lot more engineering work to do to make an AST work in your car and for zero benefit for the work.
Eliminate it and move on.
I've had no AST in my car for 10-12 years easy. Zero overheating or any problems, solid and reliable.
Dale
Gotcha, thank you both, I’ll probably go ahead with the AST delete, is it difficult to make a new nipple since I have the one piece filler neck, I might have to take it out and go to a shop.
Saw this in another guy’s thread, would just a regular drill work, drill a hole in that spot, put in a hose fitting? If so how did he get the fitting to just screw in on there, I would think it would leak?
Don't just drill a hole and hope. The AST delete requires a 2-part filler neck and a cap from an FC. I went fully custom years ago, but I'll see if I can find my filler neck in the garage for you tonight.
All you need is that bottom part and the top (banzai is selling a nice one) with a proper pressure cap.
Don't just drill a hole and hope. The AST delete requires a 2-part filler neck and a cap from an FC. I went fully custom years ago, but I'll see if I can find my filler neck in the garage for you tonight.
All you need is that bottom part and the top (banzai is selling a nice one) with a proper pressure cap.
Ah! Okay I didn’t know what you meant. If you can find it I’ll definitely buy it, thank you! I didn’t know what to search for trying to find the 2 piece filler neck.
Post a WTB ad in the Marketplace for a thermostat housing. They shouldn't be super hard to find used. May even be able to find one with an AST delete good to go.
You would have to drill/tap your current housing to put a nipple in. This is REAL tricky to do right and you will probably have more problems trying to do it than just replacing the whole thing.
Post a WTB ad in the Marketplace for a thermostat housing. They shouldn't be super hard to find used. May even be able to find one with an AST delete good to go.
You would have to drill/tap your current housing to put a nipple in. This is REAL tricky to do right and you will probably have more problems trying to do it than just replacing the whole thing.
Dale
Will do sir, probably better for me to buy one, don’t have any experience with any of this haha, thank you. I’ll probably come back to this thread once I find one or if fendamonky can find his used one I’ll buy it from him
You should inspect your overflow tank to make sure it is still ok before putting it back in service, and will also need a new thermostat O ring gasket, some suitable hoses and a new 0.9 bar (13 psi) pressure relief radiator cap, of course.
Ah! Okay I didn’t know what you meant. If you can find it I’ll definitely buy it, thank you! I didn’t know what to search for trying to find the 2 piece filler neck.
You should inspect your overflow tank to make sure it is still ok before putting it back in service, and will also need a new thermostat O ring gasket, some suitable hoses and a new 0.9 bar (13 psi) pressure relief radiator cap, of course.
Okay, will inspect before putting it in, the overflow tank hose didn’t leak, does that only open up at certain times? There’s liquid in the tank but hose isn’t leaking. For the hose, I’ll probably go ahead and take a look at my local autozone.
Originally Posted by fendamonky
You want one of these guys.
Gotcha, just put up on the marketplace, if you do happen to find yours I would gladly take it if you have no need for it
Gotcha, I actually just bought one from a different user as I didn’t know if you were still trying to find it at the time :/
Also, sorry this might be a really dumb question, do I bleed the coolant through the radiator nipple first before replacing the thermostat housing with the 2 piece version? I saw a video of a guy replacing the thermostat itself and when he took off the housing there was no spill so I’m guessing it should be fine? But just wanted to make sure.
The thermostat housing usually has coolant in it. If you want to make sure there's no spill, drain at least a couple of liters of coolant out of the radiator.
If you know the coolant is pretty new you can re-use it if you drain into a clean container. If you're not sure how old the coolant is you should replace it every 1-2 years on these cars. The aluminum and cast iron engine materials tend to rust. Don't use tap water, use distilled water and coolant. Or get 50/50 mix coolant, that seems more common than concentrated coolant at the parts stores near me.
If the thermostat housing you bought is completely stock it will have a nipple that feeds coolant out to the Air Separator Tank. If you don't have an AST you need to block that nipple or it will be a massive coolant leak. It's hard to see in the photo, but it looks like that nipple has been removed and welded shut in @fendamonky 's photo. Don't just use a vacuum cap from a parts store, those don't work well for pressure especially when hot coolant is involved. Easiest way is to find a short length of spare coolant hose, a bolt that is just the right size to fit inside it tightly, and a clamp to hold the coolant hose on the bolt. A better way is to remove the nipple and drill & tap the hole so it's threaded and can be sealed with a bolt or an NPT plug. If you know a welder that is a nice solution also.
10-12-21, 01:32 PM
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