When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Anyone have pics of AST delete with late model JDM filler neck?
Hey guys, Im wanting to delete my AST for a couple of reasons, firstly because my aluminium radiator does not have a provision for it (no nipple on the bottom of it). and secondly to clean things up a little bit more.
Problem is, I have a late model FD with the one piece filler neck.
Im not keen to change the whole housing, id sooner have a nipple welded onto the radiator and keep the AST before I did that.
Anyway, Im thinking I will drill & tap the one piece filler neck and install a barbed hose fitting.
Does anyone have a pic of a late model engine with a fitting installed for AST delete? (with the one piece filler neck)
Really I just want to know how high up the neck to drill/tap the fitting. As high as possible? Or does it just need to be above the original AST nipple?
Im planning on drilling /tapping to 1/8" BSPT, and using a 1/8"BSPT to 10mm hose barb and a new radiator pressure cap with spring.
^the pic above dosent help, thanks though. a pic looking down into it with the radiator cap off might help though.
the bottom of the stock radiator has a nipple on it, with a hose that goes to the AST. I have a twin core alloy radiator from a local shop, supposdley made for the FD...but with no nipple on the bottom of it.
The nipple needs to be installed between the lower seal seat and the upper seal seat. I looked all over for my one piece filler neck to verify that it has a lower seal seat for a pressure cap but couldn't find it.
Ok Thanks I think that's what I needed to know . Here's what I'm working with. So I need to put it below the radiator cap, but above that seat that's an inch or so down where it narrows ?
Ok well i got the fitting in ok. Now for the next issue, the radiator cap.
I picked up a random radiator cap from a local parts store without really looking at it, I assumed they were all the same other then the psi rating.
Got it home and the seal on the spring is not a big enough diameter to make a proper seal. (it does screw on properly though)
I tested the cap off the AST on the filler neck, and the seal on that was the right diameter.
Can you buy radiator caps with different diameter seals? Is that a special mazda one or something? Can I get one with the same dia seal as the AST cap but a higher psi rating?
Could anyone please do me a favor, and test fit the FC filler cap (which is used with AST delete) on an AST? OR test an AST cap on the FC filler neck?
That in theory will tell me if the FC radiator cap will fit the one piece late model JDM housing.
Bought one of those 32mm caps from Ripco or Supercrap ages ago (in green packaging from memory).....wouldn't seal.
Yep, well, the seal on the stock AST cap makes a seal with the outside of the filler neck. So appears to be the correct size, just not a high enough PSI rating.
On the random replacement radiator cap I got, the seal is a smaller diamater and does not contact the outsides (of the inside) of the filler neck like the AST cap does.
So the AST cap appears to be the correct size, just not a high enough pressure rating.
If i can figure out if the AST cap, fits on the FC filler neck. Then i know I can just buy the FC filler cap and it should fit.
...or test the cap off the stock AST on their FC filler neck that has been installed for AST delete?
thanks!!
Pretty sure I just moved my AST cap over to the FC filler neck when I deleted it and it fits fine. Assuming your one-piece filler neck is the same, they work. And I would stick with a .9 bar cap.
Pretty sure I just moved my AST cap over to the FC filler neck when I deleted it and it fits fine. Assuming your one-piece filler neck is the same, they work. And I would stick with a .9 bar cap.
oh sweet, thanks for the info
That would be an easy solution, to use the AST cap. I guess I could even put an extra spring on there as well to increase the pressure rating a bit if I needed to. I had read to use a higher psi pressure cap, but i guess if it worked with the stock setup, it should probably work like this as well.
Ill double confirm that the AST cap fits the one piece filler neck properly (i.e bottoms out on the seat at the bottom) then ill post the results back.
Also, while im at it, just to confirm iv got this correct.
I take the line that used to go from the AST to the overflow tank; and change it to go from the overflow tank to the new filler neck nipple?
cheers
Yes. The hose from the overflow tank will now connect to the nipple on the filler neck. The hose going to the bottom tank of the radiator can be deleted and both nipples removed and/or plugged.
IMO, on a street car, there's no good reason to increase the pressure cap rating. MAZDA went to some expense back in the day to change them all to .9 bar in a recall. If you have a healthy cooling system and a decent aftermarket temp gauge, .9 bar is plenty.
Thanks.
Just to update this, the AST cap does appear to fit the one piece filler neck properly.
I roughly measured the depth of the seat on both the AST and the filler neck and got the same number.
Hopefully all is well.
Ill try to remember to update this thread in a few months time so we have a definitive answer re AST delete with the one piece filler neck.
Thanks.
Just to update this, the AST cap does appear to fit the one piece filler neck properly.
I roughly measured the depth of the seat on both the AST and the filler neck and got the same number.
Hopefully all is well.
Ill try to remember to update this thread in a few months time so we have a definitive answer re AST delete with the one piece filler neck.
So just to update this again. It actually appears that normal / generic radiator caps will work with the one piece filler neck.
Im yet to finish the car off and get it running, but take a look at this. The seal does indeed contact the seat on the bottom. Just good to know, and opens up the possibility of using any psi cap you want.
they went to the 1 piece housing in 96, so every replacement has been the 1 piece style.
Had my eye out for one when I committed to the AST delete some years ago. But they were hard to find w/o paying more than it was worth given the cost of the "kit" from Ray.
Originally Posted by 96fd3s
...opens up the possibility of using any psi cap you want....
Still, unless maybe if it's a track car, I can't think of any good reason for a higher pressure cap...and some reasons against them. Additional stress on the coolant seals being primary.
Had my eye out for one when I committed to the AST delete some years ago. But they were hard to find w/o paying more than it was worth given the cost of the "kit" from Ray.
Still, unless maybe if it's a track car, I can't think of any good reason for a higher pressure cap...and some reasons against them. Additional stress on the coolant seals being primary.
Yep. Im going to stick with the 0.9bar AST cap and see how we go.
I just thought its good info to know that the generic ones will work if anyone does need to use a slightly higher pressure cap, or is just looking for a replacement.
You don't need to pay mazda prices (or go through the hassle of dealing with them) for their one. A generic $5 cap available in any PSI you want, from the local parts shop should do
