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This is probably an easy answer for someone but I am wondering if the solenoids with part numbers B6AT-18-741 and KL01-18-741 will fit in the FD's solenoid box. There is a pretty good write-up on how to take it apart on AUSRotary (Updated 08November- Series 8 Solenoid Vacuum box &disasembly - AusRotary) but when I am looking at the images on the sites selling them the top port (C) near the plug looks like it has a cap on it. Is this cap removable revealing a nipple? Don't want to drop $400 on solenoids that don't fit.
After over a year with no boost, bad emissions and mpg it looks like the culprit is the solenoids. 1 dead, 3 not building any vac/pressure and 3 with fast leaks.
So are all of the solenoids in the box effectively exactly the same and interchangeable? Can solenoid # KL01 18741 be used for all solenoids in the box?
Last edited by mikey13b; Jan 28, 2024 at 08:00 AM.
Yes, they are all identical. I got mine from Amayama (https://www.amayama.com/en/part/mazda/kl0118741). The box was a bit fiddly to split so use plenty of lubricants. The original how-to is useful but it skipped the part about pushing out the metal inserts. Took me a while to figure out why it was not coming apart and that was the reason. £150 cheaper than buying a whole new box so I think its worth the effort.
As answered on AusRotary.com, you can use KL0118741 on all solenoids. However, this guide was originally written at a time when it was hard to get genuine parts for JDM models. The part numbers listed for the guide are those that they show up on the Australian parts catalogue for Aussie delivered models, presumably because that was easier and cheaper back then. Things have changed and it is now quite easy to get parts directly from Japan. Also, Mazda Australia has had some massive price hikes and it is often twice as much to by from an Australian dealer than overseas. In other words, you may as well buy genuine parts from Japan.
The black box contains all the solenoids and check valves in it already - all new, bolt in ready to go. Part number is N3F1-20-4B0. You should be able to get this for around AUD800-850.
I also note that Mazda lists two different kinds of solenoids in the parts fiche so there must be something different about them (that said it might just be the sticker colour):
No. 1: B6AT-18-741 No. 2: FEGC-18-741
Mazda lists 3x of the No. 1 solenoid and 4x the No. 2 solenoid. They are highlighted in yellow in the diagram below. Only two of each is actually illustrated by the parts book lists the quantities required (you can see there are multiple dotted lines coming off the parts into the box showing where they go). If you were to replace all of these individually, it would cost around $800 to replace the lot. At that price, it is better to just buy the box as a whole and you get new check valves as well!
The main exception to that is if you know for certain only a few solenoids are problematic, but in that case, the Mazda 323 part is no cheaper than the parts designated for the RX7 - all of them are around the same list price, around AUD110 each. Personally, with s8 cars being 20-25 years old now and subject to the heat of an FD engine bay, I would just get the black box with everything new and be done with it - it will last another 20 years.
The black box itself has shown itself susceptible to not sealing when it gets old......which is one, very clutching at straws positive for the old hose, here, there and everywhere system . We've had people in the past tearing out hair when total solenoid replacement doesn't fix their issue.
Not long ago, Powersomethingsomething on Buyee was selling about 10 boxes for $50 each. So I suppose you could buy those ten and have an unlimited supply of dodgey old solenoids.
If that's the case over in Australia I would just replace the whole box as you suggested. I'd imagine you have a few rotary specialist who stock those kinds of things.
We don't have anyone in the UK. I think only around 240 FD's were sold because they didn't meet UK safety standards and the majority of those are either not taxed (in storage), crashed or exported from the country. Meaning everything costs an arm and a leg 😭
On the solenoid part number difference, I noticed that myself but those solenoids were also used on various other models at the time. Amayama has always been good at finding cheaper alternatives. When I did mine I could see no difference between any of the solenoids other than the filter cap which needs removed anyway. Other than they they are identical and all my issues were resolved.
As answered on AusRotary.com, you can use KL0118741 on all solenoids. However, this guide was originally written at a time when it was hard to get genuine parts for JDM models. The part numbers listed for the guide are those that they show up on the Australian parts catalogue for Aussie delivered models, presumably because that was easier and cheaper back then. Things have changed and it is now quite easy to get parts directly from Japan. Also, Mazda Australia has had some massive price hikes and it is often twice as much to by from an Australian dealer than overseas. In other words, you may as well buy genuine parts from Japan.
The black box contains all the solenoids and check valves in it already - all new, bolt in ready to go. Part number is N3F1-20-4B0. You should be able to get this for around AUD800-850.
I also note that Mazda lists two different kinds of solenoids in the parts fiche so there must be something different about them (that said it might just be the sticker colour):
No. 1: B6AT-18-741 No. 2: FEGC-18-741
Mazda lists 3x of the No. 1 solenoid and 4x the No. 2 solenoid. They are highlighted in yellow in the diagram below. Only two of each is actually illustrated by the parts book lists the quantities required (you can see there are multiple dotted lines coming off the parts into the box showing where they go). If you were to replace all of these individually, it would cost around $800 to replace the lot. At that price, it is better to just buy the box as a whole and you get new check valves as well!
The main exception to that is if you know for certain only a few solenoids are problematic, but in that case, the Mazda 323 part is no cheaper than the parts designated for the RX7 - all of them are around the same list price, around AUD110 each. Personally, with s8 cars being 20-25 years old now and subject to the heat of an FD engine bay, I would just get the black box with everything new and be done with it - it will last another 20 years.
That's good if the 2 different part numbered solenoids are indeed identical solenoids, it seems odd they have used 2 different part #s if they are identical though. I do recall it being mentioned somewhere that perhaps the difference between the 2 may be that one of them has a check valve inside whereas the other doesnt or something along those lines...
Last edited by mikey13b; Jan 29, 2024 at 06:06 AM.
That's good if the 2 different part numbered solenoids are indeed identical solenoids, it seems odd they have used 2 different part #s if they are identical though. I do recall it being mentioned somewhere that perhaps the difference between the 2 may be that one of them has a check valve inside whereas the other doesn't or something along those lines...
The two green/white check values protect the pressure and vacuum sides of the system as shown in the diagram. The solenoids are just redirecting the pressure/vac. They all appear to vent to atmosphere or in the case of the FPR into the manifold. I susect to protect the rest of the system if the diagrpagm in the FPR fails.
Sounds like your $20 worked. Think I paid £45 + Shipping (AUD $85) for mine. I'm pretty sure you would tell straight away if they didnt.
I also suspect they were manufactured by Mitsibushi because my turbo control solanoid port cap has the logo embossed onto it.
I would have guessed that the difference was that some of the rat's nest solenoids had a filter on them. If the corresponding solenoids no longer have the filter, why was the requirement dropped?
I would have guessed that the difference was that some of the rat's nest solenoids had a filter on them. If the corresponding solenoids no longer have the filter, why was the requirement dropped?
Maybe because they are contained in a box now rather that open and exposed?
Started again with turning wrenches on the 7 and thought about replacing the black box of the rats nest while I have the UIM off and installing the Rotary performance fuel and injectors, thought about replacing it and all the hoses since mine are a tad bit old and feeling hard/brittle now. Is this one a drop in for our 93-95 cars?
You’ll need the mounting bracket for the box and coils, change the connectors on your harness or make bridge harness as the length might be different. Otherwise they are the same thing, just different orientation and newer solenoid that is more common in the mid late 90s Mazda.
It's kinda on the same topic but does anyone know if the viton check valves (the ones that people have used in ages when they do silicone vacuum line upgrade) will be able to replace the two green/white valves in the box? like a direct replacement? Or is there even a need to replace the two stock valves??
The Viton ones from Mr. Clark are physically smaller than the oem ones. The black box is a set height and the short green/white check valves are the exact length they need to be to sandwich in-between. Although the body on the viton one is smaller, the nipples are much longer so it compensates some.
It looks like they may work but the barb on the viton one may cause a fitment issue. It looks like there is enough material where it can be shaved down to make it not barbed if need be. The other variable is how far into the black box the nipple actually needs to go to seal. Looks to be viable and worth the try.
. We've had people in the past tearing out hair when total solenoid replacement doesn't fix their issue.
