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Supercharger Rebuild


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Originally posted by skrenos


Hi. I just registered and an not really new to mazdas. I owned a 1985 Ford Escort that had the Mazda RF diesel engine in it. Great car. Poor maintenance by the previous owner. Lost the lower radiator hose, warped head, and cant find a replacement head. Too bad. Also, had a 93 Ford Probe. Great car. Wish I would have kept it after I replaced the auto tranny, but the next owner's daughter trashed the trans in a short order.


So, that bring me to the next car. My brother's 99 Millenia S. I decided to do a t-belt change for him, along with any other maintenence he needed on the car at that time. Pulled off the front intercooler to change the front spark plugs, and lots of oil int he intercooler. Pulled off the upper intake... lots of oil there too and apool of oil in the supercharger. Supercharger is off and starting to be taken apart...


I'm really tearing into this thing and want to see if there are replacement generic seals/bearings we could use to rebuild them cheap and on our own... but I dont want to destroy this thing as I want to give this car back to my brother and get MY car back.


So, does anyone have a cheap (ie $100 shipped) supercharger they could get rid of for the purposes of this project? It's for a good cause smile.gif






Ok, got it mostly apart. Looks like each rotor has 2 ball bearings at the snout end. Underneath those bearings is a sleeve bearing. This sleeve bearing may be the graphite bearing everyone talks about, but it doesnt seem like it's made of graphite. It seems like it's steel so it may be a regular sleeve.


The male rotor has the larger bearing and it's a NTN 1832A. The female rotor is smaller and is NTN 3215a. Those numbers are for the top bearing. I believe the bearings underneath those have the same number minus the A. I'll have to check tommorow.


The bearings seem to be unsealed caged roller bearings. They are oil bathed at the snout end which also lubes the helical gears.The portion underneath the 'sleeve' bearing on the rotors also has a chamber which receives oil. There doesnt seem to be any seal to prevent oil from flowing from the bearings onto the rotors... or perhaps mine are completely washed away? I did notice the lower oiling chamber was full of crud and it took me a whole can of carb cleaner to wash out all the sludge.


My brother noticed smoking one winter when he decided to use that Mobil 10,000 mile oil. I think he ended up putting like 15,000 miles on that oil before we changed it out.


Unfortunately, when I drove out the outer bearing, it popped the inner race, cage, and balls out, but left the outer race in the housing. It's in there. it aint coming out. I'm probably gonna have to cut them. This isnt that big of a deal since I'm going to press new ones in.


My male rotor has one of the corners cracked off at the intake end. It's not bent or anything and it still spins smooth... but looking at that, I might need a replacement piece. So again, i call out for any cheap superchargers that one could sell me for the cause.


Pics tomorrow... or soon. smile.gif


IPB Image

IPB Image




It's is still not fully understood why these things fail the way they do. You think the oily crud you found might have restricted one of the oil passages?




If you look at the top picture and can see the larger portion of the shaft. Those parts sit inside the "oil chamber" underneath the ball bearings. It sorts acts like a fluid bearing and I think it's just depending on the close tolerances of the shoulder on the shaft and the housing to keep oil out of the housing and the fact that compressed air is pushing against that portion and trying to fill the chamber full of air. So, it's a battle of oil pressure pushing out, and air pressure pushing in.


When I sprayed/scraped stuff out, it looked and felt like black velveeta.


I usually get my bearings from NAPA, and will go with the generics for replacement. If I cant get the right ones, I can always bore/sleeve it to another bearing.



*next post*


Ok, got all 4 bearings out and here's what I found... The bearings are held in by a resin/fiber ring. It's like an o-ring on the outside of the bearing. I tried using a 12 ton press to press them out and that didnt work. I resorted to using the dremel and got the outers out and then I could press the inners out. There is a piece of graphite in there. it's a spring loaded ring, but it's not really a seal. It's more of a check valve.


Then there's that 'oiling chamber' I was talking about. I think it's hooked to vacuum and sucks out any oil that may get past. What happens is the mazda t-sections on the vacuum hoses either break and it no longer provides vacuum which eventually cokes due to the heat at that area, or lack of maintenence causes that chamber to get clogged full of poo and clogs the line in the process and no vacuum is applied to that chamber. Either way, it looks like to get it properly cleaned, you'll have to pull the supercharger apart, and to get it REALLY clean, you have to remove those bearings.


When I put mine back together, I'm gonna design it for easy maintenence. No more fiber o-ring. I'll use drill, tap, and use a set screw on the side of the bearing to hold it in. I'm gonna need another supercharger in case this doesnt work though.


I'll have to wait until 30 posts before I can beg for a supercharger in the classified section. smile.gif




I'd like to take pictures, but at this point, there's not much point. It's just a hole in the casing. There's cuts and stuff for o-rings, fiber rings, and washers, but you really cant get much detail with a camera. There's a very limited field of view and you really wouldnt see much. There's holes on the sides of the walls, but thy're TINY and you have to get your face RIGHT on the casing and look to see them.




***reply by saint***

So does that vacuum problem cause s/c to fail seriously?





I truly believe so. Everyone keeps saying 'graphite seal! graphite seal!' but my graphite seals are fine. It's obviously a sludging problem which is impossible to clean unless you rip it all apart.


I'm not even sure that check valve is even graphite. I've never felt graphite like it before. it chips like a hard plastic, it doesnt seem to take any wear, but I beat on that shit with a metal rod and a hammer and it didnt shatter. I'm thinking it might actually be cast iron.




Thats an interesting point. This may be the reason for mysterious s/c failures.. I found a hole 6 months ago in one of the hoses that goes to s/c. Other than visual there is no sign of the broken hose. So the hoses that get to s/c are they all just vacuum? I guess there are two small hoses..




Yep. 2 hoses. The pipe on the left side near the exhaust port services the left bearings, and the one on the right side services that side.



The thing depends on manifold vacuum for proper oiling? That explains a lot. The miller-cycle seems to be a vacuum hose whore. But all that sludging...I wonder if that could also have been neglected oil changes or a sign that dino 10w30 every 7500 miles doesn't cut it for the IHI supercharger. Mazda was really cutting corners around the late 1990s and I wonder if service intervals were among the cuts. I also wonder if the sludge would have been a problem if Mazda had just specified a synthetic oil as factory fill on the miller-cycle in the first place.



Well, our sludging happened right after a 10-20 thousand mile winter. No oil change. We had put mobil extended oil in there. Supposedly good for 15,000 miles... but I think that would be for a regular car.


10w30 synthetic or semi-synthetic every 3000-4500 miles is what I recommend. Oil changes are so cheap, I dont see why people just dont do that. My brother wanted to be lazy/cheap about it and look where it got him now. I can only imagine what else is stuck inside the engine.




I checked the two hoses this morning. The one close to the exhaust end goes to the resonator and the other one on the inlet end goes to the intake manifold. I didnt take the plastic cover out so someone should verify me. Is there a ventilation in the oil chambers? What would happen if I spray carb cleaner through those holes?


Some sketches:

IPB Image

IPB Image




Actually, those two hoses combine together and go into a chamber on the airbox, and then go toward a barb on the front valve cover. I'm only assuming it's a vacuum line as it wouldnt make sense otherwise. If it was a pressurezed source, it would blow oil from that chamber into the compressor or blow the oil out of the bearings. If it was neutral, it really would do anything. With vacuum, at least it's sucking out any oil that happens to be getting in there.


If you spray carb cleaner into those holes, it'll reach the chamber... as long as they arent gunked up. If it's full of crud, you'll loosen it up a bit, but it has nowhere to go. My stuff was thick and I had to scrape it out with a screwdriver. I used one can of carb cleaner to clean out both sides AFTER I had gotten all the bearings and seals out. It was literally black cheese.



The resin is pushed into the s/c through holes that are drilled in the body, then plugged once the resin is forced in. The bearings are a pain in the ass to remove, buy you can remove one side (intake side) without the dremel. Just toss that side into an oven at 380 for a half hour, then press them out. The seals do crack and break, I have two sitting around here somewhere. Another source of leaks is the plate (washers) that press up against the seals, notice how they now have a groove rubbed into them?



Yeah. I noticed the holes that were drilled then plugged with balls and staked in. That does make sense that the resin is put in afterwards. I havent removed the bearings on the intake side yet. I still have to get those caps off and I think i'll need the dremel for those.


I didnt notice any wear on my seals or washers as they werent causing the problem of the leaks. They are damaged though from my rough handling of them and I ended up chipping them.




Hopefully we can get a step by step process with pics , part numbers and best place to buy parts so as to see whats going on and possibly fix our own superchargers without spending $1600 and up on a rebuild. Think this might be possible? Then slap a sticky of it up.


If this happens I will forever be in debt to the person that does so.




Bros, that is why you should be running synthetic thumbup1.gif Our S/C is oil cooled and we need the oil which resist heat the most which is synthetic. If you are not running synthetic, you should start. Our engine bays are so crammed that once they heat up they take a long time to cool down. And with the S/C at the highest point in the engine, it probably stays quite hot for a long period of time.




Sounds like the miller-cycle might be the perfect candidate for that Auto-RX engine cleaner I used on the 2.5L some time ago. I've tried to find at least some anecdotal evidence that the stuff is snake oil or otherwise not as advertised, but unless Google search results are somehow being sanitized, the stuff is real. Other engines with sludging issues like the Audi/VW 1.8T and some BMW I6s (or engines that were simply neglected) are showing significant results with the stuff as far as removing solidified oil deposits and transfering them to the oil filter.


I suppose it's possible that the oil burning starts as soon as the ports become blocked. Unblock them and oil burning ceases. If that's all it really is, I would have been driving a miller-cycle model five years ago.



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  • 4 years later...

Hello Synesthesia,


I know that this post is welll over 4 years old, but.... wish to know the outcome of this supercharger information/ rebuild/ FIX.


When I bought my 1995 Millenia s W/ ~100K miles it. the PRC Solenoid valve had a Busted/ Decomposed "Tee". IIRC that "Tee" supplies vacuum to the supercharger chambers for oil removal...?


Please help.





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