I have 2 S4 turbos-- Hitachi 18S-2S and I'm trying to figure out what to do. The one I just removed from the car has 120k on it, and very little play on the turbine shaft. It does however have slightly larger cracks in the housing where it bolts to the manifold. The other has say 50k on it, has a bit more play on the turbine shaft and smaller cracks in the same places as my original.

I'm not sure if the cracks can be repaired, I found an article on Mazdatrix's site about using cracked units being more susceptible to blowing gaskets. I do have a new OEM metal gasket to use when I re-install.

Whichever route I go, I'm leaning towards staying relatively stock from a boost and install perspective. I've got the factory sized injectors and original ECU. It does have a downpipe with high flow cat and Borla cat-back. I also have an Apexi Safc from when I needed to be able to pass emissions testing, and did install a boost cut eliminator back in the day.

What would you do?

Thanks!

Greg O.

 

the turbine housing will come right off, so use the better one. then you can rebuild the better cartridge/CHRA
or keep the nice running center as is, and rebuild the unknown/worse one

 

Might be worth investigating if porting the wastegate will benefit you in regards of boost control.

But I’d guess you’ve already seen if boost creep occurs due to your exhaust system.

 

Thanks for the feedback. I've been in touch with Tim Smith at Tim's Turbo's, he does do some wastegate porting, so I'll ask if this is an option. Not that I want to ship both turbos, but the idea of doing that may allow them to pick the best parts if they need to. After all these are 36 year old units, some stuff you just can't get.

I did see BNR Supercars lists having a rebuilt unit, I did send an email inquiry but didn't hear back. May need to call them before I pick my final direction.

Greg O.

 

Well, here it is:

 

I have worked with Tims Turbos in Virginia before. He did my holset hx40 hybrid turbo with the s5 rear housing. Good guy to work with.

 

Whoa, holset hx40 hybrid with s5 rear housing…. Peaking my interest as Ive never heard of that hybrid setup. I’ll try searching more about this on rx7club, but I might just have to reach out for some details.

 

Knight,

It was a great setup, I got it back in 2018. Total cost was $756.50 I just gave him 2 s5 rear housings and said make it fit please

I ended up selling the setup to someone several years ago. I went to a larger turbo with external gates.

 

So I've been waiting on new crush washers for the coolant inlet and outlet pipes at the turbo from Atkins. I show the washers to be Mazda p/n 9956-41-400. When I got the first order from Atkins, they had what we concluded were the 9956-41-800 in the bag, so they were way too big. After chatting with Dan, he resent me the -400's--- They're too small! Uuugh....

Looking at Atkin's site, it looks like the 9956-41-600 is the correct .64" ID of my original washers, but that p/n doesn't show as correct for my 10th Anniv which is 1988 of course.

I've owned this car since 1999, and have all paperwork back to day 1, it's the original turbo..... I don't think a 89-91 turbo would even bolt on (isn't the exhaust manifold different?)

Anyway, not sure I want to wait any longer and I'm just going to re-use my original crush washers so I can get this thing fired up before the snow flies here.....


J9fd3s-- Interested in your wisdom here. Needless to say, I'm just befuddled

Greg O.

 

There's nothing special about the OEM crush washers. I would measure the ID/OD and get from mcmastercarr or some other hardware supplier. You can also probably get an assorted kit of crush washers and find one that fits.

 

Michael,

thanks. I was able to find your thread on the turbo build, hw, manifold orientation/spacer etc. documented in my subscriptions for the future. Definitely interesting.


To the OP,
sorry for the quick thread hijack. Your rebuilt turbo looks good.

 

9956-41-400 is a 14mm ID aluminum crush washer, same as the oil pan
9956-41-600 is 16mm ID aluminum crush washer
9956-41-800 is 18mm aluminum

so like you can get these anywhere really
9956-21-xxx is copper, which are more expensive

 

No worries

Greg O.

 

For the washers for lines to the turbo, you can just just go to a hardware store and get them there as long as same material.

Or even McMaster-carr would be same or next day delivery.

I don’t see a need for a specific Mazda washer, as long as the Id, OD, and thickness are reasonable.

I tend to keep a stash of crush washers for this reason.
(& oops, I’ve used copper for all the turbo crush washers… oops..? Probably just more sensitive to torque value.)

 

I got everything re-installed Wednesday, started up, and now I have slightly more smoke coming from the vicinity of the turbo then prior to the rebuild. So I started to disassemble again, taking pics every step along the way to figure out what the source of the smoke is, now that the turbo is all cleaned up-- should be easy to see. All of the gaskets for oil and water are new, crush washers re-used. I see no signs of leakage at any of the gasket connections, crush washer connections look dry/fine as well. After I had the turbo off the car, one of the bolts that connects the intake half to the exhaust half was snug, but not as tight as all the rest. This is where I can see what I presume is an oil leak (shown in the pics), and hopefully the source of the smoke.

Questions are:

1. I presume a rebuilt turbo will smoke a little as the residual oils and paint used get heat set?

2. Is there a torque spec for these bolts? I didn't see one listed in my workshop manual, so I did my best to tighten this one closer to how the others felt.

Appreciate the feedback,

Greg O.

 

1. correct
2. Mazda doesn't publish one i'm aware of. sometimes you can find one from a Garret turbo, or you could just tighten it

 

I tightened up the bolt some, feels good. Cleaned up the external stain that I believe is oil and while looking everything over, saw oil in the exhaust section on the turbine..... thinking that can't be good.. I see no signs of any leakage at the oil inlet or oil outlet gaskets, so I'm thinking I need to reach back out to Tim's Turbos about this.

I only had the car running a few minutes prior to this point, I didn't really notice much smoke out the exhaust pipe (ie. not more than compared to my 88 vert which I have to move a lot to work on this one). I'm talking about smoke coming up in the engine bay just above the turbo.

Sigh?? Do I just install my other J-Spec motor turbo and see how that goes while I figure this out?

Only other thing I noticed-- bolts from the intake side of the turbo are clearly metric, zinc, with a 8.8 stamping. The exhaust side are A2-70, again metric, but 304 stainless.

As always, appreciate the feedback.

Greg O.

 

I asked Tim if I should send it back to him, here's his response:

The turbo is probably fine. You need to burn off the VSR oil. The bolt torque will have nothing to do with oil leak. Be sure to change the oil and just run it. If the turbo is still tight, it is most likely fine. We do a full test bench and leak test. Its only a piston ring to hold oil in. If there is any type of back up the turbo will smoke. Make sure you don't have blow by on the crank case. Also don't use RTV for the drain line. Drive it around for a bit as long as the turbo is still tight.

I told him I'd reinstall it and he replied:

Yea when we run them on the VSR its a full test with air and oil. Oil collects in the turbine heatshield from shipping. So, it will drip out the bottom bolt. 99.99% of the time thats all it is. Drive it around and burn it off. Then let me know. Either way I'll get you all set up. Be sure to check all your crank case breather systems too. Oil needs to be drained by gravity . If it has any resistance it will smoke.

I'm using all new Mazda gaskets, no RTV on anything. I will double check the oil return line to make sure it's clean I guess.....

Greg O.