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Discussion Starter · #1 · (Edited)
In another post I was asked to post some photos of my turbo rebuild. I thought I would start a new thread for those. If interested in my previous turbo issues see this post; "Do I have a turbo problem? Sticky, black compressor side."

In these photos I have finally managed to get the exhaust turbine housing removed from the rest of the turbo. See the previous mentioned post for those details. The compressor housing was put back on the turbo for these photos. It has already been cleaned. The large O-ring is from the inside of the compressor housing. The bolts and retainers are what holds the exhaust turbine housing on.
 

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Discussion Starter · #2 · (Edited)
Photos of the exhaust turbine housing.

The arrow on the 1st photo points to a crack. According to the Holset manual this is acceptable in this area. Just to the right of the arrow there is another small crack in the other part of the housing. I don't know if this one is ok or not. It's really hair line, so I am probably going to live with it.

The arrow in the 2nd photo is the machined grove that the center part of the turbo slips into. This is the area that gets carbon and rust built up and sticks the two together making disassembly difficult.

The 3rd photo is the exhaust outlet side of my turbine housing cleaned up and ready for assembly. I still haven't figured out how to measure this thing to know what size it is. Suggestions welcome!
 

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Discussion Starter · #3 · (Edited)
Dirty parts turn to clean parts. The photos with clean parts shows all of the parts in the turbo.
 

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Could you possibly measure up the turbine and compressor wheels while you've got it apart?
 

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I'm interested in the number of miles you have on these parts and what your turbine shaft bearing wear measurements are.
 

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Discussion Starter · #7 ·
[email protected], Yes I glass bead blasted just about everything.

Dougal, That will have to wait a few days. The turbo is at work, and I am going to a seminar for a few days. I will get those measurements, if I can figure out where to measure them. (the base of the wheel?)

Driverswanted, I don't know the milage on the parts. The motor was supposed to be low mileage when I bought the truck. When I dropped the pan I saw it has been rebuilt. The turbo milage I can't even guess at.
I did measure shaft movement before disassemby. The axial runout was good at .002". The radial was .020". That was enough to let the wheel hit the housing. The fortunate thing is the bearings were gummed up enough that this movement didn't happen until I cleaned the turbo in the parts washer. It truely felt good before I cleaned it.
 

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Did you take turbine shaft wear measurements at the bearing locations?
 

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Discussion Starter · #9 · (Edited)
Driverswanted,
No, but I still can. There is no ridge or scoring on the shaft at the bearing locations, so as of now I am assuming it is fine.

The turbo parts arrived today. The package is labeled H1D. I called to ask about that. I was told the rebuild kit for my H1C is the same part #. I did notice that the exhaust to turbine housing gasket does not have the divider. I also asked about that and was told this was also correct. I don't care for that. There isn't much in the box for $74.55 (includes shipping).
 

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I appreciate you posting this thread, Beck! Good info. Does that kit include a new bearing casette?

I have an HTT Stage II upgrade to put on my H1C. It's a new compressor housing and compressor wheel which will supposedly bring it up to HY35 specs. How difficult to get off only the compressor side, and any warnings there? If everything seems okay I'll only install the new parts. Thanks for any info...
 

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Discussion Starter · #11 ·
Driverswanted,
My turbo shaft is a consistant .4322" down the shaft. There is no wear at the bearing locations.

JimmieD,
There are new bearings in the kit to install in the bearing housing included in the kit. My compressor side came off easily. After taking the band off and a few raps with a plastic hammer it was off. If you want to rebearing you will have to do a complete disassembly, not just the compressor side.

I have come across another area of concern for my turbo. As I stated before the exhaust turbine housing did not want to come off. I had to soak it for a day in carburetor cleaner. After the turbo was disassembled I bead blasted the turbine housing and the bearing housing. I removed all the rust and carbon in the mating area. Now when I test fit them together there is quite a bit of slop. The Holset manual says if this is the case replace the bearing housing. Since I am cheap I am going to try to reuse my parts. I have stainless steel shim stock in all sizes. I am going to attempt to shim this to a snug fit again. Guessing now, I wouldn't think I would need more than .010 around the assembly to snug it up. Update later.
 

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Dougal, That will have to wait a few days. The turbo is at work, and I am going to a seminar for a few days. I will get those measurements, if I can figure out where to measure them. (the base of the wheel?)
Thanks.

No hurry, but I've got a small database of wheel measurements on all the turbos I've pulled apart. It'd be nice to add this ones measurements.
I just measure the large and small diameter of each wheel.
 

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Discussion Starter · #13 ·
3:15 am and the turbo rebuild was just finished. (work will be a drag tomorrow) It was nice not being disturbed while putting this back together. I would recomend you try to find a time and place to do the same. The assembly took me about 3 hr. This was really taking my time and double checking everything. After a few of these I could see this taking less than an hour.
NOTE: Before disassembly double read the balancing section of the manual. This will help you index (mark) everything that needs to be ballanced. I forgot to mark the oil slinger and thrust collar.
The balancing was the weak link in my rebuild. I just hoped it was correct from the factory and put it back like it was. The thrust collar and slinger are machined round parts. Hopefully they are ballanced pieces so they will not affect my ballance.
The manual from Holset is good! Here are some suggestions and things to watch for durring assembly.
1) When you print your manual, I got mine online, make 2 copies of the exploded view and component list. For the H1C these are pages 2-2 and 2-3. Let one copy in its place in the manual. You will constantly refer to these drawings durring the rebuild so keep the 2nd copy on the work bench.
2) Durring the disassembly and assembly I was able to hold the H1C bearing housing in a vice. I don't know if this would work with a different turbo. Place the oil inlet and outlet on the jaws. Be carefull with the clamping pressure. I have brass inserts for the jaws which protects the surfaces. You have to clamp hard enough to hold well but not hard enough to hurt the return oil gasket face.
3) The torque values are small for this rebuild. Make sure your torque wrench goes this low. 4.5 nm or 40 lb in.
4)The first thing you do durring assembly is install the inner bearing retaining rings. These are a pain to get in square. I used a socket head 3/8 bolt head stuck in from the opposite side to keep them square while installing. Do this some place where you will find the rings when you drop them, because you will. The manual says to install these with the bevel facing the bearing. I checked mine under a lit magnifying glass. There was no bevel. The bearings are then installed, then the outter retaining ring. The outers are easier, but make sure they are seated in the ring properly.
5) You are instructed to use a split ring pleirs to install the split ring seal on the turbine. Naturally I didn't have this, but the snap ring pliers will do the job if your careful. Line the ring up on the pins and gently open it to slide it on the turbine. If you have strong fingernails they may do the job.
6) Installing the turbine with the new seal ring was tricky. Make tripple sure it is lined up correctly in the bearing housing so the seal isn't damaged. Work with it until it gently pushes into position. If it won't go in pull it out to make sure the seal has not come out of the grove and try again.
7) I could not hold my compressor wheel when tightening the nut. It turned with the nut. I had to keep backing the nut off and compenstaing for the turning to get the wheel in the correct position when the nut was torqued.
8) The new piston ring seal on the oil slinger simply slides on by hand.
9) Putting this slinger with the seal into the diffuser is a bit tricky, like putting the turbine with its seal in. Be gentle and make sure it is propery aligned. If it doesn't go pull it out and look to make sure it is still in the grove all the way around. Then try again. I was about to whack mine, but pulled it out for a look. It was out on one end. I would have ruined pieces if I had hit it.
10) It seemed to me putting the compressor housing on before the turbine housing was the right thing to do. Wrong. The compressor housing is put on last so you can take your runout readings with it off. The air intake is in the way of the dial indicator. The manual does have you put the O-ring on before the turbine housing is installed. Wait to put the O-ring on until you are going to install the housing
11) I did have to tap my compressor housing back on. Oil it lightly on the mating surfaces before putting it on.

My runout readings after completion were:
radial - .012" with a spec of .012 - .018
axial - .001" with a spec of .001 - .005
Mine are right on the minimums. I would have liked to see the axial a bit higher. .001" is pretty close to nothing. Hopefully the bearing housing expands less than the turbine shaft. Initially I was concerned with the radial runout. Before looking at the specs, but after taking my readings, I thought the whole rebuild was for nothing. .012 looked like a lot of play.

Before I was concerned about the clearance between the bearing housing and turbine housing. I put it together without shims like I was considering just to see how it worked. It seems fine so I am not taking it back apart. I did use anti-seize on that joint to make removal easier later if necessary.

Originally my turbo had lock tabs used on the diffuser to bearing housing bolts. The rebuild kit had raised shoulder small head bolts that I assumed were for this that did not allow the use of the lock tabs. I assumed this was an upgrade so I used the new bolts and not the lock system.

The kit included everything I needed. There were a few extra parts in the kit since it also services other turbos. I had 8 lock washers, an E clip , and an oversized exhaust manifold gasket left over. Overall this rebuild was not as hard as I expected it to be. :D I expected ceramic seals, springs, and special gizmos. I didn't find any of that. I don't understand why these turbos don't leak more oil. The sealing isn't so great.
 

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Again, thanks for some excellent 'Beck Tech'! Service manuals often fail to warn, "Be careful when you..." and too often they just say, "Install..." THANKS!
 

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Very nice write up Beck. Who is the supplier of the repair kit?
 

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Discussion Starter · #16 · (Edited)
BobS,
The kit is a factory Holset piece.

Here are photos of the finished project minus paint.
I don't know why the Holset label didn't take in the last photo. It is there and actually looks fine.
 

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Discussion Starter · #17 ·
Thanks.

No hurry, but I've got a small database of wheel measurements on all the turbos I've pulled apart. It'd be nice to add this ones measurements.
I just measure the large and small diameter of each wheel.
My compressor wheel is 82.93 mm. at the base. This seems odd. The book quotes a 82 mm wheel for this. A 72 was also available according to my Holset manual.

My exhaust turbine wheel is 70 mm.

Now I still have to figure out how to measure the turbine housing size. I plan to call Holset tomorrow with the turbo #s again. I didn't have them last night when I talked with them. They said they may be able to tell me the size information. I just can't figure out what to measure.
 

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Those are some seriously large wheels.

The IHI-RHB6 that came stock on my Isuzu 3.9 has 60mm wheels, the Garrett T25 they used on later Isuzus had a 51.3mm compressor wheel and a 53mm turbine wheel.

Multiplying the housing A/R ratio by the wheel radius lets you compare the gas speeds of different turbos.

My IHI RHB6 has an A/R of 11cm and a 3cm wheel radius giving an effective flow area of 33cm^2.
The T25 I used had an A/R of .48inch (12.19cm) and a radius of 2.65cm giving a n effective flow area of 32.3cm^2

In practice they started to pump at almost exactly the same rpm (1400) so the theory seems to have some basis.

A H1C with a 12cm housing would work out at 12*3.5 = 42cm^2 which suggests it'd start to work at a higher RPM, but the larger compressor wheel complicates things by starting to pump air sooner.
 

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Discussion Starter · #19 · (Edited)
Those are some seriously large wheels.

A H1C with a 12cm housing would work out at 12*3.5 = 42cm^2
These measurements were at the base of the wheel. The very largest part.
Sizes in inches compressor wheel = 3.265 turbine wheel = 2.756
Never having been inside a turbo before, I thought they were small.
What is the 3.5 in the formula above? I crunched a few #s and nothing seems to work out with 8.293 and 3.14 to get that.
Is the shape of all wheels the same? (Some could have a large base but smaller blades)
 

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I was working in metric dressmaking units, so 3.5cm is the radius of the turbine.

The wheel "trim" describes the difference in size from the biggest to smallest diameter.
Bigger trims have less step in the wheel and flow more.
 
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