Topic: Rebuild the K04 Turbo cheap?

[Sly Bob]

Never seen the inside of our turbos but one time when Kelu brought his old turbo to a mod meet a few years ago but some people have been having issues lately and I was looking around for options.

If you have issues with the turbo you can replace it or you can rebuild the old one. I would think that rebuilding the old one is assuming that there isn't any damage done internally that won't be replaced with the parts in the rebuild kit. If the housing is pooched then you'll be either shopping for a new one or a used one you can use for parts. That said, does someone more knowledgeable than myself know if these instructions would do the trick for rebuilding our turbo? The Borg Warner K04 turbo is used by a lot of manufacturers.

http://www.pelicanparts.com/techarticles/Audi_Tech/24-TURBO-Turbocharger_Rebuild/24-TURBO-Turbocharger_Rebuild.htm

[GXP_Matt]

That method of marking the wheels and keeping them in the same orientation to avoid rebalancing really sketches me out.  That takes care of some of the imbalance but there is still quite a bit of imbalance introduced during the assembly process.  You might get away with it but you are taking a chance. 

That is also an older version of the K04 than the one on the LNF engine so some parts will be different (an obvious one is the BH/TH connection being a v-band).  I'm also not sure where they got their compressor wheel nut tightening spec from.  That is a critical part of the turbo assembly to get right to insure the wheel doesn't come off. 

These are also pretty stout turbos, usually if they fail it's because of something else in the system like a clogged turbo oil drain, dirty air filter, poor oil supply to the turbo, bad boost control causing an overspeed, a poorly setup BOV causing compressor surge, etc...  So you can replace the turbo but it will just fail again shortly afterwards.

Source: I am an engineer at BorgWarner Turbos.

[TomatoSoup]

Yeah Bob, I posted a similar how-to some years ago.  Can't find the KP link, but the original article was at Astra owners club.  Seems the original has now lost it's photos, but I pdf'd it back then (attached).

Probably subject to the same caveats that Matt outlined above, though.

[Kelu]

Never seen the inside of our turbos but one time when Kelu brought his old turbo to a mod meet a few years ago but some people have been having issues lately and I was looking around for options.

The broken one from the mod meet wasn't stock K04 turbo, it was EFR turbo.

As far as I know, especially diesel engines, there are some companies in my country where they to internals replacement but only for Garret, they can't do for Borg Warner turbos.

[Kelu]

Yeah Bob, I posted a similar how-to some years ago.  Can't find the KP link, but the original article was at Astra owners club.  Seems the original has now lost it's photos, but I pdf'd it back then (attached).

Don't compare that K04 with ours!!! Z20LET is a different engine than ours, port injected 190-200hp, I had it in my previous car, Opel Astra Coupe and I don't even try to search differences but I bet is a completely different turbo.
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There are many types of K04, like dozens, pay attention to this detail.

[Sly Bob]

Yeah Kelu, I remember now that the turbo wasn't a K04. It was here for a warranty replacement it I remember correctly.

Although they are different turbos the process to rebuild them would be similar I would think but what the heck do I know. Good information and thanks Matt for the clarification. Is it not possible to rebuild a turbo where only the bearings might be gone? If so, is it best to have that rebuild done at a shop that can balance everything after the rebuild is done?

Are specific instructions available for the K04 used in our cars? What SHOULD the torque be Matt?

[Sol Asylum]

Bob it's totally possible to rebuild when bearings go bad but the person doing the job has to have the right tools and knowledge to do the job.  The design of the turbo will determine just how complex the job is and having the proper manuals/tech info for the turbo is also a must, getting that information maybe the hard part.  One of the best skills for the person doing the job is knowing when to say "this is beyond me" far too often people don't have that skill and end up doing more damage than good.

[Sly Bob]

Oh I'll agree with that. There is a story on one of the forums I was looking through where a guy tried taking off the nut on the end of the turbo shaft not realizing that it was a left hand nut. By the time he figured it out it was too late and the turbo was pooched.

Yeah it never hurts to know what you're doing.

[Critterman]

My last ship in the Navy was a minesweeper powered by twin turboed Wakasha diesels.  The port turbo was 11k rebuilt and the starboard 9k.  We had a Chief Engineman who used to by bearing kits for $125 and rebuild then.  The only difference was that the branding on the outside of the turbo was different.  By turning the mounting bracket around you could mount the starboard on the port side and save 2k.   But he rebuilt them and saved tons of money.

[Kelu]

Bob it's totally possible to rebuild when bearings go bad but the person doing the job has to have the right tools and knowledge to do the job.  The design of the turbo will determine just how complex the job is and having the proper manuals/tech info for the turbo is also a must, getting that information maybe the hard part.  One of the best skills for the person doing the job is knowing when to say "this is beyond me" far too often people don't have that skill and end up doing more damage than good.

I agree 

Critterman: diesel turbos are "easier", I think everything starts from the exhaust temperatures between gas and diesel

Bob: I think we shouldn't worry too much, I would estimate minimum 200-400$ to rebuild our stock turbos. I would say if we still can find deals of 500-700$ for a brand new one that's a better option. If not, just upgrade it

[GXP_Matt]

Yeah Kelu, I remember now that the turbo wasn't a K04. It was here for a warranty replacement it I remember correctly.

Although they are different turbos the process to rebuild them would be similar I would think but what the heck do I know. Good information and thanks Matt for the clarification. Is it not possible to rebuild a turbo where only the bearings might be gone? If so, is it best to have that rebuild done at a shop that can balance everything after the rebuild is done?

Are specific instructions available for the K04 used in our cars? What SHOULD the torque be Matt?

It's certainly possible to rebuild the turbo, you just have to balance the core afterwards, which also is not as straightforward as say balancing a wheel/tire.  We have fully automated core balancing machines that run the cores up to 110k rpm while recording the acceleration in G's of the turbo to determine where the imbalance is and in what direction.  Then you have to know where to cut on the compressor wheel to make sure you don't introduce extra stress and blow up the wheel.

The larger diesel turbos are designed to be rebuilt but that is not always the case with a passenger car turbo... It makes it more complicated with the speeds a small turbo sees, 120k+ rpm compared to 30-40k rpm for a large turbo.  Those can tolerate more imbalance, also due to heavy duty bearings.

I'll see if I can find the assembly drawing for that LNF turbo, no guarantees though...

[LatinVenom]

I am with Kelu.
For the price of a new K04 that usually can be found for as low as $500.00 is the way to go.
My opinion though would be to upgrade to something else.