zogster

I'm planning to rebuild my turbocharger (ie. new seals and bearings), but I'm wondering whether I should also replace either or both of the turbine and compressor wheels.

Attached are a couple of pics… intercooler inlet and throttle body, showing what I assume is oil that's leaked from the turbo, and the inlet to the turbocharger showing the blades of the compressor. I'd welcome any advice on condition of the turbo… it looks clear to me that there's some damage to the blades, but I have no idea whether it's enough to warrant replacement. I'll be doing the work myself, but if I need to replace turbine or impeller wheels will have someone balance the assembled shaft.

zogster

Another thing I just thought of: is it likely that the intercooler needs cleaning out (as in, removing oil and residue from core)?

fast951

The compressor wheel is totally shot. This turbo requires a full rebuild and at least a new comp wheel. Once taken apart and everything is checked and measured you'll have a full understanding of its condition.
If you want to save money, try finding a used core turbo in a better condition, or at least find a used comp wheel.

The turbo rebuild is better left to a professional.

Cleaning the IC is recommended. There are a few older threads on this site describing different methods....

gruhsy

Clean things up with this stuff. It can be purchased at any auto body supply shop. I only use this stuff now along with the stronger tar wax grease remover product....same manufacturers. Nothing works better. example pics of cleaned parts on my thread.

https://rennlist.com/forums/944-turb...old-car-4.html



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Chris White

BTW - the oil that you are seeing is not from the turbo. Its from your air/oil separator which vents back into the intake before the turbo. You are probably making more crankcase pressure than it can deal with. Either much higher than stock boost or worn rings....quite possibly from scored cylinder walls from what ever passed though your turbo after destroying the impeller.

zogster

Thanks John - well that's a good, clear answer!

I figured my money saving trick would be doing it myself – I haven't rebuilt a turbocharger before, but I've managed everything else on the car OK so far, and from some reading and YouTube 'research' it looks within my ability. Is there really any compelling reason to get a professional to do it, apart from the balancing aspect? (which I figured I'd deal with by having the new bits balanced as a finished assembly)

Re. air/oil separator… that's interesting. I'm not running high boost so I guess it has to be rings/scored cylinders. Which is a pain as I believe reboring and honing cylinders on these blocks is a very specialised job

Chris White

Sometimes the DIY work is 'false economy'. When you consider the time and parts cost (seals / gaskets / etc) the cost savings to DIY a turbo rebuild doesn't make a lot of sense. I have build many engines myself but I still send the turbos out to an expert. BTW - if I were in your shoes I would be looking at a turbo upgrade....

zogster

Problem with an upgrade is that it increases the chances of some other 32-year-old component breaking!

But, just for the sake of argument, you mean a K26/8?

fast951

Balancing the turbo is important for a healthy rebuild. There are many tasks as important, like checking clearances and measuring critical areas. One needs: (a) the knowledge (b) specs (c) the tools.

A turbo upgrade is nice; it requires a proper tune... Set your goals and budget up front, before making any decision.

A leak down test and a borescope are good tools to investigate the health of your engine. I would do this first, as if there is a problem requiring engine removal you can wait on removing the turbo till the engine is out.

Hopefully all you need is a turbo refresh.

zogster

Thanks for the insights. If experienced engine builders send their turbos out, I guess I should too.

i’m inclined to keep it stock, no upgrade - easier maintenance, and as I don’t race my car’s mostly fast enough ;-)

Looking around right now, a low mileage k26/8 from a later 951 might be a good value option - is it a like for like replacement or are any of the connections different?

Chris White

that a definite yes and no! If you are going to keep it completely stock then you are correct - but if you turn the boost up you start to run the stock turbo out of its efficiency range and you actually put more stress (Heat) in the system than running the same higher pressure in the modified turbo.

Many, many choices for different turbos. There are several turbo builders here in the states that can take the stock housing a fit it with upgraded wheels along with machining the stock housing. Then you can get into more modern aftermarket stuff. It all depends on how far down the slippery slope you are ready to go!
BTW - I was just test driving a customers well built 2.5.....370 rwhp is a lot of fun in these cars!!!!

zogster

So can I just replace the existing unit with a k26/8 without any modifications? Looks like that might actually be cheaper than rebuilding my k26/6. I wouldn’t actually want to run much more boost, if any… maybe in the future but for now just get what I have running better

rlm328

The new turbo technology does not necessarily mean higher boost. The newer technology includes faster spool, larger pressure map, etc. Depending on what condition your hot side is in you can upgrade for a reasonable amount of money.

schip43

Ugh well that sucks!! Sigh and so it begins?? It would be wise to pull the head also and see if something is in the motor??? Something did that damage?? And it might still be in there or maybe the valves chewed it up ... don't know???

zogster

I'm sure whatever did the damage is long gone… I noticed that it was damaged the last time I had the intake stuff apart, and I've had the head off since then. Nothing extra in the cylinders ;-)