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New guy, picked up a 931, fix or part out?
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Fix it or sell parts?
Fix
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 92%  [ 12 ]
Parts
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Total Votes : 13

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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2596
Location: MI

PostPosted: Sun Sep 29, 2013 1:58 pm    Post subject: New guy, picked up a 931, fix or part out? Reply with quote

Hey guys, hope your in a good mood to help alleviate some of my ignorance because I bet I have plenty...
So yesterday me and a friend picked up a 1980 924 turbo for $650. It ran pretty well concidering the amount of oil it it was consuming from the cold side of the turbo all the way through and back out. Body is in excellent shape, plenty of stone dings and a couple little dimples in the metal here and there but not a spot of rust witch is almost unheard of here in salty wintered northern Michigan. Well anyway it has the 16" 928 wheels and LSD rear end and seems to be in great save able condition. Before popping on it I did some research and sourced another turbo for $350 and I thaught that was cheap enough so I bought it and drove it home.
As of now I have the turbo almost all the way off (what a PITA!!) and have some concernes I would really appreciate you guys giving me some input on.
The inside of the intake between the throttle body and the turbo had plenty of oil in it as expected but what worries me is the amount of what seems to be aluminum shavings in the inside along with the oil. I magnetically tested it because I'm sure if it was ferris chips the engine would be toast from eating all of that debris but none stuck to my magnet so the engine may be ok, I guess the only way to find out would be to replace the turbo and see if it runs decent short of pulling the head and inspecting the sleeves or as I plan doing a compression test to try to get some insight as to the condition of the engine. But as I've been reading the 1980 model seems to be the lame one because of the unreliable turbo issue having read they "eat a turbo every 10,000-15,000 miles).
So for now what I have to decide is wether to try and put this thing back together and hope it will last a while or cut and run and start selling it for parts to try to get my money back out of it and that's where you come in. I'm hoping you can give me a little hint as to what to expect and maybe some things I should check out before I dive any deeper into this thing. Please help?


Last edited by Fasteddie313 on Tue Jul 21, 2015 12:24 pm; edited 2 times in total
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morghen  



Joined: 21 Jan 2005
Posts: 8868
Location: Romania

PostPosted: Sun Sep 29, 2013 5:06 pm    Post subject: Reply with quote

It depends how you drive. It wont cook the turbo that fast, especially if you take care of it. For example, after a sprinted run dont turn the engine off and leave it there, plan a few minutes of lower rpm(no/low boost) driving before ariving at your destination to allow the oil to be cooled and further cool the turbo.
Also make sure to use good oil, not your standar crappy oils. I use Motul 300v Competition as it keeps its lube and cooling properties even at high temps.
If you can, add an intercooler and that will do good to the engine.
Set the timing right and it should be a nice drive.
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Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11723
Location: PacNW

PostPosted: Mon Sep 30, 2013 1:05 am    Post subject: Reply with quote

Agree with Morghen, a turbo properly rebuilt and balanced with modern equipment should last just fine. . .under good operating conditions.

There is one problem with this approach, though, that I know from experience - the first thing I did on my 931 was install a rebuilt turbo on my worn engine.

These engines, when high mileage and not kept in proper tune, tend to break rings. Broken rings = excessive blowby. Excessive blowby = corrosive gasses and high crank case pressure. Corrosion and turbo not properly draining due to crank pressure = short lived turbo.

I would pull it apart, reseal it, re-ring it, and replace rod bearings. Because the rings are madly expensive, member Raceboy successfully had his turbo pistons machined to accept thicker and cheaper non-turbo rings. Got some spare change? Buy custom pistons from Diamond or JE.
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  • WeiBe (1987 924S 2.5t) - 931 S3
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2596
Location: MI

PostPosted: Mon Sep 30, 2013 2:01 am    Post subject: Reply with quote

Thanks for the input guys, I think this turbo is completely fried, like the compressor wheel dusted the housing or something because there is a lot of aluminum flakes, I got the exhaust off of it allready and the shaft play is way out of spec just by pulling it side to side and in and out it moves quite a lot. If I do decide to replace the turbo and attempt to save the car would it be worth my time and money to try to sorce the 944 bearing housing and k27 cold side and try to save the hot side off of the one I have?
What about the debri from the turbo getting ate by the engine? How bad do you think that could have damaged the piston/rings/cylinder sleeves?
Tell ya what this car has a gorgeous body but the engine compartment is terrible, it looks like somebody threw handfuls of sand and pea sized gravel on top of the engine, the spark plug holes were completely full of dirt and rocks until I took my compressor and blew everything out... Seems to me somebody purposely did that to stop a compression test from being done easily.
Il going to get some pics of it up today if I can
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2596
Location: MI

PostPosted: Mon Sep 30, 2013 2:05 am    Post subject: Reply with quote

From the sounds of it these are a nightmare to keep running right and almost have to be babbied, can these things actually deal with being drove hard?
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morghen  



Joined: 21 Jan 2005
Posts: 8868
Location: Romania

PostPosted: Mon Sep 30, 2013 3:08 am    Post subject: Reply with quote

If everything is whithin spec, you can drive them as you wish
If i were you, i'd replace the turbo with a rebuilt one, but at the same time do what Rasta said.

I dont think the aluminium debri did any damage to the engine...but at least look trough the spark plug holes with an engine inspection camera.
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2596
Location: MI

PostPosted: Mon Sep 30, 2013 5:38 am    Post subject: Reply with quote

Ok well I got the turbo out just now, 2 of the three manifold to turbo bolts broke off but I guess it doesn't really matter because the hot side housing has a pretty decent crack in it on the inside where those long ports come into it. When I removed that housing there was evidence the fan blades were scuffing the inside of the housing at there smallest point some, shiny spots on tips of blades and a shiny spot on the inside of the housing. I'm not sure if that means that fan is toast also. On the other hand the cold side of the turbo is completely shot, fan blades severely damaged and all sorts of evidence of the blade contacting the housing. And for the bearing housing... Axel is pretty darn sloppy, I'm not sure if the shaft is toast or not because I didn't go any farther. It seems my only option is to replace the entire turbo, they can have this pos for a core charge there most likely isnt anything good on it, probably no salvageable parts witch sucks because I wanted to rebuild it for the most part. My buddie dave and I both bought the car together, I'm the mechanic of us two and it's at my place and whatnot, he says sell it, I'm not sure yet...
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2596
Location: MI

PostPosted: Mon Sep 30, 2013 6:37 am    Post subject: Reply with quote

I'm finding evidence of a transmition rebuild as in orange colored permatex sealing agent squeezing out between cases that I doubt would have been factory done, would there be any tag or something indicating a rebuild? And it is definately LSD
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Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11723
Location: PacNW

PostPosted: Mon Sep 30, 2013 11:10 am    Post subject: Reply with quote

Fasteddie313 wrote:
From the sounds of it these are a nightmare to keep running right and almost have to be babbied, can these things actually deal with being drove hard?



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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2596
Location: MI

PostPosted: Mon Sep 30, 2013 11:36 am    Post subject: Reply with quote

Well I'm not sure what that means but I hope I understood wrong and that means that you guys do nothing but drive the piss out of your cars and it's funny that I got that impression.
But please some good information would really be appreciated..
Does the crack on the inside of the hot housing render it scrap metal?

What about the hot turbine can having a little wear from touching the housing?

If the shaft and bearing seats in the bearing carrier aren't distorted should I rebuild this side and source a new compressor fan and compressor housing?

I'm pretty serious about putting this thing back together, it's in nice shape..
I'd hate to have to steal the wheels for my e36, sell A few parts, and crush the rest..
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2596
Location: MI

PostPosted: Wed Oct 02, 2013 3:39 am    Post subject: Reply with quote

[img][/img]
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Fasteddie313  



Joined: 29 Sep 2013
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Location: MI

PostPosted: Wed Oct 02, 2013 3:41 am    Post subject: Reply with quote



Compressor wheel
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Fasteddie313  



Joined: 29 Sep 2013
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Location: MI

PostPosted: Wed Oct 02, 2013 3:44 am    Post subject: Reply with quote



Turbine housing crack
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Rasta Monsta  



Joined: 12 Jul 2006
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PostPosted: Wed Oct 02, 2013 5:29 am    Post subject: Reply with quote

Call Majestic Turbo in Waco, TX, and see if he has a replacement on the shelf. If not, contact Dan at Ideola's garage, I believe he has some rebuildable cores.
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juha_teuvonnen  



Joined: 30 Aug 2003
Posts: 79

PostPosted: Sun Oct 06, 2013 9:03 am    Post subject: Reply with quote

As a Series 2 owner I have no reason to badmouth S2 cars. IMHO the bad rap that series 1 cars got for is irrelevant today. Ideola has trigger wheels for sale at reasonable prices, all you need to do it to get a VR sensor and make a bracket and you can use MSD programmable ignition unit. This is actually better setup than S2 Porsche DITC. You can't get replacement S2 crank sensors any more. With MSD you can program your own ignition map. You can use stronger aftermarket clutch for S1, which would be a fraction of what S2 clutch kit costs AFAIK. Besides, I don't even know whether you can get a replacement pressure plate for S2 any more.

S1 is not a bad 931 and it's not really inferior to S2. Keep it. At this day and age, the only way to keep these cars running is to modify them anyway.
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