Trying to understand why the turbo failed..

DailyDriven'88 · 03-22-2009, 01:41 PM

Sorry in advance for the long post, but I want to be as clear on everything as I can.

Recently installed a new k27 on an '86 930. After about 2,000 miles, I looked down the into the turbo (intercooler off) its got oil pooled in there. My question is how this happened in such a short duration of time? There was no oil consumption and no smoke of any kind within the 2k miles, which I was very much amazed by and even more so after I saw all the oil down there! only thing I can think of is I must have caught this in its early stage of failure. Also, overfilling of the oil did not occur, the level is between the 2 marks at oper. temp. and the breather is routed to a catch can so injesting suspected overfilled oil wouldn't even be possible.

Prior to the install of the new k27, what seemed to be adequeate oil delivery was verified as well as scavenge pump operation. It was broken in following the directions it came with and was then dyno'd in order to verify afr's. All was pretty good, albeit overly rich down low (common from what i read), but could have been better so i installed a leask wur. After adjustments, afr was checked again and was tweaked to achieve a much leaner afr below the rpm chip's 4k rpm enrichment point. I adjusted it from its high 9's/low10' to around 12.4-12.5afr before enrichment. After enrichment it dips to around 10.5 and levels off at 5k rpm and above to around 12.0 flat. Looked good to me and drove great!

I also have an additional question regarding ignition timing. When i went to check/verify it, I saw a few degrees of advance (1-2 maybe?) at idle with vac hose disconnected and plugged. I had a helper rev it to 4k rpm and noticed it was only getting about 10-12 degrees of advance. As the engine was climbing to 4k, i watched with my timing light and the timing got to around the 10 degree range fairly quickly and just stopped, no matter how high it was rev'd. What gives? Judging by where the dist. is placed in its adjustment range, it did not look like I would be able to adjust it to within specs. I did move the dist. around a lil bit but it mostly gave me more retard, not advance.

BTW, car made 320whp and 340wtq at .7-.8 of boost.

Also, I removed the turbo and there is quite a bit of shaft play. It will be getting sent off to be inspected and hopefully repaired at a reasonable cost?? *crossing fingers* haha

RarlyL8 · RarlyL8's Garage

Where did you buy the turbo? Have you spoken with them about this? What did they say?

DailyDriven'88 · 04:03 PM

Turbo was purchased from ImagineAuto. I will be calling them tomorrow.

Any thoughts/ideas on the igntion timing? I believe the spec is 26+- 1 degrees at 4k rpm, vac hose disconnected?

mb911 · mb911's Garage

wow that is very odd. I wonder what the cause is

dean · 03-22-2009, 04:23 PM

Does your motor smoke? It is ok to have some oil in the intercooler. It doesn't mean your turbo has failed. It is also ok to have some play in the turbo with no oil pressure.

DailyDriven'88 · 03-22-2009, 05:03 PM

Quote:

Originally Posted by dean

Does your motor smoke? It is ok to have some oil in the intercooler. It doesn't mean your turbo has failed. It is also ok to have some play in the turbo with no oil pressure.

Absolutely zero smoke. I realise that a normal amount of oil in the intake tract is normal for these cars, however when the intercooler was removed, it was obvious to me it was excessive, almost dripping out. I have removed the intercooler countless times so by now I think Im aware of what's normal and abnormal.

If I tweak the shaft of the turbo to one side and give it a light turn, I can faintly hear what seems to be contact between the blade and housing.

Pooled oil in the turbo is NOT ok, correct?

Oh, the oil that was cleaned out of the intake duct just before the turbo was absolutely disgusting. It was dark grey and stunk pretty bad.

DonE · 03-22-2009, 05:30 PM

Your intake could be the issue. When you say pooled oil, how much do you mean? When I look down into my turbo, I cannot see the bottom of the compressor side very well. Therefore, if you see pooled oil, yow - you have a lot. I've seen turbos that collect a lot of oil from the intake on the CIS cars and they only pool about a tablespoon or so.

fredmeister · fredmeister's Garage

Are you sure the oil was cleaned out of the intercooler and other plumbing before installing the new turbo. It could be left over from the system before replacement?
If not, why not run the turbo after thoroughly cleaning everything up and see if it repools oil.
You should not have any contact between blades and housings....this sounds bad.
As far as timing, makes sure the vacuum advance and boost retard is functioning fully and then time the car. There are so many distributors for the different models that it is hard to say what you should be running.
I have a distributor that has vacuum retard as well as boost retard and my idle timing is 4 degrees BTDC at 900rpm. Get about 31 degrees under boost and 4000rpm with this setting.

DailyDriven'88 · 06:17 PM

Quote:

Originally Posted by DonE

Your intake could be the issue. When you say pooled oil, how much do you mean? When I look down into my turbo, I cannot see the bottom of the compressor side very well. Therefore, if you see pooled oil, yow - you have a lot. I've seen turbos that collect a lot of oil from the intake on the CIS cars and they only pool about a tablespoon or so.

I can see the bottom of the compressor side quite well, maybe not the absolute bottom but close enough to see its a pool alright.

What causes these cars to collect oil? Like I said in the first post, my breather goes to a catch can. Where else does it come from, assuming the turbo is fine?

Fred: I did lots of cleaning (all ducts, inside of intercooler etc) prior to the install of the new turbo. I went thru lots of brake cleaner, lol. I really doubt its residual. If it is, that would be nuts! i would still be left with the shaft play though. I cant see the blades actually touching the housing, but i do hear what sounds like it and im assuming its in an area beyond where i can physically see. Id like to add that Ive had everything apart more than few times after the new turbo and the amount of oil was nothing alarming like this.

In regards to the timing, how would I go about checking it? I thought I was doing it correctly by disconnecting the vac hose, plugging it, and checking it at 4k rpm. If im doing something wrong here, please advise. I did some searches on this topis and Im matching what others are doing, just not getting the same results. My dist. has 2 vac hoses going to it. Im disconnecting the hose closest to the engine, not the one closest to the rear of the car.

fredmeister · fredmeister's Garage

Quote:

Originally Posted by DailyDriven'88

I can see the bottom of the compressor side quite well, maybe not the absolute bottom but close enough to see its a pool alright.

What causes these cars to collect oil? Like I said in the first post, my breather goes to a catch can. Where else does it come from, assuming the turbo is fine?

Fred: I did lots of cleaning (all ducts, inside of intercooler etc) prior to the install of the new turbo. I went thru lots of brake cleaner, lol. I really doubt its residual. If it is, that would be nuts! i would still be left with the shaft play though. I cant see the blades actually touching the housing, but i do hear what sounds like it and im assuming its in an area beyond where i can physically see. Id like to add that Ive had everything apart more than few times after the new turbo and the amount of oil was nothing alarming like this.

In regards to the timing, how would I go about checking it? I thought I was doing it correctly by disconnecting the vac hose, plugging it, and checking it at 4k rpm. If im doing something wrong here, please advise. I did some searches on this topis and Im matching what others are doing, just not getting the same results. My dist. has 2 vac hoses going to it. Im disconnecting the hose closest to the engine, not the one closest to the rear of the car.

Sounds like you have too much axial play in the turbo shaft....possibly the thrust bearing is worn out prematurely....turbo seller should be able to answer this as you still have a warranty I hope.
In terms of the distributor.....I hear your pain. I had a hard time figuring out what distributor I have in my 4th owner 30 year old car. I do have 2 ports one on the can facing the rear of the car and another nipple on a can inboard towards the engine. The rear can controls vacuum retard. You can check its range of travel by applying vacuum with a mityvac during engine running. I don't remember the range of mine but the 4 degrees at idle quoted is with vacuum attached.
The other is boost retard and that can be tested by applying 14psi of pressure during running. I found that leaving the vacuum line attached or not during this test makes no difference. This tells me the individual cans work in one direction only. The boost retards timing 10 degrees at 14psi so I use this to set my timing at 41 degrees at 4000rpm knowing I will get back to 31 degrees under boost.
The workshop manuals have charts showing vacuum and boost retard curves so you can chart the timing at 500rpm intervals to see if your dizzy is reaching factory specs. I need to do this when I get a helper to run the car at different speeds for me during timing checks. One of my honey do lists!
Good luck let me know what you find.

fredmeister · fredmeister's Garage

I forgot to mention that you must have the vacuum hose attached to a port on the throttle body below or after the throttle body to get a proper vacuum signal. The T-body has several ports so it is easy to get them wrong.
The fact that both cans on my dizzy work independently of each other allows me to run both lines to the cans on the dizzy from the same fitting on the T-body. I just have a tee in the line to branch them off to each nipple on the dizzy.
fred

911st · 03-23-2009, 08:53 AM

Been there done that.

Did you pre-lube your new turbo with the install.

This requires hooking the turbo up to the supply and turn the motor with the starter until oil starts coming out of the bottom of the turbo (do not start motor).

Turbo bearings with out pre-lube can easily be quickly damaged.

It is also good to check the supply and drain lines for coking but it is better yet to replace the supply with a new turbo.

Good luck.

Brent 930 · 03-23-2009, 08:59 AM

911st,

That is good point, something that can be easily over looked yet cause premature failure in no time.

OP, did you notice any shaft play before installing the turbo?

DailyDriven'88 · 03-23-2009, 09:47 AM

Quote:

Originally Posted by 911st

Been there done that.

Did you pre-lube your new turbo with the install.

This requires hooking the turbo up to the supply and turn the motor with the starter until oil starts coming out of the bottom of the turbo (do not start motor).

Turbo bearings with out pre-lube can easily be quickly damaged.

It is also good to check the supply and drain lines for coking but it is better yet to replace the supply with a new turbo.

Good luck.

Great point, however i did prelube it, as per the directions.

"Replace the supply with a new turbo"? Must be a typo. You mean new supply hose?

Brent: I dont recall there being any noitcable play before the install. If there was, it was probably something so slight that it could only be measured with a dial indicator, not my hand.

Fred: thanks for the tips on the timing. I just found it so odd that it stayed at 10-12 degrees advance and didnt move regardless of how high it was rev'd. If it is in fact that out of spec, i would assume the car wouldnt run well, but it runs great. So for now, im chalking it up to me not checking it correctly. After it gets running again, i will follow what you said and give it another shot.

911st · 03-23-2009, 09:50 AM

Poor build, inadequate lubrication, or malfunctioning BOV/Deaccel valve are the most likely candidates.

The best.

fredmeister · fredmeister's Garage

Quote:

Originally Posted by DailyDriven'88

Great point, however i did prelube it, as per the directions.

"Replace the supply with a new turbo"? Must be a typo. You mean new supply hose?

Brent: I dont recall there being any noitcable play before the install. If there was, it was probably something so slight that it could only be measured with a dial indicator, not my hand.

Fred: thanks for the tips on the timing. I just found it so odd that it stayed at 10-12 degrees advance and didnt move regardless of how high it was rev'd. If it is in fact that out of spec, i would assume the car wouldnt run well, but it runs great. So for now, im chalking it up to me not checking it correctly. After it gets running again, i will follow what you said and give it another shot.

Ok but if it does not move when revving, then it is highly likely the centrifugal weights are frozen or something has jammed them in position. I had similar problems with an 911SC and a maintenance item overlooked is that you need to lube the dizzy shaft with lightweight sewing machine oil every now and then. There is a little felt washer under the rotor on top of the shaft that covers a screw head. This needs a few drops of oil whenever the cap is removed so that it gets down into the sytem for counterweight shaft lubing. Otherwise they freeze up or bind.....maybe this is your problem.
Also the vacuum retard mechanism may be binding too, there is a little arm that goes into the dizzy from the can that operates the advance plate mechanism that may have jammed. This happened to me last summer causing mysterious timing issues until I removed and inspected the dizzy to find it. Until that time the car ran like a top on the track until it suddenly went out of timing.
Distributors are PITA and if I had the money I would love to swithc to programmable ignition and be able to program timing curves myself.

Brent 930 · 03-23-2009, 10:51 AM

Quote:

Originally Posted by DailyDriven'88

Fred: thanks for the tips on the timing. I just found it so odd that it stayed at 10-12 degrees advance and didnt move regardless of how high it was rev'd. If it is in fact that out of spec, i would assume the car wouldnt run well, but it runs great. So for now, im chalking it up to me not checking it correctly. After it gets running again, i will follow what you said and give it another shot.

If your timing was stuck at 10-12 deg through your power band you're burning that motor up. I doubt your reading it correctly. If you have an EGT on board and staying below 1600 F then your timing isn't off.

DailyDriven'88 · 11:10 AM

911st: Not sure what you mean by "poor build"? Do you mean engine rebuild? If so, rebuild was not done by me, but rather Steinels in Ohio many years ago and has maybe 10k miles on it. The factory bov or recirc valve was recently resealed by me along with the intake manifold gaskets/injector blocks/ new injectors etc etc. This was done prior to the new turbo. As for inadequeate lube, who knows, could be along with every other variable. How do you accurately check for proper oil deilvery? I have verified the check ball is in place, and it is.

fred: I made sure to add oil under the felt. It didnt seem to change anything. The thing is the car runs friggin great! Due to that reason, im simply going with user error, but im not completely ruling out that there could be some sort of issue.

brent: I realize that not running at full adavnce will cause a significant rise in egt's. It has crossed my mind as a role in this failure. Wouldnt the car run like a dog though? No egt gauge on board.

Brent 930 · 03-23-2009, 11:24 AM

Quote:

Originally Posted by DailyDriven'88

brent: I realize that not running at full adavnce will cause a significant rise in egt's. It has crossed my mind as a role in this failure. Wouldnt the car run like a dog though? No egt gauge on board.

From personal experience, no.

When I had my distributor re-timed (first go around) I quickly noticed my EGT's went up fast and high. I was monitoring A/F, EGT's, boost, Vacuum, and intake air. Otherwise the car was acting fine. After I got back home and checked the timing it was like 15 deg. I then questioned my timing gun, but when I compared the 29 deg. marking on the crank pulley it was dead on.

Needless to say I sent the distributor back out and sure enough it was off. Got it back and went for a drive and all my typical readings were back to normal.

DailyDriven'88 · 12:35 PM

Quote:

Originally Posted by Brent 930

From personal experience, no.

When I had my distributor re-timed (first go around) I quickly noticed my EGT's went up fast and high. I was monitoring A/F, EGT's, boost, Vacuum, and intake air. Otherwise the car was acting fine. After I got back home and checked the timing it was like 15 deg. I then questioned my timing gun, but when I compared the 29 deg. marking on the crank pulley it was dead on.

Needless to say I sent the distributor back out and sure enough it was off. Got it back and went for a drive and all my typical readings were back to normal.

Good to know. Thanks.

From my experience, on other cars when the timing is off by that much, the car does not perform well at all.

29 degree mark on the crank pulley? Didnt realize there was one! hah.