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In the Fires of Hell.....
 
kdjones2000's Avatar
 
Join Date: Oct 2007
Location: Phoenix, AZ
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Some random Turbo questions

Okay, now that I can get back into my engine, I had a couple of questions that you guys can help with.

1) I just noticed that the "Exhaust Emissions Tube" (PN 951 111 175 02) over back near the firewall next to the exhaust (The one with the blue plastic cap on it) on my engine has both of the mounts fatigued off. It feels like it's loosely attached to the crossover pipe.

My question is; what the heck is this thing used for? If it is loose, do I have an exhaust leak down there?

I have it zip-tied to the water hose over there for now, but I am wondering if I need to weld the mounts soon, or just wait for my eventual clutch replacement/turbo upgrade WYAIT.

2) When I did my DE last weekend, I was driving the car pretty hard (On boost/off/back on), and when the session ended I returned to the pits and turned off the car. The car would then have coolant start overflowing through the tube. I would lose about 1/2 of the coolant tank if the car was filled up.

The car ran fine out on the track, resting at/just above the 2nd mark. I tried idling the car for 5min after the session to let it cool (Fans were on), but it would still puke some coolant even while idling. I bought a new, OEM coolant cap less than a year ago, so I would not expect that it is worn out. The dealer says that there is only one cap PN for the Turbo, so it's not like I have a lower pressure cap.

The temperature out here in "Hell" was not too bad - 80F in the morning, rising to the mid 90's by the end of the session.

What are your thoughts on this? I had bled the cooling system like a year ago, and have never had any problems with overheating since. Any suggestions on minimizing/preventing this are appreciated.

Cheers,

Keith
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'88 951S - with LBE, Guru chips, 3Bar FPR, 1.3mm shimmed WG
3300 lbs, 256 RWHP, 15 psig boost
"Certified National PCA Instructor" Hoooohah!
1987 924S 944 SPEC racecar - '88 pistons/DME, short 5th

Last edited by kdjones2000; 10-28-2008 at 01:53 PM..
Old 10-28-2008, 01:50 PM
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1. is a tube for checking the exhaust gas content. It is purely diagnostic. You can remove it and plug the hole with a VW lug nut.
2. There are at least three possible explanations to this one. The head gasket is starting to go, it has an air bubble in it or it is overfilled. When the car pukes the coolant, is that it? Or does it puke each time? I would bleed it again, or better yet, borrow a cooling system pressure tester and bleed it that way. Then fill to the lower mark on the tank, and see if it pukes again. If it continues to puke, perform a leakdown test on it. A bad head gasket will show up real quick. Start with cylinder #4.
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Keith Belcher
'87 951 nautic/cancan
Old 10-28-2008, 03:03 PM
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In the Fires of Hell.....
 
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1) If this is the case, then if it feels loose to me where it is attached, there must be some kind of exhaust leak.

2) I just checked out the cap in detail, and it doesn't have any resistance until the last 1/8 or so of a turn when you put it on the coolant tank. I am thinking that maybe it is defective/worn out. Either that or my original coolant tank has stretched over the past 20 years and is now out of spec.

I haven't really had a chance to drive the car any more than on the way home from the track, as I don't have a hood release cable so I can't close the hood

Once I get the cable I will test it out some more and let you know where this goes.

Keith

PS: Two Keith's, two Nautic Blue 951's
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'88 951S - with LBE, Guru chips, 3Bar FPR, 1.3mm shimmed WG
3300 lbs, 256 RWHP, 15 psig boost
"Certified National PCA Instructor" Hoooohah!
1987 924S 944 SPEC racecar - '88 pistons/DME, short 5th
Old 10-28-2008, 07:34 PM
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On my second track day, I began losing coolant out the overflow tube, it was due to a bad reservoir cap. As far as I know, the only possible way you can lose coolant out the overflow tube is if the cap is bad or you have too much pressure.

Also, I read on rennlist that there was a big batch of bad reservoir caps sold (replacement parts) and out there in use.
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99 996 cab: 2004 - present,GT3 & Strosek mixed body
86 951: 2008 - present,951MaxChips,LSD,LBE,924t hood & rear spoiler, Koni/Eibach/Ground Control, 3Bar FPR, lowered,brake cooling, Lindsey spherical bushings
99 986: 2002-2006, PSE (my favorite of the three, but with kids, it had to go)
1986 951 pic
Old 10-29-2008, 09:04 AM
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In the Fires of Hell.....
 
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Well, I got my hood release cable today and installed that so life is good again

I also decided that it was time to dig through the top end of the engine and see if I could find anything. The need for this was also exacerbated by the fact that one of my injectors had started to leak

I took out the plugs and everything looks fine; no coolant in the cylinders or anything, no milkshake, coolant looks fine, etc.

The overheating symptom is that the car would overheat about 1-2 minutes AFTER pulling off the track. The car ran fine on the track, but seemed to get too hot if it was turned off just after running hard, or even if you let it idle afterwards.

I am going to get another cap and see how it goes.....

I am also hoping that I can find something in the top end that might have been causing the loss of power. So far, I have only seen 2 things that might be contributing.

1) The speed/reference sensor connector bracket was not bolted to the intake manifold like it should have been. This might have been causing some issues while cornering hard, although the connectors all seem nice and tight

2) The hose to control the blowoff valve may have been slightly loose.

So I bought all new plastic vacuum hose and new Y's and elbows (Didn't want the bling of the silicone kits), and am getting ready to put things back together. We shall see if this fixes things or not.





(Yes, I will clean things up more before bolting stuff back up :P )

However, 2 things have come up that I could use some help with....

1) Looking at the turbo cooling water pump, I noticed that is has a very slow leak:



Is this something that can be easily fixed with a new o-ring? Are these available? If not, anyone have a good one for cheap?

2) Looking at the injectors, the leaking one turned out to be bad. On the one that the screwdriver is pointing to I can rotate the metal cylinder on the injector end, whereas the other 3 are tight. I am 99% certain this is the leak and the injector is bad. Does anyone know if there are specific series of injectors used for the 951, so I would need to get a certain flow rate one for my car's VIN, etc.? I guess I will talk to the dealer tomorrow and find out.

EDIT: Talked to the dealer, and there is only one PN for the 951 injectors, so it seems that all of these are the same for all engines. I think I understand why people have theirs flow matched at places like Witchhunter... Even my Taurus has different groups of injectors tuned for particular groups of engines.



Anyone have a stock injector (Bosch PN 280 150803 (745) (060) )? Last two numbers are other markings on the injector.

I want to get this thing up and running soon, so any/all help is appreciated.

Cheers,

Keith
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'88 951S - with LBE, Guru chips, 3Bar FPR, 1.3mm shimmed WG
3300 lbs, 256 RWHP, 15 psig boost
"Certified National PCA Instructor" Hoooohah!
1987 924S 944 SPEC racecar - '88 pistons/DME, short 5th

Last edited by kdjones2000; 11-07-2008 at 08:04 AM..
Old 11-06-2008, 10:05 PM
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In the Fires of Hell.....
 
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Looks like I found an injector locally, so don't worry about that one.

Anyone have a used turbo water pump that doesn't leak, or know how to fix one?

Keith
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'88 951S - with LBE, Guru chips, 3Bar FPR, 1.3mm shimmed WG
3300 lbs, 256 RWHP, 15 psig boost
"Certified National PCA Instructor" Hoooohah!
1987 924S 944 SPEC racecar - '88 pistons/DME, short 5th
Old 11-07-2008, 07:10 AM
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Hi Keith ... just to let you know, I pulled my stock injectors and will be replacing all of them. A couple were pretty wasted but if you find you need another one, let me know and I'll send you down a couple spares...

Ryan
Old 11-07-2008, 07:36 AM
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In the Fires of Hell.....
 
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Sure thing!!

If one is going, the others are most likely not far behind.

I will PM you details.
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'88 951S - with LBE, Guru chips, 3Bar FPR, 1.3mm shimmed WG
3300 lbs, 256 RWHP, 15 psig boost
"Certified National PCA Instructor" Hoooohah!
1987 924S 944 SPEC racecar - '88 pistons/DME, short 5th
Old 11-07-2008, 07:58 AM
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Small world with two Keiths and two nautics. now if yours has option code 5R and cancan sport seats, that would be too freaky.

What kind of shape are your coolant hoses in? it is much easier to change them right now. the ones around the turbo and the rear heater are hard to reach with the intake in place.

So it overheats after you get off the track, but is fine while moving. Sounds like air flow is a problem. Are the fans working correctly? Here is a procedure to check them out:

The fans are controlled by the relay which receives open/closed circuits from the thermo switch, refrigerant temp switch, and the a/c control switch.

You should always have power available to the relay, so the fans can run at any time.

First thing to do is check for voltage...

Turn off the ignition and remove the cooling fan relay. Get a strong light and find the numbering on the fuse panel.

1. Check for voltage at positions 30 M1 and 30 M2. You should get 12v + at both positions. If not, chase down the wiring from the battery, the connections to the fuse panel (they are underneath the panel), and the fuse panel itself. You will have to pull the fuse panel up to check some of this out. Be sure to disconnect the battery before taking the fuse panel out.

2. Next check for continuity between ground and the temp switch position on the fuse panel. If you have continuity, the thermo switch is calling for fan operation. If the car is cold, the thermo switch is bad. This will make the fans run all the time.

3. Fabricate a jumper wire with flat blade connectors on each end, and a 20a fuse in the middle. You can check the fan operation from either 30 M1 or 30 M2 since they are both +12v. I like to connect the load first, and battery voltage second just in case the wires jump around and short out and blow your last fuse.

4. Connect jumper wire from M1 to 30 M1, the drivers fan should run at high speed
5. Next, connect jumper between M2 to 30 M1 (or 30 M2), the passenger fan should run at high speed.
If both of these are not true, chase down the wiring, or check the fan motor.

6. Next connect jumper between 30 M2 (or 30M1) and V1, the drivers fan should run at low speed.
7. Next connect jumper between 30 M2 and V2, the passenger fan should run at low speed.
If you do not get low speed operation, the resistors are probably bad, but it could be wiring.

If these tests all check out OK, the relay is bad. I bet at least one resistor is bad.

Radiator caps are cheap, and ours use a standard cap you can get almost anywhere. If it only pukes after boosting, you can try that first. I bet the head gasket is starting to go though.
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Keith Belcher
'87 951 nautic/cancan
Old 11-07-2008, 11:15 AM
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In the Fires of Hell.....
 
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Thanks for the help, Keith.

The fans seem to be working fine. They were in fact on while the car was idling after running a session, yet the car still spit a small amount of coolant.

I finally got a good replacement injector and ran the car last night. It seems to be running just fine, with the engine temp between the two lower white marks. After driving for ~5 miles and returning to my garage, after just a few minutes I took the coolant cap off and noticed that there was essentially no coolant pressure. The cap seems to be sealing correctly into the reservoir, and I checked all of the coolant lines when I had the intake off and they seemed fine as well.

About the only two things I am thinking could be causing this are 1) Faulty coolant cap (Haven't replaced it yet) or 2) Headgasket leaking into a cylinder. What would be the symptoms of the latter, hard/rough start and water in the exhaust, usual milkshake?

Keith
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'88 951S - with LBE, Guru chips, 3Bar FPR, 1.3mm shimmed WG
3300 lbs, 256 RWHP, 15 psig boost
"Certified National PCA Instructor" Hoooohah!
1987 924S 944 SPEC racecar - '88 pistons/DME, short 5th

Last edited by kdjones2000; 11-11-2008 at 08:20 AM..
Old 11-11-2008, 06:02 AM
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Some symptoms of blown head gasket..

-over pressurized cooling system (the upper radiator hose will be rock hard at normal operating temp)
-overflowing coolant from the expansion tank
-loss of coolant
-thick white smoke from exhaust
-misfire on cold starts after the car was run at normal operating temp previously
-steam cleaned spark plugs, plugs smell like coolant
-visible coolant pooling in the cylinders after shutdown from normal operating temp (take plugs out and look into bore with flashlight)
-wide variation of temps on factory gauge
-low compression #'s on one cylinder (not the best way to check for h/g issue however)
-high leakdown % on one or two cylinders (best way to verify headgasket issue)

Personally i dont think you really ever get a milkshake with a blown headgasket. If you do get a milkshake, its more likely to be bad oil cooler seals in my opinion. For you to get milkshake in the oil pan, you have to be dumping so much coolant into the cylinders its getting past the rings.
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1987 Zermatt Silver 924S..'The Kraut Burner' - Sold in Nov. '04
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Last edited by Techno Duck; 11-11-2008 at 06:35 AM..
Old 11-11-2008, 06:32 AM
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Running 87 pump gas with higher than stock boost settings will typically result in head gasket issues
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Old 11-11-2008, 06:47 AM
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In the Fires of Hell.....
 
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Quote:
Originally Posted by PAUERMAN View Post
Running 87 pump gas with higher than stock boost settings will typically result in head gasket issues
Never have done that, Vic..... I have for a long time run 89 octane with stock everything, but have been using 91 since putting in the LBE.

Thanks for the info, Techno I don't have any of those symptoms, at least as far as I have been able to ascertain. Plugs looked fine when I took them out, temperatures seem to be fine. I am keeping a close eye on the coolant.

Need to drive it a bit more and see.

Keith
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'88 951S - with LBE, Guru chips, 3Bar FPR, 1.3mm shimmed WG
3300 lbs, 256 RWHP, 15 psig boost
"Certified National PCA Instructor" Hoooohah!
1987 924S 944 SPEC racecar - '88 pistons/DME, short 5th

Last edited by kdjones2000; 11-11-2008 at 08:23 AM..
Old 11-11-2008, 08:19 AM
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Well, I have been driving the car for the past couple of days. Car seems to be behaving normally; boosting fine (12-13psig now with LBE), no overheating or spitting, and doesn't seem to be losing any coolant.

Basically behaving as it always has during normal driving conditions.

I did check the coolant pressure after coming home from work yesterday (8miles, mostly highway), and there was like 1psi of pressure present.

I am going to get the new coolant cap before heading off to a DE this Saturday. Let's see how it goes!!

Thanks for the help, guys.

Keith
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'88 951S - with LBE, Guru chips, 3Bar FPR, 1.3mm shimmed WG
3300 lbs, 256 RWHP, 15 psig boost
"Certified National PCA Instructor" Hoooohah!
1987 924S 944 SPEC racecar - '88 pistons/DME, short 5th
Old 11-12-2008, 08:15 AM
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Sounds like the cap may be bad. You will always have some pressure in the system after it reaches operating temperature.
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Keith Belcher
'87 951 nautic/cancan
Old 11-12-2008, 08:16 AM
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In the Fires of Hell.....
 
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Alright, answers finally!!

I went out a spent a whole $5.10 on a Stanton coolant cap from Checker and put it on the car for my Track Day today. It went on with a bit more force than the OEM one I got from the dealer a year ago.

Running hard all day long, no issues at all with coolant spitting or overheating

I like this type of solution; easy and cheap

I also found the answer to another issue I have been having with the car since I started doing some Autocrosses and now DE's. The problem was that on hard right-hand turns the car would lose power, especially while exiting from the turn. If you eased off of the turn a bit, the car would settle down and drive just fine.

I have read some threads of a similar nature on Rennlist, with about the only root causes mentioned being that the injector wiring harness shorting out, or some other electrical issue.

For my case, I have determined that it is simply a case of insufficient gas. The problem only exhibits itself when the gas tank gets down to about 1/2 tank. Today it started losing power on right turns at the very end of my 3rd 20min session, and was progressively worse on the 4th.

I went and filled the tank up and ran a 5th session, and viola! no more issues on right hand turns!

Talking with some other 944 drivers who were at the track (Two 944 S2), neither of them have experienced this issue. I am thinking that this might be due to the higher flow rates of the injectors in the Turbo (?) compared to theirs, but this is just conjecture. The pump is less than 6mo old, and the fuel filter was replaced about 9 months ago. About the only question mark I have is the screen inside the tank. If you can recall, the outlet from the gas tank to the fuel pump is on the passenger's side of the tank, so if you have enough G-forces, apparently you can cavitate the fuel pump, and lose fuel to the engine.

Has anyone here experienced something similar? Any solutions, other than keeping your tank full?

Here are the pictures putting things back together:







Much nicer!! Check out my new "White Bling" for the fuel vapor recovery lines in the rear. I ordered the stock plastic M3x1 tubing from the dealer, but the new stuff came in white for some reason. The vacuum lines that route over the engine have the same size, but come in black.





Thanks,

Keith
__________________
'88 951S - with LBE, Guru chips, 3Bar FPR, 1.3mm shimmed WG
3300 lbs, 256 RWHP, 15 psig boost
"Certified National PCA Instructor" Hoooohah!
1987 924S 944 SPEC racecar - '88 pistons/DME, short 5th

Last edited by kdjones2000; 11-16-2008 at 12:42 PM..
Old 11-15-2008, 06:01 PM
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