JLee's 1991 Toyota MR2 Turbo build thread - part 2

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jlee

Lifer
Sep 12, 2001
48,513
221
106
The new b-pipe is in. I still think I hear a leak. WTF.

It's got to be manifold/turbo...I just can't find it. I may end up tearing it apart just to look at it and replace all the gaskets anyway.
 

Squisher

Lifer
Aug 17, 2000
21,207
66
91
Disable the fan and make a diy smoke machine. You'll only get a few of minutes of run time, but desperate times, desperate measures.
 

jlee

Lifer
Sep 12, 2001
48,513
221
106
Disable the fan and make a diy smoke machine. You'll only get a few of minutes of run time, but desperate times, desperate measures.

The radiator is 10 feet from the engine bay -- it's not going to impact anything. The intercooler fan might, though, but I can disable that indefinitely if I'm not running in boost. I've put my hand around every joint on the exhaust that I could reach, from the head to the mufflers...I'm at a loss.
 

Squisher

Lifer
Aug 17, 2000
21,207
66
91
Smoke. You can see smoke, even an infinitesimally small leak. If you can't see a leak after that, check your meds (j/k) you're hearing something besides a leak.

EDIT: even 10 feet away you'll still want still air.
 

FuzzyDunlop

Diamond Member
Jan 30, 2008
3,261
12
81
Agree with squisher. Go rent a smoker. Plug one side of your exhaust and push smoke into the other side. You'll find the leak in no time.
 

jlee

Lifer
Sep 12, 2001
48,513
221
106
I ordered a smoke machine today. If anybody wants to have a party, I'm going to have a lot of fog juice left.
 

jlee

Lifer
Sep 12, 2001
48,513
221
106
The fog machine did the trick. I blocked one exhaust exit and ran the fog machine into the other one, then shut it off and ran compressed air into the exhaust. I saw fog curling up from the turbo area - turns out you can actually feel air coming out from either the lower / center manifold or the turbo adapter. So, I'll have to pull the turbo and exhaust manifold assembly and re-gasket stuff. It'll all go back together with new gaskets and Nord-Lock washers, so hopefully it'll never leak again.

I also replaced a few vacuum lines and cleaned up the routing. One of the lines on the wastegate snapped when I was trying to pull it off, so I'm glad it was getting replaced. OEM fog light connectors are on now as well.
 

jlee

Lifer
Sep 12, 2001
48,513
221
106
I am not at all impressed with Stage 8 hardware. The nuts holding the turbo to the turbo adapter were still in place due to the retention mechanism, but all four were finger-spinny-loose - I was able to take the turbo off with a screwdriver and a small pair of pliers.





I expected it to be pretty obvious, once it was apart. I was right.

 

Squisher

Lifer
Aug 17, 2000
21,207
66
91
I am not at all impressed with Stage 8 hardware. The nuts holding the turbo to the turbo adapter were still in place due to the retention mechanism, but all four were finger-spinny-loose - I was able to take the turbo off with a screwdriver and a small pair of pliers.
I don't even see how those are supposed to work. They kinda look like they're under the nut where they would do no good and what would keep them from flying off if they were up engaged with the hex?

Looks like there's plenty of thread left to put another jam nut on top of the nuts there to lock them down.
 

jlee

Lifer
Sep 12, 2001
48,513
221
106
I don't even see how those are supposed to work. They kinda look like they're under the nut where they would do no good and what would keep them from flying off if they were up engaged with the hex?

Looks like there's plenty of thread left to put another jam nut on top of the nuts there to lock them down.

The clips lock into the channel in the nut and keep the pointer from coming off. The problem is the pointers don't have infinite degrees of adjustment, so having them in exactly the right spot once the nut is tight doesn't really happen.

I am going to use Nord-Lock washers and I expect to have no more problems.
 

JCH13

Diamond Member
Sep 14, 2010
4,981
66
91
Unless the manufacturer provides some special retaining method (like a cotter pin in a castle nut) I either use plain fasteners or Nord-Lock washers.

All you really need to know is covered here: http://www.nord-lock.com/nord-lock/wedge-locking/

Specifically:

If jam nuts are your jam, well, read this to make sure you're doing it right: http://www.boltscience.com/pages/twonuts.htm

(Apologies for the side-track JLee, you know that this topic is a pet peeve of mine)
 

Squisher

Lifer
Aug 17, 2000
21,207
66
91
I'm well aware how jam nuts are to be used. I worked for 18 years as a die repairman at a forge where tooling often times could not even be fastened with nuts or bolts. There is no way for them to take the heat cycling and tonnage of forge tooling. Everything is held together with wedges with locking tapers and then those wedges were locked in place with bolts.
 

lsd

Golden Member
Sep 26, 2000
1,184
70
91
The ultimate solution would be to drill new deformed lock nuts and use safety wire. Also if you can swap out those coarse thread studs for a finer thread.
 

jlee

Lifer
Sep 12, 2001
48,513
221
106
The ultimate solution would be to drill new deformed lock nuts and use safety wire. Also if you can swap out those coarse thread studs for a finer thread.

Safety wire is a huge pain in the ass. I have yet to see a Nord-Lock-equipped fastener come loose, so I am quite comfortable just using them.

New deformed lock nuts would be a really good idea for my exhaust manifold, though...
 

lsd

Golden Member
Sep 26, 2000
1,184
70
91
Safety wire is a huge pain in the ass. I have yet to see a Nord-Lock-equipped fastener come loose, so I am quite comfortable just using them.

New deformed lock nuts would be a really good idea for my exhaust manifold, though...
Try to replace those studs too..
 

JCH13

Diamond Member
Sep 14, 2010
4,981
66
91
The ultimate solution would be to drill new deformed lock nuts and use safety wire. Also if you can swap out those coarse thread studs for a finer thread.

I would strongly disagree with this statement.

Any sort of prevailing torque nut cannot maintain a significant portion of their initial preload. See: http://www.boltscience.com/pages/the-loosening-of-prevailing-torque-nuts.pdf
Furthermore, these nuts must be replaced with every use (or every few uses) to ensure proper performance. Metal locknuts can also damage the threads that they're spun onto, limiting the useful life of their associated fasteners.

Safety wire is more difficult to use than most other locking options and isn't strong enough to retain a significant amount of torque in the fastener. Put differently, there's no way a human is getting enough tension in the wire to support any appreciable torque in the fastener, and there's no way the wire would support that tension were it applied. And, frankly, if you've already put distorted nuts on there, the safety wire becomes redundant. I know that safety wire is used in practice, especially in the aerospace applications, but that doesn't make it the best solution for automotive applications.

Both lock nuts and safety wire are really 'loss prevention' solutions, not 'torque retention' solutions. They will do a good job of keeping the nut on the stud, but if any sort of motion occurs between the two parts being fastened then they won't hold the fastener preload very well, if at all.

It is worth noting that any locking technique isn't needed if relative motion between the two clamped parts never happens. Thus a vast majority of automotive fasteners need no locking in order to stay tight for an indefinite period of time.

Please don't take this as a personal attack, it's not. I would love to hear a sound technical argument as to why deformed nuts and safety wire would be the best solution, but lets skip the anecdotal evidence, there's plenty of that on both sides.
 

jlee

Lifer
Sep 12, 2001
48,513
221
106
I would strongly disagree with this statement.

Any sort of prevailing torque nut cannot maintain a significant portion of their initial preload. See: http://www.boltscience.com/pages/the-loosening-of-prevailing-torque-nuts.pdf
Furthermore, these nuts must be replaced with every use (or every few uses) to ensure proper performance. Metal locknuts can also damage the threads that they're spun onto, limiting the useful life of their associated fasteners.

Safety wire is more difficult to use than most other locking options and isn't strong enough to retain a significant amount of torque in the fastener. Put differently, there's no way a human is getting enough tension in the wire to support any appreciable torque in the fastener, and there's no way the wire would support that tension were it applied. And, frankly, if you've already put distorted nuts on there, the safety wire becomes redundant. I know that safety wire is used in practice, especially in the aerospace applications, but that doesn't make it the best solution for automotive applications.

Both lock nuts and safety wire are really 'loss prevention' solutions, not 'torque retention' solutions. They will do a good job of keeping the nut on the stud, but if any sort of motion occurs between the two parts being fastened then they won't hold the fastener preload very well, if at all.

It is worth noting that any locking technique isn't needed if relative motion between the two clamped parts never happens. Thus a vast majority of automotive fasteners need no locking in order to stay tight for an indefinite period of time.

Please don't take this as a personal attack, it's not. I would love to hear a sound technical argument as to why deformed nuts and safety wire would be the best solution, but lets skip the anecdotal evidence, there's plenty of that on both sides.

That's exactly what happened with the Stage 8 stuff. It did a great job of keeping the hardware there and if it was a bolt-through-sleeve application, it wouldn't have been as much of a problem. However, it was a clamping application, so...yeah.
 

BW86

Lifer
Jul 20, 2004
13,115
29
91
I've had success with a small dab of exhaust repair putty when the turbo flange to the manifold flange nuts kept backing off on me.

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