water lines on GT turbo keep coming loose

[tekdeus]

My turbo is a custom billet GT35r that has the water lines excessively close to the T4 turbine housing. The banjo bolt in the pic below I had to have cut shorter, machined in a lathe, and have an allen bolt head welded on. This was the only way to install this bolt and tighten it on the turbo.

The problem is that it keeps coming loose, even after only 1 or 2 drives, it ends up loose and leaking coolant. I've tightened it so hard that now the allen bolt head has stripped. I think I will have to cut this allen head off, and source a hardened steel one to weld back on.

Just thought I'd ask you guys about the best solution for this. Is there a special hardened allen bolt head that is much longer/deeper? So that I can get more of the allen wrench in so it does not strip again?

Is there some locking part I can use? Tack weld it somehow?

Regarding threadlocker, is it advisable to use in such a hot area? I would like to be able to remove this bolt if I need to in the future, but I need to have it stay put as well.

All the fittings are just too tight like this:

 

[tissimo]

weld a 6-8mm nut to the fitting? Or just use straight -6 or whatever fittings. Its tight, but you can do it.

 

[gaboonviper85]

Looks like expansion and contraction issue...I don't think thread lock will work as heat will burn it after awhile.

I'd try to convert it to an AN fitting if possible...

 

[gaboonviper85]

Just thought of this....you'll probably bend or break an Allen wrench with this so if possible I'd try to find a banjo bolt with a twelve point head like arp...hell maybe arp makes bolts like this?! That should let you get the torque needed with a smaller head.

 

[supra90turbo]

safety wire it, sir.

 

[Enraged]

safety wire it somehow?

 

[Enraged]

wow. same posting time and everything. great minds think alike and fools seldom differ.

 

[CajunKenny]

Have the head of the Banjo Bolt (or similar) machined down. Still keeping all six sides, just make it smaller allowing enough room for a socket.

Unless you can source one that has a smaller head; but, the same shaft dimensions and thread type as the stock/original one.

 

[Poodles]

Guarantee you're not getting enough torque, and as threads don't hold all the stress over their entire length it's probably not getting enough preload.

You could also try torx bit head or just a normal 6 point bolt head in a smaller size head (already suggested)

Safety wire is also a good solution, but I still don't think you're getting it tight enough...

 

[adampecush]

Your problem is that you do not have enough thread engaged to maintain the preload on the bolt. A major component of maintaining the torque is the friction between the male and female threadforms - without enough engaged threads, you will not achieve this torque. If you continue to try torque the bolt higher and higher, the end result will be stripping of the threads.

 

[berniek]

Could be that the cooling line is vibrating and loosening the banjo. Safety wire it by drilling through the allen or hex head, and wire it with twisted ductile wire to something close and stationary. Make sure that the safety wire is positioned coming off the banjo bolt to keep it tight (wire coming off the banjo should be on the left if it goes upwards with a right-hand common thread. Should be on the right if wired to something downward of the banjo).

BernieK

Your problem is that you do not have enough thread engaged to maintain the preload on the bolt. A major component of maintaining the torque is the friction between the male and female threadforms - without enough engaged threads, you will not achieve this torque. If you continue to try torque the bolt higher and higher, the end result will be stripping of the threads.

 

[tekdeus]

Would a torx bit be stronger than an allen head of the same size?

Would I get much more preload by first freezing the fitting and washers with a can of duster sprayed upside down?

Unfortunately, there is just no room for any socket at all. Nothing other than the allen head and shortened bolt, unless I start to grind into the housing. How much could I safely grind off the housing?

In the pic below I installed the fitting first then installed the turbine housing, but then I couldn't tighten one of the turbine bolts...

 

[TurboStreetCar]

what does the manufacturer recommend? do they have a bolt kit for this turbo? they must be aware of this issue.

 

[adampecush]

You're either going to have to safety wire the bolt or figure out how to get more thread engagement.

Can you remove the cold side of the turbo and get at the bolt with a wrench? (I'm sure you've already thought of this, but I figured I'd state the obvious anyway)

 

[Enraged]

why use a banjo bolt at all? why not a straight fitting or adapter? carb adapters that straight threads and an extended AN fitting, something like this: http://summitracing.com/parts/AER-FBM2110/

 

[tekdeus]

Thanks for the help guys, I got it sorted.

I got the new piece back from the machine shop today. I used a larger allen head rated stronger than Grade 8. I left more threads on the end of it and had to grind away at the turbine housing to get it in. I think these bolts just need to be really F'ing tight to stay put, they are normally a 19mm bolt head. This one should work out better, I was able to get some serious torque on it.

Now you can see in the bottom pic how there was no hope in hell of getting the 19mm bolt head in here, let alone a socket or AN fitting! This company also offers a 1.00 turbine housing; imagine the clearance on that!

 

[IJ.]

Mine's a 1.52

.96ar left 1.52ar right

 

[Rennat]

Why not turn the fitting up instead of down? the housing gets bigger as it gets closer to the flange... and the coolant system is pressurized, so i wouldnt matter which way the coolant line is turned...

just an idea for the future...

 

[CajunKenny]

Cool beans Brad. Glad you got it sorted out!

 

[tekdeus]

Mine's a 1.52

Possibly the chubbiest turbine ever installed on a Supra!

Why not turn the fitting up instead of down? the housing gets bigger as it gets closer to the flange... and the coolant system is pressurized, so i wouldnt matter which way the coolant line is turned...
just an idea for the future...

Because of the oil drain. Wish it was that easy!