Is there an advantage to the 12pt 8mm bolts? I was thinking about replacing mine with some SS grade 8 bolts that I can get from a local harware store so it is easier to take apart if I need to in the future.

 

If they are not backing out of the housing there is no reason to disturb them...unless you are wanting to pull the turbo for recreational maintenance.

 

I will be adding a WW soon so that is why I would do it at the same time. I had to special order the 8mm 12 pt socket and woud rather replace the bolts when I have it apart, just didn't know what the reasoning for the 12pt bolts was. Would SS be ok to replace them with?

 

does anyone know the torque specs on the compressor housing bolts, (5) centersection bolts to turbine housing (4), and turbine outlet bolts (7 on wastegate, 3 on non wastegate)

so far i've found turbine outlet bolts torque spec to be 62 lb in.

and pedestal to turbo 18 ft. lbs.

 

A 5/16" 12pt socket will also work - that's what I have used with no problems. Personally - I think I'd just stick with the stock bolts. I've had mine apart a few times and had no problem getting the 12pt'ers loose - even on the exhaust side.

 

yes, i use a 5/16" 12 pt also.

5/16= .3125"
8mm= .3149"
there isnt much difference.

i have 7 new bolts from KCM Diesel perf. that i will be using for the centersection to turbine housing (4) and turbine outlet to EBPV delete flange (3) with red loctite.

 

Why didn't I know that last weekend when I had everything apart but then figured out I didn't have the 8mm 12pt socket, duh! and then put it all back together without installing the WW in the rain!!!!

 

This is what I received from Garrett:

> everything on the GTP38's and the TP38's torque to 200 inch pounds except
> for the comp. wheel it torques to 100 inch pounds. Let them know that they
> need to use loc-tite on the turbine housing, but never put loc-tite on the
> comp. wheel. I hope this helps :-)

 

wow, thanks man. so my Helm manual says 62 in-lbs? i would rather go with 200 in/lbs.


my torque wrench reads foot lbs, so 200/12= ~17 lb ft?

 

That's correct. 16.66666 to be exact.

However, I think mine are tighter than that. Given the troubles with them working loose and the fact that I was missing two of them on the exhaust housing, I wasn't taking chances. I didn't break a bolt, and that cast iron is pretty tough stuff, so I hope I'm ok. Mine were doused in hi-temp loctite too.

 

The 12-points are good for the bottom-front and rear bolts where you need the swivel extension on your ratchet...12-point has less probability of tilting to one side and stripping-off. ...IMO

 

I figured there was a reason why, I just didn't know what it was.

 

IMO what would be a great solution to this problem is some Torque To Yield bolts. Similar in theory to what is used on cylinder head bolts. That way they would have some "give and take" as the turbo heats up and cools down.

 

Never heard of the TTY bolts. Did some reasearch. Interesting theory. Would probably work well here.

 

Picture of a TTY cylinder head bolt for a 1990 VW GTI 16 valve.