Fastener Help Needed

Post by **SuperHerman** » 03 Aug 2018, 10:20

: V70Exhaust.JPG (31.16 KiB) Viewed 1487 times

I searched online under 2001 V70 2.4T and this is what the part diagram shows. I believe someone changed your studs/nuts to bolts and that is your problem. We are talking about #4 and #6 in the diagram. Even #2 and #3 are stud/bolts.

01_Nautic_V70 · Post by **01_Nautic_V70** » 03 Aug 2018, 10:27

What locks the studs in more securely than bolts?

Post by **oragex** » 03 Aug 2018, 10:49

The thing with the original studs is they are pressed in (they press in as the nut is tightened down) which keeps the stud from turning when the nut is tightened so they don't have to put two hands in there while tightening.

01_Nautic_V70 · Post by **01_Nautic_V70** » 03 Aug 2018, 10:50

Ok, then I’m going to have to improvise here. I have new bolts and split lock washers in hand.

Post by **SuperHerman** » 03 Aug 2018, 10:54

I did a search on your questions and there are theories galore. Ranging from easier to superior.

What makes the most sense based on my readings is that the stud is tightened until it bottoms out b/c of no more threads then the bolt is used for the clamping force so only the bolt takes the twisting and related forces. As the bolt is pinched it doesn't want to readily come out. Not sure what the correct answer is, but you have a problem and the best solution may be to copy the original set up.

From what I see your studs should be 8mmx40mmx1.25. Buy the studs at the dealer would be the for sure solution. If not, I don't think longer would be an issue, but you will have to judge this when you see what is readily available. Restricting parameters is the ability to get the thread to bottom out on the exhaust manifold while being inserted far enough and have the non-thread portion not be so thick that the bolt cannot exert clamping forces and the ability to get the nut on. For the nut the proper size was listed before - just look for one that is pinched. From what I have read don't use stainless steel.

Post by **amblerman** » 03 Aug 2018, 11:18

I too started researching this (as I was waiting for some long processes to run at work).

I wanted to know "why stud vs bolts" in general. Another aspect of what I read is that studs are sometimes used during assembly for alignment purposes. That applied when your engine was put together in the first place but doesn't apply in your circumstance.

Another thing to think about here is that studs are supposedly used in places where disassembly can be done without having to remove the threads from the object. At least one theory about this is that frequent removal of the stud/bolt could weaken/damage the internal threads of the softer material (aluminum in this case).

I mention this in case your internal threads have been damaged and that is why your bolts are coming loose.

-A

01_Nautic_V70 · Post by **01_Nautic_V70** » 03 Aug 2018, 12:14

This is a cast iron to cast iron application. As I need this back together ASAP I used carbon steel M8x1.25 bolts and split lock washers.

Two of four were gone completely. Two were finger loose. One was original stud so I tightened the nut back up. This has obviously been worked on at some point. I’ll order something more permanent to put in at the next oil change.

At least now I can drive to the airport without sounding like a V1 buzz bomb. So that’s a plus.

Total cost $5.62 and 1 hour of my install time which is apparently worthless.

Post by **oragex** » 03 Aug 2018, 13:37

This is what I've used here in Canada (but should be available else where as well). These were advertised as exhaust bolts. I like them because they are easy to undo later on and can take the heat pretty well. Not sure how good they are with the vibrations and heat near the turbo, though. From the local hardware store.

01_Nautic_V70 · Post by **01_Nautic_V70** » 03 Aug 2018, 13:58

Thanks oragex. I used very similar but with a zinc plate rather than the black oxide you have. I’ll try to find the real deal to put in the next time I have Inga (the V70) up on jack stands. She just got oil changed, tires rotated, new brake pads all around and new rear rotors this week before the exhaust leak.

Always in need of something it seems.

Post by **SuperHerman** » 03 Aug 2018, 16:40

Dorman has a "Help Exhaust Stud Kit" M8-1.25mmx38mm for 3.99 (Advanced Auto) which includes two studs and two bolts. Part #3109. May fit your needs, but check the length to make sure it works.