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Exhaust manifold to downpipe torque specs

SlickNerd

SlickNerd

Active member
Joined
Dec 2, 2010
Location
In the Great Lakes State yall
So what are the torque specs for the downpipe to the exhaust manifold? Not looking for torque specs of the mainfold to the head. I already know those. I'm tired of going through exhaust gaskets because the nuts shook loose and burned away the gasket. And I don't want to run the risk of breaking the 3 studs by smashing the wrench for a tight fit. Engine is a '90 b230f.

Thanks everyone!
 
what John said.
in addition also make sure the bracket between downpipe(s) and bellhousing is still there and attached. If it's missing the weight of the exhaust will be cranking on those manifold bolts in every corner the car takes since the aft of the exhaust is mounted in position to the body while the engine is slightly twisting on it's mounts while cornering and while getting on and off the gas.
it's also a good idea to check the engine mounts. If they are shot they will cause excessive twisting of the engine.
 
The mounts are about 2 years old. Diesel right(passenger side) and turbo left(driver side). The bracket between downpipe and trans have been gone on all cars, but found it interesting that it keeps happening to this car in particular and never the others.

Final thoughts on the specs? I shall try to torque the 3 nuts to 40 lbs if someone else can confirm.
 
SlickNerd said:
The mounts are about 2 years old. Diesel right(passenger side) and turbo left(driver side). The bracket between downpipe and trans have been gone on all cars, but found it interesting that it keeps happening to this car in particular and never the others.

Final thoughts on the specs? I shall try to torque the 3 nuts to 40 lbs if someone else can confirm.
Click to expand...

What size are they?
 
M10x 1.5. I don't torque them down all the way, just get them as tight as you can with a breaker bar. Those have a tendency to seize. Also use a good gasket, not a cheapo.
 
Also upgrade to the smaller 14 mm hex head copper nut. It makes it easier to remove next time. It's so much easier on a 240 as the pipes have narrow opening to slide your extension through. It's more of a pita on 7/9 cars.
 
:nod:

ExhaustNut977211.jpg
 
I have those win 1.25 pitch with nord locks. haven't had the turbo come loose since putting em in.
 
Harlard said:
I have those win 1.25 pitch with nord locks. haven't had the turbo come loose since putting em in.
Click to expand...


Well finer thread means it'll tolerate higher torque...
Look at the Merikuhn equivalent of M8 x 1.25: 5/16 UNC
Like a M8 the torque is around 17-19 ft/lbs

Now look at a 5/16 UNF...well well whaddya know...28 ft/lbs

Now the only limitation ain't the bolt, its the threads in the material..
Not a bigger for nut and bolt but you don't want fine threads in soft material like aluminum or magnesium...the material fails.

Maybe one day the Moderatistas can make a sticky of all the common bolt sizes on Volvos and sticky it and add a flashing icon TORQUE SPECs
And a simple table M6 x 1, M8 x 1.25, M10 x 1.5, M12 x 1.75, M14 x 2
And for the poor bastids with the inch cars pre-whaddEVAR the common inch sizes

One day.. maybe 10 or 15 years from now..(don't want to rush into things!)
 
Would definitely be nice to have a quick reference guide. And yes, the fine thread pitch was picked to make the damn thing more difficult to vibrate loose.
 
Harlard said:
I have those win 1.25 pitch with nord locks. haven't had the turbo come loose since putting em in.
Click to expand...


Well finer thread means it'll tolerate higher torque...
Look at the Merikuhn equivalent of M8 x 1.25: 5/16 UNC
Like a M8 the torque is around 17-19 ft/lbs

Now look at a 5/16 UNF...well well whaddya know...28 ft/lbs

Now the only limitation ain't the bolt, its the threads in the material..
Not a bigger for nut and bolt but you don't want fine threads in soft material like aluminum or magnesium...the material fails.

Maybe one day the Moderatistas can make a sticky of all the common bolt sizes on Volvos and sticky it and add a flashing icon TORQUE SPECs
And a simple table M6 x 1, M8 x 1.25, M10 x 1.5, M12 x 1.75, M14 x 2
And for the poor bastids with the inch cars pre-whaddEVAR the common inch sizes

One day.. maybe 10 or 15 years from now..(don't want to rush into things!)
 
Wait..... so am I torquing the 15mm M10x1.5 to 28ft lbs or so or tu o around 40-43ft lbs? M10x1.5 is the correct pitch, right? Before getting my hands on the 15mm flared nuts again I was using stainless 17mm unflared with and without split washers. But after losing the washers, said eff it and just skipped the washers. But like I said earlier I have the og flared 15mm nuts.
 
fastener for bellhousing bracket to downpipe

Can anyone provide the details on the fastener from the bellhousing bracket to the downpipe (and by details I mean what fastener is it, size, length, washer? nut?)? I've replaced my whole post-manifold exhaust, studs, nuts etc. but it's hanging without that fastener (the car hasn't had one since I got it) and I'd like to get this corrected. It looks like a single bolt through the bracket into the downpipe's mounting plate, and I don't see a captive nut so I'm not sure whether I'm supposed to thread a bolt into the plate or somehow cram a nut in the tiny space between the plate and the twin tubes. Here's the downpipe I got: https://www.rockauto.com/en/moreinfo.php?pk=1081274&cc=1287985&jsn=10. If it makes a difference, the car is a 1987 240 wagon, NA. TIA.

Janspeed said:
what John said.
in addition also make sure the bracket between downpipe(s) and bellhousing is still there and attached. If it's missing the weight of the exhaust will be cranking on those manifold bolts in every corner the car takes since the aft of the exhaust is mounted in position to the body while the engine is slightly twisting on it's mounts while cornering and while getting on and off the gas.
it's also a good idea to check the engine mounts. If they are shot they will cause excessive twisting of the engine.
Click to expand...
 
Last edited:
petergibbons said:
Can anyone provide the details on the fastener from the bellhousing bracket to the downpipe (and by details I mean what fastener is it, size, length, washer? nut?)?
Click to expand...

Not sure about the 2 series, but the 7/9 uses a double ended stud with a Hex in the middle. Fixes (German for "attaches") the AW or bellhousing to the redblock, and the aft facing stud (which could be M10 or M12, been too long) is one size smaller than what is used to bolt the engine/trans together. Your downpipe strap hangs on this stud..... on the 7/9's.
 
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