240 General: Leaking exhaust manifold gasket

[Scott Stephen]

Just about all my Volvo's with Bxxx engines have needed this done. Very straight forward to replace and I haven't snapped a stud yet!!!

1. The night before the job heavily soak your studs/nuts with WD40

2. Next day, start the car and let everything heat up for a while.

3. As soon as it is safe do so (without burning yourself!!) carefully remove the nuts (Dont worry if a stud comes out with one)

4. Pull the exhaust manifold clear of the studs, recover old gaskets, clean manifold to head flanges.

5. Put on new gaskets (Shiny side out, or is it the other way...cant remember anyhow you'll know with the old ones!!!)

6. Place manifold back on and torque nuts

N/A engines are easy to do, Turbos can be a pain as when I did my 940 turbo I had to disconnect oil lines and a bracket from the turbo to allow sufficient clearance of the manifold.

[jacksonb123]

I've had my exhaust problem looked at by the local garage and they say that I have a rotten/corroded exhaust manifold flange which I think is the bit that attaches the manifold to the next section of the exhaust, rather than the manifold gasket which I initially thought.

They said that due to lots of corroded nuts/bolts that they don't want to undo it as it is as that will cause more damage and have recommeneded that I locate a spare manifold & flange from a scrappy or some place else and they will then fit it for me.

Firstly, does this sound sensible or should I take it to an exhaust specialist who I'd imagine may be able to sort this out on site(could be wrong here tho).

Or, if the scrapyard manifold flange plan is the way to go can anyone recommend a Volvo breakers where I might get hold of one. GSF in Coventry have mentioned CP Motors in Polesworth/Tamworth so I'll give them a try tomorrow.

Any other sources/recommendations welcome.

Regards

Ben

[Mike_Brace]

These manifolds are prone to corroding and what they are saying sounds very possible. Effectively the bit of the manifold that should fit flushly to the engine has corroded away causing a blow. It might be possible to seal with exhaust sealant, but I doubt if it will last. A good s/h manifold would sort it. BTW new ones are still available from Volvo.

Mike

[Clifford Pope]

Just be aware that despite others' experiences, it is possible to snap a stud. Extracting that can turn a minor problem into a major one, because if it happens to be at the back it is nearly impossible to get access to drill it out.
I'm in exactly that dilema myself. Do I risk it trying to get all the nuts/studs out, or leave well alone as it isn't actually leaking yet?

I'm thinking I might do all the soaking bit, and then try very cautiously moving the nuts, starting at the back. Once I'm sure the nut is free, I'd tighten it up again and try the next one. Once they are all loose, then in safety remove the manifold. Even if you break one it's not going to leak by itself, unless you have already got the manifold off.

[Clifford Pope]

I have just successfully done as I outlined, and managed to get every nut off in turn and replaced with a fresh one. So now it is all ready for swapping for a better manifold, without fear of getting caught mid-job with a broken stud.

I think only the later engines use those horrible Volvo nuts with combined washers all in one. When they rust up they lock solid, and totally seal any access for penetrating fluid. Mine were so heavily corroded away as to be largely unrecognisable as nuts. I managed to file two reasonable flats, extanding into the washer part. Then with a frequently resharpened long cold chisel I managed to break the seam at the nut/maniflold joint, just enough to get some fluid in. I applied the blows at a slight angle, so as to shock the nut in the right direction. Then I used a blow torch and applied more fluid.

I found a Gator socket invaluable. After the first tiny movement I applied more fluid, and tightened it up again. By alternately loosening and tightening I gradually managed to increase the range of free movement, until it would turn freely enough that I was confident of not breaking the stud. With one "nut" off, I replaced it with a new nut and ordinary washer using copperease, and tightened reasonably.
Now all 8 are free.

Incidentally Gator sockets work well, but have a short life. After doing three exhaust manifolds mine is wrecked. The hardened pins fall out, and something is twisted up inside so the pins don't all pop out properly.