AD31 breather modification

[Viscount]

Some years ago, I had a modification fitted to one of my AD31s which removed the crankcase breather filter and the oil pressure release valve. It also changed the air filter and rear rocker cover to have a small tube between filter and rocker cover. It was done by Volvo under warranty due to oil blowing out release valve - no problems since. The other engine is now showing similar problems so I want to perform the modification to it as well. From memory and from examining the engine (as best I can given it is tucked away....), I think the after cooler needs removed to gain access to the securing bolts that hold the casting that has to be replaced (the present casting has the breather filter and release valve attached - the replacement casting is basically just a blanking plate).

Has anyone done this modification? If the after cooler does need removed, is it straight forward or are there any issues to look out for?

Any advice appreciated.

 

[Pendana]

Have not done the modification, but have removed the aftercooler. Probably best to remove the insert first which will take half of the weight away as they are in an awkward place at the back of the engine bay. Undo the pipe from the turbo unit and the bolts that fasten the aftercooler to the inlet manifold (later models also have bolt and bracket that the support the base of the aftercooler). Care should be taken on reinstallation that no tension stress is induced into the aftercooler which can result in a crack in the neck where it fastens to the inlet manifold. (which is why I took mine off, to have the crack welded up). Also don't overtighten the bolts that fasten it to the inlet manifold which can result in a cracked inlet manifold.

Apart from that, the aftercooler comes off and goes back on quite easlily!

Good luck
Eddie

 

[Viscount]

Thanks Eddie,

The "insert" you refer to - is that accessed by removing the domed nuts on the top of the unit?

How do the cooling water pipes disconnect? On mine, they just seem to disappear inside the unit but I don't see any securing clips.

Thanks again. Tom.

 

[Pendana]

Yes, the domed nuts secure the top of the unit that is made of plastic and the cooling hoses are usually held in place with jubilee clips. You'll need 2 new gaskets on replacing the insert and strictly speaking, once rebuilt, you should do an air test via the inlet and outlet cooling connections to check the integrity of the insert.

Hope it all makes sense!

Eddie

 

[Viscount]

Thanks again.

In my case, the cooling hoses are not rubber hoses but solid metal pipes. Maybe I will see how they attach if I remove the top cover and insert?

Tom.

 

[Pendana]

Oh, Ive only ever seen rubber hoses and jubillee clips like this
http://www.marinepartseurope.com/en/volvo-penta-explodedview-7746610-26-910.aspx

Could yours be held in place by a similar method to what HLB describes in his "bloody o rings" thread

Good luck

Eddie

 

[Viscount]

Thanks; I'll take a look once the temperature gets above zero.....