Missing petcocks on Volvo?

[njlarry]

My 1996 Volvo 5.0 FL does not have drainage petcocks on the exhaust manifolds. Instead there are rubber caps held on with hose clamps. Is this right? Is there a way of adding a proper petcock? When I removed them for winterization they were already torn under the clamps and they don't look very practical.
Now I have to leave the system open as I'm not likely to get new caps in time before the temps drop.

 

[Don S]

Re: Missing petcocks on Volvo?

They NEVER had petcocks in the ends of the manfolds, For a while Volvo used the rubber caps like OMC had.for years. Volvo finally changed that to pipe plugs in the Chevy engines, and they dropped the Ford engines completely in either 97 or 98.
If the caps are bad, replace them. Not sure if the replacement manifolds have brass plugs or not. And don't worry about the caps being off for the winter. Water freezes, expands and breaks things, air doesn't.

 

[lilmandavis]

Re: Missing petcocks on Volvo?

I'm surprised at the fact they didnt cast a port and starboard manifold. That would be more money for the boat parts people right?!! Kinda like reverse rotation. $$$ .)

 

[Doug Russell Marine]

Re: Missing petcocks on Volvo?

On another note for those of you that do have petcocks or drain plugs located in your manifolds; be sure to stick a screw driver or something "pointy" up inside. In some cases rust will plug up the hole and when you think the manifold is dry, water just can't get out. Moving a screw driver or something around will losen up anthing that may be blocking the hole, ensuring it drains completely.

 

[njlarry]

Re: Missing petcocks on Volvo?

Thank you all for your advice. If I understand what you are saying correctly, the right and left manifolds are made from the same castings so the caps cover the unused inlets. When I did remove them about 14 oz of water mixed with lit bits of rubber came out of each, so I can see having to replace the caps every couple of years. Glad I read a post here about not trusting the antifreeze through the muffs method. Even after a 20 minute warm up the thermostat appears not to have opened as I also got clear water from the engine drain petcocks after pumping three gallons of antifreeze through.

 

[Don S]

Re: Missing petcocks on Volvo?

about 14 oz of water mixed with lit bits of rubber came out of each

If you had little pieces of rubber, then you have had an impeller failure. Or the previous owner did. And the lost pieces were never found or accounted for. This can cause overheats if big enough pieces get in the wrong places.
If you don't have a service manual (oem, not aftermarket) and you really don't understand how a marine cooling system works. Then you better have enough money to replace engines, manifolds, risers, and a lot of very expensive parts.