Potential Drama

Today I started playing with the cooling system in my boat, on the AQ130 Volvo motor which is a B20 at the front of the head under the thermostat housing block is my issue, when I put water into the system it started pissing water out the bottom of the housing block, I had a look under there and here is a big hole I thought something must have been there as there was one bolt there and that was it so I did some scraping and found a broken bolt stub in the block so obviously this was the block off plate fitted during the marinising as I think the water pump in a car feeds into this hole, Im guessing no easy fix here the head has to come off ?, this will annoy me but I have a spare head on a car that wont have the corrosion issues, not even going to try and fix the busted bolt Ill just scrap the head, now I definitely want to strip the oil cooler and flush the engine out, lot of white crusty rubbish coming out of the pipes and the outlet pipe on the water pump was restricted with the same rubbish, so not going to rush things with this Ill methodically strip the lot and make sure its up to scratch

May have a fix for this that doesn't require head removal, it wouldn't be under pressure as such so Ill make a new plate up to fit where the original fitting was, Ill make another bracket up so I can run it up the front of the block to the thermostat housing and use one of the bolts up there to secure it, it will be an adjustable bracket so I can tension the front where the broken stud is, so with plenty of sealent under the plate should be all good

Likely this is a seawater run engine. The white crusty stuff is mineral deposits (mostly salt) that precipitated out when the water temp got over 150 ish, i.e., hot soak after turn off and/ or a previous issue with the raw water pump/water flow. Fortunately, these deposits are soluble in white vinegar.

Take a look at these pictures and try to describe the hole you're talking about a little better. Most of the bolt holes you see are empty and they would not be the source of the leak. There is a small brass tube going from the bottom of the thermostat housing to the head. This one requires a square o-ring. Look closely to see if that is the source of the leak or the housing o-ring itself.

Ok joe the first pic, the front of the thermostat housing which has the flat brass welsh (freeze) plugs, its directly under this casting , maybe a true penta head may not have this hole I speak off may only be the car heads, only thing that says Volvo penta on my motor is the exhaust manifold, I mentioned in another post the big heavy pipe under the engine that ran back to the exhaust outlet? well I dropped this pipe off and its been made from copper tube most of the white crunchy gunk was in this tube, yes it is a sea water fed cooling system, this hole I speak of is maybe half inch in diameter its a fair size, lying on my back looking directly under the thermostat housing area u cant miss it, theres 3 holes, 2 would be what secures the block off plate the 3 hole I think is covered by the plate too, Ill try and photo the hole tomorrow.

My engine doesn't have the cam driven water pump, my water pump is separate to the motor, its mounted to the engine and is driven of the lower balancer pulley, sorry if the aussie diction is different to what you might call something,

Here is the pic of the hole I mentioned this photo was taken lying on my back looking up under the thermostat housing

Looking at the pic on the lower left corner is the broken bolt, the hole to the right of the big hole I think is a water bypass for use with the auto mechanical pump, looking at the big hole I reckon I can get away with fitting a freeze plug there is enough thikness inside to support it, the bolt hole I can just put the old bolt back in and the bypass hole I can turn up a blocking plug out of brass stock to plug that so hopefully an easy fix

Man that is one ugly pic. Im no expert at all but i think i would change the part unless you can clean it up alot better then it looks now.

Oh yeah its a job for the dremel tool alright, Ill clean it all up I dislike corrosion

This is the remote water pump on my engine its on the lower left side of this picture

This pic just shows the water cooled exhaust manifold and the cooler, a question about the cooler I assume to remove the cooler of the engine once the filter is removed the thread for the filter has a nut on it which I just unscrew and the adaptor cooler will come off?

The caps either end of the cooler can the O seals on these be replaced with ordinary Orings?

I'll try to get a look at mine in the next few days to check on the underside of the thermostat housing area. You're right about the oil cooler. Large nut attaches it to the block. Those o-rings are available as a kit but can be purchased separately. If you're going to the trouble of removing and disassembling the cooler, would be a good idea to take it to a radiator shop and have then pressure test it for you. I had one done a few years go and it only cost $20.

There was a tiny bit of black oil inside the cooler so good its coming off