Volvo MD2B help needed Please.

[mickey1]

We have a MD2B and she blew head gasket, we changed it and popped in a new one and tightened it to 105, ran it for short time, while back cylinder piping hot, front cylinder cool.
The thermosat, removed is that normal proceeder is it normal for raw water cooled engine and what please is the proper torque for MD2B.?

 

[Searush]

Those engines are fairly elderly now & the raw water passageways in the block are sometimes blocked by limescale & similar deposits from the hot sea water. It is possible that there is a good flow across the front of the engine, but little circulation is reaching the aft end.

 

[VicS]

Trouble with these old VPs is that you can get severely restricted water flow to one cylinder while the other remains OK.

The incoming cooling water is distributed to the cylinder heads via smallish passages in the exhaust manifold. these become blocked. The one to the rear head is longer and is therefore the more vulnerable.

The cylinder blocks get choked up as well.

Also possible to block the flow of coolant to the block by putting the head gasket on upside down IIRC.

In your case I'd go for the passages in the exhaust manifold.

If when that is sorted if the temperature gauge fluctuates continuously it indicates blocked water ways in the blocks (or incorrectly fitted gasket)

You should not run without a thermostat. Several reasons. Efficiency; cold engine allows condensation in the oil and rocker covers .... can lead to rusting, cracking and failure of valve springs; hot pistons and cold cylinders means the clearances will be tight and therefore a risk of seizure.

 

[VicS]

[ QUOTE ]
and what please is the proper torque for MD2B.?

[/ QUOTE ] See workshop manual
http://www.bluemoment.com/manuals/MD1B-2B-3B_Workshop.pdf
for torques and correct sequence

 

[mickey1]

Thankyou Il pass that info on. /forums/images/graemlins/ooo.gif

 

[Bilgediver]

Must add a little to Vics answer....I think he had a Senior moment.

On the MD2b the head gasket can go either way up however some are better if the right way up but nothing to do with water ports. More to do with those wee beeds of silicone.

It is the exhaust head to manifold joints which must be the right way round .

As Vic said the blocks silt up with crud and this must be removed. SOmetimes you can get a lot out by opening the drain cocks while running. You may have to completely screw out the insert and poke wire in to clear them.

If you remove the heads then ensure that the small drilled port is clear on the manifold side of the head on the bore centreline This looks like a cored depression which fills with sludge however there is a small hole at the bottom which if blocked stops circulation in the block. The cooling becomes erratic the temperature gauge pulsates and steam comes out the exhaust. The engine should run with a thermostat.

DO NOT drill out the hole behind the lower small port in the thermostat housing unless the engine has and intercooler for FW cooling. Ensure the nipple feeding bypass water to the bottom of the thermostat housing is not blocked with bits of impeller.

If the thermostat is not drilled with a 3/32 hole to allow a small constant flow through the engine I suggest drilling one. Make sure the thermostat is fitted the right way round as some could be fitted with the element in the discharge housing.

The element goes in the manifold.

The latest head gaskets are totally intolerant to deformed blocks and unfortunately the MD2 series will over time cause the top surface of the bore to head joint to wave with the lowest points being in line with the centre of the crescent water ports. You will see dark shadows from gas blow by. At this stage consider truing up the blocks and heads or be prepared to change the head joints regularly.

 

[VicS]

[ QUOTE ]
On the MD2b the head gasket can go either way up however some are better if the right way up but nothing to do with water ports

[/ QUOTE ] Perhaps you are right. Just have some recollection that we may have fitted head gaskets incorrectly (to a MD11C) and in such a way that one of the water passages between block and head was blocked off. Distant and rather dim past. May not even be the same on the MD2B

Maybe it was the drilled port you go on to mention that was part of our troubles. I don't remember it!

Manifold gaskets are pretty obvious. I reckon you'd need more than a senior moment to fit one of those wrongly.

Do remember trying to unblock the non existent hole below the thermostat to connect with that one in the thermostat cover! Actually that's the water inlet to the manifold on the single cylinder engines I believe.