This can't work surely? - engine installation

[Steve_N]

This can\'t work surely? - engine installation

My current project is the refit of a 20yr old Countess 37 fitted with a Volvo MD21B. Although the budget would allow for re-engineing, obviously I'd rather not if I don't have to and in fact the beast tests OK and runs well.

However, thanks to the relatively flat shaft angle and the down-angle reverse gear, the engine sits 'down by the head' by a few degrees i.e. the front end of the engine (on which sit water pump, thermostat housing, expansion tank etc.) is perhaps 2cm lower than the rear end. Although I never considered it before I think this is a problem: certainly when changing coolant ready for the winter, I couldn't get in as much as I drained out! I reckon that air remains trapped in the head due to the down angle..?

Now I can unbolt mountings and coupling and lift the front of the engine to fill it - but surely any air 'bubble' will just reform during normal running from air bubbles in the coolant..? However, it has survived 20 years to date like this.

Any thoughts?
Thanks, Steve

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[roger]

Re: This can\'t work surely? - engine installation

It'd be simpler to hold a party on the stern - heavyweights only!

<hr width=100% size=1>Roger

 

[boatless]

Re: This can\'t work surely? - engine installation

Oh now that's really helpful isn't it.

I was going to ask if he could just keep it up on the plane - but refrained.

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[cliff]

Re: This can\'t work surely? - engine installation

Fill the exchanger then run the engine. This should clear the "bubble" then top up the coolant.

If you have a calofier this will probably be tapped off the top of the cylinder head or on a pipe between the head and the stat housing with the return to the block. You are more likely to have an air lock there than in the head.

"If it ain't broke, don't fix it"

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[Steve_N]

Re: This can\'t work surely? - engine installation

Thanks. I filled the system via the header tank and ran the engine (tentatively!): steady temperature and good flow through the heat exchanger and calorifier, everything uniformally warm. Yet the coolant level didn't drop - no top-up was needed. There was flow in/out of the header tank (I added some neat a/freeze and checked the specific gravity later and it had been diluted).

I wish now that I'd measured the quantity of old coolant more precisely, but I'm pretty sure I need to squeeze about 1 litre more in somehow..

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[graham]

Re: This can\'t work surely? - engine installation

run it for a few minutes to push the air out then see if you can get anymore in.

Do you have any contact with the previous owner to find out what he did?

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[Steve_N]

Re: This can\'t work surely? - engine installation

The previous owner wasn't at all hands on - the engine was professionally maintained in Greece, Spain and Portugal.

There was a dirty old second header tank in the engine compartment: mounted a full 18" above the engine and with a valve in it's hose, but not connected to anything. So it seems that perhaps the problem has been encountered before, and that that was some part of the solution..


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[boatless]

Re: This can\'t work surely? - engine installation

I had a car in which it was neccessary to raise the head of water in order to fill the heater matrix. To do it I used a plastic bottle jammed in the filler hole (bottom cut off bottle).

But, this had a bleed screw. Once filled it stayed filled. So, raising the head of water won't help unless you can bleed it.

Just wondered if they had tried to achieve something similar with that extra tank? And is there anywhere you could bleed it at the back?

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[Steve_N]

Re: This can\'t work surely? - engine installation

Yes I had that in mind too as my old Peugeot 306 was like that: needed an old antifreeze bottle inverted in the top of the radiator to raise the level (and the MD21B is a Peugeot engine after all..). So I was pleased to find that the standard header tank is comfortably the highest point in the system. I can't find any bleed orifice at the rear of the engine, and as you say, trying to push coolant in under pressure would be pointless without bleeding.

I'm beginning to think that changing the engine angle is the best solution: perhaps an Aquadrive would be a good permanent solution as that would solve other problems such as the stupidly long propshaft too.

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[boatless]

Re: This can\'t work surely? - engine installation

Citroen ZX - same car!

Perplexing, no hose connections off the head that you could break to bleed? Can't remember the engine although I've probably used one..

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[Steve_N]

Re: This can\'t work surely? - engine installation

No nothing at all to take off at the rear - all the action takes place at the front of the engine.

Ah well, thanks anyway. She's laid up now so at some point I'll probably raise the front of the engine just to see what gives. Of course those would be the mounting bolts that are currently well rusted up..

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[robind]

Re: This can\'t work surely? - engine installation

Dont most Volvos have a bleed screw at various points around an engine they certainly do have on my 6 cylinder ones you crack them open with the engine running in tick over until they exude all the air and then top the engine up. might be worth a look in the manual or a word with other owners of similar engine! how about www.boatdiesel.com
Regards
Rob

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[Guest]

But why not change \'boat\' angle ?

If the angle of engine is only a slight dip forward ..... why not raise the bow of the boat ?

Surely once water / coolant is in engine OK - when it is back to normal level - engine will be OK and continue.

If boat is in water when doing this ..... a few items moved aft to dip the stern will give enough to raise the front of engine ....

Why make hassle for yourself ?? when a few kgs / blocks will do it ?


<hr width=100% size=1>Cheers Nigel http://groups.yahoo.com/group/gps-navigator/ http://groups.yahoo.com/group/searider/

 

[Steve_N]

Re: This can\'t work surely? - engine installation

There are certainly no visible bleed points - nothing mentioned in the service manual either other than 'refill cooling system'. There is a permanent bleed, via a rubber hose. from the top of the thermostat housing to the expansion tank which would suffice were the engine at the usual angle..

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[Steve_N]

Re: But why not change \'boat\' angle ?

She's ashore so that would require a costly lift unfortunately - cheaper to wield the spanners.

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[Col]

Re: But why not change \'boat\' angle ?

Try running up to operating temp until thermostat opens, then run at high rpm for a couple of mins. You will probably find that any air lock will be moved by the shear speed of the water around the block. Worth trying before you start hitting the credit card, and as you say-"Worked OK for 20 years like this"

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