help with coolant pressure relief info, header tanks/filler necks etc- volvo MD2030.

[TactilePaul]

Hi, we have a failed filler neck (again) requiring new exchanger casing this time, we have had the copper rods banging against the casing also damaging them, so killing 2 birds really,. for £2k!, I am looking into modifying the connections to the expansion vessel, they currently go through a modified filler cap that clearly is putting too much stress on the filler neck.
Question is, can i simply engineer a manifold with 2 connections for the vessel (feed and vent) and omit the pressure relief function?, ( not entirely sure there is a spring in there?, I just never want to touch it, 'cause its the achilies heel of this engine!!) I am pretty sure there is one on the expansion vessel lid? I could easily add a pressure relief valve as well.


I think we are going to simply have what engine was designed to have in the short term once replaced - just a radiator cap and no hoses/ expansion vessel / cylinder circuit!!!, but we will want a shower at sea again one day!! don't know what will happen to the cylinder flow and return from the water pump, I guess they either blanked or joined?

any help hugely welcome

Thanks.

https://forums.ybw.com/attachments/img_8911-jpg.158335/

 

[rogerthebodger]

On my current boat I had a heat exchanger with a pressure release cap like ond type cars.

I obtained a expansion tank from a newer mini and simply connected a pipe from the heat exchanger cap to the expansion tank and replaced the heat exchanger cap with a non pressure release cap and fitted the pressure cap on to the expansion tank

The expansion of the water in the heat exchanger would expant into the expansion tank and when the water in th heat exchanger cooled down the water would flow back into the heat exchanger.

If the expansion tank got full the water would escape out of the pressure cap on the expansion tank into a collection bottle.

My old heat exchanger neck was broken when I got the heat exchanger I got a replacement nect that has a 1 1/4 inch BSP thread I tapped the new neck in to thee top of the heat exchanger and sealed it with Loctite all of 10 years later

 

[Tranona]

Why do you have that arrangement with an expansion tank? That is not standard 2030 fit.

 

[TactilePaul]

Why do you have that arrangement with an expansion tank? That is not standard 2030 fit.

just the way it came, ive seen it before for sure, can you tell me how it should be with an expansion vessel and cylinder on a higher level.?

 

[TactilePaul]

On my current boat I had a heat exchanger with a pressure release cap like ond type cars.

I obtained a expansion tank from a newer mini and simply connected a pipe from the heat exchanger cap to the expansion tank and replaced the heat exchanger cap with a non pressure release cap and fitted the pressure cap on to the expansion tank

The expansion of the water in the heat exchanger would expant into the expansion tank and when the water in th heat exchanger cooled down the water would flow back into the heat exchanger.

If the expansion tank got full the water would escape out of the pressure cap on the expansion tank into a collection bottle.

My old heat exchanger neck was broken when I got the heat exchanger I got a replacement nect that has a 1 1/4 inch BSP thread I tapped the new neck in to thee top of the heat exchanger and sealed it with Loctite all of 10 years later

thanks, yes sounds like your on the same page!, ours has 2 pipes, one for bleeding air i guess, but just like on a home cistern, i'm sure that one would do it, and your confirnming this, I think that all expansion bottle caps have the pressure releif lid?, so yes, going to look at some proper threads and manifolds and get rid of the awful filler neck, made in a different metal and glued to the engine!!

 

[TactilePaul]

thanks, yes sounds like your on the same page!, ours has 2 pipes, one for bleeding air i guess, but just like on a home cistern, i'm sure that one would do it, and your confirnming this, I think that all expansion bottle caps have the pressure releif lid?, so yes, going to look at some proper threads and manifolds and get rid of the awful filler neck, made in a different metal and glued to the engine!!

i'm wondering if we can tee the expansion bottle into the flow or return to cylinder?, then the cap would simply need a manual air vent, probably not even that as we could vent by opening slightly till green juice showed!

 

[rogerthebodger]

An advantage to the use of an expansion tank is that it eliminates almost all air bubbles from the cooling system. Coolant without bubbles absorbs heat better. Although the coolant level in the expansion tank goes up and down, the radiator and cooling system are kept full. This results in maximum cooling efficiency.

The pressure cap is just to seal the top of the radiator. The expansion tank has a pressure release cap with a pipe to allow any exces water to escape either into the bulge or as I have collection bottle.

Th radiator is just like the heat exchanger

With this arrangement there should be no need for a sperate blead pipe it could also go to the expansion tank for auto bleeding

 

[Tranona]

just the way it came, ive seen it before for sure, can you tell me how it should be with an expansion vessel and cylinder on a higher level.?

i had a 2030 for 15 years and 3500 hours in a Bavaria without an expansion tank. What boat is it in?

I had a look through the Volvo parts list and can't find an OE fitting like that. Just a plain cap and no expansion tank. Also googled MD2030 images and every one shows just a plain cap. Suspect your add on is solving a problem that may not exist - and giving you grief!

 

[ithet]

My MD2030D was fitted with no expansion tank, just an overflow hose into the bulge from the hose fitting in the neck to the filler cap. I think that is normal arrangement.
Not liking the occasional antifreeze in bilge I fitted a plastic water bottle loosely over the end the tube. This arrangement seems perfectly adequate. My calorifier is fed from hoses that do not come off the radiator cap.

 

[penfold]

Chromedome identified this; I've seen similar set ups on a few VP installations, never liked the look of it.

i had a 2030 for 15 years and 3500 hours in a Bavaria without an expansion tank. What boat is it in?

I had a look through the Volvo parts list and can't find an OE fitting like that. Just a plain cap and no expansion tank. Also googled MD2030 images and every one shows just a plain cap. Suspect your add on is solving a problem that may not exist - and giving you grief!

 

[penfold]

The whole thing is a bit of a bodge but I'm not seeing a reason to buy a new heat exchanger if the only problem is a detached filler neck and a damaged tube stack. A new filler neck can be fitted and a new tube stack is not a king's ransom, the wonky pipework can be replumbed with a bit of thinking to prevent a repeat filler neck failure.

 

[TactilePaul]

i had a 2030 for 15 years and 3500 hours in a Bavaria without an expansion tank. What boat is it in?

I had a look through the Volvo parts list and can't find an OE fitting like that. Just a plain cap and no expansion tank. Also googled MD2030 images and every one shows just a plain cap. Suspect your add on is solving a problem that may not exist - and giving you grief!

I agree. But It’s there because the cylinder it heats is above the coolant level.