Coolant in Engine Bilge MD22L B

[AB1707]

I am regularly getting coolant from the small black hose into the engine bilge if I top up the coolant in the header tank to the marked level. If I have it on minimum it still appears intermittently. Today we motored for six hours. When we started the header tank was practically empty but once the engine warmed up it was ²/³ full.
The heat exchanger/ coolant radiator cap has two hoses going to the header tank (see attachment)
The first thing I would like to try is changing the radiator cap. Does anyone know where I can obtain one?
If that doesn't work then my next option is clearing the heat exchanger. Any other suggestions.
Thanks in advance

[Stevie H]

My understanding is that the discharge you describe is usually due to excess pressure -either because of excess coolant volume or excess pressure in the system due to a fault on the engine. The header tank filling as you describe is normal, reflecting expansion of the coolant in a hot engine which reduces once it cools

Here is a link to a supplier (and parts diagram) who appears to have the parts in stock

https://www.marinepartseurope.com/en/volvo-penta-spare-parts.aspx?Catalog=7746710&Category=26&View=573

You could also try  these people who are UK based and offer a very good service and far more reasonable pricing than Volvo dealers in my experience

https://www.parts4engines.com

I am however a bit confused by your set up. The black pipe you refer to appears to be connected below the heat exchanger cap, which is where it is located on my engine (MD2030) but the parts diagram I have included above does not show this with a header tank arrangement and the header tank cap does not appear to be a pressure cap.

Typically on engines without a header tank the black pipe takes any discharge when the excess pressure releases a normal pressure cap.  With a header tank the pressure cap is fitted to the tank and the upper pipe connection on the tank recirculates any excess coolant.

Hopefully someone will be along who had better knowledge of your engine model but in the meantime I hope the foregoing is of some help

[AB1707]

Thanks Steve for your reply.
The standard filler cap won't work I need the T junction above it which is where I'm struggling to locate.

Regards

Adam

[symphony2]

I think this shows the part you need.https://www.volvopenta.com/shop/523388/part-sections/54168814 (5A)
It also shows on the parts breakdown for the heat exchanger but as a complete assembly. Got this from Volspec webstore, but not easy to find the actual part without a part number. Suggest you give Volspec a call. Be ready for the usual shock to the wallet, I think they are pricy.

Hope this helps

[chowder]

The header tank (aka expansion tank) sounds to be operating normally to me. With a warm or hot engine, the level will rise. If the leaking coolant
is not coming from the manifold T-cap, I wouldn't spend and $ on it (although the rubber seal should be replaced occasionally).

If you suspect the leak is from the line running up to the header/expansion tank, place a towel around the suspected leaking line with a zip tie and
run the engine until it is warmed up. See if the towel collects any coolant. If so, you can start to narrow down the search area. I don't suspect your
cooling system is having issues with the heat exchanger.

I just pulled my heat exchanger yesterday so if you have any questions, feel free to ask. I also drained, flushed and replaced the coolant, thermostat,
etc. MD22L-B

[IslandAlchemy]

Mine used to do this too.  Every time I topped it up, it would discharge through the little pipe into the bilge.

I concluded that it simply didn't like being that full.

I put an old lemonade bottle in the bilge and tied it to the engine, to catch any coolant that discharged.

I got about a cup full in the bottle and then it stopped.  I left it all alone and it was all fine from that point onwards.

[Yngmar]

Same as IslandAlchemy. Our engine doesn't have the external coolant expansion tank, and if the heat exchanger is filled too much some coolant is released through the PRV in the cap. I catch it in a bottle too and once it has dropped to a certain level, everything is fine. If I peek into the heat exchanger top, the level is just below the top fin, but when the engine heats up the coolant must be expanding to cover it, so everything is fine.

once the engine warmed up it was ²/³ full.

That's more than enough coolant then - stop adding more

[AFRiCA]

I experienced the same symptoms/issue a couple of years ago with the exact same engine and setup.  The problem of leaking coolant was fixed by replacing the sealing ring in the cap.

[AB1707]

Ok the problem has been found. It's the seal in the radiator cap. The attached video demonstrates this. The part number is 1543751. Please note in the video he puts it on the wrong way round. As confirmed by Service manager at James Troop VP dealers

https://youtu.be/9jsslJTx9yw