MD2020D Removed coolant drain plug - no water.

[JohnGC]

In order to change the coolant I removed the drain plug. This is the first time I've attempted this job myself.
Much to my surprise, no coolant came out and I'm seeking an explanation.

There is coolant in the heat exchanger at the normal level.
The engine runs normally and doesn't overheat with revs up to 2500.
I removed the filler cap to let air in.
The drain plug is located awkwardly and I can't see into it.
I tried poking the hole with a bit of bent wire. That seemed to fish out small bits of black gunge but I didn't want to risk damaging something internal so I didn't poke hard.

Is there an extra step which I've missed such as a seal behind the plug which also needs removing?

 

[VicS]

In order to change the coolant I removed the drain plug. This is the first time I've attempted this job myself.
Much to my surprise, no coolant came out and I'm seeking an explanation.

There is coolant in the heat exchanger at the normal level.
The engine runs normally and doesn't overheat with revs up to 2500.
I removed the filler cap to let air in.
The drain plug is located awkwardly and I can't see into it.
I tried poking the hole with a bit of bent wire. That seemed to fish out small bits of black gunge but I didn't want to risk damaging something internal so I didn't poke hard.

Is there an extra step which I've missed such as a seal behind the plug which also needs removing?

Poke harder

 

[JohnGC]

Poke harder

 

[Dipper]

Every time I drain my 2001 I have to poke the hole. I use a flexible round file which drags out the gunge followed by a surge of water. I've just done that today. The file is just under 6" long and goes in all the way.

 

[Martin_J]

I have in the past put a tube into the hole and blown through the tube until I hear bubbles... Usually disturbs any silt..

 

[JohnGC]

Thanks all. Tomorrow I'll be less timid.

 

[john_morris_uk]

Thanks all. Tomorrow I'll be less timid.

You'll struggle to damage anything. The drain hole is into the water jacket and surrounded by cast iron.

 

[Ruffles]

Take the 'radiator' cap off, put your hand over the opening and blow into the overflow pipe. Speeds things up. Well, you get something approaching a spurt rather than a trickle. And you'll get bubbling when it's empty. I've not had to poke the hole - yet.

Makes me wonder where the gunge comes from. Is it organic slime? I thought the anti-freeze was supposed to keep it clean. Not heard of anyone having to clean out a fresh water cooled system.

 

[cmedsailor]

Makes me wonder where the gunge comes from. Is it organic slime? I thought the anti-freeze was supposed to keep it clean. Not heard of anyone having to clean out a fresh water cooled system.

Indeed I have the same question. When I remove the drain plug on my Volvo MD2030D, which I guess is similar to MD2020D (that square plug at the starboard side of the engine) there's only clean anti-freeze/corrosion liquid coming out of it.

 

[VicS]

Makes me wonder where the gunge comes from. Is it organic slime? I thought the anti-freeze was supposed to keep it clean. Not heard of anyone having to clean out a fresh water cooled system.

Indeed I have the same question. When I remove the drain plug on my Volvo MD2030D, which I guess is similar to MD2020D (that square plug at the starboard side of the engine) there's only clean anti-freeze/corrosion liquid coming out of it.

I think its important with these engines and similar that use the old type antifreeze to be sure to change it regularly. Yearly preferably but certainly not to exceed the recommended time interval if it's longer.

Also with these VP engines and their rubber heat exchanger end caps be on your guard for the possibility of some interchange between the coolant and the raw water leading to contamination of the fresh water coolant with salt water. A big leak between the two will some become apparent, either by mysterious coolant loss or overflowing via the filler, but a small interchange might go unnoticed although still lead to significant contamination and antifreeze/ inhibitor dilution over time.

 

[JohnGC]

Poked harder and succeeded but was surprised just how hard and far before the coolant started to flow. I've recovered about 2.5 l, split a little and I suspect some will be inside the block still.

I have just removed the exhaust elbow to inspect it and plan to remove the heat exchanger for cleaning, so I'll look at the endcaps as Vic suggests.

Seems as though it would be a good idea to flush fresh water though the block while I have it apart. Or would it be better to use something other than water?

The engine overheated last June (picked up something in the raw water intake) and dumped some of the coolant. I replaced it with tap water which was all I had so the anti-corrosive has been weaker than it should since then. It's possible that is the reason for the gunge. From now on I will keep some spare mixed AF in case this happens again.

 

[Seadawg33]

I would think that it would be a good idea to flush the system with raw water until such a time as the water coming out of the block is clear. There is no telling what is in the water passages. I would think that any video on flushing a radiator, with some minor adjustments, would be the correct procedure. I need to do that to my boat soon as well.

 

[RichardS]

Poked harder and succeeded but was surprised just how hard and far before the coolant started to flow. I've recovered about 2.5 l, split a little and I suspect some will be inside the block still.

I have just removed the exhaust elbow to inspect it and plan to remove the heat exchanger for cleaning, so I'll look at the endcaps as Vic suggests.

Seems as though it would be a good idea to flush fresh water though the block while I have it apart. Or would it be better to use something other than water?

The engine overheated last June (picked up something in the raw water intake) and dumped some of the coolant. I replaced it with tap water which was all I had so the anti-corrosive has been weaker than it should since then. It's possible that is the reason for the gunge. From now on I will keep some spare mixed AF in case this happens again.

You could use some chemical but I just filled up with water brought the engine up to temperature before draining and repeating until the hot water coming out is just clear water. One engine took two flushes but the other took a few more. The last flush was with soft water.

I don't both carrying premix but I always top up with concentrated antifreeze. Obviously I'm only compensating for evaporation rather than a major coolant loss but as the anti-corrosion properties of the coolant are constantly depleting the top-up gives the system a boost in anti-corrosion prior to the next full coolant change.

Richard

 

[VicS]

Poked harder and succeeded but was surprised just how hard and far before the coolant started to flow. I've recovered about 2.5 l, split a little and I suspect some will be inside the block still.

I have just removed the exhaust elbow to inspect it and plan to remove the heat exchanger for cleaning, so I'll look at the endcaps as Vic suggests.

Seems as though it would be a good idea to flush fresh water though the block while I have it apart. Or would it be better to use something other than water?

The engine overheated last June (picked up something in the raw water intake) and dumped some of the coolant. I replaced it with tap water which was all I had so the anti-corrosive has been weaker than it should since then. It's possible that is the reason for the gunge. From now on I will keep some spare mixed AF in case this happens again.

Maybe after initially flushing with plain water it 'll be worth trying a car radiator flush. Wynn's Radiator Flush got a (surprising ) thumbs up from Vyv Cox in a recent thread http://www.ybw.com/forums/showthread.php?467489-Wynns-Radiator-Flush&highlight=Wynn's

 

[JohnGC]

Maybe after initially flushing with plain water it 'll be worth trying a car radiator flush. Wynn's Radiator Flush got a (surprising ) thumbs up from Vyv Cox in a recent thread http://www.ybw.com/forums/showthread.php?467489-Wynns-Radiator-Flush&highlight=Wynn's

The Wynn's flush removed some more crud but not all that much. I suspect (though I can't be certain) that what crud there was had mostly collected around the drain. Anyway it's all back together, exhaust elbow and heat exchanger tubes inspected and clear. Thanks for the help.

I do have a supplemental question though.

There seems to be a small leak around the coolant filler collar and the heat exchanger body opening. I noticed when I over filled the coolant slightly (partially up the collar but not over the top) and some leaked out. I can't see how the collar is attached to the casting but it is clearly a separate piece.

Have any of you come across this before and what do you think the best way to fix it is?

Cheers,

John

 

[rob2]

Sounds like the filler neck assembly is becoming dettached. There have been recent threads about this - some advocate an epoxy adhesive, others a new bolt-on neck. Both require the original neck to come off and the joint area cleaned up.

 

[Ilduceglider]

John, I have just completed a repair to the radiator neck on my MD 2040 http://www.ybw.com/forums/showthrea...ller-cap-neck-atop-heat-exchanger-on-the-move!
Also be aware as I said the new cap we fitted only had one rubber gasket at the end of the spring affair whereas the original VP one had a second rubber gasket resting on the top stopping any overflow at the top of the cap and forcing it down the overflow pipe. A dentist type mirror was helpful to see all the way around.

Cheers Peter

 

[JohnGC]

John, I have just completed a repair to the radiator neck on my MD 2040 http://www.ybw.com/forums/showthrea...ller-cap-neck-atop-heat-exchanger-on-the-move!
Also be aware as I said the new cap we fitted only had one rubber gasket at the end of the spring affair whereas the original VP one had a second rubber gasket resting on the top stopping any overflow at the top of the cap and forcing it down the overflow pipe. A dentist type mirror was helpful to see all the way around.

Cheers Peter

Thanks Rob, Peter,

The filler neck is leaking slightly but still seems to be well attached to the casting. So I face a dilemma. Do I try to plug the leak, risk it failing and make the process of creating a surface suitable for a gasket more difficult? Or do I try to remove the neck now and risk damaging the surface to which the gasket must seal?

Peter, when your neck came off, did it leave a clean surface or was some fettling required? I'd also be interested to know if you managed to repair it in place or if you had to remove the heat exchanger casting from the engine.

When I go back to the boat I'll check to see if the Thermex neck will fit.

John

 

[RichardS]

Also be aware as I said the new cap we fitted only had one rubber gasket at the end of the spring affair whereas the original VP one had a second rubber gasket resting on the top stopping any overflow at the top of the cap and forcing it down the overflow pipe.

Cheers Peter

The cap without the rubber gasket immediately under the flat head of the cap must have lost its gasket in transit. It cannot have been made like that as it won't work ..... when the pressure builds up coolant will push past the first gasket and probably come out from under the cap. When it cools it will suck air in from the outside rather than suck coolant in from the expansion tank so the level of coolant in the block will get lower and lower whilst the expansion tank stays full.

Richard

 

[RichardS]

Thanks Rob, Peter,

The filler neck is leaking slightly but still seems to be well attached to the casting. So I face a dilemma. Do I try to plug the leak, risk it failing and make the process of creating a surface suitable for a gasket more difficult? Or do I try to remove the neck now and risk damaging the surface to which the gasket must seal?

Peter, when your neck came off, did it leave a clean surface or was some fettling required? I'd also be interested to know if you managed to repair it in place or if you had to remove the heat exchanger casting from the engine.

When I go back to the boat I'll check to see if the Thermex neck will fit.

John

if the neck is still securely attached I would ensure the coolant level is below the filler and then use wet and dry to sand off all the paint around the bottom the the neck and the adjacent top of the H/E and then degrease it with meths or similar. Then apply a good fillet of JB Weld or similar right around the neck. You could also apply a "rolled sausage" of Milliput or similar as this will be even easier although you will need a coarser wet and dry as a rougher surface will be required to ensure a good seal.

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Richard