Adding a coolant recovery tank/bottle

[Vashon_Trawler]

My MD2030 does not have a coolant recovery tank. There is an overflow hose that runs to the bilge; the radiator cap appears to be a standard cap rated for 13 psi. I would like add a tank, so I can more easily monitor my coolant level. Volvo Penta sells a setup that includes a tank, modified cap with hose nipples, and clamps (see pics). Unfortunately, the package costs over $300 (minus the electronic monitoring system)!

Is there an alternative product I can use? I am a little confused regarding how this set-up works. I assume there must be a pressure release valve in this modified cap. If not, how does it maintain pressure to avoid boiling?

Thank you for your help!

 

[DDW]

A coolant recovery tank costs about $15 at Napa Auto parts or similar. The only issue is how do you get a hose to it from the pressure cap neck? I'm quite sure that Volvo sold MD2030 engines with this feature, might be worth checking the parts book to see what has to be swapped to get the neck with the hose barb.

 

[Vashon_Trawler]

A coolant recovery tank costs about $15 at Napa Auto parts or similar. The only issue is how do you get a hose to it from the pressure cap neck? I'm quite sure that Volvo sold MD2030 engines with this feature, might be worth checking the parts book to see what has to be swapped to get the neck with the hose barb.

Thanks, DDW. I had contemplated running the existing overflow hose on the neck to to a plastic tank (it currently runs to the bilge) but wouldn't this just be one-way (i.e., only collects coolant that overflows)? This Volvo Penta coolant overflow set-up has a modified cap that doesn't appear to have a pressure valve.

 

[RT Firefly]

Greetings,
Mr. VT. On a previous Lehman we owned I did just that and yes, it WAS one way but it allowed me to monitor how much coolant was spewed out with a quick glance. Every so often, I would simply empty the remote tank back into the coolant reservoir. Not a big deal to do during the morning ER checks. At that time I was unaware of the coolant recovery tank available from AD for the Lehmans.

 

[GregBrannon]

My Detroits had a coolant overflow line that drained to the bilge as you've described, dribbling on the engines and everything else as it went, peeling paint, causing corrosion, etc. I bought heavy duty overflow tanks that connect to the overflow hose at the bottom of the tank. If the 'cold' line on the overflow tank is installed approximately at the same level as the top of the engine's coolant tank, then expansion from the coolant tank will flow into the overflow tank when hot and then drain back into the engine's coolant tank when cold. It works very well.

 

[FF]

While the overflow tank is the big visible change , the key is the recovery thermostat is different from the old standard units.

It is the thermostat that allows the suction from cooling , shrinking coolant to pull the overflow back into the engine.

Slowly as the system operates entrained air in the engine coolant fluid becomes more effective , radiators are about 25% smaller on cars with the system.

 

[DDW]

Thanks, DDW. I had contemplated running the existing overflow hose on the neck to to a plastic tank (it currently runs to the bilge) but wouldn't this just be one-way (i.e., only collects coolant that overflows)? This Volvo Penta coolant overflow set-up has a modified cap that doesn't appear to have a pressure valve.

Any standard cap has that feature, provided the neck is a standard neck. The pressure cap seals on the surface inside the neck, under the overflow connection. If the pressure releases, it goes past that seal. There is a second seal at the top of the neck, which forces the overflow coolant down the hose. When the engine cools again, the vacuum created draws the coolant back the same route. This is the normal way pretty much every engine works. Certainly my small Volvo works that way.

The coolant overflow tank must either have the fitting at the bottom, or if at the top connected to a tube to the bottom, so that it sucks back coolant, not air. Again standard.

 

[Vashon_Trawler]

I appreciate the response--they are most helpful. I will go the "non Volvo Penta $300" route and purchase a simple recovery bottle, but I will first check to see whether my existing cap is a recovery or non-recovery type. I am thinking it is the latter. I didn't realize there was a difference! I found this site helpful with explaining the difference between the two: https://www.allpar.com/fix/engines/cooling-caps.html

 

[Gdavid]

After wrecking and rebuilding my dodge spirit multiple times in college, I didn't bother buying a new coolant recover tank for it. Instead I put a longer piece of hose coming off the nipple at the radiator neck and ran it to an empty 2 liter soda bottle wedged behind the headlight. Worked just fine.

 

[Xsbank]

Just buy the kit engineered for your engine and forget it. Many times we obsess over the cost and spend far too much time worrying about it. Get the part number and shop around dealers for the best price, don’t forget truck and agricultural sellers. You might find nos or used.

 

[Simi 60]

After wrecking and rebuilding my dodge spirit multiple times in college, I didn't bother buying a new coolant recover tank for it. Instead I put a longer piece of hose coming off the nipple at the radiator neck and ran it to an empty 2 liter soda bottle wedged behind the headlight. Worked just fine.

SNAP

That's the exact setup I used on the genset.
The main engine got the empty 5 litre coolant bottle upgrade.
Been working trouble free for 3 years now.

 

[OldDan1943]

Dont forget to mark the hot and cold level.

 

[Brisyboy]

Just a point of clarification:

A couple of posts to this thread mentioned the thermostat and how it was somehow involved in the overflow process.

My understanding is this - the thermostats role is to regulate engine temp_ when the engine is cold, the thermostat restrict the circulation of water around the engine to help it warm up quicker. As the engine/coolant heats up, the thermostat slowly opens till eventually it is fully open and allows full circulation ie engine is at its operating temp.
An overflow is caused by the coolant expanding (because it is hot) and it gets to the stage where there is too much coolant in the system - something has to give and it either pushes past the radiator cap seal and flows into the "coke bottle" or is pushed into an overflow bottle to be sucked back into the engine when the coolant cools(and contracts) via the double seal overflow coolant cap.
BTW radiators and or coolant systems without an overflow tank should have an air gap at the top of the header tank to allow for this expansion.. An overflow header tank should be filled to the top.

Here endeth the lesson

 

[hmason]

FWIW, two CAT experts advised me not to check the coolant level by looking at the recovery bottle. Both said open the radiator cap and be sure the tank is full. YMMV.

 

[Gdavid]

Just a point of clarification:

A couple of posts to this thread mentioned the thermostat and how it was somehow involved in the overflow process.

My understanding is this - the thermostats role is to regulate engine temp_ when the engine is cold, the thermostat restrict the circulation of water around the engine to help it warm up quicker. As the engine/coolant heats up, the thermostat slowly opens till eventually it is fully open and allows full circulation ie engine is at its operating temp.
An overflow is caused by the coolant expanding (because it is hot) and it gets to the stage where there is too much coolant in the system - something has to give and it either pushes past the radiator cap seal and flows into the "coke bottle" or is pushed into an overflow bottle to be sucked back into the engine when the coolant cools(and contracts) via the double seal overflow coolant cap.
BTW radiators and or coolant systems without an overflow tank should have an air gap at the top of the header tank to allow for this expansion.. An overflow header tank should be filled to the top.

Here endeth the lesson

As long as your hose reaches the bottom of the coke bottle or any old jug the engine will suck the coolant right back in when it cools back off, there is nothing magical about the overflow bottle. If there is any little crack or loose connection in the overflow hose, the vacuum will break and the engine won't be able to suck the coolant back in, this is why you need to open the cap and look in the heat exchanger to verify it is full when cold.

Many newer cars have a completely sealed cooling system which uses an expansion tank with a sealed lid versus an overflow tank open to atmospheric pressure, they tend to be harder to bleed the excess air out of.

 

[Nomad Willy]

I don’t have a surge tank.
I use a Murphy Switch .. brand.
It’s plumbed into my exhaust manifold coolant chamber. It’s a heavy duty float switch. If the coolant level goes down a warning buzzer goes off. The buzzer only went off once for us but probably saved our butts. We had just pulled anchor in Treadwell Bay and had turned down Slingsby Channel when the buzzer went off. Went back and re-anchored. After a time I found the coolant leak. It was a cracked 3/4” bronze short nipple. Took out the nipple and subed two NPT to hose barb fittings and a very short hose `that I’m glad we had. So in about 15 minutes we were running 100%.

W/O the surge tank there is a bit of air in the top of the coolant jacket in the exhaust manifold. The air must act like a spring when the coolant expands. Since I have no aluminum in the system there is no corrosion (that I have seen) so I intend to stay w what I’ve got.

You can see in the picture there's an inlet and outlet hose from the manifold (lower hose). As the coolant rises in the manifold it rises in the orange and white Murphy Switch. One can see the coolant level through the clear window in the side of the Murphy Switch.
Note: It's not an Isuzu but a Mitsubishi engine.

 

[OldDan1943]

Just a point of clarification:

A couple of posts to this thread mentioned the thermostat and how it was somehow involved in the overflow process.

My understanding is this -
Here endeth the lesson

I think you nailed the basic understanding. +1

 

[OldDan1943]

I don’t have a surge tank.
I use a Murphy Switch .. brand.
It’s plumbed into my exhaust manifold coolant chamber. It’s a heavy duty float switch. If the coolant level goes down a warning buzzer goes off.

.

Hmmm, do you have the URL please?
So many buzzer.....

 

[FF]

"A couple of posts to this thread mentioned the thermostat and how it was somehow involved in the overflow process."

OOOPS ! MY Bad!! In post # 6 i wrote thermostat , instead if coolant recovery pressure cap.. Brain Fart !

Folks with enough room above the engine can simply install a tank with a hose from the bottom of the tank. This will keep the system air free and full of coolant at all times. A clear tank would make a system check a glance.

 

[Ski in NC]

Not sure why this particular engine needs all that crap for a recovery bottle. To the OP: can you post a pic of pressure cap housing with cap off? Is there a port connected to the side of the housing?

 

[Nomad Willy]

Dan,
No links or URL’s.
Should be able to do a simple search.
All I remember is the name “Murphy”.
They sold it to me when I repowered. They are now w Horton marine engines (in the same building) in Ballard/Seattle. They call themselves “Yukon Engines” now. The old parent company was/is Klassen and they exist as before in lower BC Canada. Both Yukon and Klassen would know about Murphy. I call it a Murphy Switch as they are basically a switch. A float switch.
Re my pic above the orange and white vessel is screwed to the manifold and the coolant comes to the orange and white vessel via the hose through fittings and pipe thread ports in the manifold.

 

[Aquabelle]

Just a point of clarification:

A couple of posts to this thread mentioned the thermostat and how it was somehow involved in the overflow process.

My understanding is this - the thermostats role is to regulate engine temp_ when the engine is cold, the thermostat restrict the circulation of water around the engine to help it warm up quicker. As the engine/coolant heats up, the thermostat slowly opens till eventually it is fully open and allows full circulation ie engine is at its operating temp.
An overflow is caused by the coolant expanding (because it is hot) and it gets to the stage where there is too much coolant in the system - something has to give and it either pushes past the radiator cap seal and flows into the "coke bottle" or is pushed into an overflow bottle to be sucked back into the engine when the coolant cools(and contracts) via the double seal overflow coolant cap.
BTW radiators and or coolant systems without an overflow tank should have an air gap at the top of the header tank to allow for this expansion.. An overflow header tank should be filled to the top.

Here endeth the lesson

Agreed...thermostat is irrelevant. OP needs a new and different cap (which is why Volvo supplies one with its kit), but does not need Volvo' s outrageous pricing. NAPA bottle will be fine, just select one of the same approx volume as Volvo supplies.

 

[sean9c]

Has anyone pointed out that the coolant recovery system shown in the first post is more than just a bottle. It appears that it has sensors that likely monitor coolant level and would let you know if it's low. If this is plug and play with your current instrument panel it might be a worthwhile addition.

 

[Vashon_Trawler]

Hi, Ski. The boat is an hour away but the cap housing does have a port with a hose that runs to the bilge. My radiator cap is the double sealed variety, which I thought would work with a recovery system and provide the vacuum to return coolant.

Based on suggestions, I was going to simply mount the bottle with the cold line aligned to the radiator cap. The Volvo Penta setup has me confused. Perhaps it permits mounting the recovery bottle above the engine? It must bypass the existing port on the neck.

 

[Ski in NC]

If it uses a std recovery cap, and it has the port on the filler neck, pretty dang sure an auto parts store bottle will work. Only reservation is I have seen Volvo do some strange sh!t. Cheap to try.

I set them up with the level in the bottle about the same as the level of the filler neck. Higher and it spills in with pressure cap off (not always a bad thing), lower and it is hard for the cool down suction to drag coolant back in.

 

[kchace]

Hi, Ski. The boat is an hour away but the cap housing does have a port with a hose that runs to the bilge. My radiator cap is the double sealed variety, which I thought would work with a recovery system and provide the vacuum to return coolant.

Based on suggestions, I was going to simply mount the bottle with the cold line aligned to the radiator cap. The Volvo Penta setup has me confused. Perhaps it permits mounting the recovery bottle above the engine? It must bypass the existing port on the neck.

The filler neck merely has to have sealing surfaces for the 2 gaskets of the cap and the hose connection between.

 

[koliver]

My MD2030 does not have a coolant recovery tank. There is an overflow hose that runs to the bilge; the radiator cap appears to be a standard cap rated for 13 psi. I would like add a tank, so I can more easily monitor my coolant level. Volvo Penta sells a setup that includes a tank, modified cap with hose nipples, and clamps (see pics). Unfortunately, the package costs over $300 (minus the electronic monitoring system)!

Is there an alternative product I can use? I am a little confused regarding how this set-up works. I assume there must be a pressure release valve in this modified cap. If not, how does it maintain pressure to avoid boiling?

Thank you for your help!

In this boat, my original engines did not come with any coolant recovery. The top of the engine was often fouled with coolant when the pressure cap would release coolant out of the filler neck. My mechanic ( very familiar with all of the different VP engines, installed a pair of recovery bottles. Simple, mounted so the level in the bottle was above the top of the filler neck and the bottom of the bottle was below the neck, with a hose connecting the neck to the bottom of the bottle. That worked well. The next generation of engine had this feature as part of their original design. I have never had an overflow, never seen them dry.

 

[FF]

I call it a Murphy Switch as they are basically a switch. A float switch.


Murphy makers of the switch gauge which is a fantastic tool for engine monitoring , also make similar float switches for the oil pan.


The delight of the switch gauge is the watch stander needs to know nothing about the engine/tranny. When set close a bell will sound or a horn will blow , alerting someone responsible to come take a look.


Offshore the system can be set to shut down the engine if an alarm setting (which you get to set) is reached. The gauges are mechanical so will function at all times,but take longer to install.



Gauges | FW Murphy Production Controls


https://www.fwmurphy.com/products/gauges
FW Murphy is known for its gauges, and there's a good reason why. They're durable and dependable. They're highly accurate and long-lasting

 

[Trawler Dave]

Coolant recovery

Scroll back up to Vashon Trawler's picture of a cap. This particular cap is a coolant recovery cap. The gasket at the bottom is the one that prevents vented fluid from leaking out everywhere, Th black gasket next up is the one overcome by the rated pressure. The big spring is overcome and coolant is released between the two gaskets into the drain tube. The brass circle at the top is the key to the whole setup. It is the valve with a very light spring that allows coolant to be drawn back into the expansion tank. If you do not have this valve, your coolant cannot return to the expansion tank.

 

[Barrie]

Here's a Canadian solution eh. Next time your wife buys dish detergent, get her to buy one with a handle built in the side and in a see through plastic bottle. Wash bottle when she is done with it. Insert radiator overflow hose in bottle and secure on side of engine with a tie wrap. You can easily monitor your overflowed fluid from a distance. (if you are getting a lot of overflow fluid, it is probably your engine telling you...too much....too much)