Coolant recovery

I have a coolant recovery bottle mounted low. Unless I wanted to move a bunch of stuff that was where it went, 20 years ago. I tried it, it worked, I left it.

The only time it fails to pull back the purged coolant is when it is time to change the recovery cap. That happened this weekend. It pulled all the purged coolant back after the new cap was put on.

If low is the only reasonable place to put it, do it and see what happens. The bigger if, is how good is the seal between the hose and the fittings. Any air leakage, even if no coolant gets out, will cause poor or no pull back. If it fails to work properly then look at the hose and fittings.

Yes, I believe that mounting the bottle level with the header tank is better but it will usually work mounted low. If not and you are sure there is not another problem then try raising it.

As Walt and I have pointed out there are other places other than the engine compartment foe the expansion tank. Under a helm seat if it's boxed in. in/under a seetee seat w the overflow tube going back to the eng comp. You can put it most anywhere the surge tank will fit and you can route the two small plastic tubes to and from. I can't understand not making an easy modification to a cooling system that will make it work better and I do think it will work better 1 to 2' higher than the top of the header tank.

Marin, I'm not clear as to why, (assuming I got motivated, and wanted to convert the dreaded L120 header so it would suck the coolant back), why just replacing the cap with one of the same relief pressure, but the right return valve assembly, would not work. After all, the coolant forces its way out past the lower seal, is trapped under the top of the cap in the neck, so flows out the tube in the neck and down and in my (our) case, out into the fresh air, or your bottles. Why would it not just be sucked back, retracing its route out, as it were, with the proper type of cap, and a tube from the outlet into a vented bottle? Why does the tank neck need the extra sleeve?
I'm sure you will have a good explanation - it's just I can't imagine why so far.

Peter,You'd think so of course but in practice a lot of the time to most of the time it dosn't suck up. It happens so very slowly that just the smallest air leak ruins the vacuum. I'm sure that must be the explanation but I think so in that I can't think of any other. Of course one could explain the origin of man (that nobody knows) or any number of can't quite explain things. If I really needed to know about the vacuum leak I could just install a vacuum gauge in the line and observe. Incidentally the vacuum leak theory is further supported by the fact that a lot of surge tanks work lower than the rad cap. I think the only dependable way to mount them is at or above the rad cap.

Peter B wrote:

Marin, I'm not clear as to why, (assuming I got motivated, and wanted to convert the dreaded L120 header so it would suck the coolant back), why just replacing the cap with one of the same relief pressure, but the right return valve assembly, would not work.

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From what I was told by the Smith's at AD, the issue is both the cap and the inside of the neck.* The original neck insert-- which you have to carefully cut out and remove at which point the new neck insert that comes with the kit is put in--- does not work with a return-flow cap.* The original system--- neck and cap--- only allows coolant to be blown out under pressure.* It will not allow coolant to flow back in under vacuum (or gravity).* So you have to replace both components.

It's been years, to be honest, since I looked at the components in the kit so I can't recite off exactly how the configurations differ.* But the new neck insert is as much a part of the conversion as the new cap is.* Simply putting a recovery bottle on the end of the existing overflow tube will not result in a recovery system.* All you'll do is fill the bottle over time.* In fact, I do recall that part of the installation instructions include blocking off the existing overflow tube.* So the recovery system doesn't even use that tube or connection at all.

*

Well I accept that's what they said, and it worked, in that you bought two kits. The fact you have not gone that extra step and hacked into the existing neck and put the kits on, suggests, like me....you are not completely convinced, and nor am I. I have carefully compared the set-up on the Lehman (ok - I'll wash my mouth out for using that name later), with the set-up on my car, and can really see no difference in basic geometry, other than the fact that the Lehman cap has just one simple spring-loaded pressure valve, without the return valve in the centre. I reckon if I can get a cap of the right pressure release, but with the centre return valve, attach a bottle, position it at, or (as Eric suggests), a little above the header tank, connect it with a suitable heat tolerant tube from the over-flow to the bottom of the bottle with vent hole drilled in the cap as well, to let air in as the fluid moves back and forth, it should work. Now because it's me doing it, it probably won't - at first, but that will not phase me, as that is my usual first result with anything I do on a boat, but by being persistent I usually get it done in the end. Watch this space.

Maybe it's different for the Lehman 135. I just added a coolant recovery kit and hooked it into the little relief tube coming out of the neck. It will allow coolant flow both ways. Did the same on my Westerbeke 8kw genset.

Keith:* Did you change the cap?

Larry/Lena
Hobo KK42
La Paz, BCS, MX

Peter B wrote:

Well I accept that's what they said, and it worked, in that you bought two kits. The fact you have not gone that extra step and hacked into the existing neck and put the kits on, suggests, like me....you are not completely convinced,

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I actually bought the kits on the recommendation of our local diesel shop which has installed tons of them on FL120s in our marina.* I haven't had them install ours since it's something I can do so why pay the labor charge?*

I haven't put them on yet, not because I'm skeptical of them working--- I've talked to people who have put them on or have had them put on and they work as advertised--- but simply because I've been too lazy to do it.* Installation requires removing the header tanks, and while this would be a great opportunity to sandblast and repaint them the ease of my bottle-in the-drip-pan recovery "system" has so far outweighed the effort required to install the proper setup.

I don't know about the FL135--- it's a different (and later) base engine than the FL120--- so for all I know it may have been manufactured by Ford of England with a recovery neck and cap from the outset.* But the FL120s' stock neck and cap will not allow coolant to return to the header tank, only blow out.* I know a couple of peolpe who thought they could get a closed system by simply feeding the overflow tube into a bottle with coolant in it.* It didn't work.

*

Who'd a thunk coolant recovery would rival twins-vs-single, anchors or dripless packing for endless discussion?*

BaltimoreLurker wrote:

Who'd a thunk coolant recovery would rival twins-vs-single, anchors or dripless packing for endless discussion?*

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Did you know that there is a mud-recovery system that works terrific but is only available on Rocna and Sarca anchors?* People with Bruces and CQRs and Danforth's can't take advantage of this technology.* The downside is that its power requirements are such that you have to have a twin engine boat, another reason why twins are better than singles.

How's that.......?

*

Thorough

Now now Marin, you're being provocative - and wrong in fact. Sorry, can't let that one go. The Rocna and Manson Supreme recover mud, Sarca does not.
Lifted from Sarca website....

"The imitators marketed under the banner of new generation anchors are of concave design and of course work quite well, after all they are based on SARCA's design, unfortunately the mud problem has raised it's ugly head on many forums and confirmed to us that we had made the right decision, (convex). SARCA doesn't have the mud bucket design."

Sorry Marin, but as a stickler for accuracy, you'll understand.....I couldn't let that go through to the keeper.

Larry M wrote:

Keith:* Did you change the cap?

Larry/Lena
Hobo KK42
La Paz, BCS, MX

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No, just added the coolant recovery tank and hooked the hose to the outlet on the cap neck. My tank is above the engine level.

*

Keith this sounds interesting, as in a way, your set-up defies the laws of physics - sort of. I can see how if your bottle/reservoir is above the header tank, then excess coolant forced out when hot and expanding, could then siphon rather than suck back when it cools....except it should not be able to simply siphon back when it cools, because that could only happen if your cap had no pressure valve at all. This is because the pressure valve which it forced its way past to escape, would trap it above that valve, and unless fitted with the special inner return valve, there it would stay. Are you absolutely sure the coolant is actually being returned to the header tank when cool, or is it just that you have established the sort of status quo most of us without coolant return systems have by leaving a small space below the cap, so the expansion/contraction is going on under the cap, with only a bit of excess venting. If it truly is returning a significant volume of coolant to the header tank, then I would say it must have been fitted with a cap meant for a coolant return system all along.
For me, that is going to be the problem, and maybe why, as Marin says, to do a conversion on the L120, the actual neck of the filler aperture has to be replaced as well. There may be no cap made with inner return valve which will fit the original filler cap neck.

We ARE talking two different engines here.... The base engine for the FL120 predates the base engine for the FL135 by a fair amount.* Of course the* header tank is a Lehman component, not a Ford component, but by the time Lehman created the FL135 they may have used a recovery-type cap as standard.* In which case Keth's installation of a recovery bottle connected to the overflow tube with no other modifications would work as advertised.

I've no experience with an FL135 so have no idea of the details of its systems. All I know is that the stock neck and cap of the FL120's header tank does not permit coolant to flow back into the header tank.* But this is an engine that predates the FL135 by nearly twenty years if the FL135 did not appear until the early 80s.


-- Edited by Marin on Saturday 9th of October 2010 11:28:45 PM

Exactly...as I said.......
"If it truly is returning a significant volume of coolant to the header tank, then I would say it must have been fitted with a cap meant for a coolant return system all along.
For me, that is going to be the problem, and maybe why, as Marin says, to do a conversion on the L120, (as opposed to the L135) the actual neck of the filler aperture has to be replaced as well. There may be no cap made with inner return valve which will fit the original filler cap neck."

Peter B wrote:There may be no cap made with inner return valve which will fit the original filler cap neck."

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Could be.* The cap that comes with AD's conversion kit for the FL120 is noticeably different-- it's smaller and taller as I recall-- than the stock cap.

*