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Coolant Resevoir Keeps Filling Up.

Dave's advice is spot on. If the hoses are original, they are about ready for renewal. Sad to say bu the 'newer' stuff doesn't last as long as the older stuff, especially when it comes to hoses.

You may also wanna get the IR gun at the inlets and outlets of each manifold to make sure the 'hotspot' is the manifold. if the manifold is really the source, like Dave said, it is highly unlikely to be bad...a restriction in one of the hoses connected to it is much more likely.

Thanks everyone for the input. I am replacing both manifolds, elbows(risers) and hoses. The boat is 12 years old, I probably could find a way not to replace the manifolds but I am tired of the science experiment and I figure just replace things before my mechanic gets too busy. I did find a new mechanic I am happy with by the way. This is happening fast. The mechanic is on the boat as we speak.
 
new hoses, fittings, and clamps, too?

Enviable position to be in...good luck with the new mech. never met one yet that refused a tip.
 
Mark... my post #32... does that make any sense to you?

Just curious!

I see the 240 temp reading as a smoking gun. If, in fact, that manifold is running coolant at 240, the other side at, let's say 190 (about normal), AND the manifold is full of coolant or water, then pretty clearly to me a flow issue down that side of the engine. It will boil there, especially at higher power settings. I tend to think that severe boiling will overwhelm the stock overflow system's capacity to pull back in coolant into the active circuit.
 
Rick: somewhat. the "flaw" (or my lack of the model you are using) is that the air will easily compress and won't open the spring in the cap. Aerated coolant could be escaping and the entrained air collecting into bubbles but they would have to be accompanied with some coolant.

BigPursuit: Fittings = the hose barb-to-pipe thread adapters used where the hose connects to the manifolds. replacement isn't always necessary but typically results in a decent time savings.

I'm thinking like Dave but would like to see the inlet and outlet temps before I'd spend my money on the manifold. I believe Dave stated earlier, these manifolds live forever unless abused (freeze damage). I'm thinking it is most likely to be hot due to insufficient flow of coolant. that issue could be caused by not enough flow coming in or by a restriction in the outlet...
 
Rick: somewhat. the "flaw" (or my lack of the model you are using) is that the air will easily compress and won't open the spring in the cap. Aerated coolant could be escaping and the entrained air collecting into bubbles but they would have to be accompanied with some coolant.

BigPursuit: Fittings = the hose barb-to-pipe thread adapters used where the hose connects to the manifolds. replacement isn't always necessary but typically results in a decent time savings.

I'm thinking like Dave but would like to see the inlet and outlet temps before I'd spend my money on the manifold. I believe Dave stated earlier, these manifolds live forever unless abused (freeze damage). I'm thinking it is most likely to be hot due to insufficient flow of coolant. that issue could be caused by not enough flow coming in or by a restriction in the outlet...

In any case if I replace the manifold and both hoses that should cover it correct? The HE is working or the other manifold would be affected, also the boat itself runs @ normal temperature. The only hot spot is the manifold itself.
 
Very possible...just make sure the t-stat housing outlet is clear and ditto for the HX inlet fitting.

Sometimes, a properly sized piece of clear tubing substitued for the rubber hose aids in diagnosing these issues...Just pay attnetion to the material selected.

If you have confidence in the new mechanic, just let him do his job so you can pay him and then go boating. Life frequently throws us a never ending stream of decisions.
 
Mark and Dave.... my apologies,..... I guess I didn't see that the temps were up near the 240 range.

Has anyone given any thought to the sea water pump capacity not being correct?
 
So I replaced both manifolds and elbows and all attaching hoses. I checked the opening on the full riser and it's clear. I ran the boat on a short test and I still have bubbles in reservoir. The manifold still heats up but not at first. Meaning if I take a fairly short run, I get bubbles but the manifold is normal temperature. The just to rule it out I switched the heat exchanger with the other engine. Same result. So I have changed both heads, manifolds, elbow, heat exchange, radiated cap, hoses. I have had pressure tested(ok) combustion gas tested(negative). What's left? I really tired of spending every weekend doing test runs and climbing down in the engine room with an ir heat gun. Ideas?
 
Bigpursuit-
Thanks for the heads up about the similarity of our problem. I have not done a close study of my overflow tank but have seen bubbles on occasion. Things I have learned that may be of interest: 1) The coolant flow is split to each side of the engine at the water pump where it flows into the block. The streams exit each head at the top front and flow back to the center in the passageways cast into the front of the intake manifold, so they can meet under the thermostat. The installed temperature sensor only measures the flow from the right side of the engine so the left side could be overheating and it would not show on your gage. Shoot the IR gun on the top front left of the intake manifold to get the coolant temp leaving the left head. It should be the same as on the right side. 2) I took out the thermostat and the overheat problems went away. The higher coolant flow with no restriction overcame whatever the issue may be. Not a good long term solution as the engine will run rich (carbon up), but we fished it that way for three months. 3) Pull the brass plug with the zinc from the heat exchanger when the engine is running. If the raw water pump is good you will get an impressive stream of raw water coming out. 4) Make sure you have a factory fan belt and it is tight. You should not be able to turn the fresh water pump by hand when the engine is off. I had, for a time, an “equivalent” belt, installed by a Crusader mechanic and it was slipping.


Let's keep in touch. I will be back to my boat in July and unless I can come up with a better solution plan to start tearing down until we find a smoking gun. New head gasket did not do the job....but I definitely did have a head gasket leak and now wonder if it did not slightly erode the block face, so that the new gasket is also leaking.


CaboJohn
 
Thanks Cabo, we will definitely keep in touch. I honestly don't believe my problem is combustion gas. The boat has never overheated and actually runs fine. My symptoms are bubbles/foaming in the coolant reservoir and if the boat goes long enough the port side exhaust manifold gets hot. The bubbles only happen when the boat decelerates. I get bubbles long before the manifold warms up, so I believe the manifold happens after air is introduced into the system. I am starting to believe air is actually getting sucked in from the water pump on the closed system side. I have found auto forums where people had problems very similar to mine and the source was the water pump sucking air under high rpm's. Anyone had this experience?
 
Bigpursuit,

I was thinking about your data points and trying to understand them. He are some ideas. Let's assume that you are right, and while you have gas (air) in the system it is not combustion gas. The water pump is not a fixed displacement pump, it puts out pressure and flow is determined by the restrictions in the system. The biggest restriction, by far, is the thermostat. Even when the thermostat is open the area for flow is far less than the hose diameters, the passageways though the block and heads and the heat exchanger. So you will always have significantly more pressure before the thermostat than after. The differential will depend upon engine rpm and how much the thermostat is open. The absolute pressure at any point will also depend upon engine temperature rise, and ultimately (and quickly) the pressure cap.


Your system should hold something in the range of 6 gallons of coolant. Expansion from 60F to 170F would be about 18 oz. Since the fluid is incompressible, if the system was rigid it must all come out. Actually the hoses provide some spring effect, so likely your should see something like 14 oz come out and 4 oz go into hose expansion (I am making this up, illustrative only). That sounds about right. The pressure cap relieves at 7 psi so that is the system pressure (to atmosphere) at that point, but depending where the cap is compared to the rest of the system (particularly the thermostat) you could have some system pressures higher or lower than that by several pounds. (Ricardo got into this on #32 so I am repeating some of his thoughts in a different form.) If you have a bubble in the system, then it will also be compressed to whatever pressure is around it. It “should” be trapped at the fill cap, so that would be 7 psi. If you slow the rpm, and your fill cap is in a “low” pressure area (I don't know your model), that is, the area after the thermostat, then that region will increase in pressure (think “the water pump is not sucking as hard”), even as the high pressure area (before the thermostat) decreases in pressure. And the gas at the fill cap will expand and bubble out to bring the pressure at that point back to 7 psi, just as you have observed.


That is a correct thing. Actually, I believe that the only time the system can be degassed is when it is heating up to temperature (and gas gets pushed out in front of that 14 oz or so of fluid that is rejected) or to a lesser extent when engine rpm change causes pressure fluctuations and tank bubbling such as you observe. This is an important point not grasped by many observers. Once you are at temperature, and still have trapped gas, you are struck with it for that cycle. Of course the real problem is that the gas should not be there, and should have been pushed out in several previous heat/cool cycles. Since your overflow fluid does not get sucked back in, you start every trip with that 14 oz bubble. And as an aside, there are some clever little hoses (in some systems) to get the gas to the fill cap where it can reside and be pushed out when thermal expansion occurs. I suppose any of those (if present) are worthing looking at for clogs.


Other thoughts: When the engine starts cold, those water pump caused pressure differentials are immediately present. If the fill cap is in a low pressure area (after the thermostat), then you will have less than atmosphere at the cap, and will immediately start sucking even more air in, if your fill system is not tight. This will stop fairly quickly as the liquid expands, and the fill cap gets to a pressure above atmosphere, but it still it could be a contributer in the first minutes of running.


And if it turns out to be one of these “magic moving bubbles” (like I have theorized in my block/head), then it could move into your left exhaust manifold and get stuck (don't ask me how). At that point the manifold would overheat, and then steam would form. This would quickly expand the bubble and raise system pressure, and since the bubble is in the wrong spot (not at the fill cap), the system would eject coolant to the overflow tank and not eject the air. Now if the bubble moves, and the steam collapses back into coolant, the system pressure will quickly go negative (unless the 4 oz the hose spring effect can give back is enough to keep it positive). A negative pressure should mean the system will suck back fluid from the overflow, but since yours does not, it means it will suck in even more air........you see where this is going.


This thing can get complicated and have weird effects, but clearly the return system must function flawlessly. It is really more important than it first appears. There really is little to go wrong except the cap, the tank hose and fitting, and fill riser the cap screws into (mine had a gouge causing a leak). In fact the fill riser is particularly suspect since I think there is a sealing surface that holds the pressure in the system, and another that keeps air from entering around the cap when the system is trying to pull back fluid though the hose. Maybe the cheap solution is to replace it all.


I suppose it is possible to have other air leaks in the system, but unlikely. The leak would be one way (fluid does not go out at 7 psi), and the air would have to go in at only 1 psi or so of system negative pressure or else the cap would open a preferentially suck from the overflow tank.


I don't claim any of this is right, but it is good food for thought. Good luck.


CaboJohn


PS I have not solved my problem, but writing this has brought back one point. One reason I was convinced I have combustion gas into the coolant as a source of heat (in spite of a negative test), was that in a cold start I could rev the engine and get an immediate pressure rise in the coolant system and most of the pressure would remain even after a quick shutdown. I could not explain it other than by leaking combustion gas since the temp had not yet moved and the pressure remained. But I now realize my pressure gage was before the thermostat (where I would see water pump pressure) and my fill cap is after the thermostat near the pump input (so it would see negative pressure on startup and suck in coolant). Then on shut down that extra coolant would remain in the system and a higher pressure reading would remain (hose spring effect). And I would be deceived. Ouch!
 
Cabo,
i do suspect the fill riser and will probably switch it from the other engine to see what happens. Good luck with your boat. Keep in touch.
 
That "refill system" is key to keeping the system purged. Lots of little things can go wrong to keep it from operating correctly. a good inspection will typically find the cause.

The water pump (any pump really) will "suck air" over the fluid as it is easier. That isn't the problem - it is locating the source of the air and eliminating it that is the hard part.
 
The boat is fixed! The problem turned out to be the circulating coolant (water pump). Apparently a pump can suck air through the seal at high rpm's and put air into the system. I'm glad it's over, but I spent a lot of money on a simple problem. I learned a circulating coolant pump can fail in many ways. If any one ever tells you a 'pump either works or it doesn't' or ' if a pump isn't leaking it's fine' they are incorrect.
Thanks everyone for your help in this issue!
 
Biggie-
Congratulations! I'm curious. I am guessing you replaced the pump and the problem went away. Any other indications of an air leak (since I have replaced my pump and still have the issue)?

Thanks,
CaboJohn
 
Biggie-
Congratulations! I'm curious. I am guessing you replaced the pump and the problem went away. Any other indications of an air leak (since I have replaced my pump and still have the issue)?

Thanks,
CaboJohn

I had no indication of a leak. The pump appears to have been 'sucking air' through the seal at high rpm's. I had sent an email to the manufaturer and they responded this was possible. Do you get air in your system or just overheat? My engine never overheated. I assume it would have eventually since all the coolant was being replced by air.
 
yeah, I'm from what I've been told and read, the coolant/water pump on the engine almost never fail. Mine are original (24 yrs) and I haven't given them much thought. I guess like a car, they'll give you plenty of warning when they do fail (your problem excluded from the normal point of failure).
 
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