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yeller
09-07-2014, 05:31 PM
I've been having trouble getting my motor to run cool. It will overheat after a few minutes of driving. It uses a closed cooling system that I put together with some used heat exchangers, but I did get the HE's tested before installing. The engine HE is a 4" x 22" unit. I believe I get good enough raw water flow through the system. I base this on the fact that my exhaust header tubes do not get hot.

To rule out the thermostat, I removed it, but no luck. Engine still overheats.

My next step was to test the circulating pump. I am using an electric pump (that I did not test prior to install). I removed the hose from the manifold thermostat housing to the HE and replaced it with a clear hose so I could watch the water flow. At first, I had a large air pocket in the hose and circulation seemed very low. When I crimped off the tstat bypass hose, I could tell right away the pump was pulling a lot more water through the HE and I was/am hoping I found the problem. With the hose crimped off, the pump seemed to pull more water from the reservoir and the air pocket diminished. With the air pocket virtually gone, the circulation through the HE seems to be good regardless of whether the tstat bypass hose is crimped or not.

I haven't fired the motor back up because I don't have water where it is currently stored. I hope to fire it tomorrow.

I am vaguely hopeful that there was an air lock in the system and the pump was circulating the water through the tstat bypass instead. If the motor still overheats...which I'm afraid it will, I can only point the finger at the HE.

I'd hate to spend a grand on a new HE and still overheat. I was confident the one I have would be big enough. It's bigger than the one I had on my procharged HO and that motor never ran hot. This new motor will overheat in less than 10 minutes idling on the hose.

Is there anything else that might be missing?

gcarter
09-07-2014, 07:27 PM
One of the key features of the remote system I installed is the vent line from the top of the thermostat housing to the expansion tank. The literature "demands" that this tube runs uphill from the housing to the tank. If your housing is cast, you could drill and tap it to add the vent line.
Well anyway, maybe the schematic will help.

yeller
09-08-2014, 03:22 AM
Mine is plumbed that way George. I did find it interesting that a small amount of water continually dumped into the expansion tank from that hose. It got pulled back into the system through the bottom hose on the tank but I had expected that water would only enter the tank as the water heated and expanded. I don't have a tstat in the system right now, so as long as the pump is running, water flows into the tank, and then back into the system, even when the water is cold.


My whole system is plumbed as per your drawing, except my tstat is in the manifold housing and not at the HE, so (as per the drawing) I don't have the labelled "tstat bypass" and basically the labelled "fixed bypass" is my tstat bypass because the hose connects below the tstat.
I am curious as to the purpose of the two bypasses in the drawing. I can understand the tstat bypass, but then what is the purpose of the fixed bypass?

yeller
09-08-2014, 03:49 AM
Not super easy to see, but the arrow in this pic points at the overflow hose going from my tstat housing to the top of my expansion tank.
80778


This pic shows the fill hose going from the bottom of the expansion tank to the inlet hose for the circulating pump.
80779


....and for those that are curious. That lovely expansion tank was taken out of a VW. :boggled:

Morgan's Cloud
09-08-2014, 07:06 AM
Just a thought . You said that you had the exchangers tested , but were they dipped and cleaned ?
If they've got crusty scale on the tubes it can greatly reduce their ability to 'exchange' that heat.

gcarter
09-08-2014, 08:31 AM
I am curious as to the purpose of the two bypasses in the drawing. I can understand the tstat bypass, but then what is the purpose of the fixed bypass?

The small bypass is to help bleed air out also, as far as I can tell.

+1 on what Steve said.

BUIZILLA
09-08-2014, 09:32 AM
it sounds to me like the left bank/right bank water flow is deadheading against each other

gcarter
09-08-2014, 11:43 AM
it sounds to me like the left bank/right bank water flow is deadheading against each other

I'm not sure that can happen Jim.
I don't know about glen's HE, but ,I'd assume, all HEs of that size are multi pass, and the two outlets going to the exhaust water manifolds are on different passes.
At least mine are.
Another potential thing to investigate is circ pump water flow. On the largest version (1,100 HP) of my system, it calls for 120 GPM.
My HE (good for 500 HP) , and my circ pump is 55 GPM. I'm assuming mine is sufficient, but I don't really know yet.
Your's would fall into the intermediate size (700 HP).

yeller
09-08-2014, 01:45 PM
Just a thought . You said that you had the exchangers tested , but were they dipped and cleaned ?
Yes had them professionally dipped, cleaned and pressure tested.


it sounds to me like the left bank/right bank water flow is deadheading against each otherSorry if I'm asking dumb questions, but:
Are you talking about the closed cooling side internally in the motor? How would that would be possible?
Or are you talking about the raw water side? I am getting good flow out the exhaust. Headers stay nice and cool.
Or are you talking about the HE? I have one inlet and one outlet for both the raw water and the closed cooling water, so I don't know how it could deadhead.

yeller
09-08-2014, 01:52 PM
Another potential thing to investigate is circ pump water flow. On the largest version (1,100 HP) of my system, it calls for 120 GPM.
My HE (good for 500 HP) , and my circ pump is 55 GPM. I'm assuming mine is sufficient, but I don't really know yet.
Your's would fall into the intermediate size (700 HP).
I believe my circ pump is 55 GPM. I have no idea what the HE is rated for. I've done several different google searches, but can't find any company that lists HP ratings for their HE's. But even if I'm undersized, I wouldn't think I would overheat in a matter of minutes when just idling??

Morgan's Cloud
09-08-2014, 02:31 PM
** A disclaimer , please don't interpret my posts/suggestions as coming from someone who knows anything ** :biggrin.:

Is this a new problem or did it happen as soon as you installed the closed system ?

Does the raw water dumping out of the tailpipes even feel a weenie bit warm or is it still very cool , like it hasn't interacted with a HE that has a hot side ?

I think that the only reason I ask that is because I'm wondering if the circulating pump is not somehow able to pump the fresh water into and through the HE.

gcarter
09-08-2014, 04:56 PM
Glen, could you explain, point by point, the hook up in the picture w/no engine?
How're you splitting the raw water flow to the two manifolds?
Where would the circ pump be?

yeller
09-08-2014, 07:56 PM
MC, this is a new system. Water is definitely going through the HE.

George, I attached a pdf labelling every hose in that pic. I don't have an easy jpg editor, so I had do it in my pdf editor.
Raw water flow exits the HE and goes to a T-fitting, and then to the two headers.
I am using a crank driven raw water pump. (Same one you are using).
I have an electric circulation pump and it mounts to the block like a conventional pump.

XABICHIN
09-08-2014, 08:44 PM
Had a Nordic 25 with 496 mag that would start to overheat and go into limp mode or shut down. Finally found the water supply hose to the pump would collapse and restrict water flow. Changed the hose and the problem went away. Just a thought....

gcarter
09-08-2014, 09:47 PM
Glen, it looks correct. The only thing I might have done differently would have been to include the oil cooler in the run from the strainer to the raw water pump inlet and eliminated the long run around the transom. But I'm reasonably sure that's not your problem.
The only things I can think of are:
the size, the Monitor system for 700 HP is 4-1/8" X 32", the 600 HP version is 4-1/8" X 29". So, is it big enough?
http://www.perfprotech.com/high-performance-fresh-water-cooling-systems/category/1511
You were correct that it should cool at idle, which brings up my next question, how many passes is it? You may already know, the dividers are visible when the end caps are off. If it's a single pass (doubtful) it probably wouldn't cool.
Of course, you haven't run it since you did the purge exercise, so this discussion may be simply academic.

donzidon
09-09-2014, 12:03 AM
I don't have a lot of experience with closed cooling systems in boats, but I would think that capacity can't be the issue here if you are not running the boat at speed with that beautiful blower humming. The second bypass line is to bleed air from the system, and the flow also lets you know that the primary water pump is working. My old Jaguar XJ8 has a bypass line like that.

I guess one question to ask is whether you feel heat in the water line running from the engine down to the heat exchanger/radiator intake. With the thermostat out, that should be heating up with the engine. If it isn't, then you clearly have blockage inside the engine or heat exchanger, air in the pump or there is a plumbing problem. One idea would be to tape a thermometer to it and see if the temperature matches what you are seeing on the gauge. A remote oven thermometer might be an option.

If it was my project, I would have the electric pump in backwards or something equally clever.

Great looking engine bay.

- Don

yeller
09-09-2014, 12:33 AM
George, I thought long and hard about the cooler placement, to try and avoid circling the engine with hoses, but I just couldn't make that happen. Based on the size and style of the oil cooler and where I had to mount my fuel cooler, I didn't have much choice.
In the end, I figured it would still work ok because it is basically the same layout as what came on the HO.

I've been trying to remember if the HE is multi pass or not. It wasn't until a couple nights ago during a google session on HE's that I discovered that most are multi pass. Up until then I always thought they were all single pass. I did look at the HE without the end caps on before I had it cleaned and inspected. The trouble is, I can't remember which type it is, because at the time I didn't know there were different styles.

I wasn't able to get to the boat today to fire it up, so I don't know if it was an airlock causing the problem. Now I'm not going to bother starting it to check the airlock issue. First thing tomorrow, I'm going to go there and pull an end cap off the HE.

Part of me wants to find out it's a single pass, because then I will know what the problem is and how to fix it. The other part of me doesn't want to see that, because HE's aren't cheap. :boggled:

yeller
09-09-2014, 12:43 AM
Don...believe me...I thought about the backward pump issue. Easy to miswire and run backwards, but after installing the clear rad hose, it was obvious that's not the issue.

I do feel the hose from the tstat housing to the HE heating up. I can also feel the hose from the HE to the circ pump heating up. Temperature "feels" very similar, which made me think the flow wasn't sufficient. It's still possible that there was an airlock causing low flow through the HE, but now I'm 60/40 that I actually have a single pass HE.

Guess I'll find out tomorrow.

yeller
09-09-2014, 02:28 AM
You were correct that it should cool at idle, which brings up my next question, how many passes is it? You may already know, the dividers are visible when the end caps are off. If it's a single pass (doubtful) it probably wouldn't cool.
Of course, you haven't run it since you did the purge exercise, so this discussion may be simply academic.
George, I've been thinking about this some more. Would it really make much of a difference whether the raw water side was single or multi pass? With a single pass, I would expect a greater temperature differential between the engine coolant and all the HE tubes. The greater temp differential should result in better cooling. In a multi pass, the temp differential would be less on the 2nd, 3rd and 4th pass tubes.
My thinking is that it would be much more important that the HE be multi pass on the engine coolant side? Running the engine coolant multi times over the HE tubes would be far more effective. Am I thinking the right way? Is there any way of knowing how many passes it is on the coolant side?

In the pic below, the "tube side fluid" would be the raw water and the "shell side fluid" would be the engine coolant.

80781
EDIT: I was thinking that the above pic would be called 5 pass design on the engine coolant side because the "baffles" force the coolant across the tubes 5 times. I did some more searching and realize this is not the case. The baffles don't determine whether it is a single or multi pass HE on the shell side. Nontheless, I would think that if there are not enough baffles to force the coolant across the tubes enough times, the HE might not transfer enough heat.

I'm still somewhat confused as to why a multi pass HE (on the tube side) would give me better cooling.

gcarter
09-09-2014, 08:56 AM
Glen, in principle, these HEs are the same, but the multipass arrangement is diametrically different.
The baffles are in the plenums.
Kind of like this:

http://www.masonmfg.com/images/newhe1.gif
Well, in theory anyway.
So, when you remove an end cap, you'll see dividers. The arrangement is staggered so that water flows from end to end several times.
So for a 5 pass, there'd be 2 dividers on one end and three on the other end.
Heat transfer to water is such that longer exposure times are required to minimise the exchanger size.
I hope you get to run it today and find it works well, at least w/no load.

Since yours fits between the stringers w/space to spare, I'm a little concerned about the size.

MOP
09-09-2014, 09:19 AM
Another test is to put a clear hose from a cooler outlet to a riser, goose the engine a few times to see if trace bubbles appear, this will show if air is being sucked into the system. Even with good water flow if you have air being introduced it can accumulate in the cooler leaving some tubes uncovered with water. Another point no need to worry about circ pump flow direction, GM uses reverse flow in several applications. Don't worry about directional flow the engine does not care which way it flows as long as it does!.

Phil

BUIZILLA
09-09-2014, 09:46 AM
Another point no need to worry about circ pump flow direction, GM uses reverse flow in several applications. Don't worry about directional flow the engine does not care which way it flows as long as it does!. Phil actually, the circ pump impeller design plays a huge influence on water flow, I can factually tell you that on my counter rotating 454 Crusaders in my Cary that you don't want to mix up the pump rotations... the SS impellers were completely different from each other.

bertsboat
09-09-2014, 01:42 PM
Buz, is there two different circulation pumps? Right and left?

joseph m. hahnl
09-09-2014, 09:07 PM
Buz, is there two different circulation pumps? Right and left? Usually there is one cold water pump that runs bi directional you have to pay close attention to which side you hook the pick up and exit on as it will be opposite from an LH to an RH. As far as circulators " engine water pump" there is a an RH and an LH but most marine ones are bi directional. So buying an automotive water pump and putting it on a reverse rotation engine could be a disaster if it's not bi directional.


A porked head gasket will over heat an engine pretty quick:yes: But air bleeding into the system will too:bonk:Sea strainers can be notorious for a source of air:kingme:

bertsboat
09-10-2014, 07:18 AM
Sea strainers, I have had my eye on those. I see air in them, the tops are clear. Stainless marine sell a model with self bleeders on the top. Also, I didn't know the circulation pumps were directional. I am going to call Jerry's today and look into availability. Also, the way you hook inlet and outlet is important on tight and left?
what about these electric pumps that are being talked about? Are they recommended over engine driven pumps? I am assuming we are talking about the raw water pumps.
thanks, great info.

BUIZILLA
09-10-2014, 07:57 AM
Bert, Meziere makes electric CIRCULATING pumps, not sea water pumps, GC has an electric pump on his TR, and had one on the Minx, I used them on my race cars for years, but never on a boat, not yet anyways..

MOP
09-10-2014, 08:29 PM
actually, the circ pump impeller design plays a huge influence on water flow, I can factually tell you that on my counter rotating 454 Crusaders in my Cary that you don't want to mix up the pump rotations... the SS impellers were completely different from each other.

Your talking stock block style in which the cant of impeller blade is critical. His being electric it makes little difference though running reverse similar to LT1's will keep the top end a little cooler, maybe not a bad idea with a charger.

yeller
09-14-2014, 03:02 AM
A porked head gasket will over heat an engine pretty quick:yes: Just when I thought I had it narrowed down, you give me something else to worry about. :garfield: ;)

I finally got out to the boat today. I changed my mind on pulling the end cap on the HE and fired it up. Motor didn't overheat this time, but the temp still got hotter than it should. It went up to 160, which normally wouldn't be considered too hot, but considering I don't have a tstat in it and I was only running it on the hose, I think that's too hot. It almost certainly would get a fair bit hotter if I took it for a run and put a load on the engine.

I picked up an IR thermometer to check temperature differences. When I shot the two ends of the raw water side of the HE, there was about a 36 degree (F) difference, but I only saw about a 7 degree difference between the two ends of the closed cooling side. I couldn't get a proper reading off the inlet and outlet hoses. I'm guessing thats because of the S/S sheathing. The braiding probably throws it off. Plus the IR doesn't seem to like anything highly reflective. I couldn't get any reading off the polished headers.

The HE doesn't look to be pulling enough heat out, but I'm not yet convinced that's my only problem. Because Joseph gave me more to worry about, I'm going to do a leak down test before ordering a new HE.

On a side discussion...George, I don't understand how the raw water making multiple passes would pull more heat out of the engine cooling water. It makes sense to me if the engine cooling water was running through the tubes and making multiple passes, but not the raw water. If you look at the pic I posted, the raw water is going to keep the tubes cooler than a multi pass. In a multi pass, the raw water is going to get warmer on each pass and therefore the tubes are going get warmer, so there will be less temperature differential between the two fluids. Less temperature differential would result in less heat transfer.

joseph m. hahnl
09-14-2014, 08:19 AM
160*F is a good number for closed cooling. :yes: An over heat is when the gage needle runs away, up and over 200*F. If it runs from 160* to 190* your good. It will most likely run cooler at mid throttle than at idle, and spike from WOT to off plane slow downs :biggrin.:.

Ed Donnelly
09-14-2014, 09:04 AM
Put a piece of duct tape or electrical tape on your polished headers
Then take a reading shooting the tape..Ed

gcarter
09-14-2014, 10:04 AM
160*F is a good number for closed cooling. :yes: An over heat is when the gage needle runs away, up and over 200*F. If it runs from 160* to 190* your good. It will most likely run cooler at mid throttle than at idle, and spike from WOT to off plane slow downs :biggrin.:.

Joe, w/an electric pump, your scenario isn't true. The coolant flow rate is constant.
The indicated temperature is a true indication of the engine temperature, unlike w/a mechanical pump.
I'm still concerned it might be too small, but Glen won't know until he puts a load on it.

gcarter
09-14-2014, 04:11 PM
Duh! :bonk: I don't know why I didn't think of this sooner.
Another temporary problem Glen may be having is not enough water available through the hose he's using.
There's probably little he can do about it either.

joseph m. hahnl
09-14-2014, 07:29 PM
Joe, w/an electric pump, your scenario isn't true. The coolant flow rate is constant.
The indicated temperature is a true indication of the engine temperature, unlike w/a mechanical pump.
I'm still concerned it might be too small, but Glen won't know until he puts a load on it. I Don't buy that. The flow rate of the cold water flow will change. Won't it? In any case 160* is still a good number that is not hot in the least bit.:biggrin.:
Right on , we'll just have to see what happens under load:kingme:

yeller
09-15-2014, 01:52 PM
Thanks for the feedback guys.


160*F is a good number for closed cooling. :yes: An over heat is when the gage needle runs away, up and over 200*F. If it runs from 160* to 190* your good. It will most likely run cooler at mid throttle than at idle, and spike from WOT to off plane slow downs :biggrin.:.I agree 160 is good.....but without a tstat, running at idle, with cold water pumping through the system, I believe 160 to be high. It shouldn't have gone over 120 in this situation.


Put a piece of duct tape or electrical tape on your polished headers
Then take a reading shooting the tape..EdNever thought about that. Thanks Ed.


I'm still concerned it might be too small, but Glen won't know until he puts a load on it.I'll find out this afternoon. Putting it in the water today. George, I thought the size would be big enough. It's larger than the one on my HO and I had absolutely no issue with that setup, no matter how hard I ran the boat.


Duh! :bonk: I don't know why I didn't think of this sooner.
Another temporary problem Glen may be having is not enough water available through the hose he's using.
There's probably little he can do about it either.I don't think this is the case. I had pretty good water pressure at the house and the hose is connected directly into the cooling system, so no water is lost due to using muffs.

If it overheats this afternoon, I'll do a leak down test to check for blown head gasket or cracked head. If it passes that test, I'll order a bigger HE.

gcarter
09-15-2014, 04:18 PM
I don't think this is the case. I had pretty good water pressure at the house and the hose is connected directly into the cooling system, so no water is lost due to using muffs.

Sorry Glen, but this makes a huge difference. A typical 5/8" garden hose (and not to mention the 1/2" plumbing that supplies the hose bib) has trouble flowing 7-8 GPM. Your raw water pump is probably capable of 30-40 GPM.
There's a deficit any way you look at it. I think generally you can't run more than about 2,000 RPM on a hose.

yeller
02-06-2015, 04:04 PM
So I finally got around to pulling my H/E and sure enough...it's a single pass, which is probably why engine overheated.


I found a used 5" x 27" 4-pass H/E at a killer price.
81435

A bit beat up and I'll have to totally redo my cooling system, but that's not my real concern. I'm concerned about the inlet/outlet size of the raw water side. The closed cooling side is good, but the raw water side is only 3/4" and 5/8".
That's pretty small considering the rest of the system is 1.25".

I've googled H/E pics but can't find a pic of this one, so I don't know what the application is. I know it's large enough to cool my motor, but would I get enough raw water flow with the tiny inlet/outlet?

I got the unit cheap enough that I can easily sell it for more than I paid for...but I can also afford to spend a couple hundred on it if a rebuilder can solder on larger tubes.

Any thoughts??

gcarter
02-06-2015, 07:44 PM
Maybe.......
Your engine inlet and outlet are 1-3/4" (or at least the circ pump inlet is 1-3/4") and 1-1/2". The raw water side needs to be 1-1/4" each. I hope you can get it modified. There should be good resources there in Vancouver.

yeller
02-07-2015, 05:11 PM
Just talked to a local rad shop and they'll clean it, pressure test, and install 1.25" inlet/outlet for $200. Going to drop it off next week.