Need closed cooling system help

[donzidon]

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]

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.

[yeller]

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]

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.

Straight-tube_heat_exchanger_1-pass.bmp
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]

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:


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]

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]

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]

Buz, is there two different circulation pumps? Right and left?

[joseph m. hahnl]

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 But air bleeding into the system will tooSea strainers can be notorious for a source of air

[bertsboat]

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]

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]

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]

A porked head gasket will over heat an engine pretty quick

Just when I thought I had it narrowed down, you give me something else to worry about.

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]

160*F is a good number for closed cooling. 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 .

[Ed Donnelly]

Put a piece of duct tape or electrical tape on your polished headers
Then take a reading shooting the tape..Ed