[ron2424]

I need help identifying the lines coming off of my 70's Chevy 350 water pump. There is a fitting on the top of the pump where the previous owner has run a pipe T with 2 hoses returning to the manifold. What are the purpose of these lines. I live in So Cal and I am trying to get the motor to run cooler. I was thinking that these lines were for a heater core (there is no heater in the car) and this was just a homemade rerouting for the pump that was in the car. I was wondering if I cap off these lines or replace the pump to get more water flowing to the rad if it would be better. Thanks in advance.

[oldbogie]

Originally Posted by ron2424

I need help identifying the lines coming off of my 70's Chevy 350 water pump. There is a fitting on the top of the pump where the previous owner has run a pipe T with 2 hoses returning to the manifold. What are the purpose of these lines. I live in So Cal and I am trying to get the motor to run cooler. I was thinking that these lines were for a heater core (there is no heater in the car) and this was just a homemade rerouting for the pump that was in the car. I was wondering if I cap off these lines or replace the pump to get more water flowing to the rad if it would be better. Thanks in advance.

In spite of all the advertisements for high output water pumps, pumping enough coolant is seldom the problem with a hot running engine. Unless you spend a lot of time at elevated RPMs a stock pump should just be fine. At high constant RPM the problem is the opposite of what you'd expect from a stock pump. Since a stock pump is expected to do a of idle and mid RPM work it's designed to move plenty of coolant at those speeds, it's problem when used on a high RPM engine is too much capability where it tries to push too much coolant and the system isn't up to the flow so the pump goes into cavitation resulting in a host of other problems.

Your pump is set up for a bypass which is normally thru a heater core. The bypass is there to keep coolant circulating thru the engine when the thermostat is closed. If this doesn't happen steam pockets can form which causes local overheating even though the gauge will indicate the engine coolant is still cold. The local overheats, mostly in the area between the paired exhaust valves can and do lead to cracks forming in the heads due to the thermal stresses in the cast iron. While the SBC has a small bypass under the right horn of the pump it is not sufficient especially if you have a habit of getting on the throttle before the engine is throughly warmed.

Most overheating issues (assuming the car has a correctly sized radiator) are related either to a lack of coolant or air flow thru the radiator. Generally if the engine keeps getting hotter when cruising, there is a lack of coolant flow thru the radiator. The most common problem is corrosion and crud plugging core tubes. If the engine tends to get hotter and hotter on extended idle this is usually a lack of air flow thru the core. Inadequate fan capacity, missing or damaged factory style fan shrouds, debris in the fins are typical causes.

Radiators that need to deal with air preheated by the air-conditioning's condenser will have problems as they age and loose efficiency. Automatic transmissions that slip because of the need of a rebuild add a lot of heat to the ATF that has to be cooled by the radiator. Another hot rod source of heat in the automatic's cooling circuit is the addition of a high stall converter.

The state of engine tune has an effect, retarded spark, a cam coming out of time due to chain and gear wear cause the engine to run hot.

Hope this helps.

Bogie

[PatM]

Hi OldBogie.

Is the SBC's internal bypass not sufficient for street use when not using a heater core to supplement the bypass? I ask because I was planning on starting my engine with the (2) pipe-tapped holes in the water pump casing plugged, thinking the bypass fuction would be handled by the internal bypass.

Pat

[ron2424]

The temp has been creeping up at highway speeds. If I go up a long hill or run the A/C it starts to do it as well.
Its a 350 clipped into a 50 Merc. There was a mech fan and shroud behind a Be cool radiator. It also had a manually switched pusher fan in front of the rad and condenser for when caught in stop and go traffic. It all worked nominally well, but of course not being one to leave well enough alone, I decided to switch to 2 11" electric fans pulling and removed the pusher. They run on dual relays and kick in and out properly. I had also replaced the 185 deg thermostat with a high volume 160 Thermostat. The car was running much hotter much quicker to the point of overheat on the highway. I had fabricated a small air dam to get more air to the rad and replaced the therm with a 160 reg flow and it ran alot cooler. I took that as a clue that I was maybe moving the water thru the rad too fast when I had a low restriction thermostat. I was thinking of replacing the water pump with a higher flow, but if my problem was water moving too fast through the rad, that might make it worse. There seems to be very little to no corrosion in the radiator. The fact that the car was behaving differently with the prior set up leads me to believe that my logic or configuration just needs to be reworked....as usual.

[curtis73]

Its absolutely an airflow issue. Period. When you say "creeping up at highway speeds", and "electric fans" there is no doubt.

Ditch the electric fans is the easy answer but electric fan owners are so adamant about the 600 hp they save with them that they keep trying to make them work.

[carsavvycook]

Putting in a regular flow 180, or 190 thermostat will slow the flow down so your fans have a chance to cool it.

[curtis73]

Originally Posted by carsavvycook

Putting in a regular flow 180, or 190 thermostat will slow the flow down so your fans have a chance to cool it.

While that seems to make sense, in practice it rarely works. While the coolant spends more time rejecting heat in the radiator, it also spends more time in the block heating up. Its a simple matter of heat in minus heat out. As long as there is enough flow, more won't help, and neither will less.

The bottom line is this. I field a thousand questions like this at the shop. I will be the first to admit that electric fans can work just fine, but I get this one so often and when I blame the electric fans people jump all over me saying that OEMs do it all the time. That's true because they have multi-million dollar R&D budgets. Many times people assume that they can replace a big belt-driven fan with a 1/8 hp electric plastic fan built by the lowest bidder and cool a 700-hp big block. Its just not the case. It takes a careful and comprehensive evaluation of the whole package along with a lot of knowledge to get one to work.

In my experience, most people use electric fans because they don't have room for a mechanical one. If you use an electric fan that occupies less space than a mechanical one, chances are it isn't strong enough to move adequate air. I finally found an electric fan that would move enough air for my Caddy 500, but to get it to fit I had to move the radiator forward. Even then it was barely adequate and the whole package cost $600.

If you have highway cooling issues, the problem is that the fan is blocking more airflow than you need at highway speeds. On the highway, moving air offers thousands of CFMs of airflow, but electric fans tend to restrict that greatly. If you have a large single fan with a shroud you can usually window the shroud with some rubber flaps. That way at idle it sucks the flaps shut for max performance, but at highway speeds where the ambient air offers more flow than the fan, the flaps can push open and help flow.

[ron2424]

Thanks for all your insight and experience. I installed 2 Spal 11" fans diagonally (they wouldn't fit side by side) that are "rated" at 1390 CFM. They cool the motor down nicely around town yet not on the freeway. I'm wondering why the car ran cooler on the freeway when previously there was a pusher fan on the front of the rad that wasn't on blocking the airflow. I "assumed" that by removing it would allow better airflow to the rad and condenser. The mech fan and shroud, I also assumed would provide as much resistance as the 2 new electric fans. Yesterday I drained the rad and tried a water wetter mixture and the car is running about 10 degrees cooler yet still creeps up on the freeway. I read that less than a 50 % coolant mixture would run cooler. It recommends running more ethyl glycol in winter months, but living in So Cal I only get a few hours a night of close to freezing temps. I was also thinking of running a plate over the top of the rad to force more air through the rad and preventing it from flowing over it.

[carsavvycook]

One thing we were not informed of is what type of vehicle this is in. If it is in a truck with a lot of air space flow around the radiator, cover it up on the sides also. I am closing up the upper air space to the radiator on a 1965 Mustang right now, it's sides are closed up already.

P.S. I moved out of L.A. in 1978 to get as far away as I could from the "stop and go" traffic on the freeway, so I understand the "heating up at freeway speeds" problem you have.

[ron2424]

Don't get me started on the LA traffic nightmare.....It is a Chevy 350 clipped into a '50 Mercury with a DeSoto grill molded in. I had it out today and it seems to be running good. I had it on the freeway for a while. I didn't run the A/C but it was fluctuating between 180-200. The fans were kicking in at 190 as relayed and the temp would drop down to 180 where they would turn off and start to creep again. There are 2 screened vents that used to run into the cab but the ducts were shut off when the car was clipped. The screens had alot of paint shot over them virtually sealing them off. I removed them and installed slanted baffles that push air into the engine compartment. The rad sits up into the hood as it is a larger core Be Cool than stock and there was a 2" gap for the air to flow under the condenser and rad, I fabricated a 3" sheet of Aluminum on a 45 deg angle to push the air into the rad. I am going to mount another sheet under the cowl that sits over the rad to block flow over the rad as well.
I'm not a big fan of using "miracle chemicals" to help the heat transfer. If everything is working right and with the larger core rad, it should run real cool. I know that at 98 degrees and above outside temp, it will run up at the top of acceptable running temp, but that ambient temp is so common here in the summer, I wanted to keep it away from 220-230 degrees with the A/C on. As someone stated earlier, the engineers that design these cars weren't taking into account a different motor, grill etc. I'm just wondering if I am getting some weird turbulence and back pressures that is messing with my airflow.

[carsavvycook]

To be absolutely positive it is a air flow problem turn on your air conditioning to high max with the engine at operating temperature at 1800-2000 rpm. Let it run for 3 minutes and check the temperature out of the vents. Next spray some water from a garden hose with a water nozzle set on light spray at the a/c condenser, and recheck the temperature at the vents. If it is colder you have a air flow problem, if not your engine could be running a little too lean at freeway speeds(only between 2 and 4 am in L.A.)

[oldbogie]

Originally Posted by ron2424

The temp has been creeping up at highway speeds. If I go up a long hill or run the A/C it starts to do it as well.
Its a 350 clipped into a 50 Merc. There was a mech fan and shroud behind a Be cool radiator. It also had a manually switched pusher fan in front of the rad and condenser for when caught in stop and go traffic. It all worked nominally well, but of course not being one to leave well enough alone, I decided to switch to 2 11" electric fans pulling and removed the pusher. They run on dual relays and kick in and out properly. I had also replaced the 185 deg thermostat with a high volume 160 Thermostat. The car was running much hotter much quicker to the point of overheat on the highway. I had fabricated a small air dam to get more air to the rad and replaced the therm with a 160 reg flow and it ran alot cooler. I took that as a clue that I was maybe moving the water thru the rad too fast when I had a low restriction thermostat. I was thinking of replacing the water pump with a higher flow, but if my problem was water moving too fast through the rad, that might make it worse. There seems to be very little to no corrosion in the radiator. The fact that the car was behaving differently with the prior set up leads me to believe that my logic or configuration just needs to be reworked....as usual.

In all of Hot Roddom, there's probably nothing more miss-understood than engine cooling. Of course people selling high output pumps don't really help. For a street rod, like an ordinary passenger car or light truck. The thermostat sets the pace of events. If it can't, then something is amiss with flow capability and or other component selection. Seldom with a street vehicle is the flow capability of a stock coolant pump to blame. Its sized too big to start with and the thermostat is used to manage the flow rate which in turn manages engine temp because the flow rate establishes the BTUs that can be moved from the engine to the radiator and on to the surrounding air. So with a thermostat in the system, it becomes a self balancing/self controlling system as long as the component of the radiator is large enough for the heat load to be transferred from the engine. Forget further rocket science and forget the typical BS on this subject, what I said is all you need to build an effective system. Since most rodders aren't at a place where calculating BTUs generated by the engine nor BTUs transfered from a radiator is possible by them, it's best to follow the OEMs practice. For a Chevy 350 this is pretty easy as there's lots of OEM applications with specific radiators to fit the available space the vehicle's envelop provides. You can easily compute the face area needed based on this data. Counting the number and size of tubes will get the coolant transfer area and getting the fin count will tell you how much air transfer surface is required. You will find that whether the 350 is in a Malibu or a Camaro, whether the radiator is conventional or cross flow, it contains about the same overall face area, same tube area, and same fin area. High performance, and or air conditioned vehicles tend to have more than vehicles with standard engines and or no air-conditioning. Pickups usually have more radiator capacity since they're expected to work the engine harder. Generally, when you vary from these factory dimensions, you can expect that if your variation is smaller, you'll experience heating problems. Aluminum radiators don't have as much heat transfer capability as copper/brass as a function of the material's ability to move heat. So they need to be 10-15 percent larger to exchange the same amount of heat. (Larger can be more tube and or fin area within a given face area.) If the aluminum radiator has plastic tanks add another 5 percent to the core size, since plastic is an insulator and the heat transfer from an otherwise metal tank is lost.

So you can see that when you strike out on your own with cooling systems design you're pretty much on your own, lost in a world of people who want to sell high volume pumps whether you need them or not, whether you can make use of them or not, whether you even know what the difference, if any, between the OEM pump and "high volume" pump is. Everybody just assumes that bigger is better, this ain't necessarily true. Water wetter, there's a joke, if you need 2 to 5 degrees that badly either you really don't have a problem or need more radiator capacity for a larger problem that water wetter can't solve. Aluminum radiators cool better than old fashion copper/brass, this is patent baloney. They're lighter, the brazed and welded units are perhaps stronger, but certainly not better at heat transfer from a materials standpoint.

Inadequate heat transfer from the radiator is telling you it's too small for the job. Or it has become plugged, usually due to corrosion products reducing the number of tubes available to coolant flow.

What you're experiencing is typical of an inadequate amount of radiator from which to transfer the total heat load to the atmosphere. You can crutch such a system to a point with more air flow, and it looks like your original design did a better job of that than subsequent changes to that design. But anything that requires so much fan is being crutched and lacks basic effectiveness.

A basic rule of thumb is that fans are required to pull air at idle and in stop and go traffic. At cruise there is sufficient air flow thru the radiator to maintain thermostat selected operating temp within the engine. If you're requiring cruise air flow plus fans that's a really good indicator that the radiator is too small for the heat load it's expected to reject. It sounds like you also have air-conditioning. This leads to a situation where the condenser reduces the amount of air that can be flowed thru the radiator since it presents a resistance ahead of it. Additionally, it's (the condenser) rejecting heat which causes the air temp entering the radiator to be above ambient.

I suspect the 160 degree thermostat only results in the problem taking a few minutes longer to present itself, which is another indicator that the radiator can't pass enough BTUs to the atmosphere. Rerouting or terminating the coolant bypasses won't help either because the root problem is insufficient thermal capacity of the radiator. Eliminating the bypasses will only force more coolant into a system that's already at saturation, all you'll get for that effort will be increased pump pressure as it attempts to force more fluid thru an already overloaded system.

Some things you can do to take some BTU load off the radiator, I'm assuming the Merc is dimensionally constraining radiator size such that bigger area is not a practical solution. This is pretty common problem with custom installations in hot climates.

- First if this has an automatic transmission, and it's known to be in good shape (i.e. not slipping which causes a lot of heat) and it has a cooler in the radiator's pump side tank. The installation of an external cooler (which can be had with a fan) on the pressure side ahead of the radiator's cooler will take a lot of BTUs off the radiator since the tranny fluid will be precooled when it arrives and might actually take some heat out of the engine coolant as a result. But more importantly won't be dumping heat into the enigne coolant. It's common to see a 10-20 degree drop in radiator temp with the addition of a cooler

- Second is the converter, if you're running a high stall converter there are some things to look at:

a. Cruise engine RPM must be higher than the stall RPM. Running the engine at revs less than the converter stall results in a lot of hydraulic slippage which generates a lot of heat. This usually means stiffer rear gears to get the revs up.

b. The installation of a lock up converter completely eliminates the above situation when cruising for extended times and may prove to be more effective that stiffer rear gears used to get the engine revs up. Both of course can be done.

-Third is an engine oil cooler. Like that for an automatic transmission, these coolers can be had with an independent fan and a thermo switch that routs engine oil away from the cooler when the engine is cold. An engine oil cooler can take so many BTUs out of the bearings and from the underside of the pistons that coolant temps will reduce 10 to 20 degrees.

The use of independent transmission and engine oil coolers can take enough BTUs off the system to drop up-wards of 40 degrees off the coolant temp. This in you case will probably be enough to put the thermostat back in control of coolant temp. Those oil coolers with independent fans can be mounted anywhere they would be damaged by road debris.

If these don't do it for you; or as an alternative to try first, I offer number 4. Just Google finned tube and ton of places, many in the SoCal area, will show up.

- Fourth is the addition of a coolant loop attached to the frame. There is commercial finned tube made for larger coolers such as found in grocery stores, also used in air-conditioning systems. These can be placed in series with the radiator, the easiest being a take off from the lower outlet into the finned tube than back up front and into the pump inlet. Or you can tap into the bypass that normally goes to the heater core, though this forces a longer engine warm up cycle. But this has the ability to add a lot of cooling capacity that can mostly be hidden from view with a custom car where radiator sizing is constrained by not wanting to carve up the sheet-metal. Even running large diameter copper pipe clamped tightly to the frame is pretty effective as it not only adds capacity but can use the frame as a heat sink. Keep in mind that such a set up while using standard plumbing pipe, needs to have the fittings brazed together rather than soldered.

So there are a lot of tricks to get a considerable BTU load off the radiator which will allow the thermostat to manage the coolant flow to maintain it at the specified temp. Typically the engine should operate from 5 to 10 degrees above the thermostat's stated opening temp.

Bogie

[ron2424]

Thanks so much Bogie for taking the time to articulate the finer points on the subject. Giving me info that helps me understand the process is always much better than fast fixes without explanations.
A few further questions: 1) I haven't gottoen a clear idea as to what an acceptable running temp range for a 350. I could be chasing ghosts.
2) I have read that if your coolant mixture is too rich of a coolant you will get less cooling capacity as the concentration goes up. Because the car is running cooler when I switched to the "miracle elixir" that is probably 3 cents worth of chemicals diluted in H2O for an exorbitant price, it could be that just by running a more dilute mixture would account for the drop in temp I saw due to better heat transfer.
3) The dimensions of the Be Cool radiator is the basically the same for a "performance" Camaro/Firebird radiator (give or take a quarter inch here an there). There appears to be no pitting in the rad and when viewing the flow of water when running without the cap on I can see flow. I don't know what sort of turbulence I should see to indicate proper or unrestricted flow.
4) I was thinking of getting a stiff bristle brush to clean out the condenser to try to improve airflow but also to keep in mind not to damage the condenser fins.
Once again thanks for the input that has been given and the brain activity needed to hypothesize.

[oldbogie]

Originally Posted by ron2424

Thanks so much Bogie for taking the time to articulate the finer points on the subject. Giving me info that helps me understand the process is always much better than fast fixes without explanations.
A few further questions: 1) I haven't gottoen a clear idea as to what an acceptable running temp range for a 350. I could be chasing ghosts.
2) I have read that if your coolant mixture is too rich of a coolant you will get less cooling capacity as the concentration goes up. Because the car is running cooler when I switched to the "miracle elixir" that is probably 3 cents worth of chemicals diluted in H2O for an exorbitant price, it could be that just by running a more dilute mixture would account for the drop in temp I saw due to better heat transfer.
3) The dimensions of the Be Cool radiator is the basically the same for a "performance" Camaro/Firebird radiator (give or take a quarter inch here an there). There appears to be no pitting in the rad and when viewing the flow of water when running without the cap on I can see flow. I don't know what sort of turbulence I should see to indicate proper or unrestricted flow.
4) I was thinking of getting a stiff bristle brush to clean out the condenser to try to improve airflow but also to keep in mind not to damage the condenser fins.
Once again thanks for the input that has been given and the brain activity needed to hypothesize.

I'd consider 220 as an absolute top end safe temp. But I like under 200 much better.

Which Be Cool? Besides face area, the tube configuration and fin count has a lot of influence. Typically you see one of two tube lay outs a single 1 or 1&1/4 inch tube or dual tubes.

I'm not to crazy about 100% non aqueous coolant, it's costly and I haven't seen where it improves either cooling or component longevity. I think a 50/50 mix of good old green stuff and distilled water does a good job. I say DISTILLED water, especially where you live, I'm originally from San Diego, California tap water is too reactive, softened water has some sodium chloride in it which is a no no and filtered water cannot remove minerals in solution, which Calif water has plenty of. Water wetter is foam-less detergent which breaks down water's surface tension so the it hugs surfaces tighter, this helps, but not a lot.

Bogie

[ron2424]

The Be Cool has 2 tubes running in a horizontal fin arrangement. What is the optimum distance between rad and condenser? I had the car out again today and the pattern that's developing (granted it has been much cooler ambient temp the last 2 days) is the car heats up to 195 cruising around town and the fans kick in and it cools to 175 where they shut off. The process then repeats. When I am on the freeway it runs up to 195 and rather than cool all the way down to 180 it hangs at around 190 where the fans are still running at highway speed. I would love to get it to cool back down and not run on the fans at highway speed. I have not tried the A/C on the highway yet as it has been pretty cool out. That's when I was seeing the creeping up to 220 and when going up hills and loading down the engine, the system couldn't keep up. The catch 22 is that when it's real hot in the So Cal summer where I need the A/C most is when I am maxing out and having an overheated car ...and wife....which I am still debating which one is more annoying. As the car seems to be in acceptable parameters without the A/C or high ambient temp (I don't know how ambient temp affects the heat exchange dynamic), should I be looking more at the A/C and less at my cooling sytem?