The best location for an electric water pump SBC V8 conversion, The best location for an electric water pump SBC V8 conversion Options

[BRAVE_HELIOS]

I hope you have the hose from the header tank going to bottom of the recovery tank. I cant see it in your pictures. If its going to the top as it looks like there is no way for the water to get sucked back into the system.
I have a Meziere 316 55gpm remote pump I could send you to try. I would be a little harder to plump up but might save you from buying something you don't need.

Thanks... I may take you up on the offer. I am so afraid that I will spend the money on an electric unit just to find out it is some other issue. That's why I am now cleaning out the system the best I can (without removing the engine) to see if this makes a difference. I just have had no luck with making this car remain running at a decent temp (like 180-200). I also now know to elevate the front of the car so the petcock located on the top right of the radiator can be used to bleed the system. I use a slightly modified vacuum brake fluid bleeder like this one and it works really well in helping me bleed the system.



As for the Passat header tank (I call expansion/ tank) overflow line, it does connect to the bottom of the recovery (I call overflow) tank. The recovery tank overflow line used to vent to the ground but I now have it going into another smaller bottle located at a lower point in the engine bay by the trunk bulkhead. There may be some sort of blockage there causing the header tank to build pressure. I will check it out.

I may have neglected to mention something because I just installed it and am waiting for the results.

In the Bible V8 Conversion Book; there is one small paragraph that mentions KEP recommending the use of a restrictor washer located at the inlet of the radiator. I installed one with a 3/4 inch diameter (the inlet size of the rad is 1.5 inch). Also the T-stat has been gutted so no restriction there.

I have pretty much tried every iteration I can think of... T-stat in, T-stat out, restrictor washer out, restrictor washer in, expansion tank out, expansion tank in. The only thing I have not tried is the electric water pump.

What I do not understand is if the mechanical pumps are not efficient enough to work in this application (V8 914) then why offer them?

[914GT]

I never thought the restrictor washer was necessary. I understand the thinking behind it, such as raise the pressure on the line to the radiator to either prevent steam bubbles or reduce the flow so the radiator has more time to cool. Some of this is based on old fixes going back to the 1950s.
I'd make sure you have all the air out of the radiator and hoses at the front. This means having a bleeder petcock at top of rad you can open when you are filling the system. Also check that you don't have excessive hot air recirculation. With the inner wheelhouse openings there will be some recirculaton to the front of the radiator. I'm assuming you already have good shrouding around the radiator. One way to check recirculaton is to measure the inlet temp with the engine idling and fans running, and hood closed. Then open the hood and see how much of a temp drop you have, with the radiator heat allowed to exit up where it really wants to go. If this is more then 10 degrees then you might want to look at how the air is recirculating and block it with a spoiler or air dam under the car.
If you have a new radiator why are you doing a flush? Do you think the block has a lot of rust in it? If it does that can clog up a new radiator pretty fast. Check the water you flush out to see if it has a lot of rust particles in it.
Good luck with this. Hope you find the problem.

[BRAVE_HELIOS]

I never thought the restrictor washer was necessary. I understand the thinking behind it, such as raise the pressure on the line to the radiator to either prevent steam bubbles or reduce the flow so the radiator has more time to cool. Some of this is based on old fixes going back to the 1950s.
I'd make sure you have all the air out of the radiator and hoses at the front. This means having a bleeder petcock at top of rad you can open when you are filling the system. Also check that you don't have excessive hot air recirculation. With the inner wheelhouse openings there will be some recirculaton to the front of the radiator. I'm assuming you already have good shrouding around the radiator. One way to check recirculaton is to measure the inlet temp with the engine idling and fans running, and hood closed. Then open the hood and see how much of a temp drop you have, with the radiator heat allowed to exit up where it really wants to go. If this is more then 10 degrees then you might want to look at how the air is recirculating and block it with a spoiler or air dam under the car.
If you have a new radiator why are you doing a flush? Do you think the block has a lot of rust in it? If it does that can clog up a new radiator pretty fast. Check the water you flush out to see if it has a lot of rust particles in it.
Good luck with this. Hope you find the problem.

I am thinking the block had crud in it. When I would use new coolant, it would quickly become dark like it had been in there for a long time. I placed pieces of nylon stockings at the inlet of the rad to help capture as much crud as possible and have removed the rad and did a flush/back flush via a garden hose... flows nicely. Question, can a rad still be clogged if water from a garden hose flows through?

I had the bumper inlet well shrouded and sealed. So much so that when the fan is on, I can place a license plate on the bumper grill opening and the suction of the fan will hold the license plate firmly in place! I am trying to understand what you say about the temp delta. I will read it again!

[dyckster]

if you want to see how efficient your rad/air inlet system is, you could easily pinch off your heater hoses, then plumb in two different water temp gauges. This will tell you what your water temp is going in and out of the rad. And if it is cooler hooked up that way, maybe look at your heater core plumbing.
What I really like about the electric pump is the ability to circulate and purge air without overheating on the highway. And I think trapped air is a big issue.
With my belt driven pump, ill fill it up with coolant, go for a drive, it needs more, next drive needs more, it took a lot of driving to get it full.

[BRAVE_HELIOS]

I never thought the restrictor washer was necessary. I understand the thinking behind it, such as raise the pressure on the line to the radiator to either prevent steam bubbles or reduce the flow so the radiator has more time to cool. Some of this is based on old fixes going back to the 1950s.
I'd make sure you have all the air out of the radiator and hoses at the front. This means having a bleeder petcock at top of rad you can open when you are filling the system. Also check that you don't have excessive hot air recirculation. With the inner wheelhouse openings there will be some recirculaton to the front of the radiator. I'm assuming you already have good shrouding around the radiator. One way to check recirculaton is to measure the inlet temp with the engine idling and fans running, and hood closed. Then open the hood and see how much of a temp drop you have, with the radiator heat allowed to exit up where it really wants to go. If this is more then 10 degrees then you might want to look at how the air is recirculating and block it with a spoiler or air dam under the car.
If you have a new radiator why are you doing a flush? Do you think the block has a lot of rust in it? If it does that can clog up a new radiator pretty fast. Check the water you flush out to see if it has a lot of rust particles in it.
Good luck with this. Hope you find the problem.

If I understand this correctly; where would I measure the inlet temp with the fans running and the hood closed? Would I measure it on the outside of the car by the bumper intake grill? Then remeasure the temp with the hood open?

[914GT]

If you can measure the air temp in front of the radiator you can get some idea of how much hot air is being recirculated from the wheelwells at idle and when the car is not moving. There will always be some amount hot air get pulled back into the front depending on how you made your radiator inlet openings. If all your air is through the front with the front bumper cut out, it should be less of an issue then if you have openings in forward part of the trunk floor. If enough air recirculates it can cause your engine temperatures to creep up when the car is not moving, and you can never get the temp to stabilize. There can be other cooling system problems that can cause this to happen also.

So if you can monitor the air temp in front of the radiator, then open the hood and see if the temp drops quickly (close to ambient) that's a good sign that there's some recirculation going on. If there's not much drop, just a few degrees, then you don't have a problem. Since hot air rises the radiator heat is going to escape upward quickly with the hood open. With the hood closed it is forced out around the front wheels and it has to find its way out around the fenders. There's more turbulence going on and some of it can get sucked back into the radiator depending on the layout. So this is just a quick check to either see if this is a concern or rule it out as a non-issue.

[jmmotorsports]

i am useing a 55gph mexaire pumpin my ls1 car they recomended mounting it close to the radiator and below the radiatir centerline55 GPH mezaire pump can't spell

[cali914]

I had a small block 427 in my v8 Porsche and had the Ron Davis radiator I mounted the pump in the front compartment on low side of radiator inlet. It said stand it straight up but I kept inlet and outlet parallel to floor and had 0 problems. I was using Meizere 55gpm remote water pump. Very excellent quality part. Expensive though. What I don't understand is I have a honda v6 engine now and using the stock Honda water pump and it works fine I think it's more about line size and radiator that affects about 80 percent of the cooling in these cars

[BRAVE_HELIOS]

I had a small block 427 in my v8 Porsche and had the Ron Davis radiator I mounted the pump in the front compartment on low side of radiator inlet. It said stand it straight up but I kept inlet and outlet parallel to floor and had 0 problems. I was using Meizere 55gpm remote water pump. Very excellent quality part. Expensive though. What I don't understand is I have a honda v6 engine now and using the stock Honda water pump and it works fine I think it's more about line size and radiator that affects about 80 percent of the cooling in these cars

Well, here we go! Shall we take a survey as to best place to mount a pump... by the rad or by the engine? Highest nods to either wins!

My rad hose lines are not what is recommended by Renegade.

Radiator: 1.5 inch inlet and 1.75 inch outlet diameters

Renegade W/P housing: 1.25 inch diameter

T-stat outlet: 1 inch diameter

And 1.5 inch diameter hoses going to and fro with appropriate size down/size up adapters.

Could this be the culprit? So far, the restrictor washer located at the rad inlet (3/4 inch diameter) does not seem to be hurting things. I do need to take it for a good drive now that is has clean/clear water running though it.

[Andyrew]

Best place is by the engine feeding the inlet to the engine. The cold water will allow for longer pump life.

I run 1 1/4" lines front to back.

Again, I have much less displacement now, but thats what I did with the v8 as well.

[914GT]

I've used 3/4" I.D. steel pipe under the car for coolant lines and never had overheating problems, and that's here in southern Arizona on a car with A/C. I've also used 1" I.D. steel tubing and it made no difference. If you have larger rubber hose then I don't think that's your problem.

I think having an electric water pump on the radiator outlet makes for an easier install, and is easier to access, but remember again that during hard acceleration the coolant is moving away from the suction side of the pump and not toward it as when it's at the engine. For a street car it's probably not a big deal, but on the drag cars that can experience a few Gs that would be a different story.

I assume that you open that top radiator petcock when you fill your system and keep it open until no more air bubbles come out. I have a short length of clear vinyl tubing on mine that runs to the bottom of the car, then I keep an eye on it closing it only until there's no more bubbles. Otherwise if there's a pocket of air in the top of the radiator it will not get purged out under normal operation, and it decreases the cooling capacity of the radiator and system pressure.

You might also try to disconnect the heater core to see what effect it is having unless you have a valve on the line controlled by your dash heater lever. With it connected as it is now in the front it will bypass the radiator. On a stock SBC the heater supply line comes off the top of the intake manifold before the thermostat then returns into the suction side of the water pump. This circulates hot coolant in a separate loop then that flow going to the radiator. If you keep the heater core across the radiator you may need a restrictor in the line so it's not bypassing too much around the radiator.

[BRAVE_HELIOS]

I've used 3/4" I.D. steel pipe under the car for coolant lines and never had overheating problems, and that's here in southern Arizona on a car with A/C. I've also used 1" I.D. steel tubing and it made no difference. If you have larger rubber hose then I don't think that's your problem.

I think having an electric water pump on the radiator outlet makes for an easier install, and is easier to access, but remember again that during hard acceleration the coolant is moving away from the suction side of the pump and not toward it as when it's at the engine. For a street car it's probably not a big deal, but on the drag cars that can experience a few Gs that would be a different story.

I assume that you open that top radiator petcock when you fill your system and keep it open until no more air bubbles come out. I have a short length of clear vinyl tubing on mine that runs to the bottom of the car, then I keep an eye on it closing it only until there's no more bubbles. Otherwise if there's a pocket of air in the top of the radiator it will not get purged out under normal operation, and it decreases the cooling capacity of the radiator and system pressure.

You might also try to disconnect the heater core to see what effect it is having unless you have a valve on the line controlled by your dash heater lever. With it connected as it is now in the front it will bypass the radiator. On a stock SBC the heater supply line comes off the top of the intake manifold before the thermostat then returns into the suction side of the water pump. This circulates hot coolant in a separate loop then that flow going to the radiator. If you keep the heater core across the radiator you may need a restrictor in the line so it's not bypassing too much around the radiator.

Preferred on the radiator outlet... and close to the radiator?

When you leave the petcock open on the top side of the rad when filling the system; do you also elevate the front of the vehicle so that without a doubt; the petcock sits higher than the t-stat/top of the engine? My radiator does not sit straight up... the top is angled towards the front of the car and as in close horizontal level with the t-stat.

The addition of the heater core and lines is a relatively new thing... the run hot situation has been with me since day one. There is a shut off valve on the inlet side of the heater core (close to the bulkhead and heater core itself). I have tried filling the system with the valve opened and closed without too much difference.

[914GT]

For water pump location I prefer below the engine for the reasons stated previously.

I don't think raising the front of the car will help much if there are hoses or any part of the system (in front trunk area) that may be higher then the petcock. The main thing though is to ensure the radiator is full of coolant. Raising the front will not allow any trapped air at top of the engine to escape - that has to be bled out by your expansion tank.

Can you connect into your system somewhere, such as at heater hose fitting, and try to pressurize the system with compressed air and get it to hold at 16 psi or whatever cap pressure rating you have? The system should hold pressure up to the point that the cap opens and pushes coolant into your overflow tank.

[BRAVE_HELIOS]

For water pump location I prefer below the engine for the reasons stated previously.

I don't think raising the front of the car will help much if there are hoses or any part of the system (in front trunk area) that may be higher then the petcock. The main thing though is to ensure the radiator is full of coolant. Raising the front will not allow any trapped air at top of the engine to escape - that has to be bled out by your expansion tank.

Can you connect into your system somewhere, such as at heater hose fitting, and try to pressurize the system with compressed air and get it to hold at 16 psi or whatever cap pressure rating you have? The system should hold pressure up to the point that the cap opens and pushes coolant into your overflow tank.

Earlier in this thread, I asked about the best place to install a Prestone Flush and Fill ‘T’ to back flush my ‘special’ system. The instructions say anywhere on the inlet heater hose side of the heater core. Since my inlet to the heater core comes from the inlet to the radiator… I just did not know where to tap. So I took a WAG and decided to place the ’T’ on the heater core inlet hose, between the radiator inlet and the heater core inlet. I followed the rest of the instructions and ran the garden hose while the engine was running for around 10 minutes. The temp gauge never got past 150 (temp sensor for gauge located on intake manifold, by t-stat) and eventually all the water coming out of the open expansion tank, ran clear.
I suppose that would be a good spot to try and air pressurize the system; correct?

[914GT]

Personally I don't use back flush kits as they introduce another potential failure point in the system. If I suspect a radiator problem I disconnect the hoses and flush water through it opposite the normal direction of flow, then look to see if anything comes out. Same with an engine block removing the drain plugs. I think the flush kits leave tap water in the system and I like to start off with new antifreeze and distilled water.

For pressure testing I think anywhere you can tie into the pressurized part of the system will work as long as your expansion tank and pressure cap are connected as normal.

[BRAVE_HELIOS]

Personally I don't use back flush kits as they introduce another potential failure point in the system. If I suspect a radiator problem I disconnect the hoses and flush water through it opposite the normal direction of flow, then look to see if anything comes out. Same with an engine block removing the drain plugs. I think the flush kits leave tap water in the system and I like to start off with new antifreeze and distilled water.

For pressure testing I think anywhere you can tie into the pressurized part of the system will work as long as your expansion tank and pressure cap are connected as normal.

That should work. The VW cap is rated for around 20 psi; I think. I can pressurize the system while the cap is on and wait for the cap to open and allow the coolant to flow to the overflow tank.

[3liter914-6]

Just a couple of things.

Electric pumps flow less coolant than a mechanical water pump at nearly everything above idle, if you're having a cooling issue installing an electric pump is going backwards. The reasons to install an electric pump are if you need to remotely mount a water pump or you're trying to get the absolute most horsepower you can out of an engine. If you think the water pump is the issue, get a Stewart high flow water pump and be done with it knowing you've got the best on there and it's not a WP issue.

More flow=more cooling, it's physics. You don't want to slow down your flow, a restriction will only cause problems, not help them.

If you're having problems, I'd first make sure what I had is working correctly. It sounds like you're having issues, or at least worried about bleeding the system. When I was building my V8 Volvo, I had similar issues which took out a headgasket before I bought an Airview coolant refill kit, and eventually ditched my convoluted setup. It uses shop air to create a vacuum and then sucks the coolant back in leaving it perfectly filled without air voids. Looks like there are cheaper ones out there like this. Yeah, it's a bit of money, but it's worth it -- it makes my life so much easier on dozens of cars (but not my bugs or 914).

I don't know the history of your engine, but if you're sure that you don't have any mechanical issues (such as head gasket, or timing) that could cause it to run hot, I'd reconsider the size of my radiator and the airflow through it.

[BRAVE_HELIOS]

Just a couple of things.

Electric pumps flow less coolant than a mechanical water pump at nearly everything above idle, if you're having a cooling issue installing an electric pump is going backwards. The reasons to install an electric pump are if you need to remotely mount a water pump or you're trying to get the absolute most horsepower you can out of an engine. If you think the water pump is the issue, get a Stewart high flow water pump and be done with it knowing you've got the best on there and it's not a WP issue.

More flow=more cooling, it's physics. You don't want to slow down your flow, a restriction will only cause problems, not help them.

If you're having problems, I'd first make sure what I had is working correctly. It sounds like you're having issues, or at least worried about bleeding the system. When I was building my V8 Volvo, I had similar issues which took out a headgasket before I bought an Airview coolant refill kit, and eventually ditched my convoluted setup. It uses shop air to create a vacuum and then sucks the coolant back in leaving it perfectly filled without air voids. Looks like there are cheaper ones out there like this. Yeah, it's a bit of money, but it's worth it -- it makes my life so much easier on dozens of cars (but not my bugs or 914).

I don't know the history of your engine, but if you're sure that you don't have any mechanical issues (such as head gasket, or timing) that could cause it to run hot, I'd reconsider the size of my radiator and the airflow through it.

I've wondered about timing, quite a bit especially now. With the v8, it is almost impossible to check the timing to make sure it is correct. Time it by ear... if it starts pinging under load, back it off until it stops. Could it still affect engine temps? Possibly or probably.

I do not believe there is anything wrong with the engine itself other than it tends to run rich. No white or blue smoke out of the exhaust. No oil in the coolant or coolant in the oil.

I am waiting for the weather to get better and I'll take it for a good drive as it sits now (fresh clear water, system bled and with the restrictor) to see how it goes. I will also look into the Airview system.

[914GT]

You can check timing by relocating the timing mark/scale so it's visible from underneath the car on the driver side. I relocate the TDC mark on the balancer and just shoot the timing light up from under the car to set the initial advance. I've got photos of this if you're interested.

[BRAVE_HELIOS]

You can check timing by relocating the timing mark/scale so it's visible from underneath the car on the driver side. I relocate the TDC mark on the balancer and just shoot the timing light up from under the car to set the initial advance. I've got photos of this if you're interested.

That might not be a bad idea. Like I have said, I have wondered how far off my timing is. I don't think it is too far off... no discernible pinging under load; but if it being only slightly off can affect running temperatures, then it's definitely worth checking out. Pictures and descriptions please!