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  1. #1
    Fellow Frogger! forzamacchi's Avatar
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    Default R8 water pump question

    Hello All,
    I've finally managed to start my R8, though I have a question as to whether the water pump is functioning correctly. How long running the car would I notice any maladies? Also, if the pump isn't working is there any siphon effect that would make coolant come of the bleed screw, giving the illusion that the pump is working?

    Thanks,
    Ben

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    Fellow Frogger! Jinandfonic's Avatar
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    Heat creating pressure would cause the bleeding. Does the radiator get hot? If something isn't working it probably would be the thermostat. Worthwhile & easy to replace if car has been unused for a length of time. Test the thermostat by dropping it into a container of just boiled water. It should open therefore be ok to keep.
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    1000+ Posts jo proffi's Avatar
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    One of the things I'll do to test the cooling system of a car before i add the coolant (ie when the system is filled with just plain water) is disconnect the top hose from the radiator and elevate it. Heater should be turned on to allow a coolant bypass. but no fan.

    I'll then stick the garden hose in the radiator to keep its water level high enough that the water pump does not start sucking air.

    Once the engine comes up to temp, the thermostat should open and allow a small trickle of water out the top hose.

    It is normal for the thermostat to modulate the flow a bit as the thermal shock form the cold radiator will usualy be a little faster than the thermo can keep up with so it varies between a small flow and a medium flow.
    In reality, the thermostat only sees this shock once during warm up, and then settles down to maintain a more average radiator core temp.
    In spite of some peoples believe that a thermostat is an open or closed device, your observation of the modulating flow will show that is very much not the case, and on a well maintained system spends much of its life just open a bee's ball.

    If you get this trickle, it shows both the thermostat and the water pump are working as they should.
    Should probably be about 80 C but that totally depends on the thermostat opening temp.

    Idealy get a contact thermometer into the trickle of water and measure the temp and if you have a dash gauge, observe where it sits at this temp.

    Cooking thermometers are good because they are cheap ($5) and have enough range that they can be used for any fluid temp testing you may need to do on a car.

    Jo

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    Quote Originally Posted by forzamacchi View Post
    I've finally managed to start my R8, though I have a question as to whether the water pump is functioning correctly. How long running the car would I notice any maladies? Also, if the pump isn't working is there any siphon effect that would make coolant come of the bleed screw, giving the illusion that the pump is working?
    Which bleed screw are you talking about? The one on the heater matrix at the front of the car, or the bolt on the water pump? The bolt on the water pump is not a bleed screw as such, the radiator is to be filled until the air is bled out of the block, when coolant starts flowing freely from the bolt hole. At this stage the bolt is replaced (coat it with an anti-seize compound first), start the motor, then continue to fill the radiator until coolant starts to flow freely from the heater bleed screw, then screw that closed (the bleed screw is hollow, so doesn't need to be removed completely, just check that the hole in the bleed screw is not blocked before starting). Monitor the level of fluid in the radiator, the thermostat is open when you start to get turbulence in the radiator, top the radiator up, replace the cap, then check for bubbles in the expansion jar from the hose, once the bubbles have ceased, screw the cap on the expansion jar. If it is a brass tank instead of a glass or plastic expansion bottle, you won't be able to see the bubbles, just let it run a while, then screw the valve onto the brass tank.
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    Fellow Frogger! forzamacchi's Avatar
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    Hello Simon,
    I never saw the turbulence which was worrying...also, I could not find the bleed screw on the heater core. Where is it located? A very helpful tutorial... Thanks

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    1000+ Posts renault8&10's Avatar
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    The heater matrix bleed screw should be visible at the top of the heater matrix in the "boot" section - or trunk for americans.
    The space between the cabin and the boot. I think the outside panel is referred to as a scuttle panel, but could be wrong. For you it would be on the drivers side I imagine, as it is on the passenger side for us here in Oz.
    KB


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    Fellow Frogger! forzamacchi's Avatar
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    So, I imagine I need to remove the exterior panel in the boot to access it? I saw a panel adjacent to the windshield washer fluid reservoir, so I am guessing this would be the cover ? Ben

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    1000+ Posts renault8&10's Avatar
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    Shouldn't need to remove anything, it should be accessible in the space immediately under the windshield if it is there!
    It is in the same space as the windshield washer bottle reservoir but in the aussie cars, it is on the other side of the car from that.

    You are looking for a knurled knob that unscrews that is obviously attached to the heater matrix. I'll take a pic of my R8's one tonight and post it up.
    KB


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    Fellow Frogger! forzamacchi's Avatar
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    Found it and tried to bleed it.... not even a dribble! I am guessing the core is clogged from neglect. I am going to pull it and have my radiator guy refurbish it.

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    Stupid question I know, please forgive me, but was the heater turned on? More importantly does the heater actually work - give out heat? Check you're getting full on and full off by manually working the controller valve under the dash

    If yes then just the bleed valve or it housing might be crudded up. A judicious poke with some fine wire might win the day.

    Also try this: disconnect both heater hoses from the engine end and stick a garden hose up one of them and clamp it on. Turn the hose on gently - too much pressure will stress the o-ring in the controller tap. Take the bleed screw out and let it flow for a while. After it's been flowing clear for a bit stick the garden hose in the other heater hose and let it flow for a while.

    Some radiator people are reluctant to pressure flush old heater matrixes for obvious reasons
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    Stupid question I know, please forgive me, but was the heater turned on? More importantly does the heater actually work - give out heat? Check you're getting full on and full off by manually working the controller valve under the dash

    If yes then just the bleed valve or it housing might be crudded up. A judicious poke with some fine wire might win the day.

    Also try this: disconnect both heater hoses from the engine end and stick a garden hose up one of them and clamp it on. Turn the hose on gently - too much pressure will stress the o-ring in the controller tap. Take the bleed screw out and let it flow for a while. After it's been flowing clear for a bit stick the garden hose in the other heater hose and let it flow for a while the other way.

    Some radiator people are reluctant to pressure flush old heater matrixes for obvious reasons
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    Fellow Frogger! forzamacchi's Avatar
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    Not a stupid question at all! Trust me, I know nothing about cars. All of my experience mechanically is with air cooled vintage motorcycles. I had the heater slide all the way to fully on and there was nothing. Your suggestions are just what I need to get pointed in the right direction. Hopefully I will have enough light after work tomorrow to make another run at it!

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    Fellow Frogger! forzamacchi's Avatar
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    Tried the garden hose trick today and nothing came out of the bleeder... I did stick a probe into the bleeder and lots of rust came out. I am guessing the thing is very clogged with rust. I wouldn't mind bypassing the heater core, but I understand this would reduce my cooling effectiveness....

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    Don't give up! At least we now know what the problem is.

    Fashion up hose to slip over the bleeder body and see if you can get some pressure to push the sludge through. If you've got an air hose try that. If you remove the heater core you will likely need to replace the hoses as well. These might be getting a little hard to find.

    Disconnecting the heater should have no impact on the cooling, it gets turned off in summer when the outside air is hot and the cooling system is under the greatest load anyway. With the cooling system properly set up and maintained these cars shouldn't overheat.

    P
    Last edited by Exfrogger; 16th April 2014 at 01:51 PM.
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    Fellow Frogger! forzamacchi's Avatar
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    In Los Angeles, the weather rarely dips below 15C during the day. Thats why I am wondering if will be a big issue if I cap the the heater hose outlets for now while I sort out the rest of the engine. I did order a new water pump and a water temp gauge to help further things along.

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    1000+ Posts daffyduck's Avatar
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    Quote Originally Posted by forzamacchi View Post
    Tried the garden hose trick today and nothing came out of the bleeder... I did stick a probe into the bleeder and lots of rust came out. I am guessing the thing is very clogged with rust. I wouldn't mind bypassing the heater core, but I understand this would reduce my cooling effectiveness....
    Bah. I take care of a 4cv that lives in a very hot locale. 100 to 115 F is common. Radiator is stock. No heater core at all. No overheating and this car gets driven a lot.

    Doing the Daffyduck dance via the AussieFrogs app.

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    Capping at the engine the engine end won't be a problem. If you're in a real hurry you could try using some of the existing hose to make a U bend and connect one outlet to the other. You might need to think through how you're going to bleed the air from the motor tho.
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    Quote Originally Posted by Exfrogger View Post
    If you're in a real hurry you could try using some of the existing hose to make a U bend and connect one outlet to the other. You might need to think through how you're going to bleed the air from the motor tho.
    It is best to cap both ends, it then "forces" the water through the radiator instead of taking a shortcut via the U-bend hose without it being cooled.

    As for bleeding, with the heater inlet/outlet capped, just use the bleed bolt on the waterpump, fill up till coolant flows freely, screw the bolt up, then top up the radiator, start motor then top up until there are no bubbles, then pop the radiator cap on. If you want to go belt and braces, use a capped T-piece from a Renault 12 heater on the inlet/outlet ports, then fill until coolant flows freely from the bleed screws (using the R12 t-pieces will only apply to areas where Renault 12s are available to pilfer from, meaning the idea is unlikely to work in the States). Just capping the heater inlet/outlet, then bleeding through the waterpump bolt, then topping up the radiator works.
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    Fellow Frogger! forzamacchi's Avatar
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    Thanks Guys,
    I am going to try capping and see what happens. I think the inline water temp sensor will be a great help when determining if it is up to operating temp. I was a little concerned that the lower hose was getting hot while the top hose adjacent to the thermostat was still cold. It is possible that it wasn't up to running temp.... I was a little hesitant about getting a virtually untested motor that sat for 30 + years too hot.

  20. #20
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by forzamacchi View Post
    Thanks Guys,
    I am going to try capping and see what happens. I think the inline water temp sensor will be a great help when determining if it is up to operating temp. I was a little concerned that the lower hose was getting hot while the top hose adjacent to the thermostat was still cold. It is possible that it wasn't up to running temp.... I was a little hesitant about getting a virtually untested motor that sat for 30 + years too hot.
    Nothing beats being systematic like this!. In LA, I can't imagine you'd need the heater much but sometimes demisting is a good idea...

    I'd cap it (exactly as Simon said, not bypassing with a loop of hose in this case) and think about the radiator much easily. The whole assembly comes out of the area under the dash fairly easily when you remove the lower panel there. No doubt Jacques can get you a heater radiator OK if you need one. I imagine there are a few good secondhand ones around.

    Good luck.
    JohnW

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