Having got a few miles on my car now it would appear to be overcooling. I have a docking ally rad and the car does warm up if idling sat still for 15 mins or so but a quick blast down a road drops the temp back below 50 degrees C Yes the stat was fitted in the correct direction and with the little air bleed hole at the top. I have pulled the thermostat which has the marking 300/400-160. I'm guessing the 160 is for Farenheight which is about 71 celcius to us brits - is this a bit cool or correct ? I also have a bleed from the rear of my inlet manifold and from the top of my radiator so it is possible that coolant flow through these is keeping my system a bit too cool. I'm going to try and resitrict the bleed lines flow a little and maybe put a higher stat in the car - whats a normal stat for a 302 ? My coolant fans never come on whatsoever and I thought maybe that the temp guage sender was dodgy but the heater doesn't even get that warm - yes it is 5 degrees here in London at the moment - and I'm freezing my nuts off if I go fast ! The problem is that when you drive down the motorway that the carbs fast idle cuts in as it thinks the car is just warming up ! I know that in the warmer weather cooling is the problem but I want to use the car all year round. Any advice or info appreciated as I have no 302 or iron block V8 previous experience. I'm going to get a bowl and test this stat in it - should it start to open at 160 or be open then ?
Correct engine temperature.
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Hi Paul,
Somethings to ask before speculating: 1) Where are the temp sensors located for the gauge and fans? 2) Does the carburetor have an electric choke heater 3) Do you have a bleed at the top of the engine 4) Has it ever puked coolant or overheated 5) Is the engine sitting level, nose up or down 6) do the heater pipes leading to the rad get hot?
There's a method in my madness so bear with me
It's really important to make sure the cooling system is working properly before driving any distance. There's a lot of variables.
The picture in your avatar looking great by the way! Have any more pics to post?
Cheers
Somethings to ask before speculating: 1) Where are the temp sensors located for the gauge and fans? 2) Does the carburetor have an electric choke heater 3) Do you have a bleed at the top of the engine 4) Has it ever puked coolant or overheated 5) Is the engine sitting level, nose up or down 6) do the heater pipes leading to the rad get hot?
There's a method in my madness so bear with me
It's really important to make sure the cooling system is working properly before driving any distance. There's a lot of variables.The picture in your avatar looking great by the way! Have any more pics to post?
Cheers
Agree with Ian,
Looking at your build pics and reading your description sounds correct. If the temp sender is in the intake manifold before the T-stat your temp should not go below the T stat 160 once it has made it there. I would be very wary of air pockets causing the sender to mis-read, the pump to cavitate or other.
Looking at your build pics and reading your description sounds correct. If the temp sender is in the intake manifold before the T-stat your temp should not go below the T stat 160 once it has made it there. I would be very wary of air pockets causing the sender to mis-read, the pump to cavitate or other.
The guage sender is in the intake manifold just before the stat both it and the gauge are Smiths items and the rad fan switch is mounted in the radiator. the carb has electronic choke its an edelbrock brand new item. yes there is a bleed on the rear of the manifold connectingthe rear of both heads into a "Y" and back upto the header tank in the braided brake line hose - I think it's called dash 4. It has puked coolant whenI first got it running - a hose came off and the gauge read 100 degrees, things seemed ok afterwards though. the engine leans slightly forward ie water pump a bit lower than the flywheel end - maybe 1/2 inch approx. The pipes going to the rad do get warm - much before the engine has even warmed up. I've been really busy and not had a chance to give the car a good clean and take a few pics - a soon as I do I'll post em.
Hi Paul,
Thanks for the info. Sounds like you have air in the cooling system. Without the fans running and the car stationary it would definately come up to operating temperature and more in 15 minutes. So the sender isn't seeing coolant and the thermostat may not be opening either. No hot air from the heater is another indication of low coolant level.
The bleed (not bleed lines) you really need is on the thermostat part of the intake manifold. If there is no plugged port available you could remove the temperature sender and see if the coolant is right there, I suspect you'll find none if the car is totally cooled off.
Without knowing how the entire coling system is plumbed, the simplest way to make sure you have all the air out is to fill the system and capture the overflow from the top of the intake manifold. Get the appropriate pipe thread to nipple fitting, attach some tubing to it and screw it in the sender hole and route to a carch can.
You may want to fill the cooling system from the heater ciruit and be sure the heater flow valve is open. Autoparts stores sell rad flush kits that have the right fittings to do this fill from the heater trick.
Of course I could be completely wrong at least all you have to do is pull the temp sender and have look. You'll be astonished how much coolant it takes to fill one of these babies.
A decent rad in this application should give a 40F drop in temperature with the fans running, typically 200 in 160 out with everything warmed up. Good luck my friend...
Thanks for the info. Sounds like you have air in the cooling system. Without the fans running and the car stationary it would definately come up to operating temperature and more in 15 minutes. So the sender isn't seeing coolant and the thermostat may not be opening either. No hot air from the heater is another indication of low coolant level.
The bleed (not bleed lines) you really need is on the thermostat part of the intake manifold. If there is no plugged port available you could remove the temperature sender and see if the coolant is right there, I suspect you'll find none if the car is totally cooled off.
Without knowing how the entire coling system is plumbed, the simplest way to make sure you have all the air out is to fill the system and capture the overflow from the top of the intake manifold. Get the appropriate pipe thread to nipple fitting, attach some tubing to it and screw it in the sender hole and route to a carch can.
You may want to fill the cooling system from the heater ciruit and be sure the heater flow valve is open. Autoparts stores sell rad flush kits that have the right fittings to do this fill from the heater trick.
Of course I could be completely wrong
at least all you have to do is pull the temp sender and have look. You'll be astonished how much coolant it takes to fill one of these babies.A decent rad in this application should give a 40F drop in temperature with the fans running, typically 200 in 160 out with everything warmed up. Good luck my friend...
Howard Jones
Supporter
First, 160 degrees thermostat is a normal temp thermostat for a smog equipment free SBF. If you have smog equipment then thermostats range from 180-200 degrees. I personally think 160-180 is about right. 160 will give you a nice warm heater if the system is working correct.
Second, You most certainly have air in the system. Even with a full self bleed system like yours they still need a careful first bleed. Heater systems make the whole thing more difficult but it can be done correctly if you take your time and do it right.
1. The system MUST be full of coolant. Use 50% water and the rest antifreeze. The total will be about 4 gallons.
2. Put the front of the car up on jack stands with the rear tires on the ground. This will allow all the air in the motor to flow forward to the radiator where it can escape out the bleeds. Fill the motor thru the temp sender hole first until it is full and the water comes out the hole. Put the sensor back in and right away continue to fill the system from the radiator cap opening until it is full and coolant comes out the radiator bleeds. MAKE SURE YOU TURN THE HEATER CONTROL TO HOT AS POSSIBLE so the heater fills with coolant.
Start the car and let it get it warm so that the thermostat opens with all the bleeds closed and the radiator cap off. (I still have the front of the car up in the air at this point). THE HEATER IS STILL ON HOT. Turn engine off. Top off the system.
Close up the radiator cap and start it up again until it gets to running temp. This should be 160. Turn it off and CAREFULLY open the bleeds at the radiator to extract the last of the air.
Close up the bleeds, put the car down, start it up again and let it run at idle for awhile while at full warm with the HEATER STILL ON HOT. Turn it off and CAREFULLY check for a full coolant expansion tank. Top off again as necessary. YOU are done for now.
Go for drive with the heater on full hot the whole time and when you come back re crack bleeds again just too see if any more air is present. Don't leave them open if coolant flows out without air.
At this point the self bleeding system should be able to maintain the system free of air for some time.
If you want to check the temp sensor microwave a cup of water to boil and put the temp sensor bulb in it. It will read about 200F You can check the thermostat the same way. It will open right up in 200F degree water.
Second, You most certainly have air in the system. Even with a full self bleed system like yours they still need a careful first bleed. Heater systems make the whole thing more difficult but it can be done correctly if you take your time and do it right.
1. The system MUST be full of coolant. Use 50% water and the rest antifreeze. The total will be about 4 gallons.
2. Put the front of the car up on jack stands with the rear tires on the ground. This will allow all the air in the motor to flow forward to the radiator where it can escape out the bleeds. Fill the motor thru the temp sender hole first until it is full and the water comes out the hole. Put the sensor back in and right away continue to fill the system from the radiator cap opening until it is full and coolant comes out the radiator bleeds. MAKE SURE YOU TURN THE HEATER CONTROL TO HOT AS POSSIBLE so the heater fills with coolant.
Start the car and let it get it warm so that the thermostat opens with all the bleeds closed and the radiator cap off. (I still have the front of the car up in the air at this point). THE HEATER IS STILL ON HOT. Turn engine off. Top off the system.
Close up the radiator cap and start it up again until it gets to running temp. This should be 160. Turn it off and CAREFULLY open the bleeds at the radiator to extract the last of the air.
Close up the bleeds, put the car down, start it up again and let it run at idle for awhile while at full warm with the HEATER STILL ON HOT. Turn it off and CAREFULLY check for a full coolant expansion tank. Top off again as necessary. YOU are done for now.
Go for drive with the heater on full hot the whole time and when you come back re crack bleeds again just too see if any more air is present. Don't leave them open if coolant flows out without air.
At this point the self bleeding system should be able to maintain the system free of air for some time.
If you want to check the temp sensor microwave a cup of water to boil and put the temp sensor bulb in it. It will read about 200F You can check the thermostat the same way. It will open right up in 200F degree water.
Thanks for the info fellas. I did check the coolant level under the temp sender - this is ok and no air. When the car is sat idling it rises to about 80-90 degrees and sits there happily - fans coming on and off as and when needed, heater working so I know the system works ok. The problem only arises when you go for a drive - it overcools, a few more checks required I think. All of the pipes in the system do get hot inc. the header tank, the top of the rad, heater hoses and the little bleed pipes. The header tank level is a good 2-3 inches higher than the top of the manifold so there is a good head of water and the tank does seem to fill up to virtually the top when the system is hot.
Maybe you just need a radiator cover for the cold months.
Howard Jones
Supporter
Your problem sounds like what would happen if you take out the thermostat. Test or temporarily replace the thermostat. It may be stuck open and not controlling the coolant temperature.
Peter Delaney
GT40s Supporter
I'm with Howard on this one. If you had air/steam pocket problems (like I had huge ones), I would expect the same serious random overheating - appearing & disappearing as you run thru the revs & move the steam pockets around.
With your bleed lines, I can't see this as being the problem, and, with things stable at 80-90degC at idle, it looks right.
So under way, it must come down to heat input from the engine vs heat output from the rad - if you are getting full water flow thru a stuck thermo & lots of cold air thru the rad, it seems logical that the equilibrium temp will end up lower than when you are stationary & just getting the rad air throughput from the fan ?
Kind Regards,
Peter D.
With your bleed lines, I can't see this as being the problem, and, with things stable at 80-90degC at idle, it looks right.
So under way, it must come down to heat input from the engine vs heat output from the rad - if you are getting full water flow thru a stuck thermo & lots of cold air thru the rad, it seems logical that the equilibrium temp will end up lower than when you are stationary & just getting the rad air throughput from the fan ?
Kind Regards,
Peter D.
Hi Paul,
How's it acting? Do you loose the hot air from the heater when the temperature drops?
I'm concerned there is still air the system or being created in the system by hot spots in the heads. Just not sure and not easy to diagnose remotely.
Another question... where does the header tank connect to the cooling system? It's possible to have a full tank and still have air in the system...
Overcooling is a problem '40s don't normally experience. Make sure it's right before taking a long road trip and carrying a couple of gallons of premixed antifreeze would be a good idea too on your early outings.
Cheers
How's it acting? Do you loose the hot air from the heater when the temperature drops?
I'm concerned there is still air the system or being created in the system by hot spots in the heads. Just not sure and not easy to diagnose remotely.
Another question... where does the header tank connect to the cooling system? It's possible to have a full tank and still have air in the system...
Overcooling is a problem '40s don't normally experience. Make sure it's right before taking a long road trip and carrying a couple of gallons of premixed antifreeze would be a good idea too on your early outings.
Cheers
Tim Kay
Lifetime Supporter
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Overcooling is a problem '40s don't normally experience.
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Ian, you can say that again. A problem I'll bet we all wish we had /ubbthreads/images/graemlins/beerchug.gif I also agree with the logic Ian just brought up, make sure you eliminate all possibilities of trapped air.
Overcooling is a problem '40s don't normally experience.
[/ QUOTE ]
Ian, you can say that again. A problem I'll bet we all wish we had /ubbthreads/images/graemlins/beerchug.gif I also agree with the logic Ian just brought up, make sure you eliminate all possibilities of trapped air.
Well changed the thermostat for another slightly hotter one - 180 degrees or 82 for us brits. Took the car out last night and it is running 10 degrees hotter or therabouts. The heater in the car follows the temp of the gauge/engine, if it sits idling I warm up a bit, if I drive fast I shivver ! The header tank connects directly down onto the large cooling pipe that runs to the front of the car. I'm going to try and restrict the bleed lines slightly to see if that helps, I'm thinking that when the stat is closed pressure in the inlet can push water down the bleed into the headertank - this will be replaced by 0 degree cold water from the rad. Similarly this can also happen with my rad top bleed. Having put both my thermostats in a bowl of hot water, to test I was amazed at how little opening you get when they are fully open - I think the bleed lines will effect things quite alot especially as it is 0 - 2 degrees C outside.
Paul, 180F is always what I've heard for a proper stat temp for a small block Ford. The thing I'm wondering about now is where you said the header tank is plumbed to the main radiator hose going to the front of the car, which I assume is to the rad. My header tank is plumbed to one of the ports on the water pump (stock unit) with the other port blocked off. I'm not a coolant engineer but the main lines should go from stat to rad and back to the water pump. Maybe you are bypassing the stat somehow and are then getting open circulation with no dwell time to let the motor come to temp. Maybe you can draw or describe in detail the coolant path and the experts here may notice something.
Having now removed both bleed lines I blocked the inner end of the dash 4 fittings with a blob of solder and then redrilled a 2mm hole through it and voila the car temp is now between 70-80 C whatever speed you go. I need to get a few more miles on the car but first indications are good. Thanks for all the input fellas and I'll take a few pics and post when I get a second to spare !
