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Get rid of those fans.
All it takes is one little nick on a fan blade that can cause a stress riser and a point of fracture Any fan can fail if mistreated, I saw a factory fan crack at a rivet hole, it ended up in the shit can.
Line two is wrong and has been wrong. Slowing flow also leaves the coolant in the block to absorb more heat. You want flow. To the OP I didn't read all this but you need the water pump faster than the crank. You need a thermostat that actually works. I've only found one. That is the Stewart Components thermostats. They open BEFORE the actual temperature so it's wide open at that temp. So...if you have a 180 stat it should be opening before 180 and be wide open at 180. Also, not a big fan of electric fans. I don't care about CFM. The fan only matters at low road speeds. Once you get past about 15 MPH or maybe even less, the fan is in the way. Your fans are actually blocking air flow. Also, a 3 core radiator is never as good as a 2 core. Two big cores is always better than 3 smaller cores. 4 cores is just silly. You have a simple problem that comes up. Water pump turning too slow, electric fans, too many cores that are too small and probably a thermostat that doesn't flow enough. It's all about flow. You can't have coolant move too fast. You need the coolant out of the block and in the heat exchanger to cool effectively. So speed up the pump, and get rid of the electric fans. Edit, I forgot to mention the purpose of the thermostat isn't to slow coolant flow, it's to facilitate quicker engine warm up. Only heating the coolant in the engine is quicker and better on the oil, the block and everything else. That's all the thermostat does. That's it's only purpose. Not to slow the coolant. Although the cheap ones do slow the coolant and that's bad.
We will have to agree to disagree on this
Here's your test; (short version at the bottom) I would Make sure the Distributor has a working Vcan on it, and that the trans/TC are working properly. Then I would remove the fans, remove the shroud,remove the stat and install a gutted one,dump the coolant and install straight water, swap on a 7psi cap. Then I would start with a cold engine, point the car down a deserted road and drive it at 30/35mph, and see what happens. I would be prepared to camp for an hour if it gets hot. Then I would turn it around and go home. If it overheats at speed now,and the cooling system is not taking in combustion gasses,then; first I would make sure the lower hose is free of obstructions and the anti-collapse spring is in there. Secondly, I would remove the water pump and make sure the impeller is not slipping and that it is rotating in the correct direction. If that is good, then, thirdly; I would remove the rad and drive over it a couple of times.Ok no, first I would prove that water is not getting thru the rad fast enough and that the hoses don't still have shoprags stuck in them, as some guys do;then I would drive over that rad. Here is your rad test; with the new rad vertical as installed; the water should run out the bottom at least as fast as you can fill it from the top by pouring from a jug. In other words you can never fill it up with no hose on the bottom, no matter how hard you try. You can time it but do it right. Time how long it takes to pour a jug in the top, and time how long it takes for the water to come out the bottom.... from the instant it first starts running out; not from when you begin to pour. Use discretion when to stop the timer; I mean don't stand there 10 minutes waiting for the last drop to fall. I guess you could just do the water test first and save some diagnostic time... lol. When you get this sorted out, now you know your cooling system is up to the task. But you still have to solve your low-speed airflow problems. I don't know much about pump speeds or too-fast water circulation or how hot is too hot, but I know of a guy who does and he has a lot to say about it. His name is Smokey Yunich. His book has a whole chapter, that helped me build my powerhouse 367.
Lots of good suggestions here and I thank all. As for using a flex fan I saw one come apart or should I say the aftermath of one that came apart and that will always keep me from ever using a flex fan. However I will try to go back and use the factory 4 blade fan I have that was on the 273 originally. If that helps I will look for a 6 or 7 blade for a small block. What is the distance on most cars from the fan blades to the radiator as mine will be less then an inch? As for a fan clutch I have not found one that will fit between the pump and radiator in my car. Remember I have only 2.5" max for space. As for the question why use an electric fan there are reasons for it but the biggest is probably the 7-15 HP that it saves. Then as mentioned by J-par there is less chance on lossing fingers or hands. As for the bleeding the coolant system, since i've had the thermostat out with every change I have tried so far I have always filled the coolant thru the intake until it is just at the top then installed the thermostat and housing. Once thats all back together I fill the rest of the way thru the top of radiator so I dont see issues there. I also run the car until I can see coolant flow before I put the cap on which would move any air pockets. Im not sure what the reason khuebner250 suggests to replace the cap? What lb pressure cap are you suggesting to go to? As for the pump its an 8 vein and it also has the machined plate with a closed back just as the flowkooler pumps do. AJ/FormS I do know i dont have any rags stuck in any hoses! lol I dont have that bad habit so I can eliminate that! But im sure it has happened to people before. Im not sure what you are saying when you mention Vcan on distributor? Im running aftermarket distributor and ignition. As for the trans/convertor I havent had a chance to really check anything there since I cant drive without getting hot but I can tell you that the lines and aux cooler are running at 105-115 which I see as pretty cool. The lower hose doesnt have a spring in it and I went to NAPA Thursday but they dont sell springs and I verified that the hose wasnt sucked shut the night i took all my readings. I will do the radiator flow test to make sure that I have plenty of flow. As for driving the water pump faster then the crank, I bought a pulley kit for a serpentine belt upgrade about a year ago and havent installed it yet. I checked the pulleys for that kit last night before I left and the water pump pulley is 5" while the crank pulley is 6". So I might as well install that system while Im having this issue because that may help solve some problems as it will overdrive the pump. Again thanks for all the input. The wife has made me a spring cleanup list that will take me weeks of daylight to complete so I only have about one hour a night to get at this thing. I was hoping to drive it to Ocean City Md in May (175 miles one way) but I dont see that happening at this point. I will continue to post my changes and results as I go until we have this resolved!! Thanks, Rod
@rod7515 I'm running a very similar combo and the same exact radiator and fan set up except I don't have holes in the shroud. After we got mine on the road I noticed the temps climbing. We chased that demon until we finally put an infared temp gun on it like you did. Once I saw that my cheap AutoGage gauge was off by 10-15 degrees through out the whole range, I closed the hood and never looked back. I drove my car all last summer through the heat with the gauge saying 220 and my car never once overheated. That's because it was really running about 200-205 degrees. The numbers from your original post indicate the same thing?
Easy to test that get an accurate mercury thermomiter, and setup the sending unit in a pan of water on the stove measure the watter temp every few minutes and record the autometer ( or whatever guage it is) reading that will tell you if your guage is off or not. Regarding rad cap, I would use the pressure cap recomended by oem / rad manufacturer not any of us.
I trust my Raytec MiniTemp infared gun. I point it at the manifold near where the sending unit screws into the manifold, same as the original poster did.
Radiator caps can go bad and do go bad all the time. I'd suggest a stock replacement? Bad cap symptoms: Overheating, obviously. Cap won't hold/build pressure. Therefore, the boiling point won't be decreased by pressure. Hose collapsing after cooling means the cap won't equalize pressure. Just my thoughts, you may be able to have your cap pressure tested at a local shop for free or maybe a parts store had a stant tester you can use.
Didn't see it mentioned...any hood openings...open scoop not sealed to carb? That can cause cooling issues as well.
Fair enough, but you'll still be wrong!!! LOL that because even if we disagree that's still funny!! I'm hilarious. Ask my wife.
The 7-15 HP you think you are saving is not really all that much. With those fans blocking air through the radiator at road speeds you are most likely losing HP. Verify the gauge and then work on coolant and air flow. That's where your issues are. In my nearly 4 decades I've never seen a fan explode that didn't have other issues first. Older car chassis are NOT designed for those electric fans. Again, they are in the way.
Jimacuda, great point on a scoop. Yes it does have one and I've tried it while driving. Went the 3 miles with it (plug in) in then after sitting the 3 miles back I took (plug out) it out and still climbed in temp. Thought more air might cool better but it did not seem to help! Rod
I will say again. PUT A PRESSURE TESTOR on the radiator system. If it wont build pressure you can't increase your boiling point. if you can't increase your boiling point. You are always going to overheat in this case. Start with the diagnosis first instead of being a parts swap-er. Harbor Freight sells a test kit I believe 63862. It is worth having this on hand. It fits so many models and can be just as important as a compression test sometimes. Buy it on one of their savings days to save even more. I've had mine for years and have used it more times than I can count. Fathers vehicle, brothers, tractor. and so on. I used mine just the other day on the wife's X5. I found that the overflow tank had a leak. Saved me more money than this tools costs in just one outing. do you know what BMW shop time costs?
I just got an email that says HF is having a 72hr sale of some kind. If you where not on the other side of the world. I'd let you borrow mine. I just checked your craigslist ads and there is a used slant testor listed in Pittsburgh but don't know condition or how complete. $35 bucks. I'd still go with the HF one.
Blinidsquirrel, I dont understand what your looking to do. When I said it doesnt build pressure it meant im not blowing fluid out all over the place. Is the system under pressure, yes. I can tell you that. But im not losing any coolant at all. No visible leaks. Is the system under pressure as it heats up, yea you betcha. I think you are misunderstanding what I was trying to say. Let me know what you think I am going to see. What are you looking for? Im not a parts hanger, Im trying to get ideas and I respect yours but I think you are not understanding what i said in an earlier post. Rod
First, sorry if I came across as snarky. Not my intention. Sometimes I type faster than I think and the tone gets demented. You stated you have contamination from compression. If your pressure is bleeding off or bleeding over. You have a problem to solve. You test while at full cold and at hot. No motor running. Put pressure to the system and let her sit to see if she bleeds off. Half the time you'll hear where from and bingo. Bob's your uncle. Please trust me on this. This will give you more information than you realize and a good piece of mind in the end even if the system is a ok.
Blindsquirrel, I actually have a pressure tester so I will check that next week. I was going to do it a little different. I'm waiting for a friend to return my cyl leak tester (only been 2 months since borrowed) and I was going to do that but I could also pressure test coolant system that way as well. I also plan on running compression test. Yes, my block tester was a positive test and that probably spells bad news. They seem to be fairly accurate. Just so you know, I spent 3 years at a dealership, worked as a mechanic for my dad for 15 years and owned my own shop for another 10 years until my body couldn't go anymore and i sold out! This is my own car and I find those problems on your own car are harder to accept and sometimes you dont think straight when tackling your own problems! Hopefully i will have some solid test results by end of week and then decide what to do. Thanks for your help, i do appreciate it. Stay tuned! Rod
Rod What water pump are you running,???? Their is 1 inch hieght difference between the newer aluminum, long snout (1970 up), and the 1969 back (cast iron) these are shorter. If you have the aluminum 70, and up, and change to the 69, older cast one , you can gain 1 inch clearance. But you will have to get different rad hoses. This might help to install a mopar heat operated "clutch type fan". Dave
barracudadave67, Do you have any part numbers? Im running the high flow water pump from NAPA. It is for a 70 or later. I will do some checking but all the shorter ones I have seen and we checked have the outlet on the drivers side and my radiator is on the passenger side so if thats the difference I would have to replace the radiator as well. Thanks Rod
Rod The rad hoses Im running on my 67, and 69 small block B-Cudas with cast iron water pump, are upper, Gates 20875, and lower gates 25527. These are for BB mopars. They work with my aluminum rad, and cast iron 69, and older pump. Im going to use the same combo om my 66 B-cuda, when I install a 360, soon. I am running a " Ford","Mopar" type rad from a place in Minnesota(forgot the name). the inlet, and outlet are the same, for Ford and Mopar. Dave
If the scoop isnt connected to the aircleaner...sealed...your letting air in under the hood thru the scoop that SHOULD be going thru the radiator to cool it...and isnt. It isnt your only issue but its part of it. A bigger part than you may think. Plug your scoop and get the water pump pulley overdriven. Simple changes first. This stuff gets wayyyyy overthought.
Negative. Any good radiator shop can swap sides with the outlet lickedy split.
jimacuda, The scoop is plugged as I mentioned in the post. Actually the first complete drive was closed the whole time. The 2nd drive I removed the scoop the last 3 miles to see if it would cool it down at all, which it failed to do. The water pump pulley I will probably do this week but that is going to take some time as the lower pulley is larger then the one on there now because it will also do my power steering that will be added later. The larger pulley will hit the trans lines so I will need to make new lines. But it will get done! Rod