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Discussion Starter #1
Couple months ago my fairly new 331 started to over heat at 215 degrees or so. I discovered that there was parts of a rag stuck in the t-stat area. I pulled it apart and replaced the t-stat and flushed out the engine with a garden hose for approx 20 minutes. engine would only heat up to 150 or so and still that took forever. I verified that my new guages inside the car were right with an IR gun. The rad was clean and full of coolant right to the top. Still didn't work so I pulled the water pump off and everything looked fine with the inpellers and what not. Still didn't work. Top of the rad was cold/warm at best... same as hoses, So i had my rad rotted out and core rebuilt. Now its a little better it comes up to 160 but still takes a long time but atleast the top of the rad is much hotter than it used to be. Bottom of the rad is still fairly cold though. I have tried 3 t-stats aswell. Engine use to always run at 190 or so and the temp came up fairly quickly but not no more. Engine will run like crap for awhile cause its so cold and will not warm up. Its a real PITA. Anymore ideas. Maybe take it to a rad shop and have them pressure test it? Seems pointless though if everything is allready new. Thanks.
 

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Thanks FE - The heads are Edelbrock RPM. No pictures when being built either. However, I never had any problems for the first 1000 + miles or so then this started. It dosent seem like there is enough coolant in the system because I only put approx 4L in it, But it is full right to the top of the rad so I cant physically put more in it. I tried burping it to get any air out. This is driving me nuts, I guess i could bring it to a rad shop but I honestly dont know what they will do that i havent. Sucks but im definately going to have to pull the heads.
 

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Remember, running too cool has nothing to do with the radiator. If it ran at higher temps before, then it's not the block. That leaves the water pump and thermostat. The water pump, if NOT working will cause the engine to overheat quickly, so that's not it. That leaves the thermostat, and if it does not bypass or leak any flow, will not open until the proper temperature, forcing the engine to heat-up until it does open.

This all assumes you are seeing correct temps on your gauge. If the coolant level is low or the temp sensor is in an air or steam pocket, or the sensor is faulty, or the gauge is mis-calibrated it will not read the correct temp.

David
 

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Run a ground wire from the neg terminal of your battery to the housing of your temp sender and see if it changes. Also too low of water will result in a lower than normal temp reading while the engine is hot. Is your heater blowing hot air. You need to run coolant through the heater system just to get rid of the air. If your temp sender is OK and your coolant temp is too low you've got what we've all been looking for, a perfect cooling system. In that case, run a higher degree thermostat. Jim PS. I like to run my ground wire to the intake and the bell housing.
 

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I read your earlier post about this but I dont remember if you stated or anyone asked if your engine block has been filled with hard block? I know that when a block is filled or partially filled (usually up to the freeze plugs) that the coolant doesnt have enough time in the motor to absorb alot of heat so the temp gauge and the T stat say the engine is running cooler.
I also remember you saying you used a Infrared heat gun to test the temps. did you check right at the spark plug or at the header where it attaches to the head? I dont know what those temps should be but just throwing it out there. This is a strange situation. 99% of the time we are trying to figure out how to get the temp of an engine down.
 

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Do you have a High Flow water pump on it? Not sure how much it would effect it?

What thermostat are you running?

Are you using a Mechanical or Electric fan?

Where do you live? I know in Indiana the temps have been lower so far, I had my Falcon out and while driving it the temps haven't gone over 160. It's also a 331 with Aluminum heads. No problems with drive-ability after the choke is open all the way.

Jet
 

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Black, I think you simply need to put a flow restrictor in your system. It seems that you need to staunch the flow of coolant so it has time to heat up.

I can think of no other reason except for the fact that maybe your ultimate coolness is making the car cool too :) :) :)
Hah Hah, Thats a good one.
I like the idea of restricting the flow too. You might be onto something. :^)
 

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I encountered a similar situation years ago while working on a friend's car - a GM product with a straight six. A V8 was an option for this vehicle. We were replacing the radiator to resolve overheating. Since the V8 radiator was the same price & the hose locations & diameters were the same as his radiator, we obtained & installed the V8 radiator. The new radiator was the same height & width as the one being replaced, but the core was thicker. Even with a 190 degree thermostat (at that time, a 190 degree thermostat was the hottest available for that vehicle), the vehicle coolant temp never again got above 160. My friend moved out of state & drove the car for over 5 years & never had any problems due to the low temp, but his vehicle was used for commuting only & had no performance pretensions.
To get the temp in your vehicle up to the normal operating range you can restrict the water flow, or restrict the air flow through the radiator. I have read that restricting the air flow to keep the coolant temp up during cold weather is a somewhat common practice in geographical areas that have very low winter temps. Usually, cardboard is attached to the front of the radiator to block off a portion of the fin area. It is easy to do, does not involve a lot of labor, and is easily modified or removed. Hope this helps.
 

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Discussion Starter #13
Thanks guys, Bit of an update.

The water pump is an edelbrock aluminum, I dought there was any hard block used, Also the engine worked perfect for the 1st 4 years. Always ran at 180 to 190, never a problem, This just started a couple of months ago. I have always used a 180 t-stat, And i have tried 3 or 4 of them in the last couple of months without any change. Nothing else has been changed on this engine, Thats why I am concerned that it just will not work properly. Also I am using a mechanical fan... always have. Last night I managed to get it up to 165, But it took atleast an hour. Car runs like crap prior to that because it is so cold and i dont have a choke on the holley 650dp. It will backfire a bit and stumble till it aleast gets a bit warmed up. But the problem is it takes forever to warm up, And it never reaches normal operating temp.

I noticed i have a bit of a leak on the chrome t-stat housing, I have tried several times to make it stop. Could this be a problem? Allowing air to get in there perhaps. I personally dont think so but at this point its worth asking?

The t-stat is in the right direction but can it not be in there properly? Like it slips down a bit when you are trying to tighten the nuts on the housing. Always a PITA trying to hold the t-stat while putting the housing on and tightening the bolts.

I'm pretty sure there isnt enough coolant in the system, But it is full right to the rad cap. problem is usually when working normally the t-stat will open and the coolant will go down and then you put more in. In my case I cant do that cause the t-stat will not reach the 180 temp to open, So basically the t-stat never opens cause it cant reach the temp of 180. Thanks guys.
 

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If all of that is correct, it should be true that you NEVER see any flow in the radiator with the cap off. If you do get flow, then the engine temp is actually higher, or you managed to get 5 defective thermostats.

Chrome necks are notorious for leaking. Sand it flat on a sanding plate to even the sealing surface. This may remove the chrome from the area, but it's a necessary evil to get some of them to work. You should not need sealer. Just a gasket.

No restriction of the system is required. The T-stat IS a restrictor. It should restrict 100% and then allow less restricted flow to the extent the engine requires cooling. BTW - I'm not getting into the Cleveland "restrictor" argument. It's not a restrictor. It serves two different functions - neither of which is restricting. Even the Ford part name says it's not a restrictor. So, the only restriction you need is the thermostat.

If you have no flow through the radiator (which again - you should not if the T-stat is not actually up to temp) then other mods there will have no effect. Remember, boats use the same system to run at normal temps with a lake or ocean of cold water.

If you think you have trapped air (which will show both a cool gauge reading and also not allow the T-stat to see true engine temp) then I suggest taking a new angle, and drilling ONE single 3/32" hole in the T-stat flange at the crotch of the 'hump' where it meets the flat disc area. Sand your outlet, and reinstall it with the hole at 12:00 position. This will let any trapped air purge out for reliable readings. Yes, it will allow a tiny amount of flow, but at this point you need to solve any weirdness that may be complicating the issue.

One final note - the T-stat should be of the correct O.D. size. That means it should fit the little rabbet (recess) around the lip of the T-stat about perfectly. If there is any slop that is can slide down and allow flow around it, or fore/aft play that would do the same thing - it's the wrong type.

David
 

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Black, maybe your cooling system is just too efficient (though with a 331 I kinda doubt it) but the info you have supplied based on questions asked or suggestions given by others to me is a bit sketchy.

Have you tried running the heater on full fan and heat? If so, what happens especially after the engine temp is at it's highest indication?

Have you cracked the heater inlet line at the firewall to check flow if heat output low?

Is your gage probe mounted on the intake manifold (factory) or is it on the thermostat housing?

Adding 4L only? Do you mean total coolant added to fill both rad and engine from dry or do you mean after just pulling thermostat?

Just a side note .... I don't know where you live but if it's cold and damp, and especially if engine isn't warming up, some of that crappy running could be carb ice .... a common problem in this area.
 

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From your posts, I am reading that your car ran at normal operating temperature for several years, you recovered a rag from the cooling system, and now it runs too cold. It would appear that the rag was a flow restriction, and now a larger volume of coolant is moving through the radiator in a given time, perhaps with greater speed, leading to significantly lower temperatures. OK, to return to where you were before the rag came out, restrict the coolant flow in some fashion. Alternatively, you can restrict the airflow through the radiator.
I think you designed your cooling system around the restricted flow rate (due to the rag), & now that the restriction is gone, the system is too efficient at eliminating heat.
As an experiment, block off the majority of the airflow through the radiator, let it idle & see if the temp comes up (don't let it overheat, obviously).
On the GM vehicle I mentioned previously, we tried several thermostats, all of them identical in size & shape to the thermostat that had been working fine for years with the old radiator. The thermostats were installed correctly, were tested in a pan of water on the stove & were functioning correctly. Never could get it to operate at above 160 degrees.
If I were having the problems you are having, I would replace the mechanical fan with an electric fan.
 

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Discussion Starter #19
Thanks guys. I dont have a heater in the car. i live in british colombia Canada, Its fairly warm here. Engine has always ran fine for the 4 years I have had it, Even in the middle of winter. My coolant sencor is in the manifold closest to the t-stat housing. Also, There is no flow when the rad cap off... So i guess the t-stat isnt opening then.
 

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Black, things aren't adding up. It appears you are believing that the coolant isn't flowing at all and that's because the thermostat is still closed because the engine simply isn't getting warm enough to make it open. If this was truly the case, one could conclude that you could rip out the rad and waterpump, plug the coolant ports on the block and still never achieve normal (180/190) operating temp. And, I would want to buy your engine.:D I'm not trying to poke fun, I just want to show that we aren't getting much closer to solving your problem. We may have led you to the problem and maybe even the solution but based the suggestions given that you may or may not have followed, questions asked that you may or may not have answered, and based on the conclusions you have reached from your troubleshooting, there's no clear indication that we have.

To move forward, I suggest you go back to the last post from PSIG and ensure each of the possible problem areas listed have been clearly looked at and eliminated. Lastly, I ask again ... when you say you only added 4L of coolant, is that system total from completely drained or what?

BTW .. where in BC are you located?
 
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