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Old 09-08-2016, 01:59 AM
rexs73gto rexs73gto is offline
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Default Still getting to hot & then overheating.

Well I broke down 2 days ago & bought an electric fan out of a Taurus & I have it mounted it & wired up with a T-stat that will turn it on at 180*. I have tried a lot of things & this I hope is going to solve it. The car has an Alum. rad 3"'s thick & I pulled the water pump & put one of my NOS divider plate in that is now clearanced at about .10ths maybe a little closer then that. I also installed my NOS sleeves & seals. In the AM I'll put a new lower hose on it & put it back together to see if this fixes it. I can drive the car (before) down the road & it would stay right at 165*, but if I got into any traffic it would creep up to about 220*. Then if I had to sit for any length of time 10+ min's it would start to overheat. Yes overheat it would start to boil into the overflow jug , then if I couldn't get moving it would start to boil out of the overflow jug like an old percolator coffee pop. I haven't had it stop on me as I've always found a way to get moving again. Once I got moving again it would go back down to 165 in about 3-5 miles at speed. I also have replaced the T-stat twice to no avail. I should have it all back together in the AM to see if this electric fan is the fix. OH. I had a new clutch & 7 blade fan on it all during this to. I have heard a lot of good things about the Taurus fan for this condition, so I'll cross my fingers on this. Also this is a new engine with about 1500 miles on it now. I've had this problem for the entire time. Any one have any other ideas ??

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Old 09-08-2016, 07:30 AM
73gtolive 73gtolive is offline
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I've always been taught that low speed over heating is airflow through the radiator and over heating at speed is water flow. I've battled this with 2 Mopars and it is no fun. Watching that needle creep up while sitting at a red light takes all the fun out of driving it.

Do you have a shroud ? My belief is that in moderate situations that the factory designed cooling system is best. Even better if the factory offered a heavy duty cooling system. Find those parts. That means all the correct shrouds, fans clutches, fan, distances from Radiator etc. That also means a brass radiator that is in good condition. I know lots of people have good luck mixing and matching parts and that is the back bone of hot rodding but I have had mixed results when trying to keep some of these beast cool. The factory engineers designed these cars to run cool in all conditions. As much as we all cuss them, they were probably smarter than most of us are when they figured these cooling systems out.

I have used an aluminum radiator in a small block dart but ended up spending a good amount of cash for their custom made shroud (Wizard Cooling) and then put the right diameter fan on it. I can sit at idle in the staging lanes on a 95 degree day and leave the car running with out it overheating.

Not sure this applies to a Pontiac but I would think it would. A poor tune can cause your car to run hot. A lean condition will not be in your favor.

Good Luck !

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Old 09-08-2016, 08:34 AM
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My Questions are do you have a Fan Shroud? And if you do is it properly spaced in the Shroud? I agree that it sounds like an airflow problem.
How well is the Radiator sealed to the grill opening? Some pictures of the Fan and shroud front and back would help.
If the Taurus fans are pushers I have usually found they only help maintain a given temp when turned on, they seem to impair airflow thru the Rad.

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Old 09-08-2016, 10:46 PM
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Rex, I know you are a good mechanic, so I know you've probably covered these already.
Does the cooling system hold pressure?
Does the radiator cap hold pressure?
What camerjeff said is pretty much what John Sawruk would cover in his seminars. You have to seal off everything around the radiator to force more air through it.
Also: http://www.wallaceracing.com/water-pump-mods.php
Running the cast iron impeller?
Good idea to check/replace the lower hose.
Did the engine rebuilder use a Pontiac heater hose nipple in the head like he should?
The viscous fan clutch is adjustable. Procedures are on the internet: http://midamericachevelles.com/tech/...tch_adjust.pdf
If it didn't overheat before the engine rebuild you have to look at what was changed. For example a .060 over factory 455 block will run hotter.
Did you drill the 2 extra holes between the center cylinders to aid water flow?
Got enough ignition advance at idle.
These are just a few thing off the top of my head.

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Old 09-08-2016, 11:32 PM
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I think you know that my Taurus fan was impeding airflow. Doesn't seem to be your problem, but just putting it out there.

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Old 09-09-2016, 12:37 AM
rexs73gto rexs73gto is offline
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Default still getting hot

Well I have tried so much stuff I don't know what else to do. 1st off I have a 3" think Alum. rad which is equal to the 4 core copper/brass rad. I'll start about 1 1/2 months ago. I bought a new H.D. clutch for the fan, it is a 17" 7 blade set just inside the fan shroud. Fan is about 1-1 1/2 inches inside the factory shroud. The factory shroud on a 73 is the type where the rad. sits inside the fan shroud & all the air goes through the fan shroud. Horst you know the design. Before that I had tried 3 different fan ,2 solid & one alum. type for use with a clutch & none of those worked. Both the upper & lower hoses are Dayco & are almost new. I run a 160* super stat. The lower hose doesn't have the spring in it as I watched several times to see if it were collapsing, which is doesn't. Now this time I took the water pump off , replaced the divider plate with an NOS GM one. The water pump has the steel impeller. I went & clearanced the plate to a little less then .10ths, as I don't have feeler gauges that are long enough to get into the the plate enough. I also replaced the sleeves & seals with NOS units that I had in my stock stuff. I also installed the Taurus electric fan which is a puller & pulls a lot of air. Don't know the cfm but I have read a few times on the different sites that the Taurus fan works good when installed correctly. The relay will now turn on the elect. fan at 180*'s & off at 170*'s . I have a 6 1/2 pulley on top & an 8" on the bottom, with a 2 3/4 or 3" pulley on the Alt. The 1 thing I haven't done so far which I should have done a while ago is take the T-stat out & try it with out. My timing is at 14* advanced right now with the total at 35*'s. I don't have any way to check air/fuel mix but it seems to run very good & I know it's not rich or lean as the throttle response is great. Right now I have to get a new belt for the W/P as it's in need but not bad enough to cause any concerns. SO tonight I don't know if any of this has worked yet. At least not until the AM. I run a 50/50 mix to. Now before all this going down the road the car stays at 160*'s & when I get into traffic it continues to creep up until if I let it will start to boil out into the overflow jug. Air flow seems very good even at idle as I can at idle put a piece of notebook paper on the front of the rad. & it will stay there with no problem at all. So air flow seems good. BUT ????? P.S. The heads are E-heads 87cc heads & it has the nipple that screws into the heads that it came with. As far as drilling the block , I guess I'm not familiar with that process??

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Old 09-17-2016, 01:25 PM
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fiedlerh fiedlerh is offline
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Everything you did should help, but you might have a few little things working against you....
Quote:
It is a 17" 7 blade set just inside the fan shroud.
The factory fan is about 19-1/4. Your fan is too small. The fan should be about 1/2" away from the inside rim of the fan shroud.
Quote:
Fan is about 1-1 1/2 inches inside the factory shroud.
The fan should be about halfway in the shroud.
Quote:
The water pump has the steel impeller.
People have had issues with the steel impeller and overheating. Not sure if the clearance trick is as effective with a steel impeller. You might try going to a factory cast iron impeller and set the clearance .030". If you need a factory pump, let me know.
Quote:
boil out into the overflow jug.
Again see, if the cooling system will hold pressure. Boiling concerns me. The radiator pressure test kit from Harbor Freight is pretty cheap. Another way is after a drive, squeeze the upper radiator hose. You should feel that it is pressurized. How long does it stay that way?
Quote:
the nipple that screws into the heads that it came with.
The Pontiac nipple had a flow restriction in it. I understand if you just put a plain nipple in there, it can cause issues, but not as serious as you describe.
Quote:
As far as drilling the block , I guess I'm not familiar with that process??
Early 60's Pontiac engine blocks had two additional cooling holes near the center cylinders. Pontiac head gaskets still have these holes and can be used as a template for drilling them. Suppose to aid cooling of the center cylinders.

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Old 09-17-2016, 02:23 PM
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Have you put a lazer temp gun on the radiator and engine parts.The first thing I look at is the temp drop from where the engine water goes into the radiator and then out.I look at the temp at the thermo housing and then right at the head where the X over bolts up.Cheap tool that can show hot spots on the engine.Learned that stuff from my boat dsl mech years ago.

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Old 09-17-2016, 09:37 PM
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Unfortunately an infrared thermometer (lazer temp gun) won't give correct readings on bare aluminum. Fine for cast iron, rubber, painted surfaces, etc.

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Old 09-17-2016, 10:08 PM
bendutro bendutro is offline
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Quote:
Originally Posted by fiedlerh View Post
Unfortunately an infrared thermometer (lazer temp gun) won't give correct readings on bare aluminum. Fine for cast iron, rubber, painted surfaces, etc.
Sharpie will fix that.

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Old 09-18-2016, 12:47 AM
rexs73gto rexs73gto is offline
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Fiedlerh , I have the 5 blade 17 inch fan with a new HD clutch that I bought about 3 weeks ago. The system is holding pressure & the cap let go at 16 lbs , I have a Stanz pressure tester. The rad. holds very good pressure , I've pumped it to 18 lbs & it holds just fine. I did move the fan 1 inch deeper into the shroud the last step so it puts the fan about 2 inches from the rad. fins now. The pull through the rad. is good or so it seems because I can put a piece of paper on the outside of the rad. & it will pull it right tight to the core & hold it tight at idle. The cooling system does start to percolate into the overflow jug after it reaches about the 228 mark & then of course the cap lets go as it reaches the limit of the cap pressure while it does that. The nipple I'm using is the brass one that screws into the E-heads, also that came with the E-heads. It won't accept the push in type that is used by the factory as it has threads on the inside area where it fits. When I pulled the water pump off the last time I made sure there was only about .008 to .0010 so it is close & should be within reason. But as stated it is a steel impeller & not the cast impeller. I did take out the T-stat last night & drove it without & it got hot just like before. It just took a little longer to heat up but once it did it just kept going until it got to the point where it was percolating in the overflow again. As stated the rad. is a 3 inch thick Alum. which is fairly new & it is clean as I've had clean water in it now from removing the water pump to change all this stuff so the rad. is as good as flushed & the water thats in it is clean & clear. I did put a new T-stat in it this morning a 180* T-stat but haven't driven it yet to see if this make any difference at all. I don't have a 19 inch fan to try on it & have looked in a few of the junk yards around here but it's getting slim pickings around here to. Any more Ideas???? My next is going to be to replace the water pump with a cast impeller one possibly from GMB so i can get one of the Alum. bodied pumps with the cast impeller. Then ,,,,, I don't know whats next to do.

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Old 09-18-2016, 10:44 AM
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Trying a bigger diameter fan is a quick swap. Not sure if that is enough to help your situation. Something's not right. If there were a head gasket issue that only shows up when the engine is hot, I would think you would see it (white smoke, coolant in cylinder, one plug that is colored different, etc.).

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Old 09-18-2016, 10:56 AM
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Not sure if this was covered.The very first place I start is timing.Retarded timing will cause overheating.Tom

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Old 09-18-2016, 01:59 PM
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ID67goat ID67goat is offline
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Quote:
Originally Posted by tom s View Post
Not sure if this was covered.The very first place I start is timing.Retarded timing will cause overheating.Tom
X2...I just recently went from a mechanical advance distributor to one with vacuum and got my carb dialed in with a wideband and my car now runs 5-10 degrees cooler at idle than before under the same weather conditions.

My car before would get up to about 200-205 stopped or in slow traffic and now never see it above 185-195 in 95-100 degree weather.

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Old 09-18-2016, 04:46 PM
rexs73gto rexs73gto is offline
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Well I went on ebay last night & bought a 19 inch 7 blade fan for it, & it will be probably about 5-6 days before I get it but I'll see what happen there. As far as my timing I'm right now running the timing at 12 advance with the vacuum unhooked & the car runs great at that setting. The advance is at 34 at right at 3100, so I think I have it pretty close to where it should be. If i go much farther the car will start to spark knock, & i don't want that. I know there isn't a head gasket concern as I have none of the problems you'd have with that. I think I may get into the carb & put a little bit smaller primary rods in the richen it up a little but it runs so good right now & don't want it to be blowing black smoke out the tail when I hit the gas. But again I don't understand why I can drive it easy , hard or any between & as long as I'm going over about 30mph it will stay at 165 & then when I get into traffic for about 3-4 mins it will go right up to 220 & higher if I don't get it back up. It seems to have plenty of air flow through the rad. as it will keep a piece of paper stuck to the outside of the rad. just sitting still. ?? Will the 19 inch fan help ???? I'm hoping it will . I'm going to drive it today to see how the 180* T-stat works in it. I don't think the last 165* T-stat was stuck closed but I'll see what happens when I go out today.

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Old 09-18-2016, 08:19 PM
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Quote:
with the vacuum unhooked
does it still happen with the vacuum connected? Can you run ported vacuum or manifold vacuum?

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Old 09-19-2016, 12:56 AM
rexs73gto rexs73gto is offline
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I haven't tried to run the car with the vacuum unhooked to see if that makes a difference. I'll try that tomorrow to see if it makes a difference .

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Old 09-19-2016, 10:23 AM
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With the vacuum advance connected check your timing at idle....if it is still at 12 then you are probably connected to a ported vacuum source. If that's the case, try a manifold vacuum source so you can get more timing in while at idle.

Once you get the timing figured out, then dial in the carb mixture and with the more advanced timing at idle speeds the engine should run cooler.

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Old 09-19-2016, 12:17 PM
rexs73gto rexs73gto is offline
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The vacuum is on hard vacuum & the idle goes up when plugged in. It is not on ported vacuum. But I will try it with out the vacuum plugged in today. I will have the 19 inch fan in a few days & get that on & see what happens then.

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Old 09-19-2016, 04:31 PM
rexs73gto rexs73gto is offline
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DUH...... Well I don't know if this will make any difference but I may have just figured out why it has been acting the way it has been. While running down the road it is forcing the coolant around all the parts of the engine by pure force of the water pump . But what I saw was like a light bulb going off while out playing with it to try to figure out whats causing this. Had the car running in the drive to get it warm to see if maybe something was leaking air into the system , like a bad cap or a hose leaking & sucking air. I even chalked the rad cap to make sure it was sealing in the cap area. I used yellow tire chalk to coat the rubber seal & then double checked it with a little bit of grease to make sure it was coming in contact with the bottom of the cap area. It was. I turned the car off as it was getting hot after running for about 10 min's . I turned it off & when I stepped back i was standing there & after about 3 min's i could start to hear sounds coming from the upper hose. It sounded like it was boiling in the upper hose. That shouldn't be happening. As a stood there I got closer & the sound was getting louder so I could hear it without being close to it. Looking at it just popped into my head. The T-stat housing is one of those that can swivel 360*'s & it is higher then the valve cover. DUH, I think now that the problem. The upper hose is higher then everything else & I think it may be causing it to get air trapped in the upper hose which is the highest spot in the cooling system. The T-stat housing is about 1 1/2 inch higher then the valve cover & the sound was coming from the part of the hose thats the highest point now. Why I didn't see this before , & now thinking back I believe that this started when I put this on but had only been driving it around town for a short distance & when I did go out it was mostly highway driving which it stayed at the 165* temp while driving. I will be going out for a drive in a bit to see if this is going to take care of it. It is the logical item that SHOULD fix it, at least from what I see now. Can / could it be just that easy?? Could it be so simple as a fix ?? Why could I have missed it for so long. ?? Last thing , I did put a regular Pontiac T-stat housing back on the engine to & now that it's on you can see how much different the height difference is in the 2 housings. Now the rad. outlet is the highest thing it the mix so the coolant should be level all through the system.

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