Overheating!! Help!! Ideas

[formula_raider]

I am almost complete with my restoration of my 72, but the engine has me going insane becasue I cant seem to find the cause of my high engine temperature.
This what I have: Less then 500 miles on a Goodwrench 350, stock pistons, crank, rods, replaced heads with Iron Vortec. Aluminum vortec intake, mild flat tappet crane cam .454 .480, double roller timing set, roller rockers. Compression is around 9.25:1. Nothing real radical at all. I put a complete serpentine setup for waterpump, AC, power steering from a 92 camaro. I got a new waterpump for a 92 camaro (reverse rotation). Have NEW 4-core radiator with Classic Heartbeat dual fan shroud. Running (2) 12" puller fans and (1) pusher fan in front of condensor. A 160 degree thermostat that has been tested. This engine slowly creeps up after the thermostat opens up to 210, I have never let it reach higher than that. I have never had any problems with SBC overheating. The last SBC I had in the truck had NO shroud w/4 core and never broke 170. I am at a loss. Could I have the possibity of "air" in the water pump or cooling system....I have NEVER had this problems before on a SBC but whos to say. How do you purge air from the system. How do I tell if my water pump is really doing its job.....it is not leaking in anyway....but I wonder if it is pumping enough. The temperature seems to climb weither im at idle or on hwy. So I dont think it is the electric fans not keeping up. Any suggestions??? Sorry for the novel just wanted cover everything.

[shifty]

i am no expert, but i've heard air bubbles causing overheat. with my inline, i had problems with overheat due to low oil pressure caused by crap getting stuck in the oil pickup screen (it was coming off inside of valve cover).

[rcbildr]

What type of temperature gage/sending unit are you using? Somebody correct me if I'm wrong...But if I remember right the electrical sending unit that fits in the vortec heads will not work with the stock gages. Maybe try hooking up a mechanical temperature gage and see what happens, or at the least try a different gage/sending unit and see if it acts the same way.

[formula_raider]

Thanks for the feedback. I trust the gauge, it is an aftermarket Autometer electronic gauge w/appropiate sender that is plugged in at the intake manifold water passage close to the thermostat housing. I am running a Holley Commander Fuel Injection system and the sendor that feeds temperature information to the computer gives me an exact coolant read out. It is very close within 5 degrees of the gauge. I have also used a laser thermo probe on the radiator to verify temp. I believe the temp to be a true reading. I have opened up the radiator cap, let the thermostat open and revved up the engine to see if coolant is flowing. It looks like it is moving, but it is definately not flowing a stream. I will double check with the auto parts place to see if they gave me the right pump. Does anyone know how to get possible air out of the system or does this not need to be done on SBC. I do have an overflow tank. Electric fans are definately pulling air....you can feel the heat being pulled from the radiator.

[Oldtruckfanatic]

When I burp my coolant system on a new install I just take the cap off and start the engine cold and watch the coolant as it warms up. usually the coolant starts to rise as it gets close to the thermostat opening, Usually if there is any air in the system you can see it bubble out as the engine warms up. as soon as the coolant reaches the neck in the radiator I put the cap back on and thats it.(be careful not to let it blow out all over you)Usually burping a coolant system only applies to cars with a remote filler or an upper coolant hose that is higher than the top of the radiator in any one place that can trap air. It really shouldn't happen in your case with a properly vented cap and coolant recovery bottle the air should escape as soon as the cap vents. Hope this helps

[Gray Ghost]

Make sure your hose isn't situated with a big hump in it between the block and rad. You can rotate the ends until it is level and run it until the air gets out of the system.

If that doesn't work, I'd pull and check the thremostat. Could be you got a bad one.

Do you have the heater coer getting coolant? If not that could be the cause. Mines runs at 195* without the heater core activated and 180* with.

[Longhorn Man]

Sounds to me like poor circulation.
Open the rad and verify that the coolant is moving around.
Double check that the pump is in fact a reverse flow unti
but first, I'd check the guage.

[Oldtruckfanatic]

I'm not familiar with your fan setup but did you check the fan rotation and make sure they are turning the right way? Also is the pusher a reversible fan? I see people put the summit reversible fans on as a pusher and even if you reverse the wires you still have to turn the fan blade around so it works the right way. The fan usually has an extra push clip in the install kit for this reason. I know it's simple stuff you prolly already tried but you didn't mention it.

[mocwon]

Mine runs at 210-220 once to operating temp with
the same serpentine setup except that it's fuel injection which tend to run a tad higher than carbureted setups.

[Brainchild]

Like has already been said,make sure you have the correct waterpump for thi serpentine assembly,and that the fan is turning the right direction.
those guys at the parts supply aren't to bright sometimes,they can't understand why someone would put a serpentine belt on an old truck.

[70GMCer]

Another thing to check. Make sure that your lower rad. hose is not collapsing at a high RPM. That happened to me years ago. The lower inner spring wasn't in the hose to keep it from doing that. If you have a rubber ribbed hose, then no worry there.

[formula_raider]

Well I double checked the part number of the water pump with the autoparts store and it is the correct waterpump. Somebody at the store made a suggestion that the thermostat needs to be reversed since it is reverse rotation. I didnt relly buy it since a thermostat is not a one way valve, but I decided to take the thermostat out of the equation and remove it all togeather to see how it ran. I thought that was it. You could really see the water flowing out of the radiator when you revved it up. But all it really did was just slow the process down....after a while the temp idleing on on the hwy got up to 225+.
The upper and lower radiator hoses are Stainless Steel so they cannot collapse. The only thing I can think of is that the electric fans I have do not pull enough air.......but dont understand how on the highway that that would matter. I feel like giving up. I now have a $5,000.00 paper weight.

[TugOwar]

A motor will run hot without a thermostat also becasue the water passes through the rad too fast and won't be cooled on the way through. You could be trading one problem for another.

don't know about the reverse thermostat, never seen that mentioned on these forums.

[Longhorn Man]

reverse t stat... no such thing.
The coolant still flows in the correct direction, just the pump has to spin the other direction to do it. Odds are, you have either a faulty pump, or a restriction causing poor flow.
The fans are not at fault, the fact that it does it on the open road proves this. Once you are going 45 or so, you don't even need a fan, the air movement is enough to keep it cool, so that leaves coolant flow. (excluding internal engine trouble)
I'd remove the pump, and replace it with another one. If you get the same brand of pump, you can take the current pump back with the new reciept for your money back.

[formula_raider]

Thanks Longhorn man....I didnt think that flipping the thermostat would make a difference. I thought that the coolant flowed the opposite way....but your saying that the pump just spins the other way but the coolant flows the same direction. That makes sense. I guess I will try another new pump. I dont know what else to do.

[ratrod67]

What about the headgaskets you used? Maybe the coolant ports are different sizes or don't all line up. Just a thought.

[Longhorn Man]

The coolant flow is reversed on an LT-1, but not a normal small block.
rat rod... that crossed my mind, but aren't all the head gaskets pretty much the same? I may be wrong on this, but heads interchainge between all small block (non lt1 or ls series) so the coolant ports should all line up... right?
Or am I wrong on that?

[formula_raider]

I am using a Felpro 1094 rubber coated steel shim....which many of the "Chevy magazines" used for the Vortec Head or standard SBC head for that matter.

[Oldtruckfanatic]

Actually you guys hit on a good point here although longhorn man is right the head gaskets should be fine I think the intake gaskets have different ports between the vortec and the older heads. there are still a few other things that can cause the problem as well a big one being timing an engine running 4 degrees at idle will overheat at certain altitudes but at 8-12 degrees it wont (just another thing to check even though it's probably right) and Even though you are sure the fans are in correct rotation it only takes a second to put a rag or paper towel or piece of paper in front of the grille on each fan and make sure it sucks up to the grille one could even be right and the other wrong...If they turn the wrong way they will keep air from going through the radiator on the highway. If all that checks out I still would go with longhorn man on the faulty pump or blockage in the system. (I did install a radiator once that had packing peanuts blocking the bottom third) Hope you can get it figured out

[57sailplane]

hey, i havent messed with the newer style blocks and pumps. but you say you are using a reverse pump with vortech heads that makes sence.. but how about the block, you say its a crate motor is it of the new style reverse flow block or the standard flow... not sure if there is any differance but sure would like to know if there is and if so this might be the cause.. hmmm? now that i read on it seems that the only differance is the pump rotation and not the flow now i am confused.. it was my understanding that the newer engines draw the water though the heads first then the block as to cool the hotest spots first making for more even block temp... glad this topic came up maybe i will learn somthing

[57sailplane]

man i just looked up the lt1 on reverse flow on my search engine and as i thought the lt1 are a revers flow engines. on a standard motor water is drawn from the radiator though the pump and forced into the block then the heads then past the thermostat and back into the radiator.. on an lt1 motor water is drawn from the radiator to the pump which forces water through the heads then the block and back to the radiator.. thats my understanding on the 2 motors as i have read from literature.. so maybe your block is not of the lt1 type and won't work with that pump???

[Longhorn Man]

only the LT-1 and maybe the LS series did the reverse cooling. The perp belt set up has to spin the pump backwards, but the coolant goes the same direction as all small blocks since 1955.

[57sailplane]

man i got way off track.. i misread the reverse rotation for reverse flow.. sorry my bad...

[Longhorn Man]

On top of thatr, the LT1 has a gear driven pump, and there is no way the pump could physicly be installed on an old school small block.
Very few things on the LT or LS engines will work on an old school small block, and in my opinion, they shouldn't even be called small blocks. A small block has parts that will interchainge with any other small block. It may not work well, or might not last long, but the parts are very swapable... the LT and LS engines.... pretty much nothing swaps over to the old stuff, therefore... in my eyes anyways, they are not even small blocks.

[tcoop68]

I built alot of race motors, stock motors,I was reading all the guys ideas,the first thing that popped into my head after reading a few was the same thing Ratrod67 thought it was,I would really give that a good look.It sounds like you covered all the basic stuff.My bet would be on gaskets,intake,and head gaskets.Hope you getter fixed.