New 4 row Radiator, New Fan, New Water Pump and Stat - still running hot!

[ubtripn]

I just don't get it. This was a NAPA 4 row radiator. I jacked the front up when I filled and burped it. The pump and fan are new. Its driving me crazy. I couldn't put the shroud back on but still, that could not be it. I went around the block twice and hit 220. Somebody said it is possible for the water pump to look identical but rotate the other way. That is the only thing left I can think of.

What do you all think?

[LockDoc]

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Do you have any pictures of your pulley and belt setup you can post?

You also may have a blockage somewhere in your water jacket.

LockDoc

[Lee H]

How are you measuring the temp?
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[redmonster]

having the same problem and i found some information that a fan shroud should help

[68chevyfuelie]

^^^

That's my first question too....we had a '56 Belair 2 weeks ago that was "overheating"....aftermarket electric gauge showed 220, original mechanical gauge read 190. We used a temp gun on the intake, block, heads, etc to rule out the temps being read.

A water pump with straight fins on the impeller shouldn't care which direction water flows, you have to be careful when the impeller blades are curved one way or the other.

[ubtripn]

Which gauge was right?

I am using a new mechanical gauge.

I could not fit the shroud because the rad is thicker so I am going to shave it down and install it. I started to wonder if there is some type of necessary relationship between the flex-blade fan and shrouds. (I hate flex fans)

Red Monster - what did you learn about the shrouds?

I will try to get a pick. My worst fear is a water jacket blockage.

I did lift the front when filling to ensure the heater core was below the radiator.

[68chevyfuelie]

Is the water/coolant physically overheating though? Not too sound like a jackass, but you need to start with the basics.

Is the thermostat opening, the upper rad hose getting hot? Is the coolant bubbling and hissing? Rad cap working okay?

I disagree (as an opinion) with needing a shroud for the amount of driving you are talking about. I think you need to determine if the mill is overheating (with no help from the rad) vs. everything working together ('stat open, good coolant flow, etc.).

Also, sometimes overlooked, if it's an A/C truck, if the condenser is plugged, the rad will receieve no airflow. Sometimes those little things when overlooked will bite you in the ass trying to chase a problem.

[fastwillie 696969]

take it to a smog machine and have them check for gases at the radiator, coming from the heads or block possible

[ubtripn]

Yeah I have good flow, no thermostat right now, I have one waiting to go in but I figured a 4 row radiator with no stat should run very cool.

Thanks Fastwilly - I will do that.

Coolant boiled at 215 and expelled out.

I just burped it more, and could see the coolant running out of the flues with the cap off and the flow increased with RPM. Bubbles came out and now it is running 190 (88 degrees outside) until I stop to idle and it climbs to 210 then 220. I am hoping the shroud will fix that.

[cdowns]

i always take a known good thermometer and take the actual temp of the liquid to see if gauges are accurate

[MagmaJct]

I'm impressed that no one has asked one key question:

Does it over heat with high speed driving or low speed driving. This is critical. If the fan shroud is missing the cooling fan is almost completely useless and it'll pull air from the space between the fan and the radiator.

The shroud forces the air to be pulled through the radiator at low speeds (when the fan does most of its work.)

Also, this is further proof that removing the thermostat, or running with a cooler thermostat doesn't prevent over heating. The thermostat sets the minimum coolant temperature, not the maximum. All a thermostat does is prevent the cooling system from functioning until a minimum operating temperature is met, then it "turns it on" so to speak.

If the cooling system is broken, it doesn't matter when it's "turned on". My advice? Re-install the shroud, find a way, then see what happens. If the problem isn't solved, don't think the shroud wasn't the problem, look at it as a "contributing factor" that has been eliminated. Details matter!

[TobyArnot]

Have you checked the coolant for content? A small head gasket leak can drive you nuts trying to locate. Have it checked. (Don't ask how I know)

[MARKDTN]

Originally Posted by redmonster

having the same problem and i found some information that a fan shroud should help

X3. A fan shroud is critical to force air through the radiator

[ubtripn]

Great point ll especially MagmaJCT - I did not re-install the shroud so I will be modifying it to fit today. (I replaced the 3 row with a four row)

You were right, slow speeds and idle were the problem and I could feel no air being pulled through the rad at idle. I think you nailed it. Going to do the work today and will repost tonight. Thanks all!

[LockDoc]

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You need a thermostat, otherwise the coolant travels through the radiator too fast to be cooled. I think that, plus no shroud are contributing factors to your problem, especially for in town driving.

Just my 2¢ worth.

LockDoc

[mpotts64]

I had heating issues as well, new rad, all new hoses, new t-stat, flushed the system, had a shroud and all and still overheated, come to find out the clutch fan was not working so there was no air being pulled through when idling, I took the clutch fan off and drilled and put bolts through it to make it a direct drive, it hit 111 degrees here yesterday and it stayed right on the mark, did not run hot, that baby is pulling air now, will blow the tags on the radiator hoses now, best of luck

[Mr Chevorlet]

The thermostat needs to be in for transfer of heat from the block back to the radiator. if water flow is two fast it will not transfer heat. Shroud needs to be on to route the air flow. Also improper timing will affect How hot or cool the engine runs but. and then if you have a clutch fan is it operating correctly. that all i can think of.

[GASoline71]

Where do you have your temp sending unit installed? It should be in the drivers side cylinder head.

Gary

[mbgmike]

Have you solved this yet? I suspect bigger problems then just a shroud. we run engines on test stands w/o shrouds and they don't overheat. Even at high rpm's. Cars and trucks years ago never had them. If your blade is too far back from the radiator i could see that it may have an effect.

[mbgmike]

Originally Posted by GASoline71

Where do you have your temp sending unit installed? It should be in the drivers side cylinder head.

Gary

does the sending unit even work sorry

[ubtripn]

Still working on shroud install And stat install. Will update when done. Sending unit mounts by the stat.
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[ubtripn]

I thought a thermostat either was open or closed not metering in between. Learn something new everyday.
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[GASoline71]

Sending unit by the stat is prolly why it's reading hot. Mine is in the stock location in the drivers side cylinder head on my SBC and rarely reads over 185 to 195. I have a 180 degree stat in it as well.

I used to have a 4 row stock type radiator in there and now have a 2 row aluminum unit. The temp readings were the same with both radiators.

Gary

[wicky]

How long have u had this truck. Is it a big block or small block. Sounds stupid but i just bought my first big block in april it ran around 215. So i started thinking the same thing ur doing. I talked to couple people round my area and they told me bbc will run little hotter. But i agree now shroud and thermostat is not helping
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[Dano69c10]

Also make sure you're not running lean.