[OrigOwner77]

I've just done a cooling system overhaul on my 80 T/A with 68 Pontiac 400.

Parts include:

• New Flow Kooler aluminum water pump
• New transfer tubes (or whatever they're called)
• New divider plate
• New aluminum Be Cool radiator
• New hoses
• New 180 degree thermostat
• New 50/50 mixed coolant + water wetter
• Nylon/plastic Flex Fan, tucked inside fan shroud the appropriate distance

Fan I'm using is similar to:


While driving, my temps are a steady tick above 180 (probably about 182-183 via my 270 degree sweep AutoMeter temp gauge).

However, at idle (say, at a stop light) the temp will start climbing pretty quickly. In the span of a couple minutes, the temp will be 195+. The second you start moving, temps drop immediately. Temps will also drop while stationary and holding the motor about 2,000 RPMs.

Divider plate clearance gap seemed appropriate (going by memory, was slightly larger than the recommended spec but not large enough to warrant bending the new divider).

Initial timing is around 14 degrees, and the car does have vaccum advance connected.

What is my next course of action to look at? Any insight will be appreciated.

Thanks!

[OrigOwner77]

Edit: Car has a Milodon aluminum water pump, not Flow Kooler.

[JLMounce]

Assuming you don't have any bubbles in the cooling system and the hose isn't collapsing, which isn't as likely at idle, your statements indicate the fan you're using is not drawing enough air across the radiator at idle.

Making sure that all of the radiator baffling is in place can help here, but I think you need a different fan. People that seem to have a lot of success with keeping their cars cool are running factory fans with HD clutches.

[OrigOwner77]

Originally Posted by JLMounce

Assuming you don't have any bubbles in the cooling system and the hose isn't collapsing, which isn't as likely at idle, your statements indicate the fan you're using is not drawing enough air across the radiator at idle.

Making sure that all of the radiator baffling is in place can help here, but I think you need a different fan. People that seem to have a lot of success with keeping their cars cool are running factory fans with HD clutches.

Thanks for the quick reply. I too am suspecting the fan.

I do suppose there could maybe be an air bubble somewhere in the system (the car has only been run literally a couple times since filling the radiator). What's the best way to verify there's no air in the system?

Historically when I've drained/refilled coolant. I top off the overflow reservoir a bit on the high side and drive the car. After 1 or 2 heat/cooldown cycles the system sucks the overflow coolant in, I top the bottle off, everything stabilizes and I've never had an issue thereafter. If there's a more suited way to burp air, I'm all for trying it.

I don't know that I can run a stock-type clutch fan. The '68 block in my car was installed using motor mount adapters. This sits the motor rearward an inch or two, as well as slightly toward the passenger (?) side. I had to use a 3.25" fan spacer to get my current flex fan about halfway in the stock fan shroud. Not sure a stock fan will be far enough in the shroud from the water pump.

Maybe one of the aluminum wide-blade flex fans would move more air, rather than the plastic thin-blade fan I have now?

[Squidward]

That fan looks weak. I'd do something closer to a factory style fan, or something with a little more blade surface area. I am by no means an aerodynamic expert, but that fan doesn't give me a fuzzy feeling inside.

I am also a "fan" of the Hayden 2797 clutch and factory fan combo.

[OrigOwner77]

Thanks, Squidward. I'm looking at a larger-blade Flex Fan as an inexpensive and easy test. Hearing good things about the Derale HD flex fans.

I'm not sure I can get a spacer in order to get a clutch fan installed and inside the shroud far enough in my case, due to the motor mount adapters and motor placement in the engine bay. I'll have to research.

It took a 3.25" spacer to get the current flex fan far enough in the fan shroud at present. If I recall, the stock type spacers were only about 2-2.25" or so? I figure a stock clutch fan installed will be too far away from the fan shroud, and that decrease in efficiency will probably negate trying to move away from a flex fan in the first place.

Will see how a larger blade flex fan helps, and will go from there & update the post accordingly.

Thanks!

[OrigOwner77]

Wanted to post an update...

Picked up an 18" Derale 6-blade flex fan (found some positive posts on here mentioning it). Didn't seem to make a change, despite a number of glowing reviews. At least it looks cooler than the plastic fan. Ha!

One thing I thought of is considering a smaller diameter water pump pulley. I have the 8" pulley on the car now (part number ending 127). Wondering if something smaller (like the 130 pulley, I believe) would be beneficial.

The reason I can't tell whether it's a matter of water pump efficiency/output, or not enough low speed airflow is because I can high idle the car at 2,000 in park and the temps immediately drop. I can also drive the car and almost instantly after I take off from a stoplight, temps drop. The moment the car idles and stops, the temp starts climbing. At 2,000 rpms, there's more airflow from the fan. There's also more pumping from the water pump since it's spinning faster. Not really sure how to narrow it down from there.

I also don't know that my Milodon water pump was clearanced to the new stainless divider plate upon install. The more I read, the more this potential extra clearance could be a contributing factor.

Lastly, I'm playing a bit with power tuning the car and found the car could use a few more degrees initial timing. Unfortunately, I need to move the distributor because I don't get enough travel to advance it any more how it is currently oriented. I wonder if switching to manifold vacuum, as a test, will prove beneficial. If I'm reading correctly, overly retarded timing can cause higher temps.

Nothing like chasing a problem that can be affected by a multitude of factors. LOL!

[Sirrotica]

That fan you pictured is a Flex a lite RV fan. I have no idea of what you used because you just said it was similar. With the almost 90 degree pitch it is specifically designed to pull mass quantities of air at slow engine speeds. I have a lot of experience using the genuine Flex a lite and have nothing but good things to say about the real Flex a lite fan.

Flex a lite information for the 18 inch nylon fan:

Details

Flex-a-lite Nylon fans move a lot of air and weigh only 11 ounces! These are ideal for race and performance applications when cost and weight are very important

Standard rotation
5/8 in. pilot
1 3/4 - 2 1/2 in. bolt pattern
Must be used with Flex-a-lite spacer or warranty will be voided

I have used the Flex a lite fan pictured with outstanding success on my oval track car, T/A street car, and my 73 Jeep truck with a transplanted 455 Pontiac engine. The fan pictured moves a ton of air at low speeds and should definitely stop a Pontiac from O/Heating at slow speeds.

The fan largest diameter is I believe 18 inches, and is the one I've used on all my Pontiacs that needed more airflow at idle. The Flex a lite fan would be my first suggestion for a Pontiac V8 that is O/Heating at low engine speed based on my own experiences.

[lfdsteve]

I don't see an issue. 105-200 fine at idle. When you rev, fan moves more air thus cools engine. Same for driving. Moves more air thru grill.
Not sure how much cooler your going to get it unless i missed something
Steve

[Blued and Painted]

Agree. 240 is hot.

[TheSilverBuick]

Picture of how the fan is sitting in relation to the shroud?

[OrigOwner77]

I'll try to get a pic of the fan/shroud posted soon.

While I know 200-210ish isn't "hot," I've always understood that the temps should remain near thermostat spec (can expect a little bit of increase while stopped, due to lack of airflow).

In my case, though, I can sit at 182* (180 thermostat) while going down the road for miles, come to a stop light, and in the couple minutes I'm stopped at a light watch the temp go from 180...185...190...195...and it will keep going up from there the longer I sit. It's not that the temps climb...it's that they climb rapidly even with aluminum rad, aluminum high-flow water pump, brand new 50/50 coolant + water wetter, basically an all new cooling system.

Went out to Woodward on a 85* day recently. In the stop & go traffic, the car hit 205* and was continuing to climb. Since it doesn't seem like it wants to stop heating up at idle AND heats up at idle so quickly, that's why I'm concerned.

I have a friend with a '78 T/A, built 400, Be Cool aluminum radiator and 195* (stock) thermostat. He can sit and idle in traffic all day and his car doesn't keep heating up like mine does. Once it's at temp, that's just about where it sits whether stopped, moving, etc.

[JSPONT]

I would clearance the plate to water pump. Make sure as stated before, you have the spring in the hose to keep it from collapsing.

[OrigOwner77]

Originally Posted by JSPONT

I would clearance the plate to water pump. Make sure as stated before, you have the spring in the hose to keep it from collapsing.

Brand new hose but doesn't have the spring inside (confirmed hose isn't collapsing at idle, and I know the hose isn't collapsing while driving based on the stable cool temps even when driven hard). I've read mixed reviews on whether or not springs are actually needed - seems to be a thing of the past the more I research.

I'm trying to avoid taking the water pump off if I can help it. No, it's not a hard job...but it's one I'd rather not do until it becomes a last resort.

Did make a discovery I previously overlooked - the tanks/sides of the BeCool rad I installed are narrower than the OEM rad. As such, the sides have a maybe 1/2" gap between the rad and the shroud running vertically top-to-bottom on each side. I've read this can cause the fan to move air around, rather than through the radiator / shroud.

I'm looking to see what high-temp foam (or similar) I can find - my thought is to adhere some foam running vertically on the tanks and therefore seal said gap. Just need to make sure the hot aluminum radiator won't melt the foam / adhesive used. Suggestions on materials would be appreciated.

Figure if for nothing else, this will help further aid cooling efficiency even if not the direct source of the issue.