Inliners International Forums General Discussion Engines cooling

Hey guys,,, I,m looking for as much advice on this before, turning wrenches or spending more money,,, I have a 250 in a 65 nova, mildly done, 4bbl, split exuast, most of the normal goodies,, this car will not cool well,, water pump,"new", radiator,"new", stock configuration, 3 core, super cool, right now I'm running the 1 piece flex fan,, the engine cruises 187-195 (florida),, but at idle (800+-rpm) the temp bounces 207,213, gone all the way to 221,hasn't overheated yet but has burped, the gauge is pretty accurate, 185 high flow stat,, "tested & good",,the rad core is 18"w and 14"tall,, the fan is 16",,no shroud,, these 6cyl cars originaly had none,,a v8 shroud is for a different rad,,I almost have a shroud built,, but I'm conviced this car should cool without it,,my last two theorys,, can a fan be to close to the rad,, mine is 13/16",, I had to add a spacer so the blade clears the pulleys,, or is it possible, the supercool rad(almost double the tubes and fins at three cores)has to much surface area and the fan can't pull through it,,this idea came by looking at a electric fan zip strap,, there is no way it would pull though the core, without destroying the fins,, has anyone delt with this,???

Walt,, thanks,, I would never use a tie for a fan or a cooler,, been there, and ruined that,, the idea came from a onlooker at a weekend show,to add electric fans, but only a 6" will fit, I went home and stared at the stock rad, and noticed the fins have almost a space the size of a dime,, my new rad, I would have to use force to get a flat toothpick through...I contacted the rad shop, about possibly not being able to pull enough air through??, they thought I was crazy...said to buy a high flow pump,I don't think one exists ???

Check the radiator for coolant flow. Any restriction there will cause what you have, the rest sounds okay.

If the Rad. is ok, go back to the stock fan. They pull more air at low speeds.

Good luck.

Finger; Is your fan on backwards? I have run into this three times this year alone. It's easy to do and will cause the same symptoms you are experiencing. Just a thought.

jmoran,, I know what you mean on the fan,, right now there is a flex fan on it,, they are pretty hard to get confused with only half the blade steep pitched,,
John, I've thought about coolant flow,, with the cap off as the stat opens, you can see movement, but not as you would with a crossflow rad,, this is a down flow,,I have springs in both the upper and lower hoses, otherwise I'm not sure how to test flow,,I wondered if a 292 pump flowed more?,,, also I stare at my manifold heating and wondered if I was creating a problem,, I've tapped off the right of the stat housing, through the manifold and around the back of the engine to the 5/8" heater line,, the heater line comes from the left side of the housing,,so both flows are pushing,,,? more than one time I've been told to put the stock fan back on,,probally is a worthwhile idea,, that fan I'll have to look at so it is'nt backwards,,that will also let me remove the fan spacer,,maybe some more room for the blades to work??

To test the flow:

1) Remove coolant from radiator/engine by removing lower hose (radiator side) & save.

2) Remove upper hose (radiator side) & block with a rag.

3) Add water from 'garden hose' & watch lower radiator hose nipple.

The water MUST run out as fast as it goes in. If not; there's a restriction.

Good luck.

PS: "flex fans" are supposed to save fuel because they 'flatten out' & pull less on the engine. That's bogus; put the factory one back on. Your running TO HOT.

finger a 292 pump will not fit the 250's secondly Our 250 pumps have a by-pass whole built into the pump.

I believe you might be on the right track. I have always heard that if the fan is too close to the radiator it will not pull air through very well. Hope that works, I hate problems that won't just present themselves!

fingersix

I know you know my set-up it was at that time a 250 .030 over 12-1 a 70s(nova) 2 core Rad. with the tanks flipped to move the core Out to the front of the Rad support. And I have Just over a fingers clearance between the fan Nuts and the core itself. And I can run either a 180 or a 190 stat. And it runs Right at those numbers Even Racing it with a 190 it may?? hit 195 by the end of the Pass But by the time I hit my space in the pits the car is right back at 190.
Even when The car was still my daily driver I had the stock Small rad set-up as a 3 core( the 2core was bad so I had a 3 added in to the stock tanks) and I never had any Over heating or running Hot issue.

maybe I or we need to plain a road trip and Hook-up so I can take a look. Because i just can't seem to understand why yours is running on the HOT side.I know your set-up/combo.

Gentlemen;

"flex fans" don't/can't pull the same amount of air through the radiator core.

There an 'accessory gimic' and don't really work.

Happy trails.

i use 2 electric fans on mine. with the engine so close to the radiator, i had no room for a mech fan. there is one snuggled on left and right near the water pump pulley. i have no cooling problems. i do have a alum rad.
have you or can you run a 7 blade clutch fan. they are cheap to pick up and move tons of air. and cut loose when not needed.
also get the shroud done. it will definately help. tom

You mention the heat gain only at idle. That narrows it down to either air flow or coolant flow. There have been several good suggestions given here about air flow and you also seem to have a good knowledge of it. As far as coolant flow you may want to try a smaller diameter water pump pulley which will run the pump faster relative to crankshaft speed and create more flow. A second benefit is it will also run the mechanical fan faster. It doesn't take much, as little as 1/2 to 3/4 inch smaller, to make a difference. A little digging around checking out the small block Chevy V8 pulleys should find one. Just remember there is a short and a long water pump on those V engines depending on the year and the pulley hubs have different bolt patterns and overall the pulleys have different lengths that can cause belt misalignment. A slightly longer pulley can be spaced out correctly with a pulley shim kit.

If you have a new parts store water pump on your engine the hub flange may be drilled for both pulley bolt patterns. Most of them are. That would make it easier to come up with a pulley in that regard.

I hope this info is of some use. Running hot is no fun.

You might try blocking off your manifold heat to see if the way you have it plumbed is causeing water flow to bypass radiator. If a 1/4 of your flow was bypassing the radiator you could have the flow problem the radiator shop is talking about. Also is your manifold heat lines picking up heat from the exhaust helping to super heat the water going back. How hot is your intake itself, maybe it doesn't need heat line in summer a lot of guys run a valve on the water heat lines to manifold that can be shut off in hot weather.
Many times our problem is so simple we look past it Good Luck.

Thanks for the info everyone,,,factory pulley is 7-1/8"od,, right now I have a 5-7/8"od from a 69' car,,,Im going to swap the stock fan back on,for chance, and play with some ideas on the heater lines,they do go right over the langdon split irons..?? I'll get back with the findings,,,hopefully good ones,,
P.S. Larry thanks for the offer, let me try a couple more trys to beat this before you make the long hual my way,,,thanks

John M.
Yes they do work. I run a Flex-lite fan(Plastic) That has a 1/4 Of it cut off and It still Out draws The Stock Fan By a Long shot. And I have been running this same fan for Over 20 yrs. I can take a shop Rag Folded in half and The Air Draw Will Keep it Pined to the Grill. I have ran The Metal flex Fan (Good?????? to 8000 rpms) and Broke/Cracked two After that i went to the Flex-lite fan and Never Looked.

I had the same problem in my Chevelle. High temp at idle with a flex fan. Moved the radiator closer to the fan, clearance approximately 3/4 inch. Changed to the smaller water pump pulley. Installed an electric pusher fan. Temp now holds at 190 even at Hot August Nights cruising.

I have read test that those Flex a light plastic fans rob the most HP like 20 HP or more.
They really beat the air into submission & can't keep on track.

Supposedly the best fan is a fixed clutch type fan for less HP loss.
The HD clutches with the little spring on the front of the clutch are the good ones.

With that type of clutch fan,,, it was within 2 HP of running no fan at all,,, IIRC???


A stock 4 blade steel fixed fan will blow a lot of air,but those to, take HP from your engine.

MBHD

You have that base covered. That is the smallest diameter pump pulley I've been able to locate also. Should be very interesting to hear what the final cure is when you hit it.

I know it's been said, but if the tubes are closer together than normal, or the fin count (# of fins per inch) is higher it is harder to get the air to flow through the core. If it heats up only at idle I would expect the fan isn't drawing enough air at that speed (as from what you describe the engine as I can't fathom it being not enough water flow). I would recommend using the shroud you are building, as the smaller pulley will increase flow all the time (water and air). It (the pulley) would likely cure the problem but I would worry about cavitation at higher speeds and wear on the pump itself (but that's me).

If you are concerned the manifold heat is bypassing too much water around the radiator, could you put the water back in to the radiator (top tank or upper hose)? I expect you have it plumbed up so it returns to the suction side of the pump. I know that would reduce the flow (less pressure difference)when warm, but if it is still a problem, that could help. You should get more than enough water flow when the engine is cold (with the thermostat closed) to warm the manifold as quickly as it does now.


As for what kind of fan, I have used flex fans, steel clutch fans, electric fans,... I have had success with all. It seem that one of the car mags will run an article every 5 or 6 years on Clutch V/S Flex fans. Every time I have seen that the thermally clutched fan with the steel blades flows the most air with the least HP draw. I guess that's why all the OE's (domestic anyway) had something like it for their heavy duty applications (I'm sure they spent tons of money trying to get something cheaper to work). But whatever works.

Hey guys,, uneventful weekend,,I got out my other fans and remember why I took off the 4 blade steel one,, at 17 1/2" it smacks the cooler lines that were built into the rad,,,back to that later,,start from scratch,, removed the radiator,,flow seems well, with a hose it drops the water out the bottom faster than it can even fill the top tank,,plug the bottom and fill,, when released it's like opening a little flood gate I'll vote, radiator 'good', pulled pump, just in case,,visual, looked good, there is a strange junk on the walls of the pump,,not greasy, but wet/cakey stuff in clumps..??? not milkshake,, checked the oil, good,,,
forgot,,, first checked timing, 6bdc at 900-1000 rpm (idle)(advance off),,
back to pump,, found one from a '72' with an impeller plate on the back,,,
I'm working on finding 90's for the cooler lines, so fan swap could work,,, Larry I agree,,I tried the rag on the rad,, were talking sucked to the front not just held there,,in all areas, no dead spots,,from the fan being off and on so many times, the nylon is starting to crush,,?? verdict on which fan is still out,???
Nexxusian,,my manifold heater lines are thought of again,, it does not return a suck side,,it basically is run to each side of the stat housing (pushing)creating a loop in the push through the heater core,, the suck line is 7/8" so the tee would have to be rigged,,
Waiting for parts, and reassemble,,???is there any way to flush the block,, I thought with the pump on,, if I flush the block drain on the side of the side of the block, it should back fill and come out the pump,,,

Fingersix

Remove a side/rear freeze Plug and Flush the Block that way. and Leave the water pump off the front. This way you can see everything that may come out. It will also clean the rear of the Block much better then trying to get it to come out the Small drain plug at the rear. One thing i have seen many times in the Past On Rebuilds Is Nobody take the time to Flush and Clean out The Very end of these Blocks. And everything Cakes Up around the end of the Number 6 cyl.
When every I do a rebuild either for myself Or on someone elses Motor. When the Head is off and The Motor is out I lay the Block On it's side and Use Air & water Pressure ,Even in some cases a small Pick if need be. To Make sure the Years of trash is Fully Cleaned out of the block. Then I do the same Once the Block comes Back from The machine shop.

hey Larry,, do you yhink on that one piece fan I could use one of the thin pulley spacers in front,, so the bolts and washers don't sink further into the fan material,,I know it is probally my fualt, I tend to overtighten everything,,

I use just a good flat washer on my flex fan. What You mit want to use is The washer/Shim moroso sells. They come in a kit of different thicknesses.I'd use the thicker one If you can. this way you won't crimp it in anyway.
(moroso Pully shim Kit 64035) There is 3 in the Kit Now That I am looking at a kit i have here You should be able to use one of the thiner ones.
(If?? I knew what I did with the Open Kit I'd Just send you one)

Just got the new pump today,,one observation is pretty clear,, the new pump,the empeller blades that ride along the surface of the housing are tight,,a standard business card can be slid between the blade and the surface,, the old pumps blades are far enough away from the housing to let a quarter pass without touching it,,????? would that let to much water by-pass?

I believe it would,by having too much clearance,making the pump not work as good as if it had a tighter clearance.

MBHD

O.K. guys, Im back,,this post may be alittle mixed up,, I'm going to try to write as it comes to me,,,,
As before, rad appeared good,, got the new pump, I found a listing for a 72 nova w/HD cooling,, the pump came aluminum and had an empeller plate on the back,,, Start fan set up from scratch, stock fan,,,mmm,, stock fan doesn't fit the sm. dia pulley pattern,,I always used a flex fan,,went back got the stock pulley,,fan (16.5") doesn't clear tranny lines,, got 90's, reconfig,,fan still doesn't clear the 90 line closest to the lower rad hose,,abandon rad cooling and install tranny cooler up front,,complete reassemble, stare at it for awhile,, ready to go,,by the way digital gauges still in place, oil in rear of pass./lower blk,,water in head,,mechanical gauges also installed,, oil in place of dummy light, water in thermo housing below stat, (disconnected manifold water supply), also put a mechanical 13LB rad cap with gauge,,I even got the thing to check the antifreeze mixture,,stare at it longer,, ready to go,, Start up,,40 psi oil, idled 15 min, got temp to 235 d&m (digital&mechanical), 17psi oil,, drive car,, little cruising,, little tire chirping, got temp to 207,, stop sign,, 0-3 psi oil at idle, drive home psi comes to 17 instantly,,home cool down,,, BTW I talked to Tom Langdon a while back on the oil press. He said 6-7ish at idle was normal with the tolerances of after market bearings, givin psi comes up with rpms,,He said stock ones were installed raw, and line bored to the cam,,now with all the aftermarket, bearing are designed to fit all,, some good, some not so good,,quality control,,and even the tolerances in the pump gears could kill psi,,????
RESTART,(it is evening 7:15 so not sunshine hot)
water 150 d&m 35 psi oil,,
7:20, 205d,,197m,, 20-17 oil psi d&m
7:24 224d,,220m,, 19-15 oil psi d&m
add big floor fan to get air across rad,,
7:26 230d&m get in and drive cruise only,, came down 197d, at 50mph 1500rpm oil psi is at 20,, back home park,, stare at it again,,BTW the whole time I'm getting out and checking the mech. gauges, they seem pretty close, except the rad, it seems to always be between 160-190, unless I was real hot, I seen it get to 200's. bedtime, (actually dancing w/t stars)
Yesterday I drove to the local rad shop..it's been there forever, and has some old timers for advice,, the first guy looked, stated,"blowing exuast into cooling system" I looked, shook my head and asked why,, He said the upper hose was to hard,,?? it always seemed to be that way,,another suggestion was to put a reducer in the heater circuit, to force more flow through the rad,,,we talked, I left,,As I left I thought, I had a vette I kept outside & when I started it, it always blew water,, the exuast condensed, at cool down,or something,my father explained and blew it out,,,??? the car never had cooling problems or failures,,my six blows water when it starts, and it's garage kept,so it doesn't get the moisture from outside,,it stops blowing after the exuast is hot,,but??? What do you guys think,,??? I'm really lost now,,

For every gallon of gasoline burnt your engine produces one gallon of water. Usually vapor. But a cold exhaust system causes condensation, so you do not necessarily have a head gasket problem. To verify, remove the rad cap and rev the engine quickly. If coolant spews out your head gasket is leaky.

I like the idea of adding a fan shroud.

what oil are you running? not that it makes any difference with cooling. but it will with pressure.

add a overflow to the drain of the radiator fill tube. make it a catch can, with the hose going to the bottom.

also if a head gasket is leaking. watch the oil level and you can also fill the rad to the top and watch for bubbles when it is running.

what do you have the timing set at? does the mech advance work? tom

FrenchTown,, coolant spews out at idle,, with the cap off, I watched for flow, and I think when the stat opens and the coolant flows it builds in the top tank, as I bring the rpms up the coolant sucks down, so I can get the cap on, Fan shroud is almost impossible,, these setup from gm did not have one,, the fan blades goes below the core at the bottom tank almost 3 inches, and the top of the blade goes past the core at the top of the tank, all the ones I've half fabbed so far look terrible, and nothing really holds it together,
everyone that has looked in the engine bay,, says,mmmmm yeah it really doesn't fit,, has anyone seen one on a box chevy II with the six cylinder rad(18"w x 14"h core).
Tom, Im not really sure on the oil,, chances are, I usually buy castroll probally 10w30, the straight weights are hard to come by,,, I'm not sure why,, I thought of the overflow,,I need one for the track,, but Im confused,, if I put a overflow on it, I assume thats a sealed system,,with the stock open sys, the cap vents to purge, but it doesnt vent to suck back in,, the little purge bung on the rad is between the gaskets on the rad cap,??? or are you reffering to a catch can , so I don't leave little puddles of green everywhere,,The rad shop guy asked me if I purged the air out of the system,, I thought that was kind of worthless with an open type system,,???if not,, how do I do it, on my 96 chevy there is a air bleed on top of the thermo housing,(easy),
Oil level,,?? I have checked for water in the oil,, no milkshake,,but the level is correct,
Timing,, if I remember, I set it at 6degrees advanced,, (with the vac adv, off), when I rev it the timing mark climbs up the damper,, so I assume it is working,, they manually work, the weights slide and the bushing don't bind,,,I recently looked there when I changed to the Igniter II ignition,,the vac advance is on a port vacume signal,and working,,

Found an article on carcraft.com "keeping cool"
a few excerpts,,,crossflow rads,,
"An added benefit is that the radiator cap can be positioned on the suction or low pressure side of the radiator-- the tank that receives the coolant after it has passed through the core. The low pressure/low velocity environment in this tank allows the air to separate from the coolant and bleed off first when the cap's blow-off valve is activated by excessive pressure in the system."
mmmmmmmmmmm.
radiator caps,,,,
"Cooling systems are pressurized to raise the boiling point of the coolant, since normal engine temps are significantly higher than the boiling point of water at atmospheric pressure. The pressure level is usually maintained by a blow-off valve incorporated into the radiator cap. When system pressure exceeds a predetermined level, the valve opens and bleeds off pressure until it reaches the desired level, at which point the valve closes. If the spring in the cap weakens or the rubber seal deteriorates, system pressure drops and the coolant can boil, which then aerates it and reduces its effectiveness drastically. This condition will also allow coolant to be purged into the overflow container, though it will not be drawn back in when the system cools, Don't ignore that hissing and gurgling you're hearing every time you shut off the engine."
mmmmmmmmmmm...
I've never completely over heated yet, you know with the steam and stuff, but burped green puddles quite often, it even did it when I parked at the rad shop,, the guy said " look a leak.."

for the oil try running schell rotella 15-40. it is a diesel grade oil. it should bump up the pressure some. it is avail at all walmarts (i hate that store).

you can buy a cap that will vent and has the valve to allow coolant back into the radiator. put a 16 lb one on. tom

Tom, I am also a Walmart hater,can't stand the place,, I'll send my Dad,, ,,,I'll do the oil change this weekend,,, did you catch my post above,,what do you think,,

Have you checked for CO in the cooling system??

we were typing ontop of each other.

i guess my assumption is your cooling system was designed for the 6, so it should work as is.

something is causing the hot engine.

get the oil changed and then drive it normally. monitor the engine temps.
1. while moving
2 while idling

200 temps are not uncommon. i have a 180 stat but the temp stays there.

get a 16 lb cap that was made for use with a recovery tank. like for a 80 camaro.

your radiator was designed to not be filled to the top. it was supposed to be filled about 3/4 below the cap. so if you do fill it to the top, when the liquid expands with heat then it burps when parked. that is normal. if you add a overflow tank then it burps and is caught and then recovered to completely fill the tank.

they should issue skate boards at wallmart. they always put what i want at the rear of the store. and then they make the super sized stores. 100 checkouts and 2 people to operate them. and 2 managers watching to direct you to the self checkouts. tom

Go back to Mike Gs advice. best of the bunch. logical and accurate.
Speed up the pump and fan at idle. If it onley clin mbs otta site at idle ten that is what s worng. Even 1/2 inch on pulleys will make a huge difference.
And now for a trick i use often. if the car overheats at idle and you are not able to get it cooling with normal tricks you willl be tempted to install an electric van . ou can use a use one from a minivan or something at the wreckers. Some of te AC condensor fans run real fast.
using a relay hook the trigger part of the relay to your brake light circuit.So that the relay is energized any time you have the brakes on. Wire the otherside to the battery Positive and then feed the output of the relay to the fan Positive
The only time the temp goes beserk is at stop lights in traffic. Now when ever you apply the brakes like at a stop light the electric fan will run and bring cool refeshing sir through the rad reliveing the heating caused by no air flow while sitting. Still though you will probaly want to speed up the water pump too. In fact i would do that first then use the electric as a last resort.
Why does the engine run hot?
May need more advance at low rpm for one thing. A dist recurve could help here. Some cams are prone to running hot. I have cured a couple fo cars over the years geting rid of a crap cam in favour ofa good one. Generic or no brand name cams are usually crap. They dont all overheat but some will. A 160 stat might help.

John,, what is CO,, carbon dioxide,??? how do I do it?,,

Tom,, do I pick a cap from a 250 camaro or a v-8, the parts guy is gonna do the computer thing, I hope the cap will not have the red pressure release arm, it just doesn't look right in the '65' bay,,

D,, to go back to the small pulley, I have to add the fan spacer, because the pulley pattern accepts the larger fan bolting pattern, it will push the fan approx 3/4" away from the core, so a flex fan is required because the front of those are flat, and all pitch is to the rear,,a stock fan has pitch forward and rearward of the blade spokes,,.
There is no space in front for a fan, I have seen a 8" mounted on another chevyII, but now with the cooler there, forget it,, I could almost mount one or them, but small, behind the bumper void, but it would have to push the air around the front bump filler and grill support,,??it doesn't look to efficient,,
The cam is a Comp Cam, 262h, single pattern,

Is it possible that the transmission fluid is overheating due to a transmission problem and transferring the heat to the cooling fluid in the radiator?

There is a tranny cooler up front now,, and the one in the rad is abandoned

CO = carbon monoxide which (sometimes) gets into the cooling system via a small crack or leaking head gasket.

It 'stirrs up' the coolant so it can't absorb the heat.

A Radiator Shop will test for you.

Good luck.

Well whatever it takes to put he other puley on t would be worth doing. I would be surprised if it was cure. After 40 years of doing this for fun and a living I can asure you it will be something just that simple that will cure it. IT IS ALWAYS SOMETHING SIMPLE!
Sometimes it is so simple it doesnt sem to be worh doing. Last one I work on was exactly simialr problem . Ran ok when moving but overheated or almost so in traffic and when stopped. It was a 440 build I had done as per my book Old Reliable. The car was a 64 Didge and it was a beautiful job. I went to lok and saw the wrong pulley instaled , not what I recommened. The stream of excusues ranged from wouldnt make THAT MUCH DIFFERENCE to I could get one to fit. Since it was my motor (They are ilke my own children so i really do car) I went to the wreckers and boughtthe pulley I had told him it needed. It was just 1/2 " smaller diameter for the water pump. O took it home and painted it and then gave it to him he installed it. END OF PROBLEM COMPLETLY> Why because both the fam and the water pump are now running fast enough to move cooolant and also make sufficent airflow through the rad even at idle.
That was three years ago and nary a problem since. it never goes above 195 regardless.
D