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Overheats at speed #2661327
06/01/19 08:19 PM
06/01/19 08:19 PM
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Australia
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ozymaxwedge Offline OP
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Hi , this Barracuda of mine has always run hot on the open road, it can idle around town in the middle of a scorching Aussie summer all day and sit at 180 but get it out on the open road at 3000 rpm and it just keeps climbing. Seen 210 last night in cool air.
Engine is a half full 440/547 with Indy heads, tune is good, has large ali radiator, electric pump, powerful twin fans with cowl, using water wetter and I also have a larger engine oil cooler.
I can’t remember if I have a thermostat with small holes or a reduction spacer in there at the moment but know I have run both.
Any tricks ??


1963 Plymouth Max Wedge
1971 Barracuda
Re: Overheats at speed [Re: ozymaxwedge] #2661330
06/01/19 08:23 PM
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Sniper Offline
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Gonna tell you right now, it's your electric water pump.

Overheating at speed is almost always a water flow issue.

Re: Overheats at speed [Re: Sniper] #2661340
06/01/19 08:41 PM
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ozymaxwedge Offline OP
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Ok but looking in the radiator you can see the turbulence of the water moving. Today I am goin to try taking out the thermostat or restriction and test drive.


1963 Plymouth Max Wedge
1971 Barracuda
Re: Overheats at speed [Re: ozymaxwedge] #2661341
06/01/19 08:41 PM
06/01/19 08:41 PM
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RapidRobert Offline
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toss the stat just for a test (1) day. Are you sure the rad ain't partly clogged. I'm assuming timing/mixture are in the ballpark (I'm not leaning toward those 2, just sayin). keep us updated.


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Re: Overheats at speed [Re: RapidRobert] #2661352
06/01/19 09:27 PM
06/01/19 09:27 PM
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Andrewh Offline
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it is going to be 1 of 2 things then if it idles fine around town.
I have never used an electric pump, but it is possible.

But my bet is the fans and the fan shroud.

Put a cut off switch to the power to the fans. Once you are up to speed turn them off. I Bet it cools down just fine after that.

The solution if that is the case, is to cut some flaps into the shroud, that are hinged. Feets showed me that when we used the maxima fans. You cut out some rectangular holes into the shroud and then hang flaps over to cover them.
At idle, they get sucked shut, at speed, the blow open to alllow more air flow.

Re: Overheats at speed [Re: Sniper] #2661358
06/01/19 09:45 PM
06/01/19 09:45 PM
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Originally Posted by Sniper
Gonna tell you right now, it's your electric water pump.

Overheating at speed is almost always a water flow issue.


This guy gets it!^^^ Overheating at speed is almost always a coolant flow issue....overheating at idle/low speeds is almost always an airflow issue. My guess is that electric pump is flowing the same at idle and 4000 rpm. Works at idle not at 4000 rpm. Belt drive pump changes output based on rpm. Just my thoughts. Good luck!

Re: Overheats at speed [Re: Dcuda69] #2661379
06/01/19 11:03 PM
06/01/19 11:03 PM
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So Near, Yet So Far
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Yup, either not enough coolant flow under demand, or airflow blockage.
Some of those electric fan shrouds are essentially a box that will block airflow at speed.
If you can try a faster pulley ratio and/or a shroud with flaps that open at speed, do so.
I'm assuming your lower hose isn't collapsing at speed, and there's no blockage elsewhere in the coolant flow.

Re: Overheats at speed [Re: topside] #2661381
06/01/19 11:10 PM
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Originally Posted by topside
Yup, either not enough coolant flow under demand, or airflow blockage.
Some of those electric fan shrouds are essentially a box that will block airflow at speed.
If you can try a faster pulley ratio and/or a shroud with flaps that open at speed, do so.
I'm assuming your lower hose isn't collapsing at speed, and there's no blockage elsewhere in the coolant flow.


Electric pumps usually move at one speed, if the hose was "collapsing" it'd do it whenever the pump was on.

The thing about electric pumps is this, they are designed for dragstrip use and in that application they can be useful. On a street driven ride it's just a problem waiting to happen.

Re: Overheats at speed [Re: Sniper] #2661402
06/02/19 03:13 AM
06/02/19 03:13 AM
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ozymaxwedge Offline OP
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Thank you for your thoughts guys.
Have just been working on it, pulled the T/housing to find NO thermostat in there, (I could not remember if it had one or not), I purchased a 180 High Flow thermostat and fitted. Bottom hose was one of those ribbed flex type hoses with spring in it, I purchased a new normal bottom hose with spring, also new red coolant.
Test drive, temp reached 185 quickly and still went to 210 but took a bit longer to get there.
Will look at cutting holes and adding flaps into the plastic fan shroud next day off, might even put another gauge on just to be sure.
Sniper, going back to a belt pump is a major operation that will mean changing power steering pump and alternator locations, you may be right but hope not smile
Is 210 too hot ?
Again thanks for your input .

Last edited by ozymaxwedge; 06/02/19 03:17 AM.

1963 Plymouth Max Wedge
1971 Barracuda
Re: Overheats at speed [Re: ozymaxwedge] #2661409
06/02/19 06:40 AM
06/02/19 06:40 AM
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Installing a front airdam will make the radiator do its job better by the vacuum under the engine, helping expelling hot air.

A half-filled engine block might need a bit more help to keep cool when working.
What's the ignition timing at those rpms?
Do you run a vacuum advance?

The electric fans could indeed work as a blocker at higher car speeds. But that would mean the radiator is 'marginal' at best already.

210° leaves hardly any margin for error in case of mishap.
I never want to see 190+ on any my engines. I have one car borders that number, but it's engine isn't optimal.

Re: Overheats at speed [Re: BigBlockMopar] #2661422
06/02/19 07:55 AM
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ozymaxwedge Offline OP
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Originally Posted by BigBlockMopar

What's the ignition timing at those rpms?
Do you run a vacuum advance?




Locked up at 35 deg


1963 Plymouth Max Wedge
1971 Barracuda
Re: Overheats at speed [Re: ozymaxwedge] #2661426
06/02/19 08:08 AM
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Sounds to me like you are trying to run a race car on the street.

locked timing, electric pump, etc.

A lot of things that make sense at the strip fail to make it on the street, which it looks like you are finding out the hard way.

35 degrees might make sense at WOT throttle but it doesn't make sense anywhere else.

At cruise you want more timing than that, which is why there is vacuum advance. Probably part of your running hot issue as well.

Re: Overheats at speed [Re: ozymaxwedge] #2661428
06/02/19 08:17 AM
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Another thing to look at is your timing. Running 3000 rpm With very little load is where a vaccum advance is needed. If you only running a distributor with mechanical advance, could be contributing to an inefficient overall cooling system.

Re: Overheats at speed [Re: Sniper] #2661444
06/02/19 09:46 AM
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ozymaxwedge Offline OP
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Originally Posted by Sniper
Sounds to me like you are trying to run a race car on the street.

locked timing, electric pump, etc.

A lot of things that make sense at the strip fail to make it on the street, which it looks like you are finding out the hard way.

35 degrees might make sense at WOT throttle but it doesn't make sense anywhere else.

At cruise you want more timing than that, which is why there is vacuum advance. Probably part of your running hot issue as well.



Yes mate the car is a bit on the race side, will go 9.90’s and I understand I am asking a lot but I’ll get there.
You say I need more than 35 degrees at cruise ?
The car drives beautiful and smooth .


1963 Plymouth Max Wedge
1971 Barracuda
Re: Overheats at speed [Re: ozymaxwedge] #2661447
06/02/19 10:08 AM
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Are you running the stock diameter crank & water pump pulleys? Can the air coming into your grill go around the radiator to get past it without flowing through it? Sorry, I posted before reading the guys posts, which are on point. I also agree it's likely the electric water pump.

Yes, vacuum advance beyond the 35* total will allow the motor to run cooler at road speed. If you switch you ignition box to a programmable one like the MSD Programmable 6, I believe you can add a simulated vacuum advance feature, but I have not done it.


1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
Re: Overheats at speed [Re: ozymaxwedge] #2661469
06/02/19 10:49 AM
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Originally Posted by ozymaxwedge

The car drives beautiful and smooth .


Except for that running hot thing.

Yes, you really ought to advance the timing at cruise, maybe that programmable setup mentioned can suffice, not familiar with it so I can't say.

Re: Overheats at speed [Re: Sniper] #2661474
06/02/19 11:05 AM
06/02/19 11:05 AM
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Just my twocents here. Seeing as how you are running a 1/2 fill block on the street, you might want to consider an oil cooler and/or oil temp gauge.

Randy

Re: Overheats at speed [Re: dodgefarmer] #2661513
06/02/19 12:19 PM
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is the hood sealed to the core support ? that will maximize the air going through the radiator opening instead of just "spilling over" the top of the support.
are your electric fans aftermarket, or some type of OEM ? if aftermarket, i have found them to be optimistic at best on amount of airflow. i ONLY use OEM fans in EVERY electric fan application. they are far and above ANY aftermarket fan made. be warned, however, they require many amps to operate, so an upgraded electrical system is a must.
they also consider high speed airflow, so their shrouds are designed for airflow at speed, while the aftermarket fans and shrouds are not.
lastly, puller fans are way more efficient than pusher fans.
please keep us updated.
beer

Re: Overheats at speed [Re: moparx] #2661517
06/02/19 12:26 PM
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second to take the shroud off. its limiting aif flow through the rad.


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Re: Overheats at speed [Re: dodgefarmer] #2661566
06/02/19 03:23 PM
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ozymaxwedge Offline OP
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Originally Posted by dodgefarmer
Just my twocents here. Seeing as how you are running a 1/2 fill block on the street, you might want to consider an oil cooler and/or oil temp gauge.

Randy


See original post mate, I am running a larger oil cooler and I do have an oil temp gauge , oil temp was about 220/230 when water was 210


1963 Plymouth Max Wedge
1971 Barracuda
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