Bronco Cooling System

[Tjboriack]

I know there have been many threads discussing cooling and issues folks have going on; with a myriad of folks having different solutions. I have had cooling gremlins and have done a ton to try to work through them, only a couple more pieces to work through to see if that provides some resolution. It definitely seems like an airflow issue as I cool relatively well going down the highway (various speeds temp is 200-208) but when I sit in traffic the temperature begins to climb (close to 220 and I start getting nervous). When idling in park it seems to maintain pretty well, just when I am under a load does it climb quickly to uncomfortable levels. I have added an A/C but won't run it because of the existing temperature issues.

I have played with the thermostat, water pump, fan, shroud, even installed some biltcool fender cutouts to dump the warm air over the tires rather than force through the tunnel. All were small incremental improvements, but still fill it is running warm.

This is coming out of a complete restoration where we put in a Phoenix Engine carbureted 302, putting out 292hp. I would prefer not to go the route of an electric fan. The tough thing when in a restoration like I put the bronco through is that everything changed, so I can't just go backwards.

It currently has the WH Staggered 4-Core radiator (Item# 5010), FlowKooler 1681 Hi-Flow CW Water Pump, Robert Shaw 160 degree t-stat (would like to go to 180 once I get this figured out), 6 blade fixed pitch mechanical fan (positioned about 1.5" from the radiator at the top and about 1" at the bottom), and the steel WH shroud (Item# 5018), that I have since trimmed as it covered nearly the entire blade of the fan at the top. Running a 50/50 mix of the orange antifreeze. The timing has also been checked. As well as the Bilt-Cool fender cutouts.

I am looking at changing the water pump pulley to a 5" pulley next weekend and considering diluting the 50/50 antifreeze mix.

I was hoping for anyone that has gone through this to contribute utensils, but also looking for anyone that can give me the factory stock crankshaft pulley diameter and the factory stock water pump pulley diameter.

Trying to figure out how to upload a picture on here of the engine compartment.

 

[Tjboriack]

 

[1969]

I have seen several people mention that the 4 core radiator is to thick and actually prevents more efficient cooling.
Another thought would be adding the the WH air dam to help force more air through the radiator.
You could also try moving to a 70/30 or 80/20 water - antifreeze mix.

 

[Johnnyb]

I don't know, I have the wild horses radiator and I maintain right at thermostat temperature, even pulling in the sand for a long time at low speed.
I think the Explorer serpentine and a good fan shroud might do the trick with airflow.

-JB

 

[Yeller]

You say timing was checked. As in baseline timing? 1 degree retarded can add 30 degrees. I would begin with checking to make sure that when the motor is at top dead center the pointer is at zero. From there I’d bump up a couple of degrees and see what that does, can do that without checking baseline too, some engine combinations like a little more timing at idle. Have you checked O2 readings with a wide band sensor in the tail pipe? If lean at an idle that could be aggravating the issue. The cooling equipment is sound, feels like a timing issue to me.

 

[B RON CO]

Hi, I would recheck the ignition timing. These engines run better with more initial timing than factory specs, as long as the engine does not ping under load. You also must check the spark advance as the RPMs go up. Good luck

 

[Tjboriack]

Thanks for the input on the timing. It will be a week before I am able to do anything else to it right now, but will recheck timing when I get a chance.

still have the 5" water pump pulley coming in as well.

 

[73azbronco]

That is the shroud i have on my 347 using a stock radiator for a v8 of the age, using explorer serp stuff, steel fan, heavy duty clutch. You also have my wilwood brake booster, PS pump (PSC?) Love the cover pass fender well.

But I notice, you have AC, meaning condenser in front blocking radiator.

 

[gnpenning]

Good advice. Out of curiosity, how much space between the tip of the fan and the shroud?

 

[Tjboriack]

Good advice. Out of curiosity, how much space between the tip of the fan and the shroud?

I have about 1.25" from the fan blade to the radiator up top and about 1" at the bottom. from the leading edge of the fan to the back of the shroud, up top I have just under 1" and at the bottom I have just over 1".

 

[Tjboriack]

That is the shroud i have on my 347 using a stock radiator for a v8 of the age, using explorer serp stuff, steel fan, heavy duty clutch. You also have my wilwood brake booster, PS pump (PSC?) Love the cover pass fender well.

But I notice, you have AC, meaning condenser in front blocking radiator.

Yes I have an A/C and the condenser sits in front. It has been a concern of mine, but everyone I talk to doesn't think it is an issue. More people comment not he Staggered 4-Core Radiator over the condenser.

Explorer front end is an option, but trying to not go that route if I can. still have a few things to try.... smaller pulley, timing (again), different radiator, before I get to changing out the whole front end of the engine.

 

[Tjboriack]

any one have a stock factory engine that can measure the water pump pulley diameter and the crankshaft pulley for me?

 

[Tjboriack]

here are a couple of pictures of the engine compartment prior to cutting the shroud. the top of the fan was completely covered.

 

[Johnnyb]

Sweet looking installation @Tjboriack !

 

[DirtDonk]

Top of the fan was completely, or almost completely covered from the factory as well.
The top section of the shroud is extended for hand protection. And other body parts as well!

Most fan performance comes from the position of the fan blades within the bulk of the shroud. I don’t think you hurt any airflow by cutting the top, but I can’t say whether or not you improved it either.
However, if you say the modification worked, that’s good.

Performance doesn’t come strictly from the distance from the radiator core. It’s the fan itself, the fan speed, and it’s position within the shroud.
I seem to remember my factory fan and radiator were something around 2 inches apart. Maybe a little less.
I remember because most electric fans with any kind of performance were too thick to fit. But gaining the inch and a half from the Explorer setup would have helped.
However, since the Explorer fan is so good, most people never think about an electric fan again.

One bit of advice, though it might seem counterintuitive, would be to get rid of the 160° thermostat and replace it with a 192/195 instead.
At least to test.
I think your temperature is going up not a result of a too-high thermostat issue, Your model flows very well, but isn’t doing your engine any good in the long run.
And for most reports, lowering the thermostat on a problem setup doesn’t change the temperature. It will lower it if everything else is working well, but that doesn’t seem to be the case here.
At least go back to a 180 if you have it. But I say 195 instead.

You said timing is good. Doesn’t matter. What’s good mean?
Max your timing out just to see if anything changes. By “maxing out”, I mean, raise it up a few degrees.
If it starts to ping, back it down a little bit. If it doesn’t, turn it up a few more degrees.
What’s it at now?

Do you have vacuum advance? If not, add it.

The radiator itself is capable handling a lot of power. That’s not a problem.
The water pump is as efficient as they get.
The thermostat as well.

And in all this, have you verified that your gauge is reading correctly? If not, you really, really need to do that.
Just to make sure you know exactly what’s going on.
A laser thermometer pointed at your sending unit, and upper and lower hoses is one way, But a readily readable alternate gauge mounted temporarily would be even better.

 

[ba123]

If it's only while under load, it could be your trans temp that's making it overheat if they share the radiator. If so, you could try adding another trans cooler with a fan to keep that cooler or completely separate them.

Also, just confirming that you do NOT have a reverse rotation pump as your rad is stock sided.

 

[DirtDonk]

And by all means, try the AC just to see if it goes up when the temperature is otherwise stable when you’re driving.

 

[ba123]

I have seen several people mention that the 4 core radiator is to thick and actually prevents more efficient cooling.
Another thought would be adding the the WH air dam to help force more air through the radiator.
You could also try moving to a 70/30 or 80/20 water - antifreeze mix.

That air dam works great, and I highly recommend it, but only helps when moving. Really helps though, at least for me!

 

[Tjboriack]

Sweet looking installation @Tjboriack !

thank you

 

[Tjboriack]

Top of the fan was completely, or almost completely covered from the factory as well.
The top section of the shroud is extended for hand protection. And other body parts as well!

Most fan performance comes from the position of the fan blades within the bulk of the shroud. I don’t think you hurt any airflow by cutting the top, but I can’t say whether or not you improved it either.
However, if you say the modification worked, that’s good.

Performance doesn’t come strictly from the distance from the radiator core. It’s the fan itself, the fan speed, and it’s position within the shroud.
I seem to remember my factory fan and radiator were something around 2 inches apart. Maybe a little less.
I remember because most electric fans with any kind of performance were too thick to fit. But gaining the inch and a half from the Explorer setup would have helped.
However, since the Explorer fan is so good, most people never think about an electric fan again.

One bit of advice, though it might seem counterintuitive, would be to get rid of the 160° thermostat and replace it with a 192/195 instead.
At least to test.
I think your temperature is going up not a result of a too-high thermostat issue, Your model flows very well, but isn’t doing your engine any good in the long run.
And for most reports, lowering the thermostat on a problem setup doesn’t change the temperature. It will lower it if everything else is working well, but that doesn’t seem to be the case here.
At least go back to a 180 if you have it. But I say 195 instead.

You said timing is good. Doesn’t matter. What’s good mean?
Max your timing out just to see if anything changes. By “maxing out”, I mean, raise it up a few degrees.
If it starts to ping, back it down a little bit. If it doesn’t, turn it up a few more degrees.
What’s it at now?

Do you have vacuum advance? If not, add it.

The radiator itself is capable handling a lot of power. That’s not a problem.
The water pump is as efficient as they get.
The thermostat as well.

And in all this, have you verified that your gauge is reading correctly? If not, you really, really need to do that.
Just to make sure you know exactly what’s going on.
A laser thermometer pointed at your sending unit, and upper and lower hoses is one way, But a readily readable alternate gauge mounted temporarily would be even better.

Thanks for the notes

Gauge reads correctly - have been tracking with a laser thermometer for awhile.

Plan on going to a 180 degree t-stat once I figure out the temperature issues. Right now running a 160, 180, or even a 195 won't make a difference - they are all wide open as the engine doesn't cool back down for it to close.

As noted in an earlier post - plan on checking the timing in the next week or so. Yes it has vacuum advance and plan on checking that again when I do the timing.