[grivera]

I'm struggling with a running hot issue in my 69 Bird that started after installing a Vintage Air AC Condenser - the AC compressor and rest of system aren't installed yet. The car already had an auxiliary B&M plate style cooler installed in series with the trans cooler in radiator. Currently, the trans cooler is in front of condenser with about 1/4" clearance (see pic). Prior to installing the AC condenser, it wouldn't go past 200 in stop and go traffic (in gear) - now it will climb to 215 (I haven't waited for it to go higher). In park or neutral it'll creep slower and yesterday's testing (in Park) held about 200 in 95 degrees ambient temp. At cruising speed temperature stays under 190.

I'm concerned once AC is functional the situation will get way worse...trying to stay away from electric fan set up if at all possible.

Pertinent facts on build:

-69 Firebird, 400/461 with Edelbrock D-port heads and Sniper EFI
-Cold Case direct fit radiator with 1.25' tubes; 180 T-Stat and 50/50 coolant and distilled water
-19.5" 7-blade clutch fan w/2.25" pitch
-Hayden 2797 fan clutch- bimetal coil tab moved into new slot CCW to engage clutch at lower temp
-Factory shroud and lower/upper baffles in place
-Water pump is 11 bolt, cast iron impeller, has sleeves w/rubber O-rings in place and plate/impeller clearance is a little more than thickness of gasket
-Spring in lower radiator hose
-Sniper EFI is tuned well - idle RPM is 850 and idle timing is 25

The below pics illustrate placement of trans cooler, factory shroud/fan, and altered fan clutch spring.

[HWYSTR455]

Is it a new clutch? Can you hear the clutch engage?


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[HWYSTR455]

Is your radiator cap new?


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[grivera]

The clutch isn't new but has less than 3000 miles on it - I can't say that I ever heard it engage or make a howling noise like some describe - but it certainly pushes lots of air. The same with the radiator cap - although regarding cap doesn't that only control system pressure and boiling point? Also, keep in mind the change in efficiency changed with the addition of the condenser. I'm sure others have installed auxiliary trans coolers in front of condensers and wondering if this is "normal' cooling system behavior.

[HWYSTR455]

If it runs at desired/normal temps while cruising, and creeps at stop, that certainly suggests an air flow issue at stop.

Clutches can be finicky, can start going bad from poor handling, storage for periods horizontally, out of balance fans, etc. As they get older, they tend to not hook up at lower speeds as well, and freewheel at higher temps, progressively.

Belts can slip without making noise, too, might be something to consider.

A cap allows psi to build to prevent a barrier from forming between the coolant and block/head, not just to increase boiling point. If it's worn out, it can allow psi to escape. May be slight, and not noticeable.

All stuff to check, but thinking more along the lines of the clutch. Yes, the new high-efficiency condenser could add to the issue, as well as the trans cooler blocking some flow, but it should be minimum impact if everything else is in working order.


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[JSchmitz]

Can't tell from the picture. What size is your water pump pulley? Looks pretty big.

[HWYSTR455]

As I recall, it's the correct A/C one, but my memory isn't what it used to be.

Will?


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[grivera]

Originally Posted by HWYSTR455

If it runs at desired/normal temps while cruising, and creeps at stop, that certainly suggests an air flow issue at stop.

Clutches can be finicky, can start going bad from poor handling, storage for periods horizontally, out of balance fans, etc. As they get older, they tend to not hook up at lower speeds as well, and freewheel at higher temps, progressively.

Belts can slip without making noise, too, might be something to consider.

A cap allows psi to build to prevent a barrier from forming between the coolant and block/head, not just to increase boiling point. If it's worn out, it can allow psi to escape. May be slight, and not noticeable.

All stuff to check, but thinking more along the lines of the clutch. Yes, the new high-efficiency condenser could add to the issue, as well as the trans cooler blocking some flow, but it should be minimum impact if everything else is in working order.


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The clutch has been installed in car since 2011

Originally Posted by JSchmitz

Can't tell from the picture. What size is your water pump pulley? Looks pretty big.

Originally Posted by HWYSTR455

As I recall, it's the correct A/C one, but my memory isn't what it used to be.

Will?


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It's an original AC car and IIRC rough measurement of water pump pulley is 6.5" - will measure again today.

[HWYSTR455]

10 years on a clutch fan, regardless of how many miles, I would probably question. Wouldn't hurt to replace it, and would eliminate at least one potential cause.

Did you ever replace the pulleys? I had issues at one point and then replaced all with a RARE set.

Trust me when I say you should NEVER sand a pulley, I don't care what anyone says otherwise.

I suggest running a new belt too, eliminate another potential cause. A belt can look perfectly fine and be junk, and once they slip even the slightest for a short period, replace them. Most alternator manufacturers state to replace the belt when replacing the alt for that specific reason, and will not warranty if it hasn't been replaced with the alt.

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[grivera]

Thanks Mike - not discounting those points but I do want to reiterate the addition of condenser is the new variable. I too conclude it’s air flow, but thought others with similar set up can advise what has worked for them.

[HWYSTR455]

Not much you can do really, I don't think moving the trans cooler is going to make much of a difference, and the only other option if the above don't work, as you know, would be to go to electric fans.

And, would strongly recommend a PWM controller if you go that route, and a 150a alt. Lemme know if you want to go that route, I can help.


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[grivera]

What are thoughts on installing a small electric "pusher" fan on trans cooler?

[HWYSTR455]

I would say without knowing what your trans temps are, under all conditions per your driving style, doing so could provide little to no benefit.

If you run your cooler inline with the radiator cool, in most cases, there will not be a cooling issue for either, your trans or engine.

Usually the one in the radiator is more than sufficient, and unless you have a created condition from say, a high stall or loose converter, long periods of towing/load, or other, you really don't need an external cooler.

On-demand situations that raise the temps on a trans that are a short duration, the in radiator cooler can recover with a little time under normal conditions.

Just like an engine, it is possible to run a trans too cool.

[grivera]

So my converter is a Continental 13" - very tight under normal driving - basically like an OEM converter and the radiator is a Cold Case so not sure if its trans cooler has sufficient capacity. I do run the B&M in line with the radiator. My thought was if the B&M trans cooler was blocking flow getting to condenser and radiator but then again I'd probably just be pushing hot air from the B&M cooler onto radiator.

[HWYSTR455]

It wouldn't be pushing air hotter than what the radiator is seeing, since it's after the radiator. And with your setup, the added cooler should be allowing operation a few degrees below the temp is was without it. The key is though, that the temps would recover quicker in demand situations, better than it did without.

I think you're in a good place then way it is now, and it's not negatively impacting your engine cooling.

Sure, there may be a slight decrease in air flow across the radiator core, but really don't think that's a concern. You have plenty of capacity, and a high efficiency setup. I suspect any change in temps with the way it is now is caused by other factors.

Just to comment, IF there is a 'reasonable' reduction in air flow, AND it's causing concern, the solution is to increase air flow. Additional air flow will overcome any reduction of air flow caused by any config changes.

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[grivera]

What I meant there was if I added a small pusher fan on trans cooler

[HWYSTR455]

You could increase air flow slightly by spacing the trans cooler out a little more. Air gap between cores does help overcome some issues caused by having them touching or very close together.

I think the general rule of thumb is @ 1" gap minimum.


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[HWYSTR455]

Originally Posted by grivera

What I meant there was if I added a small pusher fan on trans cooler

I just don't see the need, it adds cost, wiring, and it shouldn't run all the time, would have to add a sensor. And adds 'complexity', another thing that can 'go wrong' or break.

Like I mentioned before, you would first need to add a temp gauge, and monitor the temps, before deciding if you need it.

And no, it wouldn't help engine cooling, would be un-noticeable.

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[ta6point6]

Well that is a huge chrome trans cooler mount, that is not helping with airflow IMO. You want a tunnel effect going through shroud that is not happening with that mount. I would find a smaller bracket (maybe a smaller trans cooler)to mount that trans cooler and maybe a little lower. That is a huge transmission cooler what are you hauling livestock..

[78w72]

i dont see that mount bracket as "huge", it looks like just a strip of aluminum about the same width as the end part of the cooler, doubt thats a contributing factor to his issue. but i do agree the cooler is on the large side & unless theres a specific reason for needing one that big it would probably help to down size it or add a temp gauge or check the pan with a temp gun after a long hard drive to see if the fluid is getting hot enough to need one. for a mostly street driven car a trans cooler may not be needed.

a big trans cooler like that will definitely increase the heat being put into the radiator since its not allowing any cool air to flow over that area, its all hot air once the trans is up to temp. in series with the rad cooler is the best way to run it since the rad cooler removes a lot of the heat first & as mentioned also warms the fluid in colder temps. bypassing the rad cooler is not a good idea for a street car since there is no cooling unless the car is moving.

i dont think all the other things mentioned like belts or the clutch fan itself are an issue or causing the overheat since they were all functioning good with no overheat issues until adding the condensor, that is the only new change & will definitely reduce air flow & increase temps as shown. if the rest of the system is in good working order & the water pump divider plate set right etc it should be able to handle an a/c condensor, but i have heard these 1st gen firebirds dont have very good air flow through the front end.

couple things to consider trying:
get a smaller aux cooler after checking trans temps or eliminate it if not needed.
use a cooling additive like water wetter or hyper cool & lower the anti freeze concentration as much as you can based on your climate. water cools better than anti freeze.
i doubt the clutch fan is bad just based on time, especially if theres no sign of leaking fluid & the fact it worked fine before adding the condensor. it is hard to tell in the pics, but what size is the fan? it almost looks like its too small in the shroud opening, if it is try a bigger fan that fits tighter in the opening. 19"?
& make sure the shroud is sealed around the radiator & core support with no gaps.
electric fans may help but can be expensive & ive read many times that they can be less efficient than the correct factory shroud set up but that varies for every car/engine.
& maybe play with pulley size, under or over drive to see if that helps.

FWIW, i have a 467 stroker with E heads & a carb & running a measly 3 row champion radiator with a warn out clutch fan & 180t-stat, runs at 180-190 tops in all situations on the street or drag strip in summer temps & on days below ~70 it will barely stay at 180 verified by the gauge & a temp gun. your system should be able to handle an ac condensor.
hope you can figure it out.

HWYSTR: can you elaborate on the sanding pulleys thing? never heard of that one & have sanded pulleys on 3 of my cars without any issues. fully sanded & cleaned of surface rust & debris in the groove but not painted in there.