Drop in radiator advice...

[Charles Young]

Don't get me wrong, my observations of oil pressure were far from scientific, it was not my intent to be monitoring oil pressure after the rad change but I am pretty confident that oil pressure did not go down and went up a little across the spectrum from idle to 80 mph. I was pretty careful to select fittings that did not further restrict flow but who knows, lots of variables I expect. What I can say is that I intended to use an external oil cooler but could not get one by the time I wanted the car back on the road. I figured the tranny cooler was better than no cooler so I hooked it up. I really appreciate those of you who, like Earl, "dwell" on these issues and would like to hear more about what I have done if there are issues. I started to just bypass the cooler but like I said figured what I did was better than no cooler at all. Also, my oil press gage was added at the original sensor location. I used braided flex to extend it beyond the other obstructions so I could add the gage and use the original wiring too. This was done before the radiator work.
Thanks!

 

[Charles Young]

X2!

The smaller inlet and outlet of the trans cooler is causing the oil to flow less, not more or the same as an oil cooler with the bigger lines which allows the oil to pass through more freely.

That is the reason why it shouldn't be used as an oil cooler.

Oil viscosity is also higher than trans fluid especially when cold and should be another consideration of why not to use the in tank trans cooler for engiyyne oil.

I as still typing, slowly, my response above before I saw this - Thanks. Isn't the in-tank cooler still better than no cooler though? Or is it just a potential restriction in the whole system that should be eliminated?

 

[earlbrown]

I as still typing, slowly, my response above before I saw this - Thanks. Isn't the in-tank cooler still better than no cooler though? Or is it just a potential restriction in the whole system that should be eliminated?

That's an overly simplistic statement (that's not very scientifical), but......



if you're seeing higher oil pressure at the entrance of the block, (and only changed one thing (the radiator)) that is scientifical.

That gauge location reads the PSI as the oil enters the engine after it makes 2 90* turns. And since the location didn't change before/after that is a valid test.

I will reiterate, I have no first hand experience with that as the thought never occurred to me to try and use my Fbody trans cooler as an oil cooler. (I don't even run an oil pressure gauge so it wouldn't work anyway. I trust the guy that built my pump ) I just found it interesting that a trans cooler and a bunch of fittings will outflow a purpose built stock cooler.

 

[robzombie]

I can't tell you what if any problem you may encounter by running the oil into the trans cooler other than you have restricted the flow path by about half.

Maybe Earl can tell you what could happen in that situation. If you plug or restrict the oil feed lines like you have it may or may not have a negative effect.

Earl knows exactly how and where the oil paths go and what might cause the oil bypass to open or other potential problems that you could encounter.

I only know that restricting flow in anyway can't be optimal for a system that wasn't designed to have that restriction introduced into it.

 

[earlbrown]

That's why I'm curious. I never would have imagines a higher PSI reading. I have an Fbody rad in my car but I don't use the cooler at all. I've never measured, or done any math on any of it.

as far as the flow circuits and whatnot... the spring under the 1" nut sets the pump pressure. Then it hits the filter, the sammich adapter/cooler, all the lines, any bends, etc... the gauge reads pump pressure - cumulative pressure drops getting to the block.

What I find interesting is the 'small' 'restrictive' trans cooler gives a higher reading inside the block!

Now keep in mind, I haven't put my hands on the OPs cooling system... but it looks like he removed a stock rad with an actual oil cooler, and the only chance was to put in an Fbody and 'incorrectly' use the ATF cooler for oil. If that was the only change with no other variables it looks like the Fbody trans cooler outflows the stock GN oil cooler.

Do have the balls to run my oil through it?..... probably not lol

 

[earlbrown]

that being said, this is the stuff I can't let alone.... I have an extra Fbody cooler and my original GN radiator. It really wouldn't be that hard to rig up some sort of flow measuring device and plot pressure drops with various vicsocities.

 

[Charles Young]

What about some existing restrictions that may have been in my original rad/oil cooler? Who knows? However, the car only has 56 k miles.
Earl - based on your comment, you're thinking what I have is worse than no cooler due to possible restrictions, right? I do not want to screw something up here. I'm showing 50+ psi at start up. Drops down into the 20ish range when warmed up at idle or low speeds but this rad replacement only transpired this weekend so I haven't watched it a lot either. What I meant by unscientific in my earlier comment was that I didn't scientifically observe the pressure readings but I still don't think I saw any drops, at least not of any significance. Before, when it was running hot at around 205 or a little higher, briefly, the pressure was down in the 12-15 range at idle. It would rise very quickly with RPM and was only this low at idle. Should I just bypass the cooler I have or do a little more observation since pressures seem in the acceptable range?

 

[robzombie]

Your oil pressure is in the acceptable range. I don't think that you would have a major problem running through the trans cooler as opposed to no cooler at all, all you are doing is slowing down the flow to about half of what the oil cooler would flow.

The main thing you have done is restrict the flow which if there are no other problems in doing so only makes the cooler less efficient.

I don't understand how Earl came up with the notion that the Fbody trans cooler out flows the GN oil cooler as the trans inlet and outlet are about half the size of the GN oil cooler inlet and outlet.

 

[Pronto]

If the oil is restricted then that means more is going through the by pass and not getting cooled anyway. Might as well not even have the lines hooked up. Hell, Grumpy hasn't run an oil cooler in ages.

 

[Coelacanth]

Well, I didn't even bother burping the cooling system or wasting another 2 hours to R & R the t-stat and drill a steam hole. I had a close look inside the rad and the scale accumulation was quite bad. It looked like sugar-frosted Mini-Wheats in there. I scrubbed a finger on it and it came out covered in white guck. When pay-day comes next week, I'll have to order a rad.

Next time I need to burp the cooling system, I'll buy a Lisle spill-free funnel or make my own...it's a much easier process.

 

[robzombie]

I do and will always run an oil cooler, I've seen the affects of what heat will do to your oil.

Higher oil temps will lower your oil pressure and also the oil will break down faster.

I've seen my oil pressure drop by as much as 10 psi when my coolant temps were at 200* plus versus when they were at 180*.

To each his own on this debate on whether to use a cooler or not but it is a fact that running a cooler whether it's a trans or oil is only beneficial and will do no harm if functioning properly.

 

[Charles Young]

Your oil pressure is in the acceptable range. I don't think that you would have a major problem running through the trans cooler as opposed to no cooler at all, all you are doing is slowing down the flow to about half of what the oil cooler would flow.

The main thing you have done is restrict the flow which if there are no other problems in doing so only makes the cooler less efficient.

Makes sense to me, thanks for the feedback! Sounds like it isn't urgent but I think I will still plan to add an actual external oil cooler, There is a write-up over on the gnttype board that lists a specific cooler and some aeroquip fittings. Are there better options that anyone is aware of? Thanks again!

 

[Red C5]

I do and will always run an oil cooler, I've seen the affects of what heat will do to your oil.

Higher oil temps will lower your oil pressure and also the oil will break down faster.

I've seen my oil pressure drop by as much as 10 psi when my coolant temps were at 200* plus versus when they were at 180*.

To each his own on this debate on whether to use a cooler or not but it is a fact that running a cooler whether it's a trans or oil is only beneficial and will do no harm if functioning properly.

I'm with you and it surprises me that people are willing to risk a motor or a transmission by "saving" money and not running a cooler.

 

[robzombie]

Makes sense to me, thanks for the feedback! Sounds like it isn't urgent but I think I will still plan to add an actual external oil cooler, There is a write-up over on the gnttype board that lists a specific cooler and some aeroquip fittings. Are there better options that anyone is aware of? Thanks again!

Any cooler like this: Summit Racing Part Number: DER-13614 is better than any in tank cooler and would be a must for me if I didn't have at least the intake cooler I have now.

 

[Coelacanth]

Good information here. I'm soon to pull the trigger on a new rad and I still have a few questions. The F-body rad seems to work great and is quite affordable, from what everybody's saying. However, hopefully those of you who are running those can answer these questions?

1) The F-body rad has tranny cooler holes, but they're not in the same place as on the stock GN rad; i.e. the lower hole is below the lower rad hose rather than above. Any special considerations required to make stock GN tranny cooler lines fit the F-body rad?

2) The F-body rad lacks the engine oil cooler. Are most people buying an aftermarket EOC or not using the GN stock EOC entirely? What did you use for an aftermarket oil cooler; or, what did you need to do to do away with the stock GN oil cooler & lines?

 

[tb3]

The 84 85 hot airs didn't come with oil coolers from the factory and that's why their dropping like flys.
your lucky to get 50,000 miles out of a hot air before the engine succumbs to all that damage caused by no oil cooler.

wait a minute.... I beat on both my 84 hot airs hard and never had any issues concerning oil temps.
nevermind.





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[earlbrown]

I don't understand how Earl came up with the notion that the Fbody trans cooler out flows the GN oil cooler as the trans inlet and outlet are about half the size of the GN oil cooler inlet and outlet.

Because Earl read that oil pressure at the block was greater using an Fbody ATF cooler than the original GN oil cooler. All else being equal the only explanation is less pressure drop across the F body unit.

 

[robzombie]

Because Earl read that oil pressure at the block was greater using an Fbody ATF cooler than the original GN oil cooler. All else being equal the only explanation is less pressure drop across the F body unit.

Maybe I'm missing something Earl, but if you have higher pressures you either have tighter tolerances, [bearings] that would give higher oil pressure versus loose tolerances which would lower pressure.

In the case of restricting oil flow by going through a smaller opening it would also raise pressure and reduce flow. How much depends on the restriction introduced versus the original design.

Take for instance that BB turbos use a restriction fitting to reduce the amount of oil that gets to the bearings of the turbo because it requires less oil than a journal bearing turbo and the amount of oil that a standard feed line supplies. This is done by design and is required but to restrict oil flow to a JB turbo or oil cooler that is designed to flow X amount and then reduced by half could have a negative effect.

PERMA COOL even recommends against the use of trans coolers for the use of engine oil because of the restrictions that could be imposed, but states that oil coolers could be used as trans coolers.

 

[earlbrown]

Because the pressure reading was taken at the block after all the flow restrictions from the filters/coolers/lines/etc..

Yes, I realize the orifice diameter is smaller on the ATF cooler (that's why I've never attempted to try and use it as an oil cooler) but it's the total pressure drop that matters, not just the size of the doorway. I get where you're coming from with the orifice diameter, and even it was more restrictive, that would just cause to bypass in the sammich adapter to handle more flow... Pressure won't drop until that bypass valve is overwhelmed.

Think of it this way... who has more money?... A guy making $100,000 a year with $95.000/yr in bills, or a guy living at home making $12,500? Since the gauge reads at the block, it's measuring the oil that's left in the bank.


When the OP changed radiators, he didn't change bearing clearances, or any other factors (that I know of). If the cooler was the only change and pressure went up, then the only explanation is his exact ATF cooler outflows his (old) exact factory oil cooler. For all we know his factory oil cooler had a glob of snot in it, and he was running off bypass flow. Only way to know is to test.

Personally, I would have to see it with my own two eyes before I ever considered doing it to my own car. But then again, I don't like in-tank oil ''coolers''. That aren't actually coolers. They're more like ''stablizers'' that increase the load on the radiator.

 

[robzombie]

Personally, I would have to see it with my own two eyes before I ever considered doing it to my own car. But then again, I don't like in-tank oil ''coolers''. That aren't actually coolers. They're more like ''stablizers'' that increase the load on the radiator.

I will agree with you there, but without a cooler/stabilizer temps would take longer to recover versus no cooler at all. The coolers job is to keep a more consistent temp in all operating situations.
Everyone knows that heat is the enemy of both the engine/trans and turbo and if no coolers are used the life of all those components and oils are reduced. How much depends on the amount of heat and the length of time those parts are subjected to.

Yes, I realize the orifice diameter is smaller on the ATF cooler (that's why I've never attempted to try and use it as an oil cooler) but it's the total pressure drop that matters, not just the size of the doorway. I get where you're coming from with the orifice diameter, and even it was more restrictive, that would just cause to bypass in the sammich adapter to handle more flow... Pressure won't drop until that bypass valve is overwhelmed.

According to OP his O/P pressure went up not down which shows there is a restriction causing higher readings. That is the point I'm trying to make, the flow/volume of oil has been slowed to the point that the restriction in the system has created higher O/P until the B/P opens.

The pressure drop is in and after the cooler where the oil flow is slowed down due to the smaller openings in the cooler. You would have pressure rise before that point which could cause the higher O/P indicated by the OP.

The volume of oil in the cooler is less because of the restriction which means you have higher total pressure trying to enter said opening and lower total pressure in and leaving the cooler. This pressure drop doesn't mean it is more efficient, just the opposite is true. If the proper sized openings and cooler size are used it would be more efficient and have less pressure drop at the same time.