Cooling issues, could use some advice

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Occurs to me that another way that you can dump a lot of heat w/o putting more load on the radiator is with a remote engine oil cooler.
 
Depends on where you put the cooler. If you mount it in front of the radiator, LOL
 
Even there, though it wouldn't be my first choice, will still improve overall cooling.
 
No, it just might HURT cooling. Putting an oil cooler in the radiator airstream will drop airflow, which seems to be what might be the problem.
 
We'll have to agree to disagree on that point. While true that it will affect airflow in it's immediate area, I've yet to seen an engine oil cooler big enough to disrupt airflow for the whole radiator and even the oil cooler heated air isn't all that large of a delta-T to have a huge impact on the radiator's cooling ability.
Still, best would obviously be if it weren't in front of the radiator.
The original oil cooler from the RX-7 would be a good choice if it is still around. Very wide and not very tall.
 
If you pop the hood and it doesn;t overheat - there's not enough air getting in to flow accross the core. You need to make some openings in the fascia. If you calculate the area of the openings, add them up, and then calculate the area of the radiator. If they are not equal, cut more to make it that way. All your fan power is still trying to pull air through too-small holes.
 
ntsqd said:
We'll have to agree to disagree on that point. While true that it will affect airflow in it's immediate area, I've yet to seen an engine oil cooler big enough to disrupt airflow for the whole radiator and even the oil cooler heated air isn't all that large of a delta-T to have a huge impact on the radiator's cooling ability.
Still, best would obviously be if it weren't in front of the radiator.
The original oil cooler from the RX-7 would be a good choice if it is still around. Very wide and not very tall.
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What part of thermodynamics theory 101 did you miss?

Look here

It is becoming "most probable" from this discussion that the trouble with this system just might be AIRFLOW

So what happens? when you stick that oil cooler in line?

You are going to cause TWO problems

First, the oil cooler is going to reject heat, and where? Right into the airstream of the radiator, so right away you might have cooled the oil a bit, and you put that heat right back into the airstream in front of the radiator. So you've reduce the cooling effect by that much

Secondly, by putting a second heat exhanger in front of the rad, you have further increased the static required to flow air through BOTH coils.

This is a lose-lose deal.
 
Like I said, we'll have to agree to disagree. All of your points are valid in theory. IME with street and race vehicles (road, desert, vintage, drag, etc.) they don't always work out that way. And as I've stated more ideal would to not be in front of the radiator, but if that's where it fits then do it. Just try to place it at the bottom of the radiator rather than the top.

Engine oil absorbs roughly 1/3 of the BTU's put into the engine as fuel. Without a cooler the oil loses it's heat in two ways, radiation - mostly thru the oil pan since it is the thinnest, and conduction thru the block into the coolant. Start actively cooling the oil and both of the other "outputs" will be reduced. So cooling the oil will reduce the thermal exchange load on the radiator before we even start considering what the change in air flow and temperature will do at the radiator. Next look at the delta-T across the oil cooler and you'll find that the 'exit' air isn't all that much warmer than the 'inlet' air, especially when you consider the temperature of the 'inlet' coolant. So the delta-T across the radiator isn't hugely impacted.

I'm not convinced that not over-heating with an open hood directly points to not enough grill opening area. It certainly points to a lack of low vehicle speed air flow thru the engine bay. But is that the grill opening not being large enough, too small of a fan CFM, bordering on too much restriction to airflow thru the engine bay behind the radiator, or?

Before we get into all of the crazy or extreme ideas I'd like to see some response from the OP on the basics that I & others have asked about.
 
autoxcuda said:
Reading all your other comments and no reading this, it seems your grille opening is just not big enough to feed your radiator.

Just like how 69 Dodge Daytona's tend to overheat at idle and low speeds. Same cooling system everthing is on a 69 Dodge Charger that does not overheat. The Daytona just has a smaller grille opening.

Open up this grille squares. Maybe redirect the brake duct cutouts to feed the air box. And you liceanse plate is blocking the main grille opening. Doesn't seem like much, but in your case everthing counts. This would be a start.
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superchargeddrt said:
I've found that my car ran a lot cooler with my hood off. I made a big improvement by sealing the hood to the radiator support. I used foam rubber from the Home Depot. Still gets hot in traffic if I sit idling a long time but it's a vast improvement. Just thought I'd throw that out there. Good Luck
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67Dart273 said:
Easy to check the grille opening...........yank that front end stuff all off (ya, ugly!!) and drive it for awhile
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I've given some serious thought in the past about getting a front bumper with a larger opening. Being a popular drift platform there are plenty to choose from that are designed to accomodate a large intercooler, but wasn't sure it would do the trick. I do like the idea of doing a little cutting to increase opening size though, and I think pulling the bumper off is a great idea to test that theory. This is now on my list of things to try for sure.
 
ntsqd said:
A couple of things come to my mind:

1) Are you sure of the timing marks really being TDC when indicated. A LOT of over-heating issues can be traced back to the wrong ignition timing.

I'm confident my balancer is reading correctly. What would cause the overheating problem, too little or too much timing? My current timing is set 20/34 with no vac advance.

2) Are you sure of the temp gauge? Just because it's a name brand doesn't mean it's right. Buy a real temperature gauge from some place like mcmaster.com, where the % error is specified, and compare it's readings to your gauge.

Either it's the location in the manifold or the gauge, but it reads about 2 degrees cool. All I know is if it reads above 225 I'm looking for a place to pull over.

3a) I know that it sounds like the wrong direction, but what happens if you go to a higher temp t-stat? More than once I've seen this move cure the problem.

No, I haven't but it may be worth a shot. I see where the logic could work though.

3b) High flow or std flow t-stat? If high flow, dump it. Go with the std flow version. The std. flow t-stat is a bigger restriction, which is what you want, it will raise the coolant pressure in the block above the cap value which makes it harder for the coolant to boil in the localized hot spots. Once the coolant has changed to steam it's a lot, lot harder to cool the engine.

Standard flow

3c) While you're messing with t-stats, are you drilling a small hole in it/them to bleed air out while filling the system? If not, do so. 1/8" or smaller. On engines where I can I rotate the t-stat to put the hole as high as I can get.

Yes

4) The radiator cap absolutely has to be at the highest point in the system. '60's era Corvettes had surge tanks due to having a cooling system layout very similar to yours. Strongly suggest putting a very high pressure cap on the radiator, putting a surge tank in the hot side heater core hose, and placing the tank in the engine bay where it's cap will be higher than any other part of the coolant system.
Also: If you can figure out a way to do it, modify the cap on the radiator to allow coolant into the overflow hose bib on the radiator's neck. Route a hose from there over to the top of the surge tank. This will make the system self-bleeding. 80's era VW Rabbits are one potential JY donor for the surge tank and there's likely others as well.

The cap is located higher than cylinder heads with a line going to an overflow tank. I originally didn't do this and it made a noticeable improvement.

5) Water pump; how new is it, and where did it come from? I once had an over-heating problem with a car that had *just* had it's pump replaced before I bought it. I tried everything and the last thing left was the pump. I put a Stewart Components water pump on it and the problem went away. I've since quit buying electrical or cooling system parts from the national chain stores. In the long run they don't save you money or time.

Pump was new last year when I revamped the cooling system, it is a standard repacement from Autozone.
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:)
 
As for the oil cooler idea, there is penty of room to install a remote cooler with a fan if needed to either side of the radiator. You guys are making me rethink the location of my trans cooler though. It blocks a good portion of the radiator right in front of the grill opening.
 
UOP said:
As for the oil cooler idea, there is penty of room to install a remote cooler with a fan if needed to either side of the radiator. You guys are making me rethink the location of my trans cooler though. It blocks a good portion of the radiator right in front of the grill opening.
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Could you easily temporalily remove it and run the lines into the radiator. Then just cruise around and idle it some and see if that helps.
 
No cooler lines in the radiator but it would be easy enough to remove the cooler and loop the lines temporarily.
 
Is the cap now on a surge tank, or is it on one of the main hoses? If it is on one of the hoses it's rated pressure is reduced by the coolant flow.

I don't trust any of the chain store water pumps. I'd put either a Milodon or an Edelbrock pump (are there other MOPAR app. mfg's?) on the short list.

On the Boss 302 R.E.D. that I crewed on years ago the owner/builder just had a 10' long coil of copper tube for the trans cooler. Obviously we didn't drive that car back down the return road.
 
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