• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

External oil cooler vs internal rad one....

Acesneights1 said:
I'm gonna look at a factory 93 brass/copper rad which has the lines on the right side but no oil cooler. I may have one of those recored. I just returned a leaky one to the junky. I'll call him tomorrow and see if I can buy it back cheap for the tanks and then have it upgraded to 4 core. I really wanted to lose that oil cooler up front too though. I still think getting rid of stuff in front of the rad will make a huge difference. I worked on 2 6.5td owned by someone I know. One is a 94 and the other a 2000. Both are 1 tons and pull heavy equipment trailers. All stock same for PMDs. Stock exhaust everything and neither truck has ever had any overheating problem....why ??? NO A/C in either truck. No condensers...Coincidence ?
Click to expand...

I've dragged some semi-heavy stuff with my 96. 10K max when you add in trailer weight. Mine never got warm, not even on a 1 1/2 mile long 7% uphill grade. Was able to maintain 50 mph and keep the TCC locked in 3rd, and the temp needle didn't budge. No A/C in mine either.

I've always thought the A/C condenser had an effect on cooling. It's not even the extra effort to cool the A/C condenser. It's just getting the air through the condenser that's the problem.
 
yep. Hey when you get a chance, I need pics of the passenger side batt in your K5. I suspect the rad in my CUCV is moved more to the drivers side to accommodate the big battery. How many inches between your rad and the fender ? I think I have 10 on the CUCV. This plays into the grand scheme...
 
Acesneights1 said:
yep. Hey when you get a chance, I need pics of the passenger side batt in your K5. I suspect the rad in my CUCV is moved more to the drivers side to accommodate the big battery. How many inches between your rad and the fender ? I think I have 10 on the CUCV. This plays into the grand scheme...
Click to expand...

you could be onto something. I"ll get some measurements and pics for you when i get out there. Have to change the rear main today. It's leaking. :prrr:

I can tell you the huge 4 core fits right where the 3 core was. No difference in length of the radiator, just thickness.
 
My problem with that truck is I am going to have to relocate the batt to the drivers side and it looks to me the factory tray won't fit. The turbo will not fit on the truck with both batts on the pass side. Maybe I shoulda went Banks. I still may. That will be another thread.
 
Acesneights1 said:
My problem with that truck is I am going to have to relocate the batt to the drivers side and it looks to me the factory tray won't fit. The turbo will not fit on the truck with both batts on the pass side. Maybe I shoulda went Banks. I still may. That will be another thread.
Click to expand...

There was a banks charger sitting in the for sale section here. Can't remember who the seller was. I think it was just the charger though, not the entire setup.

If you do move the battery to the driver's side and order a tray, order 2. I need a driver's side tray. I can paypal the cash to you, once i get some that is.
 
OK so update. I got lucky and the junky did not scrap the rad. I gogt it back for 50$ cash no warranty. The rad shop said I got a deal the tanks alone were worth more. He inspected the rad a few mins ago. To my surprise it was a 4 core but the core is shot. We had a brief chat about what I was trying to accomplish and Copper/brass vs Plastic Aluminum. He said the copper/brass absorbs heat from the coolant much better than aluminum and should cool significantly better. The trade off is the Aluminum Rads last longer and are less prone to corrsion but that is not my concern right now. He is either going to make it a 5 core or put a larger 4 core in it. He is looking it up as I type. Looking at about 500$ and it it works, money well spent. If it don't I'll shut up for good about it as I'll be out 550$. I think it's gonna work. So does the rad shop. My only regret was not having....wait, he is on the phone now. He said he thinks he can put an internal oil cooler in the drivers side of the tank...the plot thickens...more to come. I would love to lose that big douchbag oil cooler from the front of the rad.
 
I believe the 6.2 old bodys had the oil cooler lines come out just above the oil filter (like 6.5's) run up to core suport then 90* off to the pass side (cold side).

6.5 trucks Trans have the lines on the cold side also, but external engine oil cooler.
 
Acesneights1 said:
BTW just to gather some data what temp should the oil be at ? I would think same as engine correct ?
Click to expand...

I agree with that oil temps ~ normal ECT. If you are talking about avg oil temp like in the pan. It does not have to get to an avg temp of 212F that is too hot for an avg temp. Turbo's add heat to the oil 2 ways the turbo and the piston is generally hotter in a turbo so it needs to shed more heat into the oil. On a NA engine the piston is hot on only 2 strokes combustion and exhaust. A NA is cool on intake stroke and real warm on compression stroke. Our 6.5's with out intercooler is warmer on intake and hotter on compression stroke due to effective compression ratio. Therefore turbo'ed engines need better oil cooling (for the piston as well as turbo). The oil will temporarily get hot enough to evaporate any water vapor as long as it gets to a decent avg temp. Shoot for a an avg oil temp of around 160-180F Too cold would be fairly cool like maybe < 120F I would guestimate. And there its only a loss of fuel effeciency of more viscous oil.

I like the idea of an external air cooler before the radiator to dump excessive heat and let the radiator polish and normalize the oil temps.

Regular 15W-40
I think Yanmar and Kubota spec max sustained avg oil pan oil temp at 256F (intermittent to 265F iirc). I have seen it take like an hour to finish topping out completely with a sustained load. Oil temp can react faster than that but still seems to be the slowest engine temp indicator and takes the longest to top out.
 
Last edited:
I mean plumbed before the radiator not necessarily in front of it.

If in front maybe a high performance tube and fin one. I think the plate oil coolers are tough and do a good job cooling the oil but block a lot of air flow for the stack.

Permacool and others offer higher performance oil coolers with "turbulator tubes" and fins that might have less impact on air flow through our radiators. But normally the one' I see the tubes are too small for 15W-40 oil.

I bet a nickel if you lost cooling capacity going from radiator to an external air cooled one the air cooled one was undersized. It may have had a high rating but probably at some not realistic air flow compared to the normal mounting location(s). Or rating with unrealistic air temps.
 
I am confused, not hard since I am a newbie. My truck, a 6.2 N/A is supposed to have a mechanical LP but has a factory elec LP. It also is supposed to have a internal oil cooler but it has a factory external one. Is there no consistency to what GM built? How many more supprise features do I have???? LOL I am not a engineer but there is a huge condenser in front of my radiator and a oil cooler in front of that and I intend to add the biggest tranny cooler that will fit in front of the other side of the radiator from the oil cooler! That does seem like a lot of stuff stacked in front of each other???? How bout my oil in a N/A not getting hot enough to boil the water off since it aint internal???? The radiator shop replaced my old style radiator last month with a aluminum one, same size and width, I didna like it cause I figured it would not cool as well cause it looked puny. The guy told me it would cool better, so much better that some people had to adjust their system cause it would run too cool. Well the thing is doing the job, 170 degrees now not towing and 180-190 towing, I have towed my horse trailer and it runs cooler now towing than it did before with nothing behind me. Course the old radiator might have been plugged up, it did have a small seeping wet spot that actually leaked if u ran it hard with the trailer. I live in big farming country and this shop has been in business since before time began, like 3 generations and farmers overload and over tow everything and I honestly believe this guy knows his stuff, they do everything, loggers, truckers, combines, etc and they have a fantastic reputation. The guy told me they would special order and put a copper brass radiator back in my truck if I wanted for the same price but I would have to wait and also that they DO NOT WARRANTY those radiators in my type of truck cause the truck will either run hot and I will be back complaining or worse yet mess up my motor or heads and be back complaining. I dont know guys, I am a lowly newbie, just threw this out as general info,
 
Acesneights1 said:
OK so update. I got lucky and the junky did not scrap the rad. I gogt it back for 50$ cash no warranty. The rad shop said I got a deal the tanks alone were worth more. He inspected the rad a few mins ago. To my surprise it was a 4 core but the core is shot. We had a brief chat about what I was trying to accomplish and Copper/brass vs Plastic Aluminum. He said the copper/brass absorbs heat from the coolant much better than aluminum and should cool significantly better. The trade off is the Aluminum Rads last longer and are less prone to corrsion but that is not my concern right now. He is either going to make it a 5 core or put a larger 4 core in it. He is looking it up as I type. Looking at about 500$ and it it works, money well spent. If it don't I'll shut up for good about it as I'll be out 550$. I think it's gonna work. So does the rad shop. My only regret was not having....wait, he is on the phone now. He said he thinks he can put an internal oil cooler in the drivers side of the tank...the plot thickens...more to come. I would love to lose that big douchbag oil cooler from the front of the rad.
Click to expand...

Not a bad deal at all. Re-cores are pricey so the $500 is expected. If you need the cooler lines that GM used in the 80s let me know. I was going to switch to a 6.5 style cooler, as i have one here, and having the braided stainless lines made up. Now i think i'll be waiting to see which one really does work better, the internal or external oil cooler.


The deal i got on my 4 Core was insane. $35 for the complete radiator, and ~$100 for the rad shop to pressure test, clean, flow test, and re-solder all the critical areas. Flow tested at nearly 100% and from what i could see the rad looked brand new inside(looking through the rad cap opening) Sometimes i love junkys. Haven't been to one in a while. Might go saturday. Prolly a bad idea cause i'll emerge form the junky broke. :rof:
 
Last edited:
orrum said:
I am confused, not hard since I am a newbie. My truck, a 6.2 N/A is supposed to have a mechanical LP but has a factory elec LP. not supposed to be mechanical, as far as I know, all GMT400 (the 88-98 body style) diesels had the frame mount electric pump. my un-molested bone stock 91 is electric, so unless 88-90 is mechanical, I would venture to guess all GMT400 6.2Ls are electric It also is supposed to have a internal oil cooler but it has a factory external one. you arent looking at the power steering cooler, are you? there is up to 4 coolers in a manual trans truck, 5 in an auto, radiator, condenser, power steering cooler, eng. oil cooler, and trans oil cooler. the last two can be in the tanks, as my 6.2L is in the tank, unlike your 6.2L Is there no consistency to what GM built? How many more supprise features do I have???? LOL I am not a engineer but there is a huge condenser in front of my radiator and a oil cooler in front of that and I intend to add the biggest tranny cooler that will fit in front of the other side of the radiator from the oil cooler! That does seem like a lot of stuff stacked in front of each other???? How bout my oil in a N/A not getting hot enough to boil the water off since it aint internal???? The radiator shop replaced my old style radiator last month with a aluminum one, same size and width, I didna like it cause I figured it would not cool as well cause it looked puny. The guy told me it would cool better, so much better that some people had to adjust their system cause it would run too cool. Well the thing is doing the job, 170 degrees now not towing and 180-190 towing, I have towed my horse trailer and it runs cooler now towing than it did before with nothing behind me. Course the old radiator might have been plugged up, it did have a small seeping wet spot that actually leaked if u ran it hard with the trailer. I live in big farming country and this shop has been in business since before time began, like 3 generations and farmers overload and over tow everything and I honestly believe this guy knows his stuff, they do everything, loggers, truckers, combines, etc and they have a fantastic reputation. The guy told me they would special order and put a copper brass radiator back in my truck if I wanted for the same price but I would have to wait and also that they DO NOT WARRANTY those radiators in my type of truck cause the truck will either run hot and I will be back complaining or worse yet mess up my motor or heads and be back complaining. I dont know guys, I am a lowly newbie, just threw this out as general info,
Click to expand...

maybe to see if you have OEM equipment, go to www.compnine.com/vid.php and run your VIN, and maybe there will be a code for HD engine cooler, external, or something like that.

your 6.2L wont have near the issues had with the turbo trucks, as the turbo trucks run more fuel, and run higher IATs, EGTs, combustion chamer temps, etc. all around higher temps. If you keep the fuel setting stock, I doubt you will have too much issues. I am worried about the aluminum/ plastic setup. did you keep the brass one? I personally would get the brass repaired, but I bet the aluminum would still work fine, it is just more OCD than anything! :)

it may be helpful if you took a pic of your cooling stack, so we can see what all you have. I might have a trans cooler available at some point, but no guarantees. genuine GM, from low to no rust Great High Plains. (truck from NE, rusty front fenders, otherwise low to no rust, stuff is in good shape out here!)

have you gotten close to overheating yet? just curious.
 
Last edited:
Orrum, you have a GMT400 with 6.2 so you have elec fuel pump and external oil cooler as the later 6.5 trucks did but your truck did come with a factory Brass copper rad and they do work better. Plastic/Aluminum is junk IMHO but this experiment will prove me right or prove me wrong. I had many many 6.2s with brass/copper and granted, no turbo but none ever had any issues towing. Copper absorbs the heat from the coolant better . That is my theory anyway. We'll see. The oil cooler in the older square body trucks is welded into the tank so I can't swap it. we loosely talked about drilling the drivers side tank and trying to install one but for now that idea is on hold. The new rad will hold almost twice as much coolant so I can't see how that is an improvement. The guy joked and said I hope it gets hot enough, I said I don't see that being an issue...:D I still would have liked to move the oil cooler or lose it altogether to free up some airflow but I'll see how the bigger rad works out and BTW 93 6.5TD's also came stock with 4 core brass copper. I know that for a fact as that is where I got the one I am re-coring.
 
Orrum seems the 6.5 has several odd builds and not so clean production breaks from one model/design and the next.

Also, iirc Deutz air/oil cooled Diesel's also specified maximum sustained average oil pan oil temperature at 256F. All three of theses max 256F specs I saw were for conventional dino oil. No one I spoke with ever really commented if it could or could not be exceeded with synthetic oil. Mostly talked to field tech's that were testing for application approval for OEM builds and future warranty claims. Interesting enough when I questioned what was acceptable intermittant times to 265F they couldn't say. Seemed there was a rule of thumb of a few minutes to 10 minutes.

I met three different manufacturer trained technicians that had made up a fake dipstick that approximated the middle of the oil pan oil depth and attached a thermocouple to this dipstick end. When we heat balance tested the engines after they checked the oil they just put their dipsticks in place of the regular one. We would load the engine to max load and watch EGT, upper and lower radiator hoses temps, air temp in and out of radiator, the IAT at air intake, oil temp, and an ambient temp by alternator and/or starter which ever was hotter. The test usually took 40 minutes to an hour for all the temps to rise to their maximum and steady state for 10 minutes when everything was good.

To clarify I don't think our OE plate style oil cooler totally blocks air flow through the stack but it puts a big ole damper on it. It is a trade off of oil interface to air and I think toughness design consideration.

If anyone has any other oil temp specs I would be interested in learning them as well.
 
Kenny, you'll like that copper radiator, glad you found one to recore. How much is a new one now?

You'll be lucky to see less than 260ºF on 6.5 oil temps empty, except in winter. Around 240-250ºF on a 32ºF day is what mine run, IIRC.
 
Burning oil said:
I believe the 6.2 old bodys had the oil cooler lines come out just above the oil filter (like 6.5's) run up to core suport then 90* off to the pass side (cold side).
Click to expand...

You are correct. The oil cooler lines actually go across between the fan blade and the radiator core. This puts both the hot and cold side lines getting extra cooling as they pass across the radiator to the pass tank cooler and back across the radiator to the drivers side.

Don
 
I'm really interested in your results. I bought my 94 truck as a rebuilder and the aluminum radiator was damaged. I found a used copper/brass radiator, had it tested and installed it. If my memory is correct it was a four core. Heath claims these 6.5s do better with the aluminum rads, but everything I've read goes along with what has been said here, copper/brass transfers heat better. My interest is definately going here.

Don
 
You must log in or register to reply here.
Back
Top