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Discussion Starter #1
So I have a '95 K2500 (F series, 8600 GVW model with engine and transmission oil coolers in front of the AC condenser in front of the radiator, and 4.11 rear gears) with the 6.5TD, long bed, club cab with 4L80e transmission. Bought it in 2011 and have long followed the advice on this board that 210 F is where "overheating" and cylinder head damage begins. But now I'm getting into some towing applications (I've got a Bobcat to haul around; about 10,000#), and we're renting a travel trailer for the first time in a couple weeks, so I'm tuning up my cooling system.

Just the other day I was pulling a trailer of concrete (I estimate it was maybe 18,000# altogether, regrettably; it was loaded by somebody else) across town (mostly flat, but a small hill at the end) and the temp went up one or two notches past 210 F despite my babying the pull. So I started worrying if I still have work to be done or if this actually isn't bad. I never heard the fan "turn on"--but I don't hear the fan do it's thing on startup either (and the fan clutch is new)

What I've done (wrt cooling) so far:
  1. Installed new manufactured cylinder heads (2015)
  2. ARP head studs
  3. Upgraded to the dual t-stat crossover
  4. Installed higher output coolant pump (CarQuest PT-5089) w/4 stud bolt on fan clutch... (yeah, I know; just didn't know at the time to spec the ACDelco... )
  5. Installed Hayden 2839 Severe duty fan clutch with Duramax fan blade (ACDelco 1580690)
  6. Cleaned the leaves out of the radiator stack (there weren't many in there)
  7. Reinstalled the front wheel well splash skirts
The last 5 items were all in the last 2 months. Yesterday I ordered the Leroy Diesel bypass flow restrictor, and my next step while I wait for that is to do a heavy duty flush of the coolant system with Prestone radiator flush prior to getting the radiator pulled and bench tested and cleaned. I'm also looking for replacement Radiator Support Baffle Hole covers (which are missing) to improve airflow to the radiator. I'm also thinking about getting an Edge CTS system to finally have a set of "gauges" (EGT, Boost, Trans Temp, Coolant Temp) that will give me better information on what's going on in the engine, and/or set myself up to drop the vacuum actuated waste gate in favor of a turbomaster control.

So A) Is there anything I'm missing here?
B) What temperatures should I expect to see when hauling 10-12,000# at highway speeds? How hot is too hot?
C) Maybe I'm just mismanaging the truck while towing heavy loads--What's the best way to manage towing heavy-ish loads with a 6.5 in town or on the highway?
D) If I get the Edge system, what EGT and tranny temps should I be looking for?



Thanks!
 

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If you install the dual stats what stats did you install ? Should be the OEM 190-195* stats ( AC/Delco )
Did you just hand clean the cooling stack or did you deep clean with a power wash?
 
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I would pull the radiator and do a deep cleaning(degreaser & powerwash). When I pulled mine I couldn't believe how much crap I washed out of it. Just blowing air through it while it's in the truck isn't going to be enough unless it's a fresh radiator that was installed.
 
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Discussion Starter #4
Installed ACDelco 190* stats.
I only picked the leaves out of the stack, not a pressure wash. Aluminum on the fins -looked- reasonably clean, so I didn't feel compelled to pull the radiator, but I will add that to the list when I get it bench tested.
 

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I've used this also, but first clean the radiator and then when refilling, add some.

 

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Discussion Starter #6
I will have to scrutinize if any freeze protection is offered by WaterWetter. In northern Indiana, I have personally seen overnight lows get down to -19F (back in 2014), and when I looked at the back of the Prestone antifreeze (green stuff, not orange), it looked like a 40/60 (coolant/water) mix would protect to only -12F, so going less than 50/50 didn't exactly appeal to me.

I'm kinda wondering if that Carquest coolant pump is all that much worse than the ACDelco 2000 year pump; I took the truck in to have the tstat replaced (cuz I was sick of replacing it myself) and the housing/crossover broke when it came out. Since they (Stateline Diesel in Edwardsburg, MI--very reputable shop for a long time) couldnt find any replacement parts, it became an "impromptu" upgrade job and I was too busy with other stuff to exhaustively research and independently spec the pump that should be used. At some point I did talk to Kennedy Diesel (I think relating to the fan, fan clutch, and differences between 4 stud/spin on clutch styles), who disagreed with Heath's analysis of using the 2000-year pump and maybe that was bad advice? In any event, I tried to find CarQuest's phone number to call their engineering department to get more dope on the pump specs but got the runaround too many times and gave up....
 

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You should only need one 16oz bottle, freeze protection isn't going to be an issue as long as what your coolant is rated for your region. Personally I'd go with the premix AF unless your using distilled water when you mix your own.
 

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You might want to think about switching to an ELC coolant. I use Rotella heavy Duty ELC nitrate free in both my diesels. Good stuff. Dont need water wetter with it. Better heat transfer than the old green stuff. It Protects aluminum and your water pump too.
Just be sure to flush the cooling system before using it. OAT coolants and the "Green Stuff" do not mix.
 
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I have started to use the peak fleet charge coolant. It is compatible with green and it has better heat transfer. It also has an anti cavitation additive in it. They have an oat product called final charge as well.
 
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Discussion Starter #10
Ordered some Prestone 2-in-1 Coolant Flush/Degreaser and Rotella HD ELC coolant, then pulled the radiator today. The coolant coming out was icky, and after I got the rad out and tipped it over to get the last bit out of it, that stuff was positively muddy--and the system had just had the coolant changed (at least partially) when they replaced the water pump about 2 months ago. Went over the radiator and condenser cores with Simply Green, Scrubbing Bubbles, Gunk Foamy Engine Brite (all alternately flushed with garden hose pressure), then I pulled out the pressure washer when I saw a few gunky spots that the surfactants didn't seem to phase. Plenty of dirty water came out, I think, but the cores didnt appear all that dirty on the outside.

Oh, and the transmission fluid that dripped out of the transmission fluid cooler made me do a double take--It was so dirty that I thought it was engine oil at first.... mental note to change the tranny fluid (I JiffyLube "flushed" it about 50k miles ago when I first got the truck). I'll talk to a transmission shop about the fluid change this time.

Considering the muddy water that came out of the radiator, I'm looking forward to seeing what impact all this flush and cleaning will have....
 
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Ordered some Prestone 2-in-1 Coolant Flush/Degreaser and Rotella HD ELC coolant, then pulled the radiator today. The coolant coming out was icky, and after I got the rad out and tipped it over to get the last bit out of it, that stuff was positively muddy--and the system had just had the coolant changed (at least partially) when they replaced the water pump about 2 months ago. Went over the radiator and condenser cores with Simply Green, Scrubbing Bubbles, Gunk Foamy Engine Brite (all alternately flushed with garden hose pressure), then I pulled out the pressure washer when I saw a few gunky spots that the surfactants didn't seem to phase. Plenty of dirty water came out, I think, but the cores didnt appear all that dirty on the outside.

Oh, and the transmission fluid that dripped out of the transmission fluid cooler made me do a double take--It was so dirty that I thought it was engine oil at first.... mental note to change the tranny fluid (I JiffyLube "flushed" it about 50k miles ago when I first got the truck). I'll talk to a transmission shop about the fluid change this time.

Considering the muddy water that came out of the radiator, I'm looking forward to seeing what impact all this flush and cleaning will have....
The best cleaning solution you can use to help the radiator and block is to use some Cascade dishwashing powder: Engine coolant flush
 

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Discussion Starter #12 (Edited)
Interesting... might try that. Are there any tricks to reinstalling those tstats that are mounted sideways (grr!) ? Or just glue 'em in place with permatex? It's been awhile since I've done tstats, cuz the way they've got them mounted is, I think, stupid.
 

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Interesting... might try that. Are there any tricks to reinstalling those tstats that are mounted sideways (grr!) ? Or just glue 'em in place with permatex? It's been awhile since I've done tstats, cuz the way they've got them mounted is, I think, stupid.
The stats will have an arrow to tell you which end towards the radiator. but they actually point to the rad hose when installed correctly.
Use the orings provided
 

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I am not recommending this but I have done it on my parts truck and the results were insane. I removed the t stat and flushed with water. I added citric acid and topped it off with water. After a few seconds the once clear water looked like tomato soup. I ran that for a few minutes. Wash rinse repeat. The results were amazing.

For a citric acid source I used concrete floor prep. I have heard of others using muriatic acid for this. Which is just hydrochloric acid. I did not want to go that extreme and I had the floor prep left over from when I used muriatic acid to prep my garage floor for epoxy/polyurethane.
 
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1995 Chevrolet Silverado Z71 6.5 TD
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Ordered some Prestone 2-in-1 Coolant Flush/Degreaser and Rotella HD ELC coolant, then pulled the radiator today. The coolant coming out was icky, and after I got the rad out and tipped it over to get the last bit out of it, that stuff was positively muddy--and the system had just had the coolant changed (at least partially) when they replaced the water pump about 2 months ago. Went over the radiator and condenser cores with Simply Green, Scrubbing Bubbles, Gunk Foamy Engine Brite (all alternately flushed with garden hose pressure), then I pulled out the pressure washer when I saw a few gunky spots that the surfactants didn't seem to phase. Plenty of dirty water came out, I think, but the cores didnt appear all that dirty on the outside.

Oh, and the transmission fluid that dripped out of the transmission fluid cooler made me do a double take--It was so dirty that I thought it was engine oil at first.... mental note to change the tranny fluid (I JiffyLube "flushed" it about 50k miles ago when I first got the truck). I'll talk to a transmission shop about the fluid change this time.

Considering the muddy water that came out of the radiator, I'm looking forward to seeing what impact all this flush and cleaning will have....
I suggest filling your radiator with water on dump 1 cup of Cascade auto dish washer powder run it for 50 miles or more then flush it out. it cleans really well. My friend who has a radiator shop out here has been using this for 20 yrs with no issues.
 

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If you have the remote coolant tank like many 6.5s. You have to pre mix the cascade or what ever you use, with water and add it to the tank while filling the system. Pretty hard to dump in a cup of powder in a radiator that does not have a cap on top. Powder or liquid do not mix very well in the cooling system. If added to the remote tank after filling the radiator.
If the system is badly scaled up with mineral deposits. After the cascade treatment to clean. I flush again with white vinegar, about 2 quarts in water for a diesel.
Then run engine and drain. Do not leave in for more than 20 minutes. It cleans scale and corrosion out pretty good. Vinegar is a lot easier on aluminum than Muriatic or other acids. Lot cheaper too.
Also after flushing or opening up the cooling system and refilling with fresh coolant mix. You have to bleed the air out of the system. Using the bleeder valve on top of the thermostat/ crossover housing.
If not done you can get an air lock causing overheat problems.
 

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Discussion Starter #17
Thanks.

Over the course of this last weekend, I've had the radiator checked out (pressure & flow tested, and cleaned) and flushed various flushings of the coolant system.... started with Prestone 2-in-1, then rinse, then Blue Devil Radiator Cleaner & Degreaser (3-in-1), then rinse, rinse, backflush w/garden hose, then a Cascade flush (1/4 cup pre-dissolved), then backflush, now I've got Evap-o-Rust Thermacure in it overnight. I'm tempted to follow it with another cascade wash before diluting it all down with distilled water before adding the Rotella ELC, but will depend on what the flush water looks like.

The ugliest water that came out was after the Blue Devil (near black). I took pictures of them all side by side in the empty water jugs as a show & tell that I'll post up later when I'm done.
 

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Discussion Starter #18
So after the 5 day process using Prestone Cleaner & Flush, Cascade (1/4 cup and 1 cup dosages), Blue Devil Radiator Cleaner & Degreaser, and Evaporust Thermocure before ultimately charging the system with Rotella ELC concentrate and distilled water. I made a separate post comparing the flushing agents here: Coolant Flush Comparisons (w/pictures) ...

I also got the transmission serviced and boy did it need it! The fluid was black and the filter was apparently beyond saturated. Fortunately, there wasn't enough particulate in the pan or on the magnet to prompt the transmission guy to suggest the need for any more invasive repairs. It was shifting like a bucking mule for a few hours after that, but has since settled down..

Next up: get an Edge CTS3 system so I can watch the Boost, EGT, and Tranny temps. Got this scheduled for Friday so long as UPS does their part...
 

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Discussion Starter #19
Coolant temps are pretty stable at 181 F, +/-2 or 3 F, with a few observed "excursions" to 187 (that quickly return to 181) while daily driving and a few hard accelerations testing out what boost pressures and EGTs are possible--according to my Edge CTS monitor... which is fed by the OBD data.

Boost pressures have rarely gone above 4.5psi (highest I ever saw was low 5.xx) if I really put my foot in it, and most of the time are at 0.00 when cruising.

Haven't pulled anything yet..
 

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Your boost pressures are pretty low. If your edge thing is working right.
Just to compare. On my stock OBD2 PCM with the stock vacuum control., Cruise at 65 is usually around 3 psi . It will hit 10 under full throttle.
My tuned PCM will hit 14 PSI out of the hole. Usually runs 7-12 under load up hills. EGT usually under 1100. Using mechanical gauges.
 
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