misterp Posted August 16, 2011 Report Share Posted August 16, 2011 (edited) The main thing I got out of this thread is: UPGRADE THE RADIATOR ITSELF Radiator upgrades are standard fare for the Lightning guys, with a supercharger and heavy driving a better radiator is commonly needed on those trucks - as I mentioned we have a fabrication acquaintance who makes a good living TIG welding these (Hotrods By George). His comment was, he's surprised the GM trucks don't have as many radiator-size related issues as the Fords, and I tend to agree - I think we lucked-out with the 34" wide core, but it's a poor-performing 34" core.... Another issue causing inadequate cooling at idle - and credit for discoveringh this goes to finallyss, he figured out that the factory water pump circulates coolant just fine at cruising speeds (1800+ RPM) but at idle it moves almost no volume of water at all, so the engine coolant just sits in the block and continue cooking; by taking your right toe and increasing the idle RPM to about 1200 for a couple minutes you will see the engine coolant temperature drop, because the water pump is then able to actually circulate the hot coolant out of the motor to/from the radiator. I suspect this reason is why some guys report better engine idle cooling with aftermarket electric water pumps (vs. the factory pump). Another factor - oil you use. I switched to Mobil1 5W-40 "Turbo Diesel Formula" (WTF??) because with the blower I wanted an oil that would hold-up to WOT bottom-end heat better, but an unexpected effect was that immediately my running ECT dropped 8-10 degrees, the change was drastic. I don't know how, or why, or wtf... but the change has been unmistakable and significant; since then I have done another oil change and confirmed that was the source of the lower ECT. Go Figure. So guys running exotic oils might see a difference in operating temperatures, before seeing this with my own eyes in May I would have called BS but there you go I learned myself sumthin' new. Mr. P. Edited August 16, 2011 by Mr. P. (see edit history) Quote Link to comment Share on other sites More sharing options...
matt 2k12 Posted August 17, 2011 Report Share Posted August 17, 2011 Radiator upgrades are standard fare for the Lightning guys, with a supercharger and heavy driving a better radiator is commonly needed on those trucks - as I mentioned we have a fabrication acquaintance who makes a good living TIG welding these (Hotrods By George). His comment was, he's surprised the GM trucks don't have as many radiator-size related issues as the Fords, and I tend to agree - I think we lucked-out with the 34" wide core, but it's a poor-performing 34" core.... Another issue causing inadequate cooling at idle - and credit for discoveringh this goes to finallyss, he figured out that the factory water pump circulates coolant just fine at cruising speeds (1800+ RPM) but at idle it moves almost no volume of water at all, so the engine coolant just sits in the block and continue cooking; by taking your right toe and increasing the idle RPM to about 1200 for a couple minutes you will see the engine coolant temperature drop, because the water pump is then able to actually circulate the hot coolant out of the motor to/from the radiator. I suspect this reason is why some guys report better engine idle cooling with aftermarket electric water pumps (vs. the factory pump). Another factor - oil you use. I switched to Mobil1 5W-40 "Turbo Diesel Formula" (WTF??) because with the blower I wanted an oil that would hold-up to WOT bottom-end heat better, but an unexpected effect was that immediately my running ECT dropped 8-10 degrees, the change was drastic. I don't know how, or why, or wtf... but the change has been unmistakable and significant; since then I have done another oil change and confirmed that was the source of the lower ECT. Go Figure. So guys running exotic oils might see a difference in operating temperatures, before seeing this with my own eyes in May I would have called BS but there you go I learned myself sumthin' new. Mr. P. Wow that is funny. Believe it or not, my plastic radiator leaks like a sieve so I top it off about once a week. Shocking, I know. When it starts getting low the temps start to rise but ONLY at idle, and ONLY when my cam has calmed down after a long drive. Funny thing is that I noticed the little gas pedal tap you are talking about will cool it down dramatically in these instances, without the car even moving. So that is the weak pump... I see now. My cooling upgrade list is starting to materialize. Mr P, can you recommend a certain brand of all aluminum racing radiator? To be honest the Flex-a-Lite units look just fine. (http://www.flex-a-lite.com/auto/html/aluminum_radiator.html). Has anyone used the Flex-a-Lite radiators on these trucks?? The Flex-a Lite 58000 is looking pretty good about now. Quote Link to comment Share on other sites More sharing options...
misterp Posted August 17, 2011 Report Share Posted August 17, 2011 Wow that is funny. Believe it or not, my plastic radiator leaks like a sieve so I top it off about once a week. Shocking, I know. When it starts getting low the temps start to rise but ONLY at idle, and ONLY when my cam has calmed down after a long drive. Funny thing is that I noticed the little gas pedal tap you are talking about will cool it down dramatically in these instances, without the car even moving. So that is the weak pump... I see now. My cooling upgrade list is starting to materialize. Mr P, can you recommend a certain brand of all aluminum racing radiator? To be honest the Flex-a-Lite units look just fine. (http://www.flex-a-lite.com/auto/html/aluminum_radiator.html). Has anyone used the Flex-a-Lite radiators on these trucks?? The Flex-a Lite 58000 is looking pretty good about now. It's not that the factory water pump is "weak", it's that its been designed for the lowest possible drag (to meet Congressional CAFE targets) - so the impeller/vane design inside the pump is substandard at idle. Then again, the original LS-engine designers intended the motor to operate at 210+ so by their judgement, there's nothing at all wrong with the water pump... I cannot recommend the FAL radiator simply because I haven't seen one first-hand. I can tell you I have seen the FAL fan kit, it's lower than OEM quality. And I have seen the FAL fan control box/harness, it had caught fire. Soooooo I am skeptical of the FAL company's products. The thing that I look for in a good radiator is the fin design (how are the fins attached/soldered to the tubes?? hint, most aren't!), core design, and how the tanks are mechanically attached to the core itself (paste soldered? TIG? glued? etc). A quality radiator has to be built, at a factory or at your local radiator shop, but either way somebody will have to sit at a bench and weld/solder it and test it etc so whether you choose to fabricate locally or buy aftermarket the price will be just as expensive IMO. Let me explain what a GOOD radiator & cooling system behaves like: I had a custom radiator made for my 1970 Ram Air Firebird, it was a 36" 4-row copper Modine core (heavier as hell lol!) and the motor was a very warmed-over 441 cu-in Pontiac with a 180* thermostat. When driving that car the temp needle would rise to just over 180, then suddenly plummet to about 165 (because the thermostat allowed the motor to take a fresh gulp of cold water from the radiator) and over the next couple moments warm to 180 again, then suddenly the ECT would drop 10-15 degrees, repeat repeat repeat... In other words, the radiator had waaay more thermal capacity than the motor required during normal cruise. Of course during "extended spirited driving" lol the ECT would stay pretty consistant at 180-ish because the radiator was sized correctly for the heat (aka horsepower) being generated at heavy load. The hot trick these days is an aluminum core, with 2 "wide" rows of tubes - that design sheds more heat to the atmosphere better than a 4-row high-efficiency copper core of prior generations and is a ton lighter. Then you've got the water pump to deal with... but with a radiator having that much "thermal capacity" the stock water pump may be just fine at idle with such an improved radiator, I dunno. Someday I will get around to finding out, for now in my own truck it's great in the winter time (radiator has plenty of capacity then, I see the ECT 'cycle' up & down) it's just hard-driving in the 100* summer heat that the ECT will run away to 205+. I don't mind the heat, it's the "run away" issue I'm wanting to improve, I might throw a little Cool Ice (water wetter) in the system when I next service the cooling system, that might help a squeak. Mr. P. Quote Link to comment Share on other sites More sharing options...
Cramer Posted August 17, 2011 Report Share Posted August 17, 2011 Mr.P. Try the coolant additive sometime. I put Royal Purple's Purple Ice in about a month ago and can tell a big difference in the amount of time it takes to generate heat, and to shed the heat. It has only reduced the ECT by5* going off my previous log to my last log, but that was in different weather. The main difference is that the second the fans kick on, or the rad gets airflow, the ECT drops substantially. Quote Link to comment Share on other sites More sharing options...
misterp Posted August 17, 2011 Report Share Posted August 17, 2011 Cool, will definitely try Purple Ice - thanks for the feedback! Quote Link to comment Share on other sites More sharing options...
matt 2k12 Posted August 19, 2011 Report Share Posted August 19, 2011 I sure wish there was a name brand racing radiator for this truck. It is hard for me to fathom that on a SS vehicle there is no market for aftermarket purpose built radiators... Quote Link to comment Share on other sites More sharing options...
dgrov3r Posted August 31, 2011 Author Report Share Posted August 31, 2011 So i replaced the fan clutch assembly as it was the cheapest route at this point. About a week or two later in no more than 80* weather its tipping 210 again, im going to get my coolant flushed and cleaned out to make sure theres nothing in it but do you guys have any idea the next step and which direction i should look it. BTW the most recent time it did it today the truck had been sitting for about 4 or 5 hours and i took a 5 minute ride and it was tipping 210 Quote Link to comment Share on other sites More sharing options...
chpspecial Posted August 31, 2011 Report Share Posted August 31, 2011 210 is the operating range.... Quote Link to comment Share on other sites More sharing options...
T-Bag Posted August 31, 2011 Report Share Posted August 31, 2011 (edited) I always ran about 205-210* until I put in a 160* t-stat. Now it runs at 180* and fans kick on nicely just where Rey set em if it goes up at all then drops right back down to 180* I say 160* and be done. Edited August 31, 2011 by Bad Ass Silvy (see edit history) Quote Link to comment Share on other sites More sharing options...
dgrov3r Posted August 31, 2011 Author Report Share Posted August 31, 2011 Today it was 3/4 and its sparatic as it always has been. My mechanic beleives its the thermostat so im getting a 160* tomorrow is the truck going to run alright while i wait for a tune Quote Link to comment Share on other sites More sharing options...
T-Bag Posted August 31, 2011 Report Share Posted August 31, 2011 (edited) Yeah you'll be fine until re-tune. MPG might slightly decrease until re-tune. If you change it yourself follow Mr. P's How-To and make sure you purge your system. Purged mine twice. http://www.silveradoss.com/forums/topic/13760-how-to-replacing-your-thermostat/ Edited August 31, 2011 by Bad Ass Silvy (see edit history) Quote Link to comment Share on other sites More sharing options...
Cramer Posted August 31, 2011 Report Share Posted August 31, 2011 While you have the coolant out of the block, pull the coolant temp sensor out and clean it up too. It's located on the drivers side of the block just below the hear above the #1 sxhaust primary. Also check the connection and connector for corrosion. That might be some of the reason why you are having erratic swings at the gauge. Also the gauge isn't usually correct. Mine is almost 10* higher on the dash than my scans. Quote Link to comment Share on other sites More sharing options...
dgrov3r Posted September 1, 2011 Author Report Share Posted September 1, 2011 Wow thanks for all the great info, it was at the mechanics and im positive he doesnt do half of this stuff but the 160 he got didnt fit so he put in a regular replacement to get me up and running. I will be doing the 160 myself now with all this info present. My other question is im doing a mail order tune so i plan on doing both at once my question is about the ecu installation, it cant be as easy as swapping them out? are there security problems or anythihng Quote Link to comment Share on other sites More sharing options...
dgrov3r Posted September 1, 2011 Author Report Share Posted September 1, 2011 thats a sweet -how to- thread btw Quote Link to comment Share on other sites More sharing options...
dgrov3r Posted September 1, 2011 Author Report Share Posted September 1, 2011 also he put in a 190 or 195 i forget but its still running 210 hopefully now it wont go above that atleast but its not cooler at all. It seems to get to 210 within 15 minutes in 70* weather. Is this normal truck has 124k and this is after the new tstat and a coolant flush Quote Link to comment Share on other sites More sharing options...
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