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2003 Suburban 5.3l close to overheating when towing
Tahoe & SuburbanThe power, space, and brutal towing ability make the Tahoe and its longer sibling, the Suburban, arguably the best full size SUV's on the market today.
2003 Suburban 5.3l close to overheating when towing
I have a 2003 Z71 Suburban 5.3l that I use to tow approx 5500lbs. It is a tough tow in NorCal from the Bay Area to Lake Tahoe. 2-3 very tough grades on Hwy 80 going from sea level to 7200ft over Donner Summit in 80-90deg weather in summer. Had a 2002 suburban for 16 years and towing the same boat on the same highway barely ever got hot at all. Hardly remember the gauge going past ~1 o'clock ish on the worst grades. On the toughest grades both the trucks are in second gear going approx 50-55mph at ~4000-4300 RPM.
Now I have the 2003 with an E-Fan, towing Cam, and cold air intake mods along with a tune from BlackBearPerformance and the damn thing is almost hitting the red (~250deg?) when going up the same grades in the Sierra's. I was hoping with the all the modifications, especially the towing cam from Summit Racing, it would help considerably, but it the power seems to be about the same and I have the heating issue I never had with my 2002 Suburban. Any ideas on why the darn thing is so close to overheating? The e-fans are working fine.
Last edited by Levahj; August 2nd, 2020 at 12:36 PM.
IN ENGINES IN VEHICLES I ADD ONE LEVEL TEASPOON TO NEW OIL. In lawnmowers I run a ice cream sample taste spoon to one quart of oil. Same for my generators.
THE ABOVE CONTAINER SHOULD LAST YOU ABOUT 20 YEARS. ONLY IN ENGINES. DO NOT PUT IT IN TRANNY BECAUSE IF YOU DO IT WILL NOT SHIFT AS THE INTERIOR SURFACES ARE EXTREMELY SLICK.
iT IS ONLY ADDED AT OIL CHANGE AND MUST BE PRE MIXED IN LAST QUART AND SHAKEN VIGOROUSLY UNTIL DISSOLVED.
I add the last quart and crank and drive it immediately. DO NOT ADD DRY POWDER TO ENGINE ! ! ! ! !
I took a course at Rock Island Arsenal in 85 and we were educated in the benefits of moly in all applications. I have run it about 700,000 miiles in fives vehicles with no lubrication problem. When I got my 07 last year the engine had already been into and had problems and I had a new Jasper engine installed and at 1000 miles I added the moly powder. I run nothing but Mobil 1 in my engines.
WARNING YOU CAN'T USE JUST ANY MOLY POWDER IN ENGINE. IT HAS TO BE ULTRA FINE WHICH RUNS 1 TO 1.5 MICRONS. OIL FILTERS WILL PASS UP TO 5 MICRONS WITHOUT CLOGGING. Moly is sold in bigger micron sizes but I don't touch anything but the smallest available..
I run it till the indicator says oil life has expired which is about 10,000+ miles. Prior to Suburban I ran it 15,000 and changed oil and filters with ZERO problems.
It is my understanding that Jasper redesigned several things in 5.3 engines and so far I have about 16,000 on this engine and 95% of it is road miles.
I ran it in Durango for 266,000 and it purred right along till it dropped a valve seat which was a problem in those engines. The Jasper rebuilds on Dodge engines are tac welded in place. I would still be driving it had a young lady not crossed the center line and got me on left front and rolled me.last year.
Friction causes heat thus you should get cooler running engines if you keep the oil cooler.
Last edited by Humpy; August 8th, 2020 at 7:32 AM.
I would start by check thermostat for proper opening temp. Inspect the rad and condenser for blockages. Where i am, fluff from all the field crops can accumulate and block air flow thru the heat exchangers. if blocked...blow or wash them out. make sure all flan shrouds are in place.
you should also confirm good coolant flow thru the rad. if the tubes are blocked from corrosion the system will overheat.
Thanks for the reply's. Not too keen on putting anything but oil in the motor. Since I have had no heating issues at all towing the same boat for over 15 years with my first Suburban with an LS7 motor, I am certain I just have to find the issue with this one. I might just replace the radiator seeming it is so old and I just dont know what has gone through this thing since I just purchased it 6 months ago. I wish there was a way to test flow through a radiator but they are not too expensive so I will give that at try.
a good flowing rad will have at least 10 degree C drop from inlet hose to outlet hose.
drain the rad...with it empty...remember music class...blow thru the rad...if clogged it will have a resistance.
Last edited by tech2; August 9th, 2020 at 11:09 PM.
a good flowing rad will have at least 10 degree C drop from inlet hose to outlet hose.
drain the rad...with it empty...remember music class...blow thru the rad...if clogged it will have a resistance.
LOL. Never played an instrument .
Found a almost brand new radiator in a 2003 Suburban at a Pick N Pull junkyard today while taking out a BCM and PDM out of a 2005 Tahoe. I am currently replacing these modules so I can have TPMS sensors for tire air pressure monitoring on my '03. Kind of a cool upgrade but I digress....
The radiator looks brand spanking new out of that '03 at the junkyard. They must have just replaced it before the car was totaled and they want $50 so I am going to pull it out tomorrow and just replace mine for piece of mind. Especially since I just purchased this Suburban 6 months ago. Its in great shape but who knows why it is heating up when my other Suburban never did. Just checked compression and all cylinders are at 180 PSI +/- 5PSI so its not due to an worn out motor.
I am also going to the local LS motor expert here in the Bay Area to get a custom tune done by him on Tuesday. Who knows, maybe the mail in tune I got from BlackBear Performance has the timing too advanced in the 4000 RPM range where I am towing and is causing it to heat up. Because its a mail in tune I am starting to focus on that as possibly being the culprit as well. A true Dyno tune will be good for this thing to make sure all is well...
Last edited by Levahj; August 9th, 2020 at 11:30 PM.
inspect the old rad when you get it out and let us know what you find.
might as well replace the thermostat if the cooling system is drained. any overheating fault or vehicle that has run hot for any reason...I replace the thermostat for pom, especially if its old.
Last edited by tech2; August 10th, 2020 at 8:23 AM.
inspect the old rad when you get it out and let us know what you find.
might as well replace the thermostat if the cooling system is drained. any overheating fault or vehicle that has run hot for any reason...I replace the thermostat for pom, especially if its old.
Thats a good point. Will change out the thermostat as well. I did hook up my ODBII scanner yesterday. It drives fine and cool (~200deg) and that was in 90degree ambiant temperature. Its just when I put the load on it towing it spiked.
I am also going to the local LS motor expert here in the Bay Area to get a custom tune done by him on Tuesday. Who knows, maybe the mail in tune I got from BlackBear Performance has the timing too advanced in the 4000 RPM range where I am towing and is causing it to heat up. Because its a mail in tune I am starting to focus on that as possibly being the culprit as well. A true Dyno tune will be good for this thing to make sure all is well...
More like 4200-4300, in second gear, on the worst parts. Just depends if I want to go above 50ish MPH. Hwy 80 up and over 7200ft Donner Pass is no joke pulling 5000+. Makes that 5.3 LM7 feel like a 4 cylinder. The truck site below mentions WB, but if you are stopping in Tahoe and not going all the way into Reno, EB is a tougher climb.
Last edited by Levahj; August 10th, 2020 at 4:44 PM.
August 2nd, 2020, 12:21 PM
2003 Suburban 5.3l close to overheating when towing
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