Well I was seeing some issues with my last trips pulling my enclosed trailer with the temp creeping up at higher speeds when climbing up bigger hills out west and I have done a through cleaning of all the bugs up front from the tranny cooler, AC condenser, and such. I think my thermostat might be hanging up a bit since I see it cycling up at temp. Maybe about 5 degrees or so but it has never done that before. It was plenty easy enough to do a flush on the old radiators but these new systems do pose a bit more of a challenge. Also, has anyone see any history of the reservoir cap going bad? Maybe what I am seeing is related to the cap not holding 15 psi. Cap looks fine and is tight. My LMM has 220,000 miles on it with a 70 hp aftermarket tune on it. I don't push my truck hard when pulling a trailer, most of this trailer time is pulling an enclosed trailer with a bike in it or the bass boat. Dean
Coolant flush on the LMM
- Thread starter Dean E
- Start date
My 2008 hasn't had a cap problem. I did run a 20 lb cap for a few years, but I didn't need that much pressure so put the old 15 lb cap back in. They're pretty problem-free as long as you change the coolant every once in a while.
Yeah now that the mornings are getting a bit cooler I see my temps cycling once warm and it is getting a bit cooler than it used to. Pretty sure my thermostat is acting up. It is only about 3 years old. Gives me an excuse to get in there and do a full flush on the system. Thanks, Dean
What is in the res tank looks very clean. You thinking a possible head gasket issue? D
I'm thinking more along, is it dirty and in need of a flush and thus contributing to the engine heating or is it more likely to be something like fan clutch, thermostats, plugged radiator, etc
I replaced the coolant when I did the thermostat about 3 years ago. Even then the fluid had a good orange tint to it. This time I'll make sure to drain everything and look at removing the radiator to try to flush it out. Just can't see it being the fan since I don't see any issues in town or in heavy traffic. Like I stated earlier now that it is much cooler in the mornings when I get the truck out the temp oscillates from 210 to 195-200 range. Before it was rock solid at 210. Dean
Maybe temperature sensor?
The gauge is weighted or buffered so the fluctuations of the thermostat doesn't cause the needle to move around. So, inorder tor the needle to move as you describe, the temperature must be more then the range of a properly working thermostat/radiator setup
I'd try thermostats first
The gauge is weighted or buffered so the fluctuations of the thermostat doesn't cause the needle to move around. So, inorder tor the needle to move as you describe, the temperature must be more then the range of a properly working thermostat/radiator setup
I'd try thermostats first
He did mention cleaning them. But didn't really say if he removed the radiator to do it
Considering the trans cooler and intercooler completely covers the front of the radiator I'm not sure how blockage could be in front of it. Don't get me wrong, there were plenty of bugs in front of both the cooler and intercooler that have been cleaned off. Once again if there was that kind of blockage in the radiator or issues with the fan I would think this would make this more of an issue driving around town in stop and go traffic. I am going to do a full flush, pull the radiator to back flush it and replace the thermostat again. Dean
Well I was going to use the day tomorrow to replace the thermostats and flush the coolant system. I drove the truck to work today and as soon as I got home I popped the hood and looked at the surge tank coolant level and it was above the full mark. With the engine still hot I very carefully started to remove the pressure cap on the surge tank and there was no pressure. Kinda thinking my pressure cap died. There is no coolant leaks anywhere so I'm gonna go down to NAPA and pick up a new 15 psi cap and give that a try in the morning. Fingers crossed. Dean
Every time I have pulled a radiator out of a truck with a decent amount of miles on it, the radiator is packed full of dirt, grass, bugs, etc. You would be surprised how much junk can pass through the trans cooler, a/c condenser, and intercooler only to get stopped by the radiator.
Well I was able to get enough off to pull the radiator back a bit and yes it certainly is dirty as @JoshH said it would be. I'm trying to get the radiator out and I am down to these last fittings. I thought they were for the heater but following the lines it appears these are for the tranny cooler. Apparently the Allison uses both a cooler from the radiator and a external unit that is in front of the AC condenser. The C clip is out but the line is not budging. Any advice from those who have pulled these radiators out? The project is at a standstill till I can get these off. Thanks, Dean
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Twist, wiggle and pull. They can be stubborn when they've been in there for many years. When you install them, the clip goes in first, then push the fitting in. It will open or spread the clip and snap back when the pipe is all the way in
Also a good time to inspect and or replace the O rings for them
Also a good time to inspect and or replace the O rings for them
