As some of you LB7 folks may know, some of us with LLY's are having overheating issues.

One of the possible contributing factors (though not the sole issue) has to due with the way hot air from the fan, is litererally directed at the passenger side fender, and more importantly the airbox intake.

Would a couple of you guys mind popping your hood after a decent run to see if in fact your trucks also have a large volume of air being dumped to the airbox side, and little to no air in the same area on the drivers side?

I'm just trying to determine if anything has changed under the hood that would direct airflow differently between the two engines.

Thanks for your help!

What do you want us to do after popping the hood?

Could take temp readings of both sides of the engine complartment?

Could just feel for air flow, but wonder whether that would be indicative of what the airflow is like while underway?

Doubt I could get it hot enough to have the fan kicked when I pull over.

I'll see what I can do tomorrow, I have to run out to my new job to see what the commute time will be. (Since I don't start for another month) On the way back I'll try and run it hard to see what I can get.

Have a good one!!

Dan

Thanks guys. It doesn't take much, even the more or less free wheeling fan moves some air.

I'm just looking for how much air you feel on each side. On the LLY, the driver side, where the battery is, there is pretty much zero air. On the airbox side, it feels like your standing in front of a giant hairdryer.

I'm just looking for how much air you feel on each side. On the LLY, the driver side, where the battery is, there is pretty much zero air. On the airbox side, it feels like your standing in front of a giant hairdryer.[/quote]

This is very similiar to my LB7 using the back of my hand to feel for heat/air flow. It is very quiet on the drivers side in a relatively large area around the battery. There is hot air pulsing over the top of the airbox and on the front side of the air box. The fan is not centered on the truck and is closer to the airbox than the drivers side battery. Tonight I will have my son's temp gun and I can measure the tempreature of plastics on each side to see if the there is a significant difference. I will look for areas that should be heated primarily by air moving in the engine compartment.

Of course the real experiment you want to run is to have an LB7 and LLY side by side down the road and measure the temp of the air entering the air box on each truck.

why dont you all try a cawl indected hood to get better air flow into the engine bay? just an idea

Not trying to be a smartass, but do you really think that your engine is cooled by cold air blowing into the intake?

What changes were made to the cooling system of the LLY relative to the LB7?

Not trying to be a smartass, but do you really think that your engine is cooled by cold air blowing into the intake?

What changes were made to the cooling system of the LLY relative to the LB7?

Well if the engine isn't cooled by intake air, then what does keep it cool?
That big black fin'd thing up front? :D

Seriously, LLY's (looks like a high percentage, when pulling loads greater than 10k) are experiencing overheating issues. One of the factors that we're after, that is a possible contributor, is the ingestion of super heated air, when the fan engages. The airbox is soaked in hot air, and intake air temps soar.

We have not been able to conclude why there is such a difference between the LB7's and LLY's other than EPA requirements, and turbo design. Most everything else seems to be the same. If you're real interested, there is a 50 page thread going on in the LLY engine forum. Get some popcorn and a case or two of beer. It is a long read, going for almost a year.

Thanks for everyone's help.

Not trying to be a smartass, but do you really think that your engine is cooled by cold air blowing into the intake?

What changes were made to the cooling system of the LLY relative to the LB7?



Work is being done to find root cause(s) for the overheating problem, and work is being done to find solutions. Sometimes you can't tell the difference between the two efforts.

You can sometimes find a solution without ever knowing root cause and the solution doesn't necessarily have to be connected to the root cause.

Usually when you are comparing LB7 and LLY you are looking for root cause. Those LLY guys are looking at all the ways that heat is added to and subtracted from the system It might be something small that triggers the overheating.

hmmmm, wonder if its the different heads and resulting changes in the water jackets..

hmmmmm iM THINKING i SHOULD SELL THIS THING AND GET AN LB7!!!

took a run to the fairgounds. outside air temp about 97. The air box (top, sides and inside bottom) along with other things around air box like foil covering opening in fender were all 150-155 degress which was about the temp of the air coming off the fan. The drivers side battery (top, front, and back) windshield washer cap, and inside fender were about 125-130 degrees. The part of the battery near the upper radiator hose was about 145 degrees.

I think the air box is primarily injesting air coming off the fan. Maybe the turbo can more than make up for that, but seems like a bad setup for summer.

On my way home outside air temps had dropped to 83. Above temps dropped about 20 degrees, but there was still the clear and definite 25 degree difference between the two areas under the hood.

hmmmm, wonder if its the different heads and resulting changes in the water jackets..

Hope not, cause that could be hard to overcome. Maybe higher volume water pump? better oil cooler?

Oilbrnr, I haven't forgot about you, I just keep forgetting to see whats up after I make some highway runs. I will do it tomorrow. Every time I come on here I see this and go dammit.

Have a good one!!

Dan

OK, I didn't want to shove my hand way down, I have the dual alts, but from what I could tell, there is more air moving to the airbox (passenger) side than the battery (driver) side.

Hopefully this helps some!!

Have a good one!!

Dan