Lly runs hot

[Big Block 88]

Test driving a nice lly, has twins s475 over stock and built trans. Truck is a 05 cc dually. Its 99 degrees outside and as i was driving it around the temp gauge made it too 252* waaaay to hot. I do hear some ignition knock in it i think the tune is pretty aggressive.

I need it to run cooler to really get out and drive it. The fan is running and coming on pretty good maybe a bit late but not bad.

My question is with the owners permission i would like to load a different tune and see what happens. With the twins can i get away running a smaller tune okay? I sure dont want to hurt it as it is a really nicd truck and the owner is a hell of a guy and i want to work out a deal but if its runnin that hot empty there is an issue and towing wont work

 

[dirty_max]

no dsp5? and are the heads studded? I know the lly had head gasket issues.

 

[Big Block 88]

No studs, i have a set and would do it relatively soon. No dsp i would be getting with rob shortly after purchaseing truck should it all work out. Guy selling truck is a member here

 

[THEFERMANATOR]

Sounds like it needs the heads to come off now. Twins without head studs is begging for trouble. I know I always read and was told 500HP is about the limit of stock bolts. Twins and aggressive tuning will push the cylinder pressures even higher sooner. Check the radiator hose to see if it is hard before you start it cold. Look to see if it is pushing coolant out the tank.

 

[Big Block 88]

I will check the truck hasnt been twined long, and i do agree it needs studs but i would get around to that in time.

 

[plowboy_lbz]

Sounds like it needs the heads to come off now. Twins without head studs is begging for trouble. I know I always read and was told 500HP is about the limit of stock bolts. Twins and aggressive tuning will push the cylinder pressures even higher sooner. Check the radiator hose to see if it is hard before you start it cold. Look to see if it is pushing coolant out the tank.

Head gaskets fail due to design not boost/cylinder pressure unless your pushing high number (70psi+). Lbz and lmm use the updated (riveted gaskets) and failures are far and few in between. It's a good rule that you'll either crack a piston or bend a rod before blowing a hg. My truck has been over 500 hp for 50,000 miles and over 600 for the last 15,000 pushing 50 psi of boost without a problem.

Llys are prone to over heated but that sounds a bit excessive. Check the cooling stack over good, make sure anti freeze is good and a new set of thermostats will rull out a defect in the cooling system. The tune might be hot but I would lean towards a mechanical issue as to why its getting so hot. At that temp you wouldn't want to know the oil temp!!

 

[IOWA LLY]

Sounds like it needs the heads to come off now. Twins without head studs is begging for trouble. I know I always read and was told 500HP is about the limit of stock bolts. Twins and aggressive tuning will push the cylinder pressures even higher sooner. Check the radiator hose to see if it is hard before you start it cold. Look to see if it is pushing coolant out the tank.

Factory head bolts hold better on a twin turbo LLY then a single charger "max effort" tune.....

Heat is the enemy.

 

[Big Block 88]

Awsome thanks guys. Im gonna try a clean 125 i have saved. It may not lite the big charger but it will show if the tune is too hot. The big turbo is a bit close to the overflow tank which could cause excessive heat the owner suggested maybe a sock

 

[Big Block 88]

Does anyone have a simple small twin tune you would recomend? I would pay for a decent tune to hold me over

 

[Chevy1925]

Put the stock one in with the maf rescaled and your good. Either way, the twins should not be making it run hot, it's got other issues

 

[Big Block 88]

I made a thread with tune hot running tune attached. I did bleed the system may have helped

 

[Big Block 88]

Egt does climb quickly, half throttle i see 1450 and she blows some soot with just moderate tuning. My max effort tune in my lbz didnt blow that much soot wide open

 

[SickLL7Crenshaw]

My truck has had twins on it for almost 3 years. LLY, stock head bolts, 127k miles and has made 40+ passes under 12.5. Tow 15k regularly also. So I don't see how 500hp+ is asking for trouble on stock HGs But to the OP just like James mentioned you have other problems that's causing your heating. Who tunes the truck? Sounds like the cooling stack may be dirty.

 

[Big Block 88]

its been tuned by a guy named tim, he used to be at st. joe. I have never used him and no very little about him.

You all don't think ht egt I causing the issue? The overflow tank is near where the 475 is, I was thinking egt is heating it up from heat soak? Cooling stack look clean and it has a spearco cooler. But I will pull top cover..

 

[Big Block 88]

tune im running

 

[paint94979]

The age old debate on head gaskets... 01's seemed to have the largest issue with popping gaskets not the LLY's.

The turbo could cause the coolant temp to rise but 40-50*? I dunno about that. I would hop in the truck after sitting over night so its good and cold then drive it really easy like take it on a 50-55mph road and just drive until its up to operating temp and if it continues to just climb and climb then i would guess its got some issues going on. if i stays at normal operating temps then once you hammer on it the temps go up overflow position could come into play.

 

[yellowchevy]

I've never ran his tunes but alot of people around kansas city area seam to like his tunes. You'll see pickups that have stickers in the window saying "Tuned by Timmy" or something like that.

I'm talked to more than one person that has ran his tunes or taken an engine apart that had his tunes and it wasn't good.

I hope you get all these problems figured out Jordan. It sounds like a nice pickup.

Yellowchevy

 

[Big Block 88]

is the height of the overflow tank as important to these engines as they are to gassers? I am assuming that the overflow needs to be at the highest point of the coolng system due to the cap being there? I have cracked the bleed screw on the thermostat housing and did get some air out at idle. Should I bring revs up and make it spin the water pump up with screw out?

Paint the truck ran decently cool in the 80* morning air with the cruise set at 55. Didn't get hot till I needed to merge on the hghway and then it wouldn't cool back off, clmbed to 230-240 and stayed till it sit for a bit.

 

[IOWA LLY]

Sounds like the truck has blown head gaskets.

The turbo being close to the coolant tank is not causing the overheat issue. There is very little fluid exchange between the tank and engine once the system is bled properly.

To test for blown head gaskets, go drive the truck normally until up to operating temp. Then slowly remove the coolant cap. If air bubbles rush up through the tank the head gaskets are leaking.

The cooling stack being dirty will cause overheat issues but usually only while towing heavy. If its overheating while driving normally something is seriously wrong.

 

[IOWA LLY]

The age old debate on head gaskets... 01's seemed to have the largest issue with popping gaskets not the LLY's.

The turbo could cause the coolant temp to rise but 40-50*? I dunno about that. I would hop in the truck after sitting over night so its good and cold then drive it really easy like take it on a 50-55mph road and just drive until its up to operating temp and if it continues to just climb and climb then i would guess its got some issues going on. if i stays at normal operating temps then once you hammer on it the temps go up overflow position could come into play.

LLY's are very notorious for blowing head gaskets. And early LBZ's.

Not from increased power or big boost numbers. Simply from heat cycles. Proper warm up so the thermostats are open before you romp on it is critical.

I've repaired LLY trucks with as little as 58,000 miles on them with blown head gaskets. Bought new and still bone stock. It was a service truck, so lots of quick short trips. (Lots of heat cycles)