duramax overheating

[jmilner]

I have a 2005 duramax and have had a little overheating problem . I think I read in the Trailer life magazine that there was a guy who put a different radiator hose on his truck and it took care of the problem. I believe he had a hose with a 90 degree elbow and put one with two 45's witch he said that it cut down the restriction with the 90 and the water flowed better . I have been looking for the info so I can show it to my mechanic and see what he has to say about it. If you know where I can find this info I would appreciate it .

[64thunderbolt]

larry barnhart wrote:
Combined weight of 22920 lbs. Highest engine temp has been 214 in heat and long climb but not for very long as the fan brought it down very quickly. Using a Scanguage.

chevman

Bring it to southern Az in summer & pull some 8/9 mile 7% and it will get hot. Mouthpiece has made the biggest improvement according to my friend. I don't know first hand cause my 7.3 powerstroke never gets hot.

[ktmrfs]

Jetstreamer wrote:
I have a 2004.5 Dmax... What exactly constitutes an overheat situation....going into a limp mode?

I guess it depends on the individuals definition. Some say it overheats when the temp gauge gets above about 220, others when it hits the red zone and limp mode.

On my 04.5, at 20K combined and long 6-8% grades in 90-100F, the temp gauge will climb to about 230, verified on my scanguage as well. Fan roars, but doesn't go higher. To me that is NOT overheating. But to some owners it is overheating.

If it was pushing near the red zone for me another story.

[Jetstreamer]

I have a 2004.5 Dmax... What exactly constitutes an overheat situation....going into a limp mode? Or is it just the red zone on the gauges?

[larry_barnhart]

Combined weight of 22920 lbs. Highest engine temp has been 214 in heat and long climb but not for very long as the fan brought it down very quickly. Using a Scanguage.

chevman

[rkortes]

I have the 05 as well and have experienced heating issues. I know that this sounds super obvious, but all of my heating issues are related to up hill towing on hot days with a load. My solution has been to plan ahead and try NOT to drive when this scenario is present. When crossing the major mountain passes I make it in the mornings and evenings with no problems in the summer time.

I tried a different intake, but didn't noticed any real improvement when heat, hill and load (towning) were present.... returned it for $$.

[ktmrfs]

edbehnke wrote:
just talked to my neighbor who has a '05 duramax.

1. change out air filter to a cold air intake (per his dealer)
2. he added a manaual electric fan in front of his cooler
3. keep in tow haul mode
4. he also said that if you keep the tow haul mode button in that it keeps you in 3rd gear. interesting, didn't know that.
5. he also added a mister
6. added a coolant into the radiator coolant
he said he solved his over heating.

tow haul mode does NOT, repeat Does NOT keep the vehicle in 3rd gear.
Tow haul raises shift points, and locks up the torque converter full time in 2nd-5th gear. And it enables the grade brake operation. Does NOT limit the gear selection. it will shift from 4-5 at about 55 mph.

If you hold in the tow haul mode button for several seconds the "overdrive" symbol on the dash will come on with a slash through it. It locks out 5th gear. You can do this independent of tow/haul mode. Believe me, you don't want to drive on the highway limited to 3rd gear.

[ktmrfs]

when you say "overheating" what temp does the truck get to? Does it just go up to 230F or so?? If so, don't worry.

Has it got hot enough to go into a safety low power mode??

Yes, LLY does get hot and in some cases will get hot enough to go into low power mode. Haven't had that happen to mine, but I only tow about 11K lbs. and about 19K overall.

However, the fan does come on. You know when!!. And coolant temps have gone up to about 230F at times, (measured with a scanguage not the dash temp guage) but never anywhere near the red zone, and when the fan comes on, it has always stopped the temp rise, and eventually brought it down.

I did install the newer mouthpiece. Yes, it helps, keeps temps from rising as fast on steep climbs, lets it drop quicker. Doesn't keep the fan from coming on.

and use tow haul mode. It locks up the torque converter full time in 2nd-5th gear, which will limit transmission fluid heat buildup and help the radiator temps.

[edbehnke]

just talked to my neighbor who has a '05 duramax.

1. change out air filter to a cold air intake (per his dealer)
2. he added a manaual electric fan in front of his cooler
3. keep in tow haul mode
4. he also said that if you keep the tow haul mode button in that it keeps you in 3rd gear. interesting, didn't know that.
5. he also added a mister
6. added a coolant into the radiator coolant
he said he solved his over heating.

[RCMAN46]

To the OP. Are you running any tuners? Go back to stock and install the aftermarket mouth piece and your heating problem may go away.

I am using the 05 Kodiak mouth piece and have not had an overheat pulling a 11,000 lb 5th wheel.

05 chevy crew cab with LLY Duramax.

[big_buford]

I added the mouthpiece and a secondary radiator. 219* is the hottest I've see it after mods.

[christopherglen]

Most of your problem is in the intake. Hot air off the radiator is getting sucked into the filter housing, up to the turbo, which has to work harder to compress the hot air, which makes a hotter air charge going into the intercooler, which ends up pre-heating the air going into the radiator more then normal, which makes the cooling fan run more. The hotter air going into the radiator means there is less of a temp difference between the air and coolant, so the efficiency of the radiator drops, meaning the coolant temps rise. You can get the LBZ parts from the air filter to the turbo elbow and eliminate thate issue - but it will not be CARB approved. You may want to look at an aftermarket cold air intake (I run a banks with scoop). After you have the intake side taken care of, if you still have overheating, look on diesel place for a overheating lly's...

[KD4UPL]

The LLY Duramax has a smaller fan than the previous LB7 or the '06 model LBZ. I don't know if there's much to change there. The other issue is the turbo mouthpiece is a poor design. The largely accepted solution is to install the mouthpiece from an '06 or early '07 with the LBZ engine. You could probably find one at a wrecking yard. Or, just buy the after market replacement.

[time2roll]

2004.5 and 2005 LLY seem to have this issue by poor design.

Duramax LLY overheat search results

Same talked about on DieselPlace forum

Sorry I have not read anything on related radiator hoses.
And I think the solution is more complex than just a hose.

[bob213]

Don't believe it has anything to do with the cooling system. 05's were prone to overheat due to "Thermal Feedback" caused by too tight of a turn in the turbo mouthpiece. Easy to replace. Parts available from somewhat controversial "KillerBee Performance" or AFE. I have the Killer Bee intake overhaul kit and although a little more expensive all the parts are there and you just bolt on.
Read up on thermal feedback on the LLY motor before you change any radiator parts.
overheaters