# Duramax No Heat



## LapeerLandscape (Dec 29, 2012)

2004 gmc 4500 6.6 duramax with no heat. I just run it for about 45 minutes and the temp never moved until I got within 1/2 mile back to my yard and the temp gauge goes all the way to the red and then back to just below normal and no heat out of the heater until that point. My first thought is thermostat but it has 2 and whats the chance of them both going bad. This has been going on for a little while and it has been going through anti freeze and doesnt seem to be leaking it.


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## Ajlawn1 (Aug 20, 2009)

Air pocket...? I think there is a bleeder if I remember...


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## gcbailey (Jan 26, 2014)

check your coolant level.... We've got an '04 3500 and if the coolant gets the least bit low, no heat unless it's on full blast.


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## LapeerLandscape (Dec 29, 2012)

Ajlawn1 said:


> Air pocket...? I think there is a bleeder if I remember...


Thats what it acts like but wouldnt the engine/temp gauge still get hot.


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## LapeerLandscape (Dec 29, 2012)

gcbailey said:


> check your coolant level.... We've got an '04 3500 and if the coolant gets the least bit low, no heat unless it's on full blast.


Topped it off this morning to salt and still put 3/4 gallon in it tonight.


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## 1olddogtwo (Aug 6, 2007)

Head gasket(s).


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## LapeerLandscape (Dec 29, 2012)

1olddogtwo said:


> Head gasket(s).


I think thats the anti freeze issue but would that cause no heat and nothing to register on the temp gauge?


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## 1olddogtwo (Aug 6, 2007)

https://www.littlepowershop.com/how...duramax-head-gaskets-and-what-to-do-about-it/

I don't know the 6.6 but head gaskets come to mind.


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## Randall Ave (Oct 29, 2014)

Replace the therms first, It has two, but they are NOT the same, make sure you put them in the correct holes. I have remove duel Cat therms and seen both of them broken.


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## Hydromaster (Jun 11, 2018)

The coolant is either going out the talepipe and/or in the oil, 

Q If you removed your oil fill cap What does it look like on the underside


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## Randall Ave (Oct 29, 2014)

If there is no fluid against the sensor, sometime they will not read correctly.


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## LapeerLandscape (Dec 29, 2012)

1olddogtwo said:


> https://www.littlepowershop.com/how...duramax-head-gaskets-and-what-to-do-about-it/
> 
> I don't know the 6.6 but head gaskets come to mind.


Thanks Pat that was helpful.


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## LapeerLandscape (Dec 29, 2012)

Hydromaster said:


> The coolant is either going out the talepipe and/or in the oil,
> 
> Q If you removed your oil fill cap What does it look like on the underside


Its not getting in the oil, more than likely head gaskets.


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## 1olddogtwo (Aug 6, 2007)

I hope that isn't the case, t-stat cheaper


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## Ajlawn1 (Aug 20, 2009)

I put one of these in an old loader before might be an option for ya....


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## LapeerLandscape (Dec 29, 2012)

1olddogtwo said:


> I hope that isn't the case, t-stat cheaper


With the anti freeze loss I'm pretty sure its the gaskets after reading the article I just wasnt sure how the no reading on the temp gauge tied into it. I'm not big on snake oil type product but we tried some K-seal as I had heard good things about it but it didnt seem to work.


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## LapeerLandscape (Dec 29, 2012)

Ajlawn1 said:


> I put one of these in an old loader before might be an option for ya....
> 
> View attachment 188968


Its are primary salt truck that my son usually runs, he can suffer. We need to get it fixed but it will have to wait till I fix the other sreader that I broke Saturday. Broke the output shaft from the gear box, maybe I will take a ic of it. Good thing is we have a spare.


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## Brndnstffrd (Mar 8, 2013)

Ajlawn1 said:


> I put one of these in an old loader before might be an option for ya....
> 
> View attachment 188968


The 12v harbor freight heater/defrosters are $8 with a coupon


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## Randall Ave (Oct 29, 2014)

LapeerLandscape said:


> With the anti freeze loss I'm pretty sure its the gaskets after reading the article I just wasnt sure how the no reading on the temp gauge tied into it. I'm not big on snake oil type product but we tried some K-seal as I had heard good things about it but it didnt seem to work.


Do you have a cooling system pressure tester? If yes, fill with coolant, put on the tester and run the engine at high RPM, see what you get. If it jumps up high right away, points to a head gasket.


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## LapeerLandscape (Dec 29, 2012)

Randall Ave said:


> Do you have a cooling system pressure tester? If yes, fill with coolant, put on the tester and run the engine at high RPM, see what you get. If it jumps up high right away, points to a head gasket.


Yes I have one, will have to get the adapter for the plastic reservoir. Thanks


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## Mark Oomkes (Dec 10, 2000)

LapeerLandscape said:


> Its are primary salt truck that my son usually runs, he can suffer. We need to get it fixed but it will have to wait till I fix the other sreader that I broke Saturday. Broke the output shaft from the gear box, maybe I will take a ic of it. Good thing is we have a spare.


Defcon loves to run without heat.


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## LapeerLandscape (Dec 29, 2012)

Mark Oomkes said:


> Defcon loves to run without heat.


I found out this afternoon that I dont.


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## Speedplow (Dec 5, 2016)

If your nose is good, take a whiff inside the coolant reservoir when the truck is cooled down enough and see if you smell Diesel. If so then you have combustion gases leaking into the coolant. This can be caused from several things, head gasket, cracked head, or injector sleeves(cups).

The earlier Duramax motor had injector cups that could leak coolant into the combustion chamber. This is an easier repair if that is the case.


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## gcbailey (Jan 26, 2014)

which engine is in your '04? LB7 or LLY? Luckily we have a end year '04 with the LLY. The LB7 is the 6.0/6.4 powerstroke of the Dmax world.


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## LapeerLandscape (Dec 29, 2012)

gcbailey said:


> which engine is in your '04? LB7 or LLY? Luckily we have a end year '04 with the LLY. The LB7 is the 6.0/6.4 powerstroke of the Dmax world.


How do I tell


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## gcbailey (Jan 26, 2014)

http://www.duramaxhub.com/duramax-vin.html


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## LapeerLandscape (Dec 29, 2012)

gcbailey said:


> http://www.duramaxhub.com/duramax-vin.html


LB7


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## Mark Oomkes (Dec 10, 2000)

LapeerLandscape said:


> LB7


Lucky you...


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## Philbilly2 (Aug 25, 2007)

gcbailey said:


> The LB7 is the 6.0/6.4 powerstroke of the Dmax world.


Why is this?


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## gcbailey (Jan 26, 2014)

Philbilly2 said:


> Why is this?


There's plenty on the interwebs to read about the 1st gen Dmax, just google "LB7 problems".... Most of the issues are injector related and overheating. Chevy was in a hurry to get something out after years of lack luster diesel performance and the future changes that were being shoved down our throats from the EPA.

I'm a chevy guy and have 2 Dmax's and a 6.ohhhhh powerstroke. The Dmaxs are just easier to work on vs. taking off the cab for major repairs like you gotta do with the Ford.


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## Philbilly2 (Aug 25, 2007)

gcbailey said:


> There's plenty on the interwebs to read about the 1st gen Dmax, just google "LB7 problems".... Most of the issues are injector related and overheating. Chevy was in a hurry to get something out after years of lack luster diesel performance and the future changes that were being shoved down our throats from the EPA.
> 
> I'm a chevy guy and have 2 Dmax's and a 6.ohhhhh powerstroke. The Dmaxs are just easier to work on vs. taking off the cab for major repairs like you gotta do with the Ford.


I have also owned dozens of duramaxs and one 6.0 powerjoke.

I would hardly compare an LB7 to a 6.ohno - I have not yet had to replace a whole motor in an LB7...


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## gcbailey (Jan 26, 2014)

This is a recent (last week) LB7 that started crapping out, diesel and oil don't mix.

Both of my Dmax's are the LLY, late '04 and '05 and outside of a set of injectors on each, 0 issues, just routine PM.

I will say the 6.0 has got a bad rap due to the head gasket issue but the '06 and '07s are MUCH improved from the 2003.5 through 2005 models. Mine is an '06 with 180k and the only things that's been done to it is EGR delete (which all diesels need!), and the upgraded factory oil cooler. I can't complain about it, honestly. The worst thing Ford ever did was make it almost impossible for a guy to work on the engine without having to pull the cab. I don't know too many shade tree mechanics that have a lift in their garage.


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## Philbilly2 (Aug 25, 2007)

I have personally done tons of sets of LB7 injectors. Done quite a few handful of LLY's also. Yet to do a set of LBZ on as of yet. But as the miles climb on them only time will tell. If a set of injectors is the worst that you have to do, I would say that they are pretty good in my book. I agree that the LB7s are harder to get to, but after enough times, 2 guys can un-stick and re-stick by supper

Google "reluctor wheel" for your LLY's. Done quite a handful of them when your just driving along and your truck just shuts off cause 3 little screws back out... :angry:

My 6.0 was a 05. It was a pile of shot from day one of ownership. Did EGR, oil coolers, headgaskets and studs, downpipes, hurts my head thinking about the amount of down time with that turd. Finally just had to put a new motor in it, ran it for a few thousand more and let some other sucker deal with it.

You think boat owners are happy when they unload a boat... not near as happy as a 6.0 owner.


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## leolkfrm (Mar 11, 2010)

gm ran a 200,000 mile replacement on injectors and glow plugs.....


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## gcbailey (Jan 26, 2014)

I was of the raising "if you have to put it on a trailer and haul it to enjoy it, you probably won't"..... So I've never owned a boat/jet ski, etc.... 

Worst thing I've had happen in "diesel land" has been limp mode on an Allison tranny.... Which I've pulled this thread waaaaay off topic, so I digress.


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## leolkfrm (Mar 11, 2010)

get him one of those ice fishing propane heaters and mount it securely


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## LapeerLandscape (Dec 29, 2012)

leolkfrm said:


> get him one of those ice fishing propane heaters and mount it securely


He put one in the truck for this mornings run and he said it was a life saver.


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## Defcon 5 (Mar 20, 2014)

leolkfrm said:


> get him one of those ice fishing propane heaters and mount it securely


Been there done that many times....They will roast you out and the fumes make you not remember the night...So I guess that's a plus


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## Philbilly2 (Aug 25, 2007)

gcbailey said:


> Worst thing I've had happen in "diesel land" has been limp mode on an Allison tranny.... Which I've pulled this thread waaaaay off topic, so I digress.


NSBU Switch?


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## Philbilly2 (Aug 25, 2007)

gcbailey said:


> Worst thing I've had happen in "diesel land" has been limp mode on an Allison tranny.... Which I've pulled this thread waaaaay off topic, so I digress.


I had a 12 second - 1/4 mile LB7 plow truck that I fused an ATS 5 Star converter together on doing a 4wd burnout and launch.

The things you do when a Cummings guy starts talking shot about your truck.... he started screaming like a little girl when we hit 130mph and still pulling hard on a two lane country road... :laugh:


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## jomama45 (Dec 25, 2008)

Philbilly2 said:


> I had a 12 second - 1/4 mile LB7 plow truck that I fused an ATS 5 Star converter together on doing a 4wd burnout and launch.
> 
> The things you do when a Cummings guy starts talking shot about your truck.... he started screaming like a little girl when we hit 130mph and still pulling hard on a two lane country road... :laugh:


How many beers did you have in the cupholder?


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## jomama45 (Dec 25, 2008)

leolkfrm said:


> gm ran a 200,000 mile replacement on injectors and glow plugs.....


It was limited to 7 years though. I had a set go out on our '01 at about 100k, and ~8 years old, no warranty. Over 210K now, and still seems to be fine.


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## Ajlawn1 (Aug 20, 2009)

Philbilly2 said:


> I had a 12 second - 1/4 mile LB7 plow truck that I fused an ATS 5 Star converter together on doing a 4wd burnout and launch.
> 
> The things you do when a Cummings guy starts talking shot about your truck.... he started screaming like a little girl when we hit 130mph and still pulling hard on a two lane country road... :laugh:


Lol, I was one of those Kummings guys... Put dual CP3's on after this but never ran it again low 13's...

Should of put the tow mirrors down...


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## gcbailey (Jan 26, 2014)

Philbilly2 said:


> NSBU Switch?


 correct......


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## Philbilly2 (Aug 25, 2007)

Ajlawn1 said:


> Lol, I was one of those Kummings guys... Put dual CP3's on after this but never ran it again low 13's...
> 
> Should of put the tow mirrors down...


Yeah it was fun... but super expensive hobby. Always fun when one of them racers would pull up to you at a stoplight before a merge... first thing your hand did was reach for the 4wd... game on!


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## Philbilly2 (Aug 25, 2007)

jomama45 said:


> How many beers did you have in the cupholder?


Lol... I have no idea what you are talking about...


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