LML thermostat replacement

[cudakidd53]

Waiting for a neighborly hour to fire up the compressor and tools, so I’m putting some pictures up so you all can use this for instructional purposes - either what to do or NOT do!  That’s waiting to be determined!

So, first up, is the dreaded CODE thrown on my way to the LAST DAY OF SCHOOL for this year, with the plan of trucking off to the North Woods with my buddy Ray, tomorrow morning......isn't that always the way!

Second image shows areas of concern/operation!  Green = hefty hose clamp to be loosed so I can spill coolant all over everything (see third photo for preparations to address that event).  Red = Fuel System Port? (Ken alluded to that previously).  Yellow = Oil fill tube; either gets loosened or removed - we'll see!  Blue = some electronic gizmo clamped and mounted RIGHT where the bolts are to remove the thermostat housing.......ENGINEERS!  This appears to be a spring clip of sort, but rather stout looking so I envision me trying to remove it and busting something....knuckles, wires or something important and expensive!  I should mention, that a search of the interweb shows no easily available service manuals etc. of the LML Engine and it's lay-out!

Third image is my preparations for a coolant storm, predicted to hit anytime during said operation!  Green oval = two totes for under shelf of my dog area in truck cap, taped together since if left separate, will certainly allow coolant to hit directly between them!  Red = mobile container to try and avoid the previous preparations being necessary.....year right!  I'm predicting entertainment for Nate, Ken, Charles and Shawn, while Don will understand and feel my pain while the rest giggle politely in the background!  Notice this is being done OUTSIDE of the garage, so I can hose down the mess easily...some trick of the trade that Ken mentioned!

[cudakidd53]

To make Charles feel better about Nate breaking his "reward truck" budget......I bought 200+ dollars of tools I won't probably need for this operation since I based it upon some video of how to do this on previous evolutions of the Duramax!  Nate sent the links.

Large 1/2 drive long armed ratchet, off set ratcheting box end wrenches (metric & standard), universal joints for each drive size, extensions that will probably be just an inch short for each application, and a torque wrench!  What can I say, Sears was having "sales" on Crapsman stuff!

[stlaser]

Pretty pictures..... 

[KensAuto]

Don may understand, but I bet he will still giggle his butt off.
You done yet?


Sent from my Pixel using Tapatalk

[Sammconn]

Don may understand, but I bet he will still giggle his butt off.

So will this guy...

And I might too.
It looks a little more plugged than my LBZ.

You done yet?

[cudakidd53]

Finished in about 1 1/2 hours -  started after 8 AM to be more neighborly, had a couple cups of coffee, did some prep work and then put some clothes on and went out to attack the beast.  Not too difficult but glad I did the prep work.  Videos online show all older versions of the Duramax and not the LML forward.

[cudakidd53]

 First you need to remove 2-13 mm bolts holding the fuel excess gizmo.  You fold that back out of the way and then pull the expensive looking gizmo out of the spring bracket.

[cudakidd53]

 Then you remove 2-13 mm bolts holding the oil fill tube to the block and thermostat housing. Be careful not to drop the lowest one down on the block.  The lower white arrow, is holding the Fan Shroud in place and to the right of it is the plastic protrusion that indexes with the thermostat housing.

[cudakidd53]

 Here are two photos that illustrate what I’m talking about and a method to help avoid doing so.  Of course I dropped it on reassembly! Luckily it fell down into the skid plate holding all of the spilt anti-freeze!

[cudakidd53]

 Now you want to pump anti-freeze out of the coolant reservoir. I used this pump to remove about 1 1/2 gallons.  I also milked the upper radiator hose - squeezing & releasing repeatedly to pump more into the reservoir for removal.

[cudakidd53]

 Take a large pair of channel locks and grip both parts of the clamp holding the upper radiator hose to the thermostat housing. Of course it’s going to spill some but not too much anti-freeze. I then took a piece of bailing wire and wired the upper hose back out of the way with the added benefit of keeping coolant from for spilling everywhere.

 The second photo shows all the 13mm bolts you must remove (5) to access the thermostats.  Some are hidden in the photo but the arrows point to where they’re located.

[cudakidd53]

 At this point you should try to remove some additional anti-freeze from the now accessible thermostat housing. Go in from the point where you just remove the hose. Of course I say this having not done it myself!  If you don’t, antifreeze spills down over the top of everything. Luckily I blocked off the oil fill hole - otherwise anti-freeze would enter the engine!

 Give the housing a firm smack with your hand to loosen it at this point, while pushing back on the plastic fan shroud mount (toward the front of truck. There is a plastic protrusion that goes into a hole along side the upper 13 mm bolt removed earlier.  This will now spill some more anti-freeze because you can’t get it all out.

Once removed you will see the thermostats stuck to the upper part of the housing - notice the two brass backflow valves (red arrow) on the rear most thermostat.  These must be in the back most hole on top of the block with the two backflow valves oriented to the back of the engine. The left yellow arrow is where the spring clip for the expensive gizmo and the right on is where the bolt from the fan shroud and the plastic protrusion reside.

[cudakidd53]

 Remove both old thermostats and scrape any residual rubber from the housing.  I also used a Scotch-Brite pad to clean that surface as well.  Install the two new thermostats - the shorter one with the brass backflow devices go into the back most hole. The taller of the two goes in the front.  I carefully set the upper thermostat housing in place while again pulling forward on the fan shroud mount to keep the protrusion out-of-the-way. Once that all was in place I gently wiggled everything around to line up the holes.  I then installed 4 - 13 mm bolts and loosely tightened them in place. I used my hand to do this and the 13 mm socket on a long extension. I left enough play so I could again wiggle everything to make sure that the thermostats were in their correct depressions. Once that was done I tightened everything up using a crossing pattern and torqued them to 18 foot pounds.

I then reinstalled that gizmo clip and installed the gizmo into said clip.  Then I put the oil fill tube back in place after cleaning it up. I removed the O ring and a lubed it using dielectric grease, slid it home and reinstalled the bolts.

[wyorunner]

Nice write up! However I’m confused which gizmo is what gizmo :) not that it matters cause I do not have an LML!

Job well done!

[cudakidd53]

I reinstalled the upper radiator hose and clamps making sure everything was firmly in place. At that point I refilled with anti-freeze; burping the upper radiator hose to remove as much air as possible and getting as much new coolant in as well.   

I then took the garden hose - just natural pressure and wet everything down from the top of the engine to remove as much antifreeze from everywhere including the skid plate.   I paid particular attention to the belt and pulleys of the serpentine belt per Ken‘s instructions!

Started it up waiting to see it come up to temperature and make sure anti-freeze was at the proper level. Took it for a test drive with no issues.  I noticed that the temp was in the correct range again - it had been running around 165 degrees previously, indicating that one of the suckers were stuck open I guess.  I also ran it through the car wash to remove any other residual anti-freeze. Besides the truck was dirty! The blue tape was painters tape that I used to mark a couple bolts that weren't interchangeable.

 Last picture are all of the tools I used including a wooden step stool so I didn’t have to lay on top of the engine. I guess only Don has that problem because he’s tall enough to actually stand there and reach over. Being shorter I guess has its advantages?

[Flyin6]

Why can't I get into any projects that I can write about in like ten posts!

Nice write up Mike!

[stlaser]

Why can't I get into any projects that I can write about in like ten posts!

Nice write up Mike!

You normally break or run over something or the red dog runs off with a tool or you break yourself pulling wheelies or a mulch bed gets involved or..... I think we get the idea.....

[Flyin6]

Why can't I get into any projects that I can write about in like ten posts!

Nice write up Mike!

You normally break or run over something or the red dog runs off with a tool or you break yourself pulling wheelies or a mulch bed gets involved or..... I think we get the idea.....

Yea, tell me about it

Just broke a few more things...

[JR]

Think the LBZ was harder than that as it has an O ring on the rear I replaced.

Sure would be nice for someone to put a petcock in that main hose. I mean no drain??

[cudakidd53]

Just returned from a long trip to Eagle River area of Wisconsin with NO cell service, so in the process of catching up with all the Realman shenanigans I’ve missed. Thermostats are functional with no issues so I’m calling this a success without Murphy showing his ugly face!