Head gaskets?

Dm23

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Mar 8, 2019
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What’s going on guys. Still been having trouble with my truck. So id thought I’d let people know what was going on to see if my idea is right.

12LML.no egr. After getting the truck up to operating temperature and sitting over night the upper radiator hose is hard. Let the truck sit for another day. Tube was still stiff. I fired the truck up and it got up to 115 degrees and the coolant started to come out of the wc fab reservoir breather tube. There’s no white smoke while driving or at an idle. There are no visible leaks apart from the coolant tank. I thought maybe it was air stuck inside the cooling system. Opened up the reservoir and let the truck get to temp, with the cap off, with the heater on high, capped it and truck was driving normal. But here we are after about 2 days of letting the truck sit and the upper radiator house is still hard. And now pushing coolant out of the breather tube.

I just had my oil tested and they found no traces of coolant in the oil. Thermostats were just replaced to rule that out also I had a leak from the oil cooler which was fixed. I’m really thinking I have a head gasket issue. Any info / thoughts would help. I really don’t think it’s the cap either. Radiator was just replaced not to long ago as well

Garrett
 

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Chevy1925

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Yup, sounds like a head gasket. Put a coolant pressure tester on it and see if you build past 16psi at idle and how quickly it builds. Be prepared to shut the truck down quick if it gets to 25psi quickly.
 
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Dm23

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Stupid question. I have the wc fab reservoir tank. I don’t think the harbor freight tester kit threads onto this aftermarket tank.
 

Dm23

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Mar 8, 2019
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And as far as the head gasket job itself. Should I bite the bullet and have a shop do it? Or do it myself with some help? My brother and I have experience with engines. But it seems like a real pain in the ass to do.

Only thing, all the shops are about an hour out and I’m not sure I want to drive the truck the way it is and be stuck on the side of the road.
 

Bdsankey

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Personally it sounds like a bad head gasket. As for who should do the job, it's not a super difficult job it just has tons of steps and areas that can easily get mixed up.

If you're confident in your skills you can save a ton of money on labor. If you doubt yourself at all I would recommend having a shop do it.
 
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Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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Phoenix Az
And as far as the head gasket job itself. Should I bite the bullet and have a shop do it? Or do it myself with some help? My brother and I have experience with engines. But it seems like a real pain in the ass to do.

Only thing, all the shops are about an hour out and I’m not sure I want to drive the truck the way it is and be stuck on the side of the road.

It ain’t fun, that’s for sure. Make sure you check the pistons real well for cracks. We see it in LML’s a lot as do others on here.

Lots of helpful info on this site. Take your time, don’t rush and you can do it. Biggest thing is organizing parts, pics to know how things are ran and putting the head gaskets on right lol
 
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Dm23

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Is there anything since its going to be open that should be replaced as a pre caution? water pump, injectors, etc? I would like to throw 100% overs in it while its apart.
 
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Chevy1925

don't know sh!t about IFS
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DM23 1FastBrick both mentioned replacing the water pump. If he goes there, I have a suggestion or two for him.

I mean, I don’t mind a water pump but far as I remember, upper oil pan has to come off for the oil pump to be changed. You might be able to snake it out but the pick up tube going to be a fight getting off and back on.
 

Bdsankey

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I mean, I don’t mind a water pump but far as I remember, upper oil pan has to come off for the oil pump to be changed. You might be able to snake it out but the pick up tube going to be a fight getting off and back on.
Yeah, front cover really has to come off to get the pump out reasonably. Could someone snake it out with tons of curse words? Probably, I've never personally tried.

----To the OP----
I agree with water pump/thermostats. My shop typically does the below on a HG job:

1) New HGs (Mahle)
2) Mahle head gasket kit
3) Head studs (Gator or ARP)
4) Water pump (DHD on 01-05, GM on 06+)
5) GM thermostats
6) GM glow plugs
7) Merchant/ARP rocker shaft bolts
8) Any hoses that are rotted/needing replacement
9) Hex head valve cover bolt kit from DHD (my area the OEM fasteners rust/corrode terribly so we just replace them all)
10) Clean the cooling stack
11) Check clutch fan and replace as needed