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Discussion Starter · #1 ·
I have LMM with 408,000 miles on it. It is building pressure in the coolant system. It started off gradually and now it is puking coolant out the overflow. I have an EGR blocker plate installed. Could the EGR cooler be leaking exhaust gas back into the cooling system or does the blocker plate stop the exhaust gases reaching the cooler? Im new to the duramax as i bought the truck with 392,000 miles. ANy help would be appreciated. Just hoping its not the head gaskets!!!
 

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the blocker plate blocks exhaust from the cooler.
 

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Have you checked the radiator hoses in the mourning after siting all night not running? Are they soft or hard? If they are hard i would bet you have a bad head gasket.
 

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Discussion Starter · #4 ·
Yes the hoses stay hard
 

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You have the first stages of bad head gaskets-! You will also note that the heater is erratic-!
 

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Discussion Starter · #6 ·
Thats what i was afraid of. I've been in denial!!! Hoping it was something else. Thanks for the replies.
 

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I would recommend putting arp head studs while you are at it.
 

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Discussion Starter · #8 ·
Any other suggestions or suppliers to get the head gasket kit with arp studs from? Looks like the going rate is around $1000 bucks. Do you guys think it's worth putting the money in the head gaskets with that kind of mileage? The truck ran excellent before blowing the hg!
 

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I would change your overflow cap before replacing head gaskets. What temps are you seeing when it's puking over.

It's a cheap test to see if it's not holding pressure anymore and is a maintenance item.

If you do need head gaskets I would recommend buying based on someone who can support the work and not based on price. You'll likely have questions come up.

You'll want ARP studs and Grade C GM gaskets.

Copper Head Diesel, ATPTrucks.com, Troll Performance Tuning, Creatures of the Night are just a few companies you could buy your parts from.
 

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Discussion Starter · #10 ·
Already tried new cap. I can start the truck with the cap off and it just bubbles out immediately.
 

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Atptrucks can certainly answer your questions and help you out. :)
 

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get rid of the K&N filter while youre at it and Clean the MAF..
 
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