LLY Headgaskets/ studs and everything else I should replace...

DieselDaze

DieselDaze

Midnight Maniac
Oct 26, 2008
88
1
8
Tulsa, OK
Well my gaskers finally went, i've contemplated buying a new truck but have decided to fix ole betsy myself...

2nd owner and ive had her for 16yrs 250k and its time to dig in... I want to pick your brains and see what other parts i should replace while im in there...

my list so far:
gaskets/studs
reman bosch cp3
glow plugs
up/down pipe
new cp3 fuel lines
water pump

looks like i may have to source from a few vendors but would like to just get a package deal from one store..

what else should i replace?
 
malibu795

malibu795

misspeelleerr
Apr 28, 2007
7,998
368
83
42
in the buckeye state
What's end goals?

Grab the following as well
arp harmonic balancer bolt some had TTY crank bolts, which would not get tight enough again and you spin your crank reluctor wheel and break a crank.. first hand experience 🤦🏻‍♂️
Injectors hold down bolts, can use 10.8 mm flanged head bolts
Rocker arm shaft bolts
Injectors coper washer and O-rings
Some replace the fuel pressure relief with LBZ or shim the lly to get to 26k rail
Upgrade fuel supply line to cp3

If cp3 isn't bad, I wouldn't change it, if I was dedicated on getting a cp3, I'd get the exergy sportsman cp3 pump, that will support 650ish rwhp with supporting mods. Can be had with various FCA

Swap to LBZ water pump will need new lower radiator hoses as inlet is bigger. Might be missing few things in that im sure someone will correct me if wrong.

Swapp fan clutch to 2886.
Might be able to stuf the LBZ/LMM fan blade in there as well.. IIRC LLY is still black blade.
LB7 49 state up pipes work on 01-10 trucks
I wouldn't go much over stock HP those 5spd. like to go 3rd and reverse easy
 
Last edited:
DieselDaze

DieselDaze

Midnight Maniac
Oct 26, 2008
88
1
8
Tulsa, OK
malibu795 said:
What's end goals?

Grab the following as well
arp harmonic balancer bolt some had TTY crank bolts, which would not get tight enough again and you spin your crank reluctor wheel and break a crank.. first hand experience 🤦🏻‍♂️
Injectors hold down bolts, can use 10.8 mm flanged head bolts
Rocker arm shaft bolts
Injectors coper washer and O-rings
Some replace the fuel pressure relief with LBZ or shim the lly to get to 26k rail
Upgrade fuel supply line to cp3

If cp3 isn't bad, I wouldn't change it, if I was dedicated on getting a cp3, I'd get the exergy sportsman cp3 pump, that will support 650ish rwhp with supporting mods. Can be had with various FCA

Swap to LBZ water pump will need new lower radiator hoses as inlet is bigger. Might be missing few things in that im sure someone will correct me if wrong.

Swapp fan clutch to 2886.
Might be able to stuf the LBZ/LMM fan blade in there as well.. IIRC LLY is still black blade.
LB7 49 state up pipes work on 01-10 trucks
I wouldn't go much over stock HP those 5spd. like to go 3rd and reverse easy
Click to expand...
my end game is to get another few hundred thousand miles out of it, a good portion of its miles have been city so pretty hard miles i guess... it lost weight at 90k miles, truck was stolen 2 yrs ago got it back 3 days later 2 miles from stolen area as they blew the elbow off Y bridge and were rolling smoke everywhere and got spooked is what i think happened... then i installed HSP Y bridge and a few tubes

forgot about lb7 up pipe... i had a low fuel rail pressure code at one point so was thinking cp3 trade out while im there, unless it can be swapped without removing Y bridge i can do it down the road if needed...

basically just want to replace as much worn stuff as possible while im in there, rather than kick myself later digging in there again to replace a part i could've before

have lbz mouthpiece didnt know i could swap other stuff... you've definitely given me some homework to do no doubt about it...
 
malibu795

malibu795

misspeelleerr
Apr 28, 2007
7,998
368
83
42
in the buckeye state
DieselDaze said:
my end game is to get another few hundred thousand miles out of it, a good portion of its miles have been city so pretty hard miles i guess... it lost weight at 90k miles, truck was stolen 2 yrs ago got it back 3 days later 2 miles from stolen area as they blew the elbow off Y bridge and were rolling smoke everywhere and got spooked is what i think happened... then i installed HSP Y bridge and a few tubes

forgot about lb7 up pipe... i had a low fuel rail pressure code at one point so was thinking cp3 trade out while im there, unless it can be swapped without removing Y bridge i can do it down the road if needed...

basically just want to replace as much worn stuff as possible while im in there, rather than kick myself later digging in there again to replace a part i could've before

have lbz mouthpiece didnt know i could swap other stuff... you've definitely given me some homework to do no doubt about it...
Click to expand...
I forgot to add L5P engine oil cooler swap,
IMO if staying around stock HP or within HP limits of stock 5sp trans, studs are over kill, GM upgraded the head bolts around 10 or so.. they're silver vs black in color and have 12point. I did the route with much beheast to the forum members on my LMM hotshot years ago ran at 400/800 HP/TQ years. Never lifted a head with new bolts that I installed correctly , lifted everyone with black head bolts

Yes the CP3 can be swapped with Y-bridge in place IIRC. Just more things to wiggle around.

LBZ/LMM cp3 pump with LLY FCA/FPR would be an upgrade as well.

Yes the "while we're here" is a big can of worms🤣🤣
 
Bdsankey

Bdsankey

Vendor
Vendor/Sponsor
Feb 1, 2018
3,975
1,117
113
Larsen, Wisconsin
DieselDaze said:
Well my gaskers finally went, i've contemplated buying a new truck but have decided to fix ole betsy myself...

2nd owner and ive had her for 16yrs 250k and its time to dig in... I want to pick your brains and see what other parts i should replace while im in there...

my list so far:
gaskets/studs
Click to expand...
With studs, we tend to use Gator or ARP. I've had pretty good luck with Xotic but their customer service (even as a dealer) leaves too much to be desired. I don't want that headache again so I've avoided them for the past year or so.

With gaskets, please do NOT run GM gold gaskets, only Mahle gaskets. The GM golds are not worth the time for the few dollars they save.

DieselDaze said:
reman bosch cp3
Click to expand...
The bosch reman CP3s are good, we tend to go with Exergy Sportsman/S&S Supersport pumps as you get an LBZ based pump without the hassle of returning a core or paying a core fee.

DieselDaze said:
glow plugs
Click to expand...
Only run GM! Nothing else.

DieselDaze said:
up/down pipe
new cp3 fuel lines
water pump

looks like i may have to source from a few vendors but would like to just get a package deal from one store..

what else should i replace?
Click to expand...


Overall I like your list, I would only add the following:

1) New valve cover hardware
2) 17-19 oil cooler
3) New damper bolt (ARP is my go to)
4) Rocker shaft bolts (Merchant, they're ARP)
5) Head gasket replacement set (includes all seals except the HGs themselves)
6) Relief valve shim kit or aftermarket relief valve (shim is cheaper and works very very well)
 
Chevy1925

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,334
5,267
113
Phoenix Az
Bdsankey said:
With studs, we tend to use Gator or ARP. I've had pretty good luck with Xotic but their customer service (even as a dealer) leaves too much to be desired. I don't want that headache again so I've avoided them for the past year or so.

With gaskets, please do NOT run GM gold gaskets, only Mahle gaskets. The GM golds are not worth the time for the few dollars they save.


The bosch reman CP3s are good, we tend to go with Exergy Sportsman/S&S Supersport pumps as you get an LBZ based pump without the hassle of returning a core or paying a core fee.


Only run GM! Nothing else.




Overall I like your list, I would only add the following:

1) New valve cover hardware
2) 17-19 oil cooler
3) New damper bolt (ARP is my go to)
4) Rocker shaft bolts (Merchant, they're ARP)
5) Head gasket replacement set (includes all seals except the HGs themselves)
6) Relief valve shim kit or aftermarket relief valve (shim is cheaper and works very very well)
Click to expand...

Why are you suggesting a 17-19 cooler over a 2020+? I would run a 2020 over the 17-19
 
DieselDaze

DieselDaze

Midnight Maniac
Oct 26, 2008
88
1
8
Tulsa, OK
oh boy... $$ keeps going up, i figured $3k off the top of my head with my original list... should've known better to post this question lol... regarding oil cooler, can i just buy an L5P oil cooler and expect plig and play or is banks conversion the ticket?
Regarding head studs: GM upgraded them and malibu said something about hotshot are we talking hotshot towing or some kinda dyno? sorry for my ignorance, while ive been in the diesel scene a while im no where near as versed as you guys and while being mechanical im far from a mechanic
 
malibu795

malibu795

misspeelleerr
Apr 28, 2007
7,998
368
83
42
in the buckeye state
DieselDaze said:
oh boy... $$ keeps going up, i figured $3k off the top of my head with my original list... should've known better to post this question lol... regarding oil cooler, can i just buy an L5P oil cooler and expect plig and play or is banks conversion the ticket?
Regarding head studs: GM upgraded them and malibu said something about hotshot are we talking hotshot towing or some kinda dyno? sorry for my ignorance, while ive been in the diesel scene a while im no where near as versed as you guys and while being mechanical im far from a mechanic
Click to expand...
My apologies, I was playing baby semi truck driver that didn't like slowing down for hills. My avg trailer weight was 20-30,000lbs.
I cooked a few engines to death because of it. Basically you don't want sustained engine oil temp over 220-230° or you split pistons. Personally preferred 200-220 temp range while towing..
IDK what the L5P run for oil temp,
I know dirty hooker diesel has an L5P oil cooler swap package https://dirtyhookerdiesel.com/i-240...-cooler-assembly-2020-2021-repl-12701592.html

We can easily spend your paycheck 🫣🤷🏻‍♂️
 
Bdsankey

Bdsankey

Vendor
Vendor/Sponsor
Feb 1, 2018
3,975
1,117
113
Larsen, Wisconsin
malibu795 said:
IMO I prefer it on the cooling stack vs my pistons kinda cheaper that way
Click to expand...

While I don’t disagree, overheating the coolant side isn’t ideal either. The 01-05 radiator is much smaller than 06+.

These trucks have been worked hard for over 2 decades. Horsepower outputs (both OEM and enthusiast) have been climbing so any improvement is beneficial.

Plus anyone who may have a stockpile of filters (I know I have customers who buy cases at a time) can continue to use their stock since 01-19 see the same filter.


Sent from my iPhone using Tapatalk
 
PureHybrid

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
3,375
395
83
Central OH
I'd skip the water pump and oil cooler. Yea it's a good idea but not really a pain to change later on. With those miles I doubt it's the OG water pump anyhow. Made it this far with the LLY oil cooler, I'd leave it. Skip the studs and do stock bolts. I WOULD do the cp3, that's a pain by itself, and at least have the injectors cleaned & tested
 
DieselDaze

DieselDaze

Midnight Maniac
Oct 26, 2008
88
1
8
Tulsa, OK
PureHybrid said:
I'd skip the water pump and oil cooler. Yea it's a good idea but not really a pain to change later on. With those miles I doubt it's the OG water pump anyhow. Made it this far with the LLY oil cooler, I'd leave it. Skip the studs and do stock bolts. I WOULD do the cp3, that's a pain by itself, and at least have the injectors cleaned & tested
Click to expand...
I replaced water pump @120k ish , that and batteries and tires are really the only thing that has failed me, until now
 
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