Thermostat Cracked?

19Nasty1le · 07-25-2025, 07:27 PM

I’ve been smelling coolant after my built and finally noticed just under the little tube at the top of the thermostat there’s a small line of coolant. So I’ve looked into the DMS Billet Housing but it uses a LS3 style Stat, I already have a Katech 160 stat that was added during my build but I guess it won’t swap in.. has anyone changed to this stat? Also was told by my tuner that they vacuum filled the system for no air, I do have a Cordes Expansion tank would that not self bleed the system and prevent the air lock?

*Joshinator99* · 07-25-2025, 09:22 PM

Quote:

Originally Posted by 19Nasty1le

I’ve been smelling coolant after my built and finally noticed just under the little tube at the top of the thermostat there’s a small line of coolant. So I’ve looked into the DMS Billet Housing but it uses a LS3 style Stat, I already have a Katech 160 stat that was added during my build but I guess it won’t swap in.. has anyone changed to this stat? Also was told by my tuner that they vacuum filled the system for no air, I do have a Cordes Expansion tank would that not self bleed the system and prevent the air lock?

The billet thermostat housings work well. I will say most of the LS3 style thermostats are of pretty low quality unfortunately but I’d rather have the billet tstat housing anyway.

The Cordes expansion tank is likely for your intercooler circuit and separate from your regular cooling system.

19Nasty1le · 07-25-2025, 09:56 PM

Quote:

Originally Posted by Joshinator99

The billet thermostat housings work well. I will say most of the LS3 style thermostats are of pretty low quality unfortunately but I’d rather have the billet tstat housing anyway.

The Cordes expansion tank is likely for your intercooler circuit and separate from your regular cooling system.

Yeah just realized that about the SC system vs the engine system. Wonder if there’s a trick to getting the air out of the Eng side without vacuum fill? I wondered about the LS3 stat, kinda wasted money on the Katech stat for the stock housing to just crack. Hell might even see if I can JB weld it lmao.

*Joshinator99* · 07-25-2025, 11:20 PM

Quote:

Originally Posted by 19Nasty1le

Yeah just realized that about the SC system vs the engine system. Wonder if there’s a trick to getting the air out of the Eng side without vacuum fill? I wondered about the LS3 stat, kinda wasted money on the Katech stat for the stock housing to just crack. Hell might even see if I can JB weld it lmao.

You can just buy a new OEM tstat housing if you want to reuse the Katech LT tstat. But keep in mind the first time the blower belt breaks you’ll snap that OEM housing and spray coolant everywhere.

You don’t HAVE to vacuum purge the cooling system. It actually does a great job of working air out of the system itself. I’ve done it both ways. Vacuum method is great but I did it the “regular” this last time and it was pretty easy.

cdb95z28 · 07-26-2025, 06:05 AM

Quote:

Originally Posted by 19Nasty1le

Yeah just realized that about the SC system vs the engine system. Wonder if there’s a trick to getting the air out of the Eng side without vacuum fill? I wondered about the LS3 stat, kinda wasted money on the Katech stat for the stock housing to just crack. Hell might even see if I can JB weld it lmao.

I was into my cooling system this past winter. I just did a simple cooant bleed with no vacuum. Next track day I blew the upper radiator hose off. I still had air somewhere. The cars with the aux coolers are probably difficult to get all the air out of. I bought a vacuum bleed tool off of Amazon and used it. My next track day was a two day weekend...no problems. I believe the service manual says to vacuum bleed.

Evansa22 · 07-26-2025, 09:57 AM

The service manual shows vacuum fill as well as static fill. Like Josh said, both can be done with success. I've only done the static fill when I drained the coolant and didn't have issues. Just keep adding coolant with the top cap off and the bottom chamber cover open as you run the car. Can work out the bubbles faster by squeezing the hoses.

Tim M · 07-26-2025, 11:39 AM

I kept the OEM housing and added a thermostat belt guard. I've refilled the cooling system several times and never vacuumed it. Just topped it off on first few drives.

ZLRob · 07-26-2025, 12:55 PM

I run a DMS with a factory Vette LS3 186* t stat. It has never caused me a single issue since I installed it a year and a half ago or so.

07-25-2025, 07:27 PM	#1
19Nasty1le Craig Drives: 2019 ZL1 1LE Join Date: Jan 2019 Location: Peterborough, ON Canada Posts: 440	Thermostat Cracked? I’ve been smelling coolant after my built and finally noticed just under the little tube at the top of the thermostat there’s a small line of coolant. So I’ve looked into the DMS Billet Housing but it uses a LS3 style Stat, I already have a Katech 160 stat that was added during my build but I guess it won’t swap in.. has anyone changed to this stat? Also was told by my tuner that they vacuum filled the system for no air, I do have a Cordes Expansion tank would that not self bleed the system and prevent the air lock? Attached Images __________________

07-26-2025, 09:57 AM	#6
Evansa22 Drives: 2018 HBM ZLE Join Date: Aug 2017 Location: In the garage Posts: 876	The service manual shows vacuum fill as well as static fill. Like Josh said, both can be done with success. I've only done the static fill when I drained the coolant and didn't have issues. Just keep adding coolant with the top cap off and the bottom chamber cover open as you run the car. Can work out the bubbles faster by squeezing the hoses. __________________ Check out my youtube channel https://www.youtube.com/@evans.educa...ocxUzC1ferqeg8 Full SPL suspension / Ported blower / NW 103mm / Rotofab BG / 2" Headers / Ported heads / Upgraded Valvetrain w/ DOD delete / Custom 38% Cam / C7.R Timing chain / Katech Oil pump / BMR motor mounts and chassis braces / Katech 174* Thermostat / Pierburg Supercharger coolant pump / PLM HX / JMS voltage booster / ATI Damper w/ 8.6 Lower / MM Mild catch can / ADM Resevoir / soon to come... Rebuilt Engine / XDI +30% injectors / PWR Oil cooler setup / GMS Hood bracket 760 Whp / 700 Wtq E50

07-26-2025, 11:39 AM	#7
Tim M Drives: 2018 Camaro SS 1LE Join Date: Jul 2018 Location: Stuttgart, Germany Posts: 901	I kept the OEM housing and added a thermostat belt guard. I've refilled the cooling system several times and never vacuumed it. Just topped it off on first few drives. __________________ 2018 SS 1LE German Based Nurburgring Visit #19 202 MPH Ring Laps: 86

07-26-2025, 12:55 PM	#8
ZLRob Super Stock Drives: Chevrolet Camaro ZL1 Join Date: May 2022 Location: Concordia Posts: 782	I run a DMS with a factory Vette LS3 186* t stat. It has never caused me a single issue since I installed it a year and a half ago or so. __________________ 2017 Red Hot ZL1 A10 - Apex ARC-8's, 305/ 325 PS4's, DSX 9.06 12% lower, Griptec 2.5 upper, NGK HR7 Ruthenium plugs, Nostrum 22+ injectors, XDI Goliath HPFP, Katech dual in tank low side pump, Katech oil pump, LME tensioner, DOD delete, LT1 big fuel cam, Jokerz ported blower, MPI lid, GMS hood extractor bracket, Soler ported 87mm (91mm eff) TB, Granatelli SS plug wires, Cordes LTR reservoir, DMS T-stat housing, 186* LS3 T-stat, Black Widow Angry Housewife/ Corsa NPP mufflers, Borla X pipe, BMR engine mounts, Banks iDash, Lithium Battery, AEM X- Series, HP Tuners, E85, 16.5 psi 834 HP/ 840 TQ Last edited by ZLRob; 08-10-2025 at 12:14 PM.

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