I have a freshly built LQ4 that's built for boost that i'm having a hell of a time getting to run without overheating, so much so that after 10-15 minutes of idling it will hit temps of 230+ and start boiling over.

Here's a list of my cooling parts and part of my motor build.

Engine:
2001 LQ4 bored .030 over
Wiseco 4.03 -15cc pistons
Callies Compstar H-beams
Brutespeed blower cam
stock 317 heads with 3 angle valve job
Patriot Dual springs
GM LS9 MLS head gaskets
76mm Turbo - crossover running close to the radiator but wrapped with header wrap.

Cooling:
C&R single pass 2 row radiator
New LS1 water pump (heater core fittings plugged)
Mr Gasket 160 thermostat (6367), bleed hole at the top
CSR straight thermostat housing (modified to fit t-stat)
2 - 12" pusher fans (1600 cfm each)
2 LS6 front steam vent tubes T'd together and returned to fitting in top of water pump outlet

When filling the radiator with distilled water and water wetter, I unhooked the hoses going to both steam vent tubes until water started flowing out of each. I used a Lisle spill free funnel to help "burping" the cooling system. with the motor running I squeezed both upper and lower hoses to free as many bubbles as possible, which worked well. Everything was going good for about 10 minutes until it got to 180* on my Autometer electric temp gauge in the pass head, which is usually about 20* lower than HP Tuners via the stock temp sender in the driver head. Water level in the funnel began to rise until it started to bubble over. it's almost as if the t-stat isn't opening and the water has nowhere to go but out of the radiator. last week I pulled the t-stat and tested it by boiling it in a pan, slowly opens right around 160 and is fully open in less than a minute.

I'm at a loss right now. Does anyone have any suggestions for me.

Please let me know if I need to add details or pics.

Thanks ffor the help in advance.

Avery

 

Hose from steam crossover tube: where does it go...?

Fans: did they turn on...?

Post pics of the thermostat housing and thermostat that you have.

 

When i was working for gm i used to have the same problem, they only way i could get them to stay cool was by pulling a vacuum and then letting that vacuum suck the coolant in, that way their was absolutely no air in the cooling system

 

rear ties into the front, and then both go to the top of the water pump above the return outlet to the radiator.

yes, fans turn on. have them set to turn on at 170 and off at 220 for now until I can get it all to work correctly

i'll have to get pics later done for the day and busy week.

 

I had that problem till I tied my steam lines into the hose going from radiator to the overflow. also a trick I uses was to pull the steam line off and then pull the top hose off at the radiator. jack the front end up and pour coolant down the hose till it fills the block up. after I did this I idle at 197 on a hot day have to put a load on it to even kick on the fans. I can tell you tho I fought it for a while and im convinced it was because the steam line was not tied into the system in a high enough location. it should be at the highest point possible

 

Joe asked.... Would be interested in seeing how the stat hsg was "modified".
Did you try with the stat out?

 

i'll get pics of my exact housing but I basically did the same thing as shown in this thread https://ls1tech.com/forums/generatio...using-mod.html

I have not tried without the tstat.

 

Yes, try what OG said, without the thermostat, let us know what it does.

When you assemble the thermostat to the housing, and place the whole thing inside the pump, does the housing sit all the way on pump, or do you have to push it down/in (i.e. compressing the bypass valve's spring)...?

Measure the depth of the bypass port in the pump and compare with the depth of the bypass valve on the end of the thermostat.

 

the housing sits all the way down on the pump with out resistance (compressing the bypass valve).

i'm going to try and pull the WP off in the next day or so and will provide better visuals

 

What's your tune like! How lean/rich.

 

Try looping the Heater core fittings together.by plugin them u do block internal coolant flow.

 

put a 180 thermostat in it... with a 160 the radiator/fan setup you have doesnt cool fast enough. the water keeps flowing through and your not cooling anything. with a 180 thermostat it will allow the coolant in the radiator to stay in there longer hence increasing the cooling effect. ive had the same issue in the past. now my car never goes over 190

 

Logical thinking.