Coolant Question
Thread Starter
TECH Regular
Joined: Aug 2009
Posts: 430
Likes: 77
From: Grand Valley
Coolant Question Car : 2001 Z28
Motor : Fully rebuilt LQ4 with LS1 heads
Waterpump : Stock LS waterpump, new gaskets
Problem :
Car doesnt overheat, runs good. If I check coolant when warm, shows near top of rad, after car has sat for 2-3 hours, level is maybe 2-3" down into rad. No leaks underneath.
Car is had about 1000km since motor build, Im assuming air is out of system bu now.
Any suggestions?
Motor : Fully rebuilt LQ4 with LS1 heads
Waterpump : Stock LS waterpump, new gaskets
Problem :
Car doesnt overheat, runs good. If I check coolant when warm, shows near top of rad, after car has sat for 2-3 hours, level is maybe 2-3" down into rad. No leaks underneath.
Car is had about 1000km since motor build, Im assuming air is out of system bu now.
Any suggestions?
Depending on your steam pipe setup, you could still have pockets in the engine/tops of heads. How is yours connected? Have you tried filling the radiator when cold then warming the car up to see what happens?
TECH Junkie
Joined: Dec 2012
Posts: 3,614
Likes: 1,326
From: Iowa
Is your overflow tank empty? Sounds like the rad should pull from the resivoir when it cools to keep it full to the top, then puke some out back into the tank when it gets hot.
In an f body, the coolant reservoir is located under the battery box.
In an f body, the coolant reservoir is located under the battery box.
Thread Starter
TECH Regular
Joined: Aug 2009
Posts: 430
Likes: 77
From: Grand Valley
Its in a 01 Z28, at this point the overflow is over the full mark. I suspect the rad cap isnt allowing flow back into rad when cold. I just put a new one on and we'll see.
I have the x pattern factory LS steam pipe style. How would I check for air, how to bleed these?
I have the x pattern factory LS steam pipe style. How would I check for air, how to bleed these?
IMO, if you've got a 4-corner pipe setup and the engine isn't mounted tilted forward(unlikely), then you likely don't have steam pockets in there.
What I did was hold the top water pump--> radiator hose up all the way(connected to water pump; not to rad) and filled through there and had the steam pipe output disconnected. when steam pipe is full, connect it, then continue filling and connect radiator. Then heat cycle and top off. But with all 4 corners hooked up and connected properly, that system is literally designed to evacuate the steam pockets in the tops of the heads. (Do you have this hooked up properly?)
It sounds like you are on the right track trying the cap. Usually the simplest explanation wins. Check the rad-->overflow hose for blockages as well. It could be slightly clogged up or kinked and hot, pressurized coolant could flow out but it would be more of a battle for the vacuum to pull cooler coolant back in.
What I did was hold the top water pump--> radiator hose up all the way(connected to water pump; not to rad) and filled through there and had the steam pipe output disconnected. when steam pipe is full, connect it, then continue filling and connect radiator. Then heat cycle and top off. But with all 4 corners hooked up and connected properly, that system is literally designed to evacuate the steam pockets in the tops of the heads. (Do you have this hooked up properly?)
It sounds like you are on the right track trying the cap. Usually the simplest explanation wins. Check the rad-->overflow hose for blockages as well. It could be slightly clogged up or kinked and hot, pressurized coolant could flow out but it would be more of a battle for the vacuum to pull cooler coolant back in.
Last edited by Mercier; Jun 14, 2016 at 10:33 AM.
Thread Starter
TECH Regular
Joined: Aug 2009
Posts: 430
Likes: 77
From: Grand Valley
Let it run with cap off, coolant comes in (no air) from steam pipe inlet. Let it get hot, no bubbles seen, put cap on, drove it. Letting it cool now, so we will see if it drops again with new cap.
I blew air through line from rad to over full tank, flows good and hear bubbling in tank when I do so, so I assume shes not blocked.
I blew air through line from rad to over full tank, flows good and hear bubbling in tank when I do so, so I assume shes not blocked.
Does the overflow in those vehicles feed into the bottom of the tank, or is it top with a straw going to bottom? If the latter, straw could be broken, cap not sealing, hole in tank, etc. preventing vacuum from sucking coolant in. If it feeds into the bottom it can't really pull anything but coolant until the overflow is empty.
Trending Topics
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
Did you try a new rad cap...?
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Does the overflow in those vehicles feed into the bottom of the tank, or is it top with a straw going to bottom? If the latter, straw could be broken, cap not sealing, hole in tank, etc. preventing vacuum from sucking coolant in. If it feeds into the bottom it can't really pull anything but coolant until the overflow is empty.