Thermal issues, aka over heating question - Lateral-g Forums

rkleypas · #1 07-21-2015, 03:10 PM

Is the best way to get air out of the system to jack up the front of the car and run it with out the radiator cap? Should I do this a couple of times over a few days? I don't mind buying a tool if that's what I need...

**GregWeld** · #2 07-21-2015, 05:59 PM

Do you have an overflow with a return? Do you have steam vent return plumbed?

The thermostat most likely isn't the issue. Steam pockets are more likely. Had this issue on my LS3 480HP --- and I spent 3 days tearing into it.... the culprit was no overflow tank and every time it warmed up - and cooled down - it sucked in air which eventually built up and created a steam pocket. That AND the fan was running slow.

I'd check your voltage at the fans and make sure they're cranked up -- this would show up even if you had a 20% voltage drop - say the alternator is cranking out 14.2V and your fan is only seeing 12V...

There have also been some issues with the water pumps loosing their impellers -- they have broken off right at the shaft - so the pump is turning but there's no water circulation. You should be able to see water circulating in the radiator.

Vince@Meanstreets · #3 07-21-2015, 11:47 PM

Quote:

Originally Posted by rkleypas

Is the best way to get air out of the system to jack up the front of the car and run it with out the radiator cap? Should I do this a couple of times over a few days? I don't mind buying a tool if that's what I need...

do you have the air bleed tube hooked up?

and what greg said. also ls is not a reverse flow system. something i learned with gregs issue.

**GregWeld** · #4 07-22-2015, 08:10 AM

LS water flow is IN to the motor from the bottom hose towards the thermostat -- and OUT to the radiator at the top hose.

It's easy enough to check flow with a infrared temp gun.... or even using your hand and feel the hoses. Also use the gun to check for temperature DROP from the top (inflow) and bottom (return) --- on in the case of a crossflow radiator -- side to side --- This should drop 20* or so at idle with the fans running.

Use the gun to check front and back of both heads - near the steam vents (I'm assuming your particular LS model has these).

You can also "crack" the seal on these vents (they're O-ringed) one at a time to see if you can hear or see air (steam) vs water flow etc. The temp gun should also show you a temp differential if there is one...

The very first thing I'd do is to use a temp gun to see if the THERMOSTAT and other areas on the block - are reading the SAME as your TEMP gauge.... In fact - I'd do that before I did anything else.

Chad-1stGen · #5 07-22-2015, 01:00 PM

What happens if you rev the motor to 2,000 RPM or above? Will the temps come down at all?

I had trouble getting all the air out of my LS3 also. What I did to finally get all the air out is:

1) Raised the front of the car about 1.5-2 feet on jackstands.
2) filled the motor through the upper radiator hose
3) then filled the radiator
4) Ran the car with the front end still raised and the radiator cap off. With my dual pass radiator is was super easy to look down the open fill and see when the thermostat opened. I allowed the thermostat to cycle open and closed 3 full times with the cap off and then buttoned everything up.

No problems since.

ErikLS2 · #6 07-22-2015, 02:03 PM

I'm not saying you have air in the system necessarily but if you do, this is a handy tool for filling cooling systems:

http://www.tooltopia.com/uview-550000.aspx

rkleypas · #7 07-22-2015, 04:50 PM

I think I made progress last night. I pulled the t stat and it appears to work fine in 160 water. Reinstalled that and filled the system. It got hot with the cap off. I shut it off and lots of steam came out. Filled the radiator and over flow canister and started to get air bubbles out of the overflow. This only started to happen after the cap was back on the radiator. My top hose gets real hot, bottom hose not so much. I'm going to run it when I get home to see if it runs around 160. The overflow bottle was drawing fluid into the radiator After I re capped it. Should I keep coolant in the overflow? I was never able to see coolant moving. It seemed like the hoses were flimsy until I capped it. Lots of info I know so thanks for the help...

Vince@Meanstreets · #8 07-22-2015, 05:02 PM

Quote:

Originally Posted by rkleypas

I think I made progress last night. I pulled the t stat and it appears to work fine in 160 water. Reinstalled that and filled the system. It got hot with the cap off. I shut it off and lots of steam came out. Filled the radiator and over flow canister and started to get air bubbles out of the overflow. This only started to happen after the cap was back on the radiator. My top hose gets real hot, bottom hose not so much. I'm going to run it when I get home to see if it runs around 160. The overflow bottle was drawing fluid into the radiator After I re capped it. Should I keep coolant in the overflow? I was never able to see coolant moving. It seemed like the hoses were flimsy until I capped it. Lots of info I know so thanks for the help...

yes, keep the over flow half to 3/4 full when hot.....check the level when cold. You should have fluid in the bottle with a engine cold.
Top off the radiator. Reinstall cap. Run, let it get to normal op temp. Verify the fans run and note temp. See what the bottle level is.