GMC Terrain, Equinox, and SRX Forum banner
1 - 4 of 4 Posts

·
Registered
08 LS AWD Summit white(SOLD), 07 Torrent FWD Black, 05 Pursuit Sedan, '16 F150 XLT Sport Blue Flame
Joined
·
67 Posts
Discussion Starter · #1 ·
07 Torrent 3.4 FWD.

Replaced the heater core in March and could never get the car to retain heat. Have to add a gallon of coolant over the span of 4-6 months give or take, car has maybe 10,000KMs/6000Miles put on it annually. No visual coolant loss, no smoke, or other visible or notable loss of coolant other than reservoir being low.

I did do a combustion leak test via the overflow, the tester i got doesn't use a squeeze bubble, but hooks up to a vacuum line- I used the brake booster line on the intake manifold. Fluid only bubbled but never changed colour once after running for 20 minutes

Bled the system to the best of my ability/to the limit of my sanity. Let the car run for two hours, overflow cap off, letting it idle for five minutes, hold it at 3000RPM for a minute, let it drop down, repeat and start the car a few times over. Still no heat.

Car only seems to have heat when I initially turn it on after the car gets to operating temp, or accelerating moderately or hard. No drivability issues when warm, but when cold, idle stumbles and if I go into reverse about 15 seconds after car starts, idle drops really low and occasionally stalls.

I am at a loss. I dont want to jump the gun, but the only thing that I can think of that theres a small enough head gasket leak to introduce air into the system, but not enough to overheat or cause white smoke, both of which I am not experiencing. However, the last oil change I did in July, the oil cap did have froth, but I've never seen it since, and the oil was dark, but "clean"/free of any evidence of coolant contamination.

Has anyone else experienced this? Any advice?
 

·
Super Moderator
'16 Equinox LTZ AWD 3.6
Joined
·
1,731 Posts
UV dye in the cooling system will find any small leak. I've used it in the past and found the smallest leaks. Even picked up dye traces in the oil in one of my old 3.1 Malibu's with the notorious intake manifold gasket leaks.
Have you changed the thermostat? Temp gun is handy to see actual temp of coolant going into the heater.
Any codes stored in the system?
 

·
Registered
08 LS AWD Summit white(SOLD), 07 Torrent FWD Black, 05 Pursuit Sedan, '16 F150 XLT Sport Blue Flame
Joined
·
67 Posts
Discussion Starter · #3 ·
UV dye in the cooling system will find any small leak. I've used it in the past and found the smallest leaks. Even picked up dye traces in the oil in one of my old 3.1 Malibu's with the notorious intake manifold gasket leaks.
Have you changed the thermostat? Temp gun is handy to see actual temp of coolant going into the heater.
Any codes stored in the system?
Replace tstat with dealer unit and replaced it with the same temp that was in there before- I believe the higher temp one, don’t remember what exactly it was has it was a while ago. No PCM codes whatsoever. No history codes either.
 

·
Registered
08 LS AWD Summit white(SOLD), 07 Torrent FWD Black, 05 Pursuit Sedan, '16 F150 XLT Sport Blue Flame
Joined
·
67 Posts
Discussion Starter · #4 ·
UV dye in the cooling system will find any small leak. I've used it in the past and found the smallest leaks. Even picked up dye traces in the oil in one of my old 3.1 Malibu's with the notorious intake manifold gasket leaks.
Have you changed the thermostat? Temp gun is handy to see actual temp of coolant going into the heater.
Any codes stored in the system?
I think i found it...

At the lower intake where it mates to the cylinder head. Slight coolant leak that drips down and pools on top of the transmission. Makes sense now, that the car stumbles at idle. I think the car has had a head gasket replacement in the past, but Im not too sure, as we got no service history aside from a car fax when we bought it back in 2011. Im wondering if the dealer did it under warranty and they rushed it. I did another combustion detection test and still nothing. I never noticed it but when I tilted my head ever so slightly, I found it.
 
1 - 4 of 4 Posts
Top