View Full Version : Cooling Problem after Timing Chain Replacement

06-27-13, 08:19 AM
Hi all,

I have been reading and learning from the forums for a couple of years. Last weekend I replaced the timing chains on my wife's 2005 SRX 3.6L V6 LY7. I replaced the water pump and thermostat. The timing chain part went fine. The motor is much quieter now.

I followed the factory "special coolant filling" instructions.

They are essentially:
Remove the upper radiator hose and fill with 50/50 mix.
Fill overflow bottle to 1" above full cold mark
Run engine for 3 mins with throttle advance to 3,000-3,5000 RPM
Check coolant flow through overflow bottle
Repeat steps if no flow through overflow bottle

There is no coolant flow through the overflow bottle. The radiator hose is full of anti-freeze, so I tried to run the engine with rpms to 3-3.5k.

With the engine hot and idling, the upper radiator hose is not pressurized. You can easily flatten it with your hand. It does get very hot. If I flatten it I see coolant spray into the overflow tank.

Yesterday, my wife drove the car for about an hour. When she arrived she said it smelled "hot" and the check coolant level message came on the interior display. Temperature gauge stayed right in the middle; it's normal position.

Last night, the coolant was about 1" below the full cold mark. I attempted to perform the factory filling procedure, but the upper hose was full of coolant and running the motor produced no coolant flow through the overflow tank.

The upper hose is still soft with the engine running. It seems that it is not pressurizing. I see (and feel) no leaks, but I have not yet raised the car to do a better inspection on the rear of the motor.

Can someone suggest something else I need to check or do? At this point I am stumped. I have added 9 quarts of coolant to the system so it should be full. I removed about 9 while doing the timing chains.

Thank you,

06-27-13, 08:57 AM
Let it run for 10 minutes heat on full blast does it get hot (the temp inside the cab)?

Still no flow and no or little heat you have a bad or stuck or installed backwards thermostat.

06-27-13, 09:52 AM
Wrong procedure, from the SM-
"Slowly add a mixture of 50/50 DEX-COOL antifreeze and clean drinkable water to the cooling system through the top of the surge tank opening. Refer to Approximate Fluid Capacities .
Slowly fill the cooling system until the coolant stabilizes at 25 mm (1 inch) above the FULL COLD mark on the surge tank.
Install the surge tank cap.
Start the engine.
Run the engine at 2,000-2,500 RPM until engine reaches normal operating temperature.
Allow the engine to idle for 3 minutes.
Shut the engine OFF.
Allow the engine to cool.
Add or remove coolant as necessary from the surge tank until the level is stabilized at the FULL COLD mark."

06-27-13, 11:08 AM
Glake has it I had the same issue after my chains new pump and thermostat started running hot. Let it cool for hours and did it again the coolant system burped the air bubble and I was good also you can't install this thermostat backwards its all part of the housing ;)

06-27-13, 11:11 AM
I am the original poster. I changed my email address this morning and have been locked out of replies every since. (Still waiting to hear back from contacting the admins.)

@1BadCadSTS I will drive the car to lunch and see if the interior heat is working.

@glake89 I use AllDataDiy to get the SM. It lists two fill procedures. One is the normal method, and one is "speical." It lists the special fill as being required, if the seal on the water pump was broken. That seal was broken. AllDataDiy is down right so I can not check, but I think the procedure I listed is correct for the special fill. I will double check once AllData is back up.

Thank you,

06-27-13, 01:31 PM
I drove the car during lunch and the interior heat is working very well. It is 80F here today, but with the heat on 90 inside, the vents are blowing very hot air.

The upper radiator hose is still soft while the car is running.

I follwed glake89's fill procedure. It is not all that different from what I posted. After my idling and luch time driving, the coolant in the overflow bottle is still at the same level.

At this point, I think it must be a small leak that is preventing the system from developing pressure. Tonight, I will try replacing the clamp on the upper radiator hose at the engine end. If that does not fix it, I guess I will need to remove the thermostat and replace the seal on it. I can feel all the way around the lower radiator hose connection and it feels dry. The hose from the overflow bottle to the thermostats housing also feels dry. They are just rather hard to see.

Thank you,

06-27-13, 02:05 PM
Sounds like a bad thermostat to me, even if it is new. I would check it by putting it in a pot of boiling water to see if it does indeed open.


06-27-13, 02:53 PM
If you're not developing pressure, the coolant cap is bad.

06-27-13, 03:50 PM
@glake89 Do you mean the overflow tank cap? It would need to be stuck open to vent the pressure right? I will try to depress the vent inside it with a screw driver and see if it still has movement. I could also put a balloon over the overflow tank vent outlet and see if it inflates. That should tell me if the pressure is escaping there.

Your first response mentioned the thermostat in backwards, but that is not possible. The thermostat is built into a housing (the part is about $55! Expensive just for a thermostat.) If the thermostat is bad (stuck open or closed) would that prevent pressure buildup? It seems the entire coolant system, including the overflow tank, is designed to be pressurized to 15psi.

Thank you,

06-27-13, 04:27 PM
T stat has nothing to do with pressure. Pressure develops as liquid heats up and expands, The cap seals until about 15 lbs. is reached then vents anything over that. If it's bad (cap) car will get hotter than normal when idling for long periods and in slow stop&go traffic. The pressure raises the boiling point of the coolant. [primmer over]

06-27-13, 07:31 PM
You beat me too it, that is grade 10 high school mechanics, man that was a long time ago, can't believe I remember it.

06-27-13, 10:22 PM
If you're not developing pressure, the coolant cap is bad. Granted that is a posibilty but if the thermostat doesn't open there isn't going to be much pressure because the upper hose and radiator will be relatively cool and isolated while the water pump will tend to isolate the the hot water from the radiator. To me the one of the key things he said was "no coolant flow".


06-28-13, 08:41 AM
Hello again,

I got home late last night and was not able to do much. I did however, check the overflow tank cap this morning. The pressure relief part (spring loaded piece in the cap) has movement. The holes that allow pressure to escape are closed and when I press the stainless steel piece inside the cap they open. This was a very non-scientific test, but at least the basic function appears to be working.

I felt around the thermostat housing with a clean paper towel. When I pulled it back up, there was a drop or two of orange coolant. I am fairly certain I have a small leak near the thermostat. It is a PITA to inspect better. I will take the engine cover off this weekend and see if I can reseat the thermostat and replace the seal for the lower radiator hose. The hose from the overflow tank has only a spring clamp on it. I need to inspect it as well.

One more data point, with the engine at idle, the upper radiator hose is very soft. With the engine at 2-2.5k RPMs, the hose is more firm, but not as much as it should be.

Thank you,

06-28-13, 08:28 PM
I'm pretty sure your to put sealant tablets in when change coolant or break system open.That would take care of coolant your seeing on paper towel.

06-29-13, 12:16 AM
Those sealants clog the system up and can cause more damage I wouldn't use those.

06-29-13, 02:57 PM
In service manual it tells you to use GM's sealant tablets and gives you part number for tabs. When ever the dealer works on cooling system they use them. I Use them the GM brand have not had a problem. I don't use off brand I believe they can give you problems with heater core ,etc.

06-29-13, 04:20 PM
From the OWNERS manual-
"Notice: If you use the proper coolant, you do not have to add extra inhibitors or additives which claim to improve the system. These can be harmful."
GM used to use the sealer tablets but I believe they no longer do.

07-08-13, 03:55 PM
Wanted to post an update. Prior weekend, I removed the thermostat housing and the lower radiator hose (metal tube at the point it connects to the housing). I did not have the correct gasket and had no vehicle to drive and get another one. I cleaned the existing rubber seal and metal tube (using a kitchen scrubbing pad), coated the channel it sets in with RTV, put the gasket back in and connected everything back up. The thermostat housing seal was new; I simply re-used the one that had been on the car for a week.

The lower radiator tube definitely had a small leak at the thermostat housing. I am unable to detect a leak now. A clean paper towel run around the thermostat housing and radiator hose comes back clean. The upper radiator hose still feels too soft, but I did not check it prior to replacing the timing chains. It may be that 15 PSI does not make that hose very stiff.

After quite a bit of driving this weekend, including several trips of 1 - 1.5 hours, the car never ran hot.

The car idled for about 15 minutes yesterday after 30 mins of driving. Never ran hot.

It seems the cooling system is working as it should. The temperature has been cooler than normal for June/July (mid 80s versus 90s).

Unless I see something wrong I do not plan to do anything else with the cooling system.

Thank you,