Coolant leak and smell inside

[comfreak]

2011 Tahoe 5.3 - 210k miles

Replaced the two heater T connectors because they were leaking at o-rings near firewall.

Found it’s still leaking fluid, small amount directly under the water pump so I am going to replace that next.

The question is why is there a coolant smell inside the vehicle? It’s mostly when it sits in the garage for a day, next morning will be heavy smell that dissipates mostly when driving.

Heat still works fine.

Could leak from water pump be causing smell inside vehicle?

 

[Doubeleive]

2011 Tahoe 5.3 - 210k miles

Replaced the two heater T connectors because they were leaking at o-rings near firewall.

Found it’s still leaking fluid, small amount directly under the water pump so I am going to replace that next.

The question is why is there a coolant smell inside the vehicle? It’s mostly when it sits in the garage for a day, next morning will be heavy smell that dissipates mostly when driving.

Heat still works fine.

Could leak from water pump be causing smell inside vehicle?

yes, I can smell even the tiniest coolant leak, finding the source is the hard part but sounds like you found it.
after you replace the pump then hose it all down real good, you may still smell it for a while afterwards until it all vaporizes, it likes to puddle up under the fog lights (plastic brace there) if you drain the coolant out and it splashes up in there it will stay there for days......

 

[petethepug]

The outside air inlet catches that smell pretty easily. The cooling system seems to go out for leaks all at the same time.

Our 08 YXL Denali was the coolant recovery reservoir and then the radiator plastic end tanks and lastly the reservoir cap. All within 90 days.

 

[comfreak]

Thanks for the info.

Amazingly, it does seem like the water pump leak started right around the time the T connectors failed.

I have been really concerned it’s something like the heater core leaking but there really are no symptoms of that.

I will replace the water pump, clean her up, and see if it can dissipate on its own.

 

[petethepug]

If it’s that strong it’s probably another cracked plastic part. Once the motor reaches operating temp the plastic crack opens just enough for the coolant to vaporize as steam and leave only a white residue behind. A strong smell, but little or no evidence of a leak.

Let the truck idle with the a/c on at home after you get back from an errand. In 10-15 on a warm day you’ll be able to find the ****** leak if it’s there.

 

[Joseph Garcia]

With that age and mileage on your truck, when you replace the water pump, replace ALL the cooling and heating rubber hoses in the engine bay, as they are probably original. Not an expensive job, and it is good insurance against a hose rupture while on the road somewhere away from home.

 

[opfor2]

Do you have the rear auxiliary heater? If so, you may want to check to see if that is where the smell is coming from.

 

[Ken Casher]

2011 Tahoe 5.3 - 210k miles

Replaced the two heater T connectors because they were leaking at o-rings near firewall.

Found it’s still leaking fluid, small amount directly under the water pump so I am going to replace that next.

The question is why is there a coolant smell inside the vehicle? It’s mostly when it sits in the garage for a day, next morning will be heavy smell that dissipates mostly when driving.

Heat still works fine.

Could leak from water pump be causing smell inside vehicle?

Check carefully before you change the water pump. I had the same problem and changed the pump only to find out it was a head gasket leak. I cleaned everything very well and took the gravel plates off and the coolant was coming from the head which is less than 1/2 from the water pump. It was hard to see but the coolant was running from the head to the water pump and dripping off the bottom of the pump. By the way, I have used water pump that is in very good condition. That happened at around 240k.

 

[Doubeleive]

Check carefully before you change the water pump. I had the same problem and changed the pump only to find out it was a head gasket leak. I cleaned everything very well and took the gravel plates off and the coolant was coming from the head which is less than 1/2 from the water pump. It was hard to see but the coolant was running from the head to the water pump and dripping off the bottom of the pump. By the way, I have used water pump that is in very good condition. That happened at around 240k.

On a gmt900? that's almost unheard of

 

[comfreak]

Check carefully before you change the water pump. I had the same problem and changed the pump only to find out it was a head gasket leak. I cleaned everything very well and took the gravel plates off and the coolant was coming from the head which is less than 1/2 from the water pump. It was hard to see but the coolant was running from the head to the water pump and dripping off the bottom of the pump. By the way, I have used water pump that is in very good condition. That happened at around 240k.

Not a bad idea. I have a combustion leak test kit from a while back. Will give it a try just to make sure. Thanks!

 

[comfreak]

UPDATE

Performed a combustion leak test, results were negative. No head gasket leaks.

Installed a new water pump (and thermostat) and found the issue was the seal(s) between the pump and the engine. They disintegrated and caused a slow leak, likely once it cooled down I would suspect. There was a ton of old coolant gunk (see images) behind the pump coming from the seals.

Scraped off the old seal and gunk, changed the belt, and put it all back together and it's running fine. Now it's a waiting game for any leaks and the smell to go away.

 

[R467X]

Consider adding some cheap UV additive to your coolant and run your engine until warm. Makes it extra easy to find leaks. It could be a number and may not be the pump at all.

I second replacing all the hoses. I did a complete replacement two years ago on my 250k mile suburban. Water pump, radiator, fan, all hoses. Took a couple of hours. Fairly easy if you know what you're doing.

 

[Fless]

It could be a number and may not be the pump at all.

What "number" would cause something like this?

 

[R467X]

What "number" would cause something like this?

Number of things*

 

[mjgirard]

I had a water pump leak too in my 2001 Tahoe with 125000 miles. I decided due to the age of my Tahoe to replace anything associated with the water pump at this time so I did not have to do piecemeal jobs.
I replaced the following: water pump, radiator, thermostat, serpentine belt tensioner, pulley, new belts, all hoses and T-connectors, coolant recovery tank and cap. I really did all of this for preventive maintenance and to get my Tahoe ready for the summer vacation trips.
Good luck with the work.