after coolant flush, need to top off?

[Spykem4e]

Hi guys,

recently, I had a sweet smell once in a while in my car and I went to my mechanic and we say coolant under the car and it pointed out to be the water pump leaking when getting very hot + when load is applied.

They changed the water pump and while at it, I asked them to flush the entire system (radiator, heater..). They put fresh new coolant in it to the full cold line.

The car is a 2005 Cadillac CTS and I don't have a radiator cap, only a surge tank cap on the reservoir.

200 miles after the repairs, I had to add about 100 ml since I'm a perfectionist and just love when things are right at the line!

1000 miles after topping off, I had to had another 100 ml of coolant.

Could air trapped in the system cause coolant level to drop slowly? I'm going to change the reservoir cap as a preventive maintenance next week because I'm not sure if it could be a bad cap or not.

If air trapped in the system can cause my problem, is there a bleeder valve somewhere?

Thanks a lot.

 

[demarpaint]

There could be trapped air from them not properly bleeding the system. It should work its way out. If not get a shop manual and they will tell you the proper bleeding procedure for you car. It could take a while to get all the air out though. If the level continues to drop pressure test the system it could have a leak.

Trapped air can cause hot spots in the engine. In certain engines proper bleeding of the system is very important.

 

[Boss302fan]

I think you can run/idle that car with the cap off or loose for the air to work its self out. You may want to also replace with a new cap. Check with someone to make sure you can do this.

 

[mechtech2]

This is common. It is tough to fill a system completely after it has been drained.
The best cures are a few drive cycles of cold/hot.

 

[Chris142]

Are you overfilling the coolant tank? If you fill it when it;s cold it will expand when it gets warm and push some out.

I have a customer that cant get this through his head and is always putting water in his Cad, fills it up to the top and after driving it's lower than it was.

It's pretty difficult to see the level in that tank. If your low coolant light is not on do not add anything and dont worry about it.

 

[The Critic]

This always happens to me when I flush the coolant on any brand of car.

The morning after the I do the flush, I always have to add 8-16 ounces.

 

[Spykem4e]

thanks a lot guys! I was kinda worried since it was the first time I did a flush in that car with that pressurized system without a radiator cap.

I know 200 ml after 1200 miles run after a flush is not bad at all but I was just scared a little since I don't know a thing about coolant, radiator and a/c.

I'll keep an eye on the oil level for the next week (1000 miles).

Chris142, I always fill up the reservoir tank at the FULL COLD line. Ive got about 3 to 4 inches of spare in the reservoir and its not spilling. When hot, there is way room for it to expand even more before spilling out of the tank. Thanks for the advice!

 

[KrisZ]

My Mazda has a pressurized tank, and there is no cold/hot level, it only has a min and max. and it always stays at maximum when cold and hot.

The procedure to bleed the coolant system on my car is to bring the system to the operating temp. with the cap off. Once the car is wormed up, rev. the engine at 2k-2.5k RPM for 2-3 mins. (the cap is off the whole time), you will see bubbles in the tank. Top to max. and repeat until the level stops dropping.

Worked well for me, although I did multiple radiator drain and fills, and never drained the block, so that probably helped.

 

[Boss302fan]

Originally Posted By: KrisZ
My Mazda has a pressurized tank, and there is no cold/hot level, it only has a min and max. and it always stays at maximum when cold and hot.

The procedure to bleed the coolant system on my car is to bring the system to the operating temp. with the cap off. Once the car is wormed up, rev. the engine at 2k-2.5k RPM for 2-3 mins. (the cap is off the whole time), you will see bubbles in the tank. Top to max. and repeat until the level stops dropping.

Worked well for me, although I did multiple radiator drain and fills, and never drained the block, so that probably helped.


This is a good way to do it...