2000 5.3 with slow coolant leak

2000 5.3 with 67K Miles. In Dec, I noticed it was a little low on coolant. I filled it back up and did a pressure test and could not find a leak. When I did the pressure test, the engine was not running.

Well today it was down about a quart. I refilled and let the engine run for about 5 minutes and I can not see anything leaking.

This weekend, I plan to do the pressure test while it is running. I also have a Tracer Light so I can try adding some dye to the coolant and use the light to look for a leak.

The coolant has been serviced and the water pump is original.

Are there some common problem areas that I should be looking at for the 5.3?

Thanks,
2000CAYukon

2000 5.3 with 67K Miles. In Dec, I noticed it was a little low on coolant. I filled it back up and did a pressure test and could not find a leak. When I did the pressure test, the engine was not running.

Well today it was down about a quart. I refilled and let the engine run for about 5 minutes and I can not see anything leaking.

This weekend, I plan to do the pressure test while it is running. I also have a Tracer Light so I can try adding some dye to the coolant and use the light to look for a leak.

The coolant has been serviced and the water pump is original.

Are there some common problem areas that I should be looking at for the 5.3?

Thanks,
2000CAYukon

If you have not used dexcool with distilled water with at least 50% concentration , the corrosion affects the gaskets ...common failure is like the water pump / engine mounting gasket...It could also be the heater hose connections at the firewall...

your coolant system capacity is 4.5 gallons...so If you flush out the system and DO NOT DRAIN THE ENGINE AS WELL , this means you will only get out 2 gallons of coolant with the radiator drain plug ...

when servicing this system you must install about 2.5 gallons of coolant...then the rest with distilled water ...

If you have not used dexcool with distilled water with at least 50% concentration , the corrosion affects the gaskets ...common failure is like the water pump / engine mounting gasket...It could also be the heater hose connections at the firewall...

your coolant system capacity is 4.5 gallons...so If you flush out the system and DO NOT DRAIN THE ENGINE AS WELL , this means you will only get out 2 gallons of coolant with the radiator drain plug ...

when servicing this system you must install about 2.5 gallons of coolant...then the rest with distilled water ...

j cat,
I only use Dexcool and 50/50 mix with distilled water. When I did the coolant, I removed the tstat and used a large vacuum pump to remove as much as I could. I am pretty sure I got over 4 gallons out of it.

When I pressure tested it, it held 16 psi for an hour but I did the pressure test while the engine was off.

//2000CAYukon

j cat,
I only use Dexcool and 50/50 mix with distilled water. When I did the coolant, I removed the tstat and used a large vacuum pump to remove as much as I could. I am pretty sure I got over 4 gallons out of it.

When I pressure tested it, it held 16 psi for an hour but I did the pressure test while the engine was off.

//2000CAYukon

as long as you had done this from day one your problem maybe those heater hose fittings..or a water pump seal leaking out the weep hole...

hopefully its not the defective heads that GM had made for them ..

those had the cracks..

hopefully its not the defective heads that GM had made for them ..

those had the cracks..



if it was a defective head, would the leak be obvious from new or would it take time for the leak to develope?

as long as you had done this from day one your problem maybe those heater hose fittings..or a water pump seal leaking out the weep hole...

hopefully its not the defective heads that GM had made for them ..

those had the cracks..

Yes from day 1. I first noticed the leak in Dec 2009. I am going to pressure test tomorrow. If I will post my findings.

If it was the heads, wouldn't I see some white smoke out the tail pipe or some other signs?

//2000CAYukon

Yes from day 1. I first noticed the leak in Dec 2009. I am going to pressure test tomorrow. If I will post my findings.

If it was the heads, wouldn't I see some white smoke out the tail pipe or some other signs?

//2000CAYukon

remove all plugs and mark / label what cylinder they came out of .Then compare for color and tip debris..the plug , that is with no debris is the cylinder with the problem of coolant getting to it...All plugs should look the same..if you have no head gasket issues..

the water pump is a hard one to check as you must remove some componets...using a good light and a mirror keep checking this area ...

I know it has been a while but I finally got around to looking at this again.

I tried a dye with a UV light and I did not find anything. I also pressure tested to 17 lbs and could not find any leaks. I did not pull the plugs since I did not have much time.

The leak is slow and I am not sure what to do next.

Is there anything I can do short term to fix this? Or do I need to pull the heads and have them checked and replace the head gaskets?

Thanks,
//2000CAYukon

I've been reading your posts for years and have come to respect your input and help for others.

With that said, I'm a bit disappointed in the fact that you did not check the plugs as previously mentioned. This one simple thing can tell you volumes about what's going on in each combustion chamber.

As far as previously mentioned about the plug that may be using coolant I have to disagree. My '98 Sub 7.4 used about a pint of coolant every six months and I know exactly were it went. #7 cylinder. That plug had a nice build up of orange Dexcool on it's tip. That head was off about 6 years ago due to a mechanics screw-up (dropped something into the intake during gasket replacement).

Last winter I used a product called Jones "motorpurr" stop leak. My coolant loss is gone and #7 plug is as clean as all the others.

Hope this helps.

Hello all
My wifes 05 Equinox had same problem, slowly loosing coolant, but with no visual leaks.
The old pulling one plug at a time told the story. Head gasket was bad, making the coolant run into cylinder, an being burnt-evaporated or whatever thru that cylinder. Just looking for a leak, did never find one.
Vehicle did finally throw a code, misfire on #1 cylinder (on this vehicle).
The more I started to read about the 05 Equinox, head gasket sounds like a major defect on this year model, tons of people having same problem. I really love GM products, but they offer no help with this one?
I rebuilt entire engine, and got away from dex-cool. Shame motor only had 80,000. All this work over a faulty head gasket. The newer gasket you purchase, for same year model, totaly better made all together.
Hope this helps
Good Luck
Rob

I've been reading your posts for years and have come to respect your input and help for others.

With that said, I'm a bit disappointed in the fact that you did not check the plugs as previously mentioned. This one simple thing can tell you volumes about what's going on in each combustion chamber.

As far as previously mentioned about the plug that may be using coolant I have to disagree. My '98 Sub 7.4 used about a pint of coolant every six months and I know exactly were it went. #7 cylinder. That plug had a nice build up of orange Dexcool on it's tip. That head was off about 6 years ago due to a mechanics screw-up (dropped something into the intake during gasket replacement).

Last winter I used a product called Jones "motorpurr" stop leak. My coolant loss is gone and #7 plug is as clean as all the others.

Hope this helps.

777Stickman, you are right, I should have pulled the plugs. Life for me is crazy right now and I need to make time to pull the plugs and check them.

Even if the heads need to come off, I won't have time to do it until fall.

Let me pull the plugs this weekend and see what I find.

Given the fact that I could not find a leak with the dye or pressure testing, I pretty much know it has to be head gasket (or worse a cracked head).

It did pass smog on Saturday.

//2000CAYukon