Thanx and Question

[BriK]

My first post here. Wow, I have a lot of reading and learning to do. I'll toss my question in the mix.

I have a Silverado 5.3L, 2000, Z71 with about 145K miles. I have been experiencing slow coolant loss with no puddles, no noticeable smell and the oil looks clean.

In the past couple weeks the problem has been getting worse. I can tell I'm low when I get no heat and/or the temp gauge is rising.

Prob started this past summer, added some coolant and was good for a couple months. Then a month, then a couple weeks, now a couple days.

I have put in a bottle of bars leaks and checked the driveway, checked the oil on dipstick and sniffed around. Still no obvious signs of leaks.

From reading all the posts it seems that a pressure test may be a waste of money. I have a UV light and may try a bottle of florescence dye. Its right before Christmas, I need tires on my suburban. I'm somewhat mechanically inclined but do not want to spend hours working on the truck in the cold. I don't want to pay for unnecessary diagnostics or "we could try this and that" type troubleshooting.

Yeah the coolant is dex. My first add was H2O then straight DEX, my ratio may be off, in favor of dex.

So, I guess this post is a bit of a rant and a bit of a request for what you all think may be most likely culprit on a 2000 silverado 5.3L.

Thanks for any guidance.
Brian

 

[bullwinkle]

Don't know if you have any AutoZone stores near you, but they will loan out a cooling system tester for free, you (unfortunately) probably have a intake manifold gasket leak, if you don't see external leakage-then get your oil tested ASAP for glycol contamination before it kills your bearings!

 

[bullwinkle]

Oh, and

 

[BriK]

Thanks bullwinkle!! Reading here was the first time I heard about oil analysis. I will do that. Is there a DIY at home kit? A visual inspection of the oil on dipstick all looks normal, no gunk, no white stuff. I change oil every 3K or so and I'm due soon.

And, yes, there is a brand spaken new autozone near me. I'll pay them a visit.

 

[Scienceman]

A new Autozone?

 

[BriK]

Originally Posted By: Troy_Built
A new Autozone?

haha - its sooo new its not even listed on the AutoZone website!

 

[Chris142]

Look for a leak where the water pump meets the block. There are 2 small metal gaskets with rubber seals that seal the coolant passages. The seals go bad and the thing springs a small leak.

Usually the leak starts on the passenger side for some odd reason.

I've replaced 3 of those pumps in the past week due to the gaskets leaking but since you must pull the pump off the customers opted for a new pump while I had it off.

 

[Chris142]

Originally Posted By: bullwinkle
you (unfortunately) probably have a intake manifold gasket leak, if you don't see external leakage-then get your oil tested ASAP for glycol contamination before it kills your bearings!
The 4.8,5.3 and 6.0 do not have coolant in the manifold...It's just an intake manifold and thats all.

 

[BriK]

Well, went to AutoZone at lunch today. They had the pressure tester for loan but didn't have the correct cap for my Silverado.

I bought some of that UV florescent dye and added it. I'll see tonight with the UV flashlight if I can detect a leak that way.

 

[defektes]

The 5.3L is a dry intake so you dont have to worry about intake coolant leaks.

 

[BriK]

I'm praying its just a hose or clamp. After that, I suppose a thermostat (which seems to work fine), then the water pump. Hopefully not a head gasket. I don't work on my truck too much. The water pump looks like a pain to get to. I have done a head gasket on an old S10 blazer about 20 years ago, maybe that would be easier than the water pump. Nah, couldn't be. I just don't feel like busten my knuckles in the cold for just a possible. I want to be fairly certain before I work on it or take it somewhere.

Thanks all. Any more suggestions keep em coming.

 

[Chris142]

Originally Posted By: BriK
The water pump looks like a pain to get to.
It's probly the easiest WP to replace! Drain the system. Pull the top of the fan shroud off, Remove the fan and it's clutch, remove the 2 small heater hoses, then the 2 larger radiator hoses, Pry the autommatic belt tensioner back and remove the belt. All thats left are 6 bolts that take a 10mm socket.

The whole job shouldn't take you more than 45 minutes which includes running it after to burp the air and swapping the stat and belt tensioner onto the new pump if your going to replace it. If you not then you can just replace the gaskets.

I can have that pump on the ground in 6 minutes once the system is drained!

 

[Steve S]

Chris you practice a lot!!!

 

[HTSS_TR]

You should check heater hose(s), specially the one from engine to heater core, that piece is usually failed after 100+k miles. All my cars that had a coolant leak over the years, always the heater hoses were the culprit. Even if the heater hoses weren't leak, I would change it because the outside may looks good, the inside are dis-integrated and the crumbs may clog the heater core.

 

[Chris142]

Heres what the pump looks like.

 

[mechanicx]

I think if you have the original waterpump then it is high time that it would go out. I agree that it is the most likely place to be leaking. It can be hard to detect if it's leaking internally and out the weep hole while running though. You could have a leak in a lot of other places though but that is where I'd suspect one.