5.3 Coolant Loss, 2000 chevy silverado Options

[larry111069]

I have a 2000 silverado 1500 5.3 .I have serious coolant loss ,and slight miss in engine.I'm 100% sure its goin out the tail pipe.Is there any common issues here etc.weak head bolts,bad gaskets ,bad head castings?just want to know before I tear it down.It still runs decent but not like it should .This thing has been serviced,taken care of properly.

This post has been edited by larry111069: Dec 17 2007, 01:33 PM

[C & A s Dad]

Larry, I am not a Tech but am in the Auto Parts Industry. I have read a few post of head gasket issues but from what I can tell this is not a common issue in the 5.3. I would be sure it is not the WP gasket before tearing into it. The WP gasket has been a big issue and the leak is almost impossible to see.

[TahoeMike]

If it has just started, get it fixed quick! My 2000 Silverado used coolant slowly for about 2 years, half a gallon every 3000 miles or so. Then it started getting worse so I decided to replace the head gaskets. Well, when I took the valve covers off, their was a ton of sludge in the tops of the heads and the drivers side with the PVC valve had a bunch of butterscotch colored junk in it also. I cleaned out the heads as best as possible and put it all back together. When I went to change the oil after replacing gaskets I pulled the drain plug out and nothing came out! Ran a screwdriver up in the hole and had to clean a lot of sludge out to get the oil to drain. Not good! I decided now was a good time to change the engine. Found one with 50,000 on it for $900 complete with intake, injectors and coils. When I got the old motor out I pulled the oil pan off and there was an inch or more of sludge in it. Nasty stuff. I take care of my truck. It had 116K miles on it at this time and I ran Castrol GTX until about 85,000 miles and only Mobile one since then. I'm guessing the sludge was from coolant mixing with the oil for quite a long time. It was going to be only a matter of time before the oil pump pickup got that sludge in it and seized up.

[larry111069]

Larry, I am not a Tech but am in the Auto Parts Industry. I have read a few post of head gasket issues but from what I can tell this is not a common issue in the 5.3. I would be sure it is not the WP gasket before tearing into it. The WP gasket has been a big issue and the leak is almost impossible to see.

Thanx for info but im gettin steam out exaust .Changed coolant and have noticable smell at exaust.

[larry111069]

If it has just started, get it fixed quick! My 2000 Silverado used coolant slowly for about 2 years, half a gallon every 3000 miles or so. Then it started getting worse so I decided to replace the head gaskets. Well, when I took the valve covers off, their was a ton of sludge in the tops of the heads and the drivers side with the PVC valve had a bunch of butterscotch colored junk in it also. I cleaned out the heads as best as possible and put it all back together. When I went to change the oil after replacing gaskets I pulled the drain plug out and nothing came out! Ran a screwdriver up in the hole and had to clean a lot of sludge out to get the oil to drain. Not good! I decided now was a good time to change the engine. Found one with 50,000 on it for $900 complete with intake, injectors and coils. When I got the old motor out I pulled the oil pan off and there was an inch or more of sludge in it. Nasty stuff. I take care of my truck. It had 116K miles on it at this time and I ran Castrol GTX until about 85,000 miles and only Mobile one since then. I'm guessing the sludge was from coolant mixing with the oil for quite a long time. It was going to be only a matter of time before the oil pump pickup got that sludge in it and seized up.

Man THANKYOU! finaly the real heads up on whats goin on.Were you able to pinpoint the leak being the gaskets?I'm tearing mine down asap.

[TahoeMike]

I don't think it was the gaskets because it was still using coolant for the short time I drove it after changing them. I think there was a crack in one of the heads but haven't checked them yet. I don't think you can magnaflux aluminum heads, probable have to be x-rayed. I know there is also a Tech Service Bulleting about some heads cracking but the TSB I saw covered 01-03 I think. I'm thinking it may have cracked when I put SeaFoam in it through the power brake vacuum line. Maybe I put too much in at one time and got a mild case of hydro-lock that cracked it.

[Kania2k1]

I actually just had my water pump changed yesterday. The SES light was coming on every once in a while, and I finally had someone other than the dealer do a code read. THere was a small leak at the waterpump, but nothing to the effect that I would have to add coolant every 3k miles. I've also heard that this is an ongoing issue with some of the trucks in our model year range. Could be it. Have you thought about adding the die to the coolant and trying to trace the leak? Or does it seem to be only an internal leak?

[TahoeMike]

Pretty sure mine was only an internal leak. Had a dealership check it out once and found no evidence anywhere on the outside either.

[Geno]

Pretty sure mine was only an internal leak. Had a dealership check it out once and found no evidence anywhere on the outside either.

Bulletin No.: 06-06-01-019B

Date: June 12, 2007

INFORMATION

Subject:
Information on Gradual Coolant Loss Over Time With No Evidence of Leak Found.

Some vehicles may experience a gradual coolant loss over time. A very low percentage of cylinder head(s) manufactured with an embossed Castech logo may develop a porosity crack in a very specific area.

[PunchT37]

And you`ll have to pull the rocker arm bridge to see the logo. The cracks are usually around the center headbolt area under the v/c where the oil drains back. Most heads iv`e seen do this are the "706" casting and not the "862".

[svensk]

Oh great... Well I'm not pulling that crap off just to see if I have those heads. I'll just continue to monitor my levels.

[Cadha13]

Metal porosity is a big problem especially with aluminum. Sludge build up is a sign of a coolant passage porosity and need to have those heads changed pronto. I have never seen any vehicle use more than a pint of coolant in normal service in any of the vehicles I have driven in a duration of a year. But I haven't driven a car with aluminum heads just cast iron ones. That includes a 1972 Chev pickup (350 V8), 86 Caprice (305), 1993 Chev Pickup (4.3L), 2000 Monte Carlo and Impala (3.8L and 3.4L), 78 GMC truck (250 L6 and 305 V8 now) and my 2005 GMC (4.3L).

[TahoeMike]

Pretty sure mine was only an internal leak. Had a dealership check it out once and found no evidence anywhere on the outside either.

Bulletin No.: 06-06-01-019B

Date: June 12, 2007

INFORMATION

Subject:
Information on Gradual Coolant Loss Over Time With No Evidence of Leak Found.

Some vehicles may experience a gradual coolant loss over time. A very low percentage of cylinder head(s) manufactured with an embossed Castech logo may develop a porosity crack in a very specific area.

I thought that bulletin was for 01 and up, does it cover 00's also?

[tmicklet]

Hi guys, how many of you have had problems with cracked heads? I have the 706 casting heads on my 04 gm crewcab. Its using coolant, sometimes smoking on cold start, valve lifter tick on cold start, cream coloured sludge on underside of valve covers. Sound like a cracked head to you guys?? Any info or ideas would be great. Thanks , cheers

[northern rider]

Hi guys, how many of you have had problems with cracked heads? I have the 706 casting heads on my 04 gm crewcab. Its using coolant, sometimes smoking on cold start, valve lifter tick on cold start, cream coloured sludge on underside of valve covers. Sound like a cracked head to you guys?? Any info or ideas would be great. Thanks , cheers

I have a 1999 GMC 4.8l 150,000 miles and have had the same symptoms so ended up changing the head gaskets. Have put about 150 miles on since and so far it has not used anymore coolant and the condensation on oil filler cap has pretty much disapeared so it looks like that may have fixed it.
The only thing I found real obvious is the 5, 8mm bolts along the top of the heads had lost torque, they supposed to be 22 ft lbs, so I would be tempted to pull the intake manifold and check the the bolts mentioned above before changing the head gaskets.

This post has been edited by northern rider: Aug 29 2008, 09:52 PM