2004 5.3L Silverado Losing Coolant

TxTruckMan · August 30, 2007

I'm betting that the noise you're hearing at cold startup is regular ol' GM piston slap. My '96 Z71 has it on cold mornings. And even the people with the NBS pickups complain about it. Can't speak to the oil or coolant loss though.

The pre-2000 year models had a common problem with coolant leaking at the back of the intake manifold where it meets the heads. It would only leak under pressure and was caused by a coolant passage in the head terminating at the intake manifold. The pressure would push out on the intake gasket over time. But I think this problem was fixed with the newer 4.8/5.3 engines. Might want to take a look back there anyway. It wouldn't leak much or any when stopped, only while driving and the pressure was higher.

Good luck.

big mudder · August 31, 2007

Hey guys I just signed up cuz I saw this thread and thought id contribute I have a 99 sierra 5.3 with 530,000 on it, its ticked since about 240,000 and has always used a little oil one day I even got a lil smoke on startup. It has used coolent for years we just top it up and drive it. It ticks almost every morning sometimes it goes away other days it doesnt I find when it ticks we get a check engine light and it runs kinda rough but I have found if you rev it right to the limiter for a couple seconds it shuts right up I know that sounds dumb but It has a ton of miles and you cant really expect much more. I have been told the tick can be loose plugs a grouding wire or a cracked flex plate but I have not checked any of those things because the truck runs rough and seems to be an internal issue but over all ive been amazed at how it the truck has held up even with the issues only thing ive done to the truck is brakes and tires.

AirForceAngler · August 31, 2007

99 gmc, 530K!?!?!? Wow, that motor don't owe you much anymore does it?

As for the check engine light and rough running when it ticks, I wonder if this isn't caused by the knock sensors thinking that the motor is detonating and therefore retarding the timing a bit? If it was a newer engine I'd say there would have to be a better way than revving it to the moon, but with yours, what's it going to hurt?

Trace01YukonXL · September 7, 2007

Hello all,

I hope you dont' mind me chiming in...

I think this has been a great thread with lots of good info.

I have an 01 Yukon XL with the 5.3L Engine.

A week ago I pulled the oil dipstick, and it had a burnt, tar-like residue coating one side of the dipstick from the bottom to the top off the oil level.

I could not whipe it off with a rag.

I was able to scrape it off with a knife. It peels off easily with a knife. It's kinda gummy.

I pulled the oil filter, and the whole top of the oil filter was coated with the same tar-like gummy residue.

I had only changed the oil 1600 miles ago (5 months ago).

We have only owned this for a year, but the local GMC dealer had a service history on it, and it had been regularly serviced.

The oil was kinda redish-brown... not good.

It was Valvoline Dura Blend, but I don't think that was the cause, with a Fram Extra Guard filter.

I took the filter to the GMC service place, and the shop foreman had never seen anything like it.

I thought maybe it was because I had put some silicone and teflon tape on the drain plug, but GMC guy said he didn't think so.

Coincidentally (this is where it gets interesting...), a week ago or more, our "Low Coolant" light came on.

I had checked the coolant level afterwards, and it seemed only a little low, so I bought some DexCool, and filled it 50/50 with water a little, to the mid-way marker.

I am watching the coolant level now. Too early to tell if it is dropping over time. My wife doesn't drive it much during the day, just very short trips. I will try to take it out more this weekend.

I'm wondering if anyone has seen this same burnt tar-like film on the dipstick and oil filter?

I can post pics up if anyone is interested (I saved the oil filter).

Thank you for any help!

- Trace

99xjsport06 · September 10, 2007

Trace,

If you dont mind, please post a couple of pictures. I'm betting your issue has more to do with sludge forming from "very short trips" than anything else.

teegee · September 11, 2007

Trace,

If you dont mind, please post a couple of pictures. I'm betting your issue has more to do with sludge forming from "very short trips" than anything else.

I have a 1999.5 (5.3L) with 180K on it. It likes to sip the coolant and shows no real signs of leakage. The old gear head down the street wants to bet me it's the water pump. If I do the water pump I might as well change the timing gears and sign up for another 180K.

AirForceAngler · September 28, 2007

Trace,

If you dont mind, please post a couple of pictures. I'm betting your issue has more to do with sludge forming from "very short trips" than anything else.

Mine sludged up quite bad and I don't make any short trips. 25 miles one way to work. I'm guessing it had something to do with the coolant getting into the oil or a lot of blow-by from the pistons slapping themselves silly in the cylinders.

99xjsport06 · October 27, 2007

Just thought i'd throw in another update to say that the problem continues. It has been getting cooler in the mornings now, and i've yet to hear (or been told) that the knocking has come back, but i'm sure it's only a matter of time. Coolant loss is at the rate of full-empty in about 3 weeks, give or take a couple of days. Oil consumption ranges anywhere from 1/2 to 1 quarts every 3K. About the only thing I can do now is keep the oil changed and keep a couple of bottles of coolant in the truck at all times until we can find the time to get this thing tore apart.

Chad17 · July 16, 2008

I found the TSB for the gradual coolant loss with no leaks on alldata....but I don't have a subscription to their site. If anybody on here does and would be so kind as to look up the info on the TSB, it would be greatly appreciated.

HERE YOU GO. GOOD LUCK

Document ID# 1986750

2004 Chevrolet Chevy C Silverado - 2WD

Subject:Information on Gradual Coolant Loss Over Time with No Evidence of Leak Found #06-06-01-019B - (06/12/2007)

Models:2004-2006 Buick Rainier

2001-2006 Cadillac Escalade Models

2001-2006 Chevrolet Avalanche, Blazer, Silverado, Suburban, Tahoe, TrailBlazer Models

2001-2006 GMC Envoy, Jimmy, Sierra, Yukon Models

2001-2004 Oldsmobile Bravada

2005-2006 Saab 9-7X

with 4.8L or 5.3L VORTEC® GEN III, GEN IV V8 Engine (VINs V, T, M, B, Z -- RPOs LR4, LM7, LH6, L33, L59)

This bulletin is being revised to include engine RPO L59. Please discard Corporate Bulletin Number 06-06-01-019A (Section 06 - Engine/Propulsion System).

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.

Inspect the cylinder head assembly to determine if the casting was manufactured by Castech. This can be accomplished by inspecting for their casting logo located on top of the intake port, under the rocker arm support rail and in the spring deck cavity portion of the cylinder head.

Important: If the cylinder head(s) are Not a Castech casting, follow normal diagnostic procedures in SI to determine the cause of the coolant loss.

Refer to the following illustrations on how to identify Castech casting and/or the very specific areas of the cylinder head(s) for a coolant leak from porosity.

Cylinder head(s) location of the Castech manufacturing casting logo (1).

Close up view of the cylinder head(s) showing the Castech manufacturing casting logo (1).

If the cylinder head(s) is a Castech casting (1), inspect the area around the five oil drain holes for witness marks indicating coolant seepage over time (2).

Important: If No evidence of coolant loss is found on inspection of Castech casting cylinder head(s), follow normal diagnostic procedures in SI to determine the cause of the coolant loss.

The crack location can be found in any of the five cylinder head(s) oil drains. This can be seen as a clean or shiny area, on an otherwise stained surface (1). Pressurizing the cooling system at this time may reveal coolant, air, or a combination, weeping in the described area. If inspection reveals evidence of coolant witness marks (1), replace the entire cylinder head(s) assembly.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

Document ID# 1986750

2004 Chevrolet Chevy C Silverado - 2WD

Chad17 · July 16, 2008

I bought a 2000 suburban a few years ago with the Castech heads. Prior to me buying it, it had leaked a significant amount of coolant through the heads into the oil. Enough that it caused a loss in oil pressure and wear to the ends of the pushrods and rocker arm. The antifreeze also ruined the diaphram in the oil pressure sending unit, causing the oil pressure gauge to read only about 10 psi. I bought the truck cheap, planning on an engine replacement, but I changed the oil and then used a head gasket/block sealant. After this, it did not use coolant and there was not longer any evidence of coolant leaking in around the heads. Also ran perfectly, except it smoked when idling. I ran this motor for a year and a half and then changed it because my wife was embarrased by the smoke in the carpool lane! I reccomend that if you are losing coolant through these heads, you try the head gasket/block sealant. Some may be skeptical about these sealants, but if you follow the directions exactly, these sealants work great with no problems. I have built race engines for 15 years and use these sealants on every engine I build and have never had a problem. The important thing is to make sure you do not mix them with antifreeze and you drain the block and allow them to dry for 24 hours.

tmicklet · August 14, 2008

Hi guys, I have the same problem with my 04 gm crewcab. Just wondering if anyone has anymore info or experience to add before I pull the heads off. Anyone else have a problem with headgaskets or cracked heads? I just pulled the valve covers off tonight and found the cream coloured snot/gunk described above. I believe it to be the dex-cool and oil mixed together. Nothing on the dip stick just stuck to the top of the valve covers. Its been slowly using dex-cool and occasionally smokes on cold start. It recently started the valve lifter tick on cold start. Sounds identical to the video posted on a previous page. Something is wrong for sure, just looking for some ideas. Thanks for any info. Cheers

LR_Dave · September 4, 2008

I have the same problem with cracked cylinder head due to leaking coolant as described in TSB. 2004 Tahoe 5.3L, 79,000 miles. I'm asking for GM to pay for it but I doubt they will. My question (and I am neither "technical or advanced") is this: GM dealer says that he would only replace one head with hairline crack he can eyeball, but not the other that appears (at least for now) to be OK.

Independent shop says he would do both of them, which makes more sense to me. Second guy can do both for basically same price that GM dealer wants to replace one. I'd appreciate your opinion on whether to do both and, in general, GM dealer v. indie shop. Thanks guys.

tmicklet · September 13, 2008

Hello,

LR Dave, I would recommend doing both sides. Its not a pile more work to do both. I just pulled the heads off my 04 gm 5.3l today. It has the castech heads as well. I plan on dealing with both heads. As for dealer vs. independent cant say, it would depend on their reputation. But if you can get both done at the indie, thats the way I would go. Now I just need to figure out what I am going to do with my heads. Anyone wanna buy a gently used set of castech heads??lol

mxdpa · October 21, 2008

I have the same issue with my 2002 Silverado with the 5.3L. I have a lot of miles on my truck, but I have been losing coolant for a lot of miles. I pulled off one of the valve covers yesterday and I found the Castech logo just as the TSB described. I also found a clean spot that indicated a coolant leak in exactly the area described in the TSB.

Today I called the dealership where I bought the truck, and they said that GM did not authorize them to replace the heads. The TSB is only for helping the techs diagnose this coolant loss issue. I have read many posts from many frustrated GM owners and I think that GM should help us out with this problem. Obviously, GM is aware that the Castech heads have a manufacturing defect and that it is NOT an inexpensive repair. To replace the heads would cost $3000. and more at a dealership.

Has anyone been successful in getting help for this problem from GM with a vehicle that is now out of warranty?

Is there a block sealant that really works long term?

rich0372 · November 22, 2008

Well I was one of the lucky ones too. I had to replace both heads due to a cracked head. I was noticing my low coolant light come on and had it checked out a couple times over a six month period at the dealer only for them to say there was no problems just a little low on coolant. Well last week I almost overheated so I put my defrost on high and drove to the dealer and would you know cracked heads. He said the tech knew about a problem with a certain type of heads and there was a buletin on this issue. Not what I expected, the dealer says it's a $3000 job. I'm upset I only have 62000 miles on this truck and of course I don't have any warranty. So then I go researching the the net only to find out about these crappy heads and all the problems people are having.

So I ask the dealer if they could help me out since there's a kown problem they say they could give me a 10% discount but would talk to there regional boss to see if there's anything they could do. Well I call 1800chevy and complain I told them these are faulty heads and you shouldn't have to replace heads after 62000 miles. I told them I read on the internet about numerous people having probems with these heads. Also bought my truck new and have had all the service done at my dealer. They asked about how many other GM cars I've owned I told them 4 and all from new. Well a day later I get a call from my dealer saying chevy called them and they will pay half. I was going to press it more but was happy they paid half and needed my truck back ...that nasty rental sucked.