2004 5.3L Silverado Losing Coolant, Coolant Loss Rating Options

[bbb]

Probably did not need a pump(never seen a bad one yet)...as stated earlier, the gskts are a common problem.
As for the engine knock...it goes away for a while after an oil change? Service it every 500 miles a couple of times and use 5 0il and 1 ATF to clean out your engine.

[99xjsport06]

The WP was fine, but i'm not about to take all that apart and not replace the pump, because knowing my luck, the pump would go out like a week later.

For the knocking, changing the oil has no affect on it. It will still knock in the mornings, although lately it really hasn't done it....seems to be 80% of the time it only does it when its cool in the morning.

[John Canada]

I have similar problems with my 1994 Sonoma Truck. I loose about 1 liter of collant every 2 weeks. I took it into a GM service center and they couldn't find the leak but suggested that I flush the coolant system, change the the thermostat and change the fan hub for $385. I couldn't imagine how this was going to fix the missing coolant problem and so I did nothing.
I also had a what I thought was a noisy lifter a few months ago and put some Wynns snake fluid in the oil which seemed to cure the problem but now after 3 months the lifters are acting up again.
GM Service center can't give me answeer as to what they think is wrong so I think a can of Reslone will be my next home cure the lifter type noise.

The real answer may be to trade it off and let someone else have the headache.
John

[99xjsport06]

I'm desperately trying to talk him into trading this thing in before it's too late....but he's too stubborn and wouln't do it....he loves his truck too much.

I have been checking the coolant level every weekend since changing the pump and gaskets, and it was looking good, even after a month had gone by since doing the work.....Until last weekend....checked it and it was almost bone dry once again.

Havent' heard the lifters or seen any smoke in quite some time though...

[ryank1]

There is a TSB for a gradual coolant loss on this engine if it has heads with a mastech casting in the head. The casting mark is under the valve cover. What you need to do is pull the valve covers and look in the oil drain holes at the bottom of the head and look for a clean hole. If one of them is cleaner than the rest then the head is pourus and has to be replaced.

This post has been edited by ryank1: Jun 19 2007, 06:16 PM

[99xjsport06]

You wouldn't happen to have a link to that TSB would you?

[99xjsport06]

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.

[GMTRUCKTECH]

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

© Copyright General Motors Corporation. All Rights Reserved.

Document ID# 1986750
2004 Chevrolet Chevy C Silverado - 2WD

[99xjsport06]

Absolutely beautiful! GMTRUCKTECH...thank you SO much! I definitely owe ya one buddy!

[mooreapi]

99,
I have a 2k Silverado 5.3l 2WD with 348K miles on it. I have had the same coolant loss thing for a while and I suspect that it's actually the water pump, but it's good to hear that your replacement of both W/P and gaskets has cured the problem. I just check my level every couple of weeks (I don't drive it as much as I used to) and top it off as required. I know it's not a "bad" leak as the system still pressurizes when hot.
My biggest concern now with the cooling systems is that if I idle for long periods, especially with the AC on and in hot weather, the temp starts to climb. It will stay in the upper half of the gauge range, and eventually overheat. If I give the engine some revs, or start driving, the temp will drop back to normal. (Coolant level is good)

Since almost day-1, my truck has "used" a quart of oil over the 6K miles I run between oil changes. I did a lot of sitting and idling. It now has a lot of weeping from the valve covers and I suspect a rear main seal. It definitely uses more oil now than before.

The "lifter" noise may not be a lifter. I have heard that a lot of these engines experience piston slap or scuffing when cold. My truck will be noisy when I first start it, especially after sitting for significant amounts of time. I believe that this is caused by the way the engines are put together now (same phenomenon where two vehicles from same assembly line, one runs great with no problems, next is lemon).
Since my truck is still running well, even with all the noises and leak issues, I don't have the inclination (or time and $$) to mess with it.

Matt

This post has been edited by mooreapi: Jul 24 2007, 09:02 AM

[sparky76]

I would sugest a comression test. I have had this problem with other GM engines. The problem is almost always a small crack in the head between the intake and exhaust valves. The root of the problem, IN MY OPINION, is the DexCool. Every cracked head has had this jelly like stuff cloging the cooling ports. No coolant equals cracked heads. In all the cracked head cases I have seen there has been Oil and Coolant consumption problems.

[99xjsport06]

Matt,

I thought that for a while the WP and gaskets had solved the problem, but alas....there's more to it. It's still using coolant, just not at the same rate. I still check it every weekend, but only have to add more about every other weekend to every 3rd weekend. And this truck is still seeing about 60-70 highway miles a day. I can once again, smell the coolant when I open the hood after its been running. I'm going to be probably replacing the head gasket and if necessary the head.

In your case however, that sounds like a bad water pump, or even a faulty fan clutch. I work on mainly Jeeps, and usually when I see them overheating like that at idle, it's due to mostly a bad fan clutch, or if thats good, it's the water pump.

Just changed the oil last week, and it used a quart in about 4000 miles, and it just clicked the 100K mark this week.

348K eh? Any other major problems with that kind of mileage, aside from routine maint.?

And i've heard not so nice things about DexCool also. Which is why i've got most of it out of the system and i'm running Peak global now.

[mooreapi]

I think that I may have to replace the fuel pressure regulator, as it doesn't want to start on the 1st time, but will most of the time start on the 2nd, always start on 3rd try.
Other than the coolant leak/overheat problem, she uses a little more oil. She's a little more noisy on startup, but that could also be because she sits for long periods.
I've mashed the seat cushion to hell, and the back section is broken internally so it leans, but the seatbelt side still holds with the adjuster/recline.

She still pulls strong and without hesitation, original engine and trans.

i think I've gotten my money's worth out of her

Matt

[TahoeMike]

My 2000 Silverado has had a slow coolant leak for some time, about half a gallon every 3000 miles. Lately it started getting worse and could find no external leak, figured the engine was burning it. Well, I finally decided to put head gaskets on it. Pulled the valve covers and the left valve cover was covered with butterscotch looking snot, oil/water. The passenger side valve cover and valve spring galley were gunked up something terrible. I've been running Mobil 1 for about 25K (115k on truck total) but ran Castrol dino oil before that. Well, cleaned everything up as best I could got it all bolted up and went to change the oil before starting it. PUlled the plug and nothing came out! Had to run a screwdrive up in the drain hole to clear out sludge so it would drain!
Not sure it this is a result of water/Mobil 1 mixing? Or years of Castrol? Never had a problem with Castrol before. Well, I'm at the point now that it will either keep going or some sludge will get in an oil passage and grenade the motor. Hopefully the gaskets fixed the water loss.
By the way, GM sells a top gasket kit that has Head Gaskets, Intake gaskets, exhaust gaskets and o rings for the vapor vent pipe. It's about $140 for all of it, not bad.

[99xjsport06]

My 2000 Silverado has had a slow coolant leak for some time, about half a gallon every 3000 miles. Lately it started getting worse and could find no external leak, figured the engine was burning it. Well, I finally decided to put head gaskets on it. Pulled the valve covers and the left valve cover was covered with butterscotch looking snot, oil/water. The passenger side valve cover and valve spring galley were gunked up something terrible. I've been running Mobil 1 for about 25K (115k on truck total) but ran Castrol dino oil before that. Well, cleaned everything up as best I could got it all bolted up and went to change the oil before starting it. PUlled the plug and nothing came out! Had to run a screwdrive up in the drain hole to clear out sludge so it would drain!
Not sure it this is a result of water/Mobil 1 mixing? Or years of Castrol? Never had a problem with Castrol before. Well, I'm at the point now that it will either keep going or some sludge will get in an oil passage and grenade the motor. Hopefully the gaskets fixed the water loss.
By the way, GM sells a top gasket kit that has Head Gaskets, Intake gaskets, exhaust gaskets and o rings for the vapor vent pipe. It's about $140 for all of it, not bad.

Interesting. I've heard mixed results on Castrol, but a lot of good on Mobil 1. I run Mobil 1 in two Jeeps and this truck, and havent had a bit of problems out of the Jeeps (except mine likes to leak a little oil here and there, but they all do that ).

In the case of the truck, I switched it to Mobil 1 roughly about 30K ago (last year) and it now has about 102K on it. Before I started working on it, the oil was changed by the GM Dealer he bought it from every 3-5K (for the most part), with what ever they put in it. His daily commute is 35-40 miles one way, plus whatever errands he has to do after work. So we're lookin at roughly 100 highway miles a day easily. Short distance driving isn't really much of an issue with this one, so I don't really suspect sludge to have built up inside (atleast from short distance driving, from coolant mixing with the oil (if thats the case), then maybe there is some in there).

Still haven't had a chance yet to tear it apart and look at the head and gaskets. I'm back in Charlotte at school as of this week, so my time's even more limited at the moment.

All these 100* days for the last 3 weeks, all we can do is keep coolant in it and hope for the best.