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TSB Mysterious Coolant Leak

JohnBChef

SM 2004
Full Member
Joined
Apr 1, 2004
Messages
1,698
Location
Wake Forest, NC
I have recently been plagued by a coolant leak. Unlike most of the driving public. I enjoy spending time inspecting my truck inside and out from time to time. In search of dreaded Gremlins. They will occasionally grab on to ones vehicle and wreak havoc until they are exposed and killed. Today I have killed another one. I want to share with everyone the results of the autopsy.

? ? ?It is NOT a "Normal" thing for one to lose coolant. It can evaporate a VERY little bit over time but for the most part it will stay at the same normal level for years. When it starts to go down one should mark the bottle and begin a leak detection study first daily then weekly. In the event you have detected a leak this study where you make the coolant levels for a period of time will protect you and your truck from added extra expenses. 98% of the time the root cause of a coolant leak will be a Water pump seal failure roughly around 70,000 miles. It happens. I know this. GM knows this. Any mechanic that has ever worked on the generation III 5.3L engine knows around 70,000 miles your water pump seal will fail. (Incidentally this was supposedly resolved in the generation IV engines) It is also a "Normal" thing for a certain amount of burping to occur shortly after the replacement of a water pump. The 5.3L engine wasn't designed with a pressure relief valve to aid in the relief of air in the normally coolant only environment of the water jacket on your engine. So what will occur for the first couple of weeks after that repair is coolant will be replaced with air in the overflow bottle while it is burping. This is all considered "NORMAL." If you take it back to your dealership they will top it off and all will be well.

? ? ?What happened to me was shortly after the replacement of my coolant pump I continued to leak coolant. Despite it being topped off twice for 3,000 miles. That is well beyond a "NORMAL" period for it to burp. I asked the dealership to conduct a pressure test. They pressurize the system if it holds pressure for an hour it is declared passed. My truck passed. But it was still leaking coolant! I continued my leak study for a couple of more weeks, and was able to calculate a coolant loss of 3-6 oz per week. I was also able to make a correlation between the number of miles I drive VS: the rate of coolant loss. The more I drove The more I lost coolant. That told me that whatever the problem was. It was occurring while it was under pressure. This indicates to me that I have a pinhole leak somewhere in the waterjacket or the cylinder head. Not any of the seals because I can observe them under direct observation. I took it back to my dealership...PROBLEM!!!

? ?I had a GMPP Majorguard Policy that covered me to 76,124 miles. I had the water pump replaced at 74,500 miles. SO it was covered. I now have 78,421 miles so I am now out of warranty. And am looking at a potentially costly leak somewhere in the water jacket of the engine. I return to my dealership. I spoke to the mechanic that fixed the water pump, because at that time he and I were now on first name basis. I asked him to conduct research for a no evidence coolant leak before he started going crazy. I spoke to the management of the dealership. Because I brought the truck to them originally for a "customer complains of coolant loss" they detected the actually leaking water pump. I detected the burping, and made them write it up when they refilled the bottle as a "Customer complains of coolant loss" So now that's 2 documents before the GMPP warranty expires. Once I went over the line and still had a coolant loss they agreed to cover the expenses of the repair and rental car.
Here is the TSB notice the title really closely and you can see it's not very old but no one really knows about it yet...
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GM TSB# 06-06-01-019B (came out 06-12-2007)
Subject: Information on Gradual Coolant Loss Over Time With NO EVIDENCE OF LEAK FOUND

Models:
2004-2006 Buic Rainier
2001-2006 Cadillac Escalade
2001-2006 Chevrolet Avalanche, Blazer, Silverado, Suburban, Tahoe, and Trailblazer
2001-2006 GMC Envoy, Jimmy, Sierra, and Yukon
2001-2005 Oldsmobile Bravada
2005-2006 SAAB 9-7X

With 4.8L or 5.3L VORTEC GenII, GenIV; V8 engine (VIN's V,T,M,M,Z --RPO's LR4, LM7, LH6, L33, and L59

Information:

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.

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.
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? ? ?I do not have pictures available yet. However when the Technician pressurized the system It was clear blatant and obvious exactly where the leak was. Right at the leading edge of the oil drain in the cylinder head. It was as if the pictures in the TSB were taken from my truck. The TSB calls for both cylinder heads to be replaced, and as such they are doing so at no cost to me. I did ask about port and polishing them while they were at it but they politely declined. I will tell you that I do conduct my own oil changes, and I inspect the oil every time. I did not detect any coolant or water in it. Nor did I detect any frothing in the oil a tel-tail signs of coolant in the oil. It was explained to me that what was occurring that a lot of the coolant was evaporating on the coolant head, and the rest a stronger more viscous version of the coolant was leaking back down to the oil so it wasn't churning like one would expect. If I can get some picture I will try my best but I think there is more than enough information to diagnose and resolve this problem. Any questions just ask.
JB
 

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You most likely wouldn't find evidence of water in the oil at the low level of loss you were incurring. As long as you were driving more than short trips, it would be evaporating due to the engine heat.

I worked as Quality Manager for a diecast manufacturer for 6-1/2 years and it's amazing there aren't more complaints about leaks than there are. There is an impregnation process that pulls an anaerobic material into any porous areas in the casting under vacuum. We used this process and were normally able to recover about 50% of the castings that leaked on pressure test. These were machined parts; that's where you normally start finding issues. Once you remove the skin of the casting, you open up a leak path. There are not nearly as many issues with leaks on non-machined castings.
 
? ? ?Okay so I have uploaded a few important photos. I don't want to hear any crap about how dirty my cylinder heads are. I used dino oil for 65,000 miles and switched to Synthetic at the 70k mark... so needless to say Dinosaur oil sucks... I got the pictures to prove it. I think the general uses Castrol... I now use M1. Let's try to remember... New heads Next week. :D... Anyway...Photo #1
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? ? ?This is the overview shot of the 2nd bank passenger side head. Clearly a little dirty.

Photo #2
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? ? ?This is the Castech logo on my cylindar head. If you got one of these you have the potential to fall under this TSB and a potential $1,200 bill from the general to replace it.

Photo#3
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? ? ?If you look directly under where it says GM you can slightly see an almost flouresent orange pool in the oil. that is where the crack is at the oil drain.
HTH
JB
 
    I thought I'd update this thread a little bit... Since Last Friday my new heads arrived. I was told that they were currently in the machine shop. I forget what they are doing to them however I am monitering the dealership very closley. I have some new photos to show everyone. Today I had a very rare oppertunity to get to know the 8 pistons that have been hauling me and the rest of the truck around for the past almost 80,000 miles. Overall they said that they were feeling a bit vulnerable however they are excited about having a new head to work with. I can tell you from first hand knowlege these pictures tell a an interesting tale. I will use up a couple of pusts to get them uploaded then go through them one by one...
JB
 

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man that sucks about the heads..... maybe you could upgrade the rocker arms for little more power... guess maybe i need to switch over to the good oil.. do you have the extened warrenty on the Av? where are you having the work done.. and one more how did find out about the leak waz it gradely going away?...
 
John, please tell me that isn't coolant sitting on top of the pistons in the cylinders.? ?:eek: :eek: :eek: :eek: :eek: :eek: :eek: :eek: :eek:

Vetman
 
Okay A lot of new information today. First let me put 3 pictures in a row so we can get this into perspective...

Bank 2 Passenger Side Where the leak was detected cylinders
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Bank 1 Drivers Side No leak was Positively detected.
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    Once the leak on one side was discovered the Repair in the TSB required replacement of both heads. So no investigative process was started on the drivers side. The technician assumed that it was either bad or going to be bad so replacement of both was warranted... Now take a look at this picture...
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    As I examined these parts one obvious thing came to my attention... If the leak was positively confirmed on the Passenger side Bank 2... Why the HELL are all of the parts from the Drivers side Bank 1 looking so Horrible??? The mechanic stated to me that the coolant acted like a solvent when it was injected up to the cylinder head on the right side cleaning some of it out while it mixed. However when it drained back down the oil pump churned all of that nastiness up and dumped it onto the Left side. Anyone that knows me will testify that I am absolutely anal about preventative maintenance. As I said I bought a maintenance contract when I bought the truck. So for every 5,000 miles I took it to the dealership for regular oil changes up until 65,000 when my contract expired. After that I began to conduct my own oil changes switching from Dinosaur oil to Mobil 1 Extended performance synthetic. So since I took over the oil services I have conducted 2 oil changes. I currently have 78,500 miles. For anyone who is in doubt about switching. Here is your proof after 65,000 miles of regular oil your engine will look like this. It will lose performance, and get gunked up. I now have a uniquely fortunate experience. I get to start all over again.
    So because of this situation I will receive
  • 2 New Cylinder Heads
  • An upper engine rebuild
  • Complete coolant flush
  • Engine oil flush
  • Free oil change

    Questions answered... Moosc, Unfortunately I can't upgrade anything. Since it is being done at a Chevy Dealership Under a GM Warranty. They will only do a one for one replacement on stock parts, consequential damage related to the part failure, and the labor supplies to get the new stuff in there. My total out of pocket cost will be $0. I bought the GMPP Major Guard policy I don't even have a deductable! By the end of this they will be out roughly around $2,500. Yeah that GMPP Major Guard was money well spent for me! The way I found the leak out was just simply looking at the fluid lever on the overflow bottle Normally, for 3 years it never moved then one day I noticed it dropping. You know me I hate mysteries, I hate Gremlins that chew up my trucks vital fluids MORE! I never took "normal" for an answer, and I used broad general terms with my adviser up here to give myself the best chances with them. However it took about 3 months to get it locked down to this. If you read my first post you can see what led to me discovering this.
    Vetman... Yes that is coolant. It was spilled out of the waterjacket when the mechanic removed the head. I wiped it out myself right after I took the picture
 
JohnBChef said:
? ? ?Vetman... Yes that is coolant. It was spilled out of the waterjacket when the mechanic removed the head. I wiped it out myself right after I took the picture

Thank Goodness.

Anytime I've done a tear down like that I've always coated the upper cylinders with motor oil. Keeps them from rusting..
Hopefully your mechanic is planinng to do a upper cylinder polish before putting everything back together.
 
    Good question Steve. I was planning another suprise visit tomorrow. I'll find out then. Either way I want to see the old heads so I can see what the underside looked like!
 
That is A LOT of sludge build up in the Lifter valleys and on the rockers, when i took apart that 6.0L motor I had with 90,000+ miles on it it was cleaner then that looks... I hope that was some how related to the leak...

If they everything right she will be good to go and ready to play... Its too bad you couldn't get it bored our to a 5.7L while they were at it.  >:D
 
Finally I got a call back from my dealership here in Baltimore telling me my truck was ready. Sure it was at 8:00am, and he woke me up but he had good news. Apparently the mechanic that has been working on my truck decided to come into work on Saturday his day off to finish my truck. When the Service writer came to work he found the incomplete paperwork on his desk with a sticky saying the job was done. You know me I double check everything!
    When I got there the first thing I did was ask to see the old heads. I examined them and shot photos of them to be included in this thread. Next I confirmed that the new heads were installed, and they weren't re-manufactured heads. They were new. I checked the oil. It was new, fresh, and full. The coolant level was full. I started the engine. I set 2 traps to verify that the maintenance was done correctly. #1 I zerowed out the bread crumbs on the nav system so I would be able to retrace the driving that my truck did while at the dealership. The second thing was I cut off the charging to the 2nd battery. The Electric fans draw power exclusively from the 2nd battery the reduced state of charge would give me a general idea of if the restart was done correctly. The GPS indicated the mechanic completed a 15 mile circuit around the dealership. There was varied terrain, and speed on it. The state of charge on the 2nd battery was 12.89V on Friday it was 11.34V when I picked it up. So I have enough information that it idled in the service bay for about 20 minutes then went on a 25 minute test drive.
    I can say that the mechanic that worked on my truck did a pretty good job on it. I don't doubt that he was prudent with the work he did. One of the hardest things for any vehicle owner is sending your truck in for a major repair. When I lived in Florida I had a really great dealership there. Maroone Chevy Green Acres. Dangerranger works there I had good rapport with most of the technicians. They knew me, they knew my truck. The treatment my truck received was as good as me just doing it myself. When you go on the road you never know how you will be treated. I would say that Fox Chevrolet in Timmonium, MD treated me fair. Once they knew I wasn't gonna give up on my truck they started to treat me better. I would say that they represent the average dealership. By average I mean they try to help their customers within the guidelines that General motors sets. Your better dealerships do that, and give a little more here and there to make sure their customers feel like they are real people not another person to deal with. Me just bypassing the service writer made things easier because their service writers aren't very knowledgeable on the mechanics on our trucks especially when tested. On the cars I would say they are very good. Most of their work in the service bay is related to fixing broken Baltimore city, Baltimore county, and MTA Impala Police Package cars. Apparently they are a little hard on the suspension and cooling systems in Baltimore (damn pot holes). In Florida, my service writer knows Avalanches as good or better than me. I know that, and that's what keeps me going back. I feel that if I hadn't been pro-active on trying to figure this problem I would have gotten SCREWED BIG TIME! All said and done the Bill was $3359 at the dealership. I paid them $0. Obviously I could have done this repair myself for a lot cheaper and I would have installed upgraded parts, but when you can get The General to pay for it. GO THAT ROUTE!
    With that said I have 8 pictures to upload... These are the The tops of the heas on the Left side of the truck...Here we go!
 

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Cylinder Head Right Side of the truck where the leak was confirmed
 

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Cylinder Head Right Side of the truck where the leak was confirmed
 

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I'd say my conclusions are the underside of the heads indicate everything is pretty normal. I think once I put in the Thundervolt plug wires, and the new NGK plugs this weekend it should get a little bit hotter and keep things a little bit cleaner. The oil galleries on top of the heads are much dirtier on the side that did not have the leak on it. Now they are gone. I received a new oil change and I will change it out in 1,200 miles back to synthetic. If during that oil change the oil is pretty crapped out I will begin a series of engine oil treatments, and increase my oil change interval from 5,000 miles to 2,000miles between oil changes for a couple of changes then bump it slowly back to 5,000. I hope this thread is informative, and when this happens to someone else they will take this information and get a good outcome.
JB
 
Great job JB..  I know Jack will be excited to have his truck back soon, and in great working order..

Hugz
 
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