Hey Vortec Guys! / Sierra pickup / Suburban / Yukon etc - Finally has Index!
- Thread starter rayra
- Start date
rayra
Expedition Leader
"I've got a bad feeling about this..."
/said every Star Wars character ever
http://tahoeforum.com/archive/index.php/t-15467.html
-----------------------
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.
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.
© Copyright General Motors Corporation. All Rights Reserved.
Document ID# 1986750
/said every Star Wars character ever
http://tahoeforum.com/archive/index.php/t-15467.html
-----------------------
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.
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.
© Copyright General Motors Corporation. All Rights Reserved.
Document ID# 1986750
Last edited:
rayra
Expedition Leader
I'm going to keep researching this, but I've got a 150mi drive to make Friday morning. So I'm packing 5gal MWC, maybe a gallon of coolant, probably some Alumnaseal. Just in case.
https://www.google.com/search?q=identifying+a+castech+head+on+LM7+motor&ie=utf-8&oe=utf-8
Here's a good topic with the info for identifying the problematic Castech heads.
http://speedtalk.com/forum/viewtopic.php?f=1&t=28519
Castech company logo -
"
Re: GM Casting defect with LS heads
Postby Rizzle » Thu Oct 13, 2011 10:19 am
Its only the castech 706 5.3/4.8 head that has issues that I know of. Not all 706's are made by castech though so you have to pull the valve covers and check.
"
========
http://forum.73-87chevytrucks.com/smforum/index.php?topic=23211.15
"An 03 usually has 12559862 heads. Are they 12561706 heads, the early ones are the only ones I have heard with issues." <----- so there's the casting number to look for.
That topic also have images of where the casting number is as well as a visual of what the 'clean' oil drains will look like.
I didn't notice anything in particular when I changed my valve cover gaskets a couple months ago, but I wasn't looking for this. Nor was I experiencing any sort of unexplained coolant loss then.
And I still have my oil pan gasket and oil pickup tube o-ring to change, which will give me a real look at what's going on in there.
On the plus side, I'm seeing a bunch of comments that replacement heads are inexpensive. I won't enjoy doing the work, but I can.
-----
appears 706 and 862 heads are the same. Looks like reman 706 are $350-400/pair. plus core of $100 ea
http://www.performancetrucks.net/forums/internal-engine-modifications-158/862-vs-706-heads-434041/
Casting Number 706 and 862
Head: 1999+ LM4 4.8L / LM7 5.3 Liter Truck
Material: Aluminimum
Part Number:
12559862
12561706
Combustion Chamber Volume: 61.15cc
Compression Ratio: 9.5:1
Intake Port Volume: 200cc
Exhaust Port Volume: 70cc
Intake Valve Diameter: 1.89 inches
Exhaust Valve Diameter: 1.55 inches
--------------
Seeing a couple references to this eBay seller, who has a huge positive feedback. $374 for remanf 862 heads.
http://www.ebay.com/itm/REBUILT-4-8-5-3-GM-GMC-TAHOE-CYLINDER-HEADS-862-CASTING-NUMBER-/272318344374
Same vendor has 706 remanfs for $350
http://www.ebay.com/itm/REBUILT-4-8...VERADO-SUBURBAN-YUKON-1999-2007-/351792068129
Getting ahead of myself on heads. But doesn't seem likely that it's anything else, right now. We shall see.
https://www.google.com/search?q=identifying+a+castech+head+on+LM7+motor&ie=utf-8&oe=utf-8
Here's a good topic with the info for identifying the problematic Castech heads.
http://speedtalk.com/forum/viewtopic.php?f=1&t=28519
Castech company logo -
"
Re: GM Casting defect with LS heads
Postby Rizzle » Thu Oct 13, 2011 10:19 am
Its only the castech 706 5.3/4.8 head that has issues that I know of. Not all 706's are made by castech though so you have to pull the valve covers and check.
"
========
http://forum.73-87chevytrucks.com/smforum/index.php?topic=23211.15
"An 03 usually has 12559862 heads. Are they 12561706 heads, the early ones are the only ones I have heard with issues." <----- so there's the casting number to look for.
That topic also have images of where the casting number is as well as a visual of what the 'clean' oil drains will look like.
I didn't notice anything in particular when I changed my valve cover gaskets a couple months ago, but I wasn't looking for this. Nor was I experiencing any sort of unexplained coolant loss then.
And I still have my oil pan gasket and oil pickup tube o-ring to change, which will give me a real look at what's going on in there.
On the plus side, I'm seeing a bunch of comments that replacement heads are inexpensive. I won't enjoy doing the work, but I can.
-----
appears 706 and 862 heads are the same. Looks like reman 706 are $350-400/pair. plus core of $100 ea
http://www.performancetrucks.net/forums/internal-engine-modifications-158/862-vs-706-heads-434041/
Casting Number 706 and 862
Head: 1999+ LM4 4.8L / LM7 5.3 Liter Truck
Material: Aluminimum
Part Number:
12559862
12561706
Combustion Chamber Volume: 61.15cc
Compression Ratio: 9.5:1
Intake Port Volume: 200cc
Exhaust Port Volume: 70cc
Intake Valve Diameter: 1.89 inches
Exhaust Valve Diameter: 1.55 inches
--------------
Seeing a couple references to this eBay seller, who has a huge positive feedback. $374 for remanf 862 heads.
http://www.ebay.com/itm/REBUILT-4-8-5-3-GM-GMC-TAHOE-CYLINDER-HEADS-862-CASTING-NUMBER-/272318344374
Same vendor has 706 remanfs for $350
http://www.ebay.com/itm/REBUILT-4-8...VERADO-SUBURBAN-YUKON-1999-2007-/351792068129
Getting ahead of myself on heads. But doesn't seem likely that it's anything else, right now. We shall see.
Last edited:
Stryder106
Explorer
Interesting, I hadn't heard of this issue before. My 02 Avalanche does suffer some minor coolant loss, but no leaks, nothing out of the tail pipe, nothing in the oil. Now I wonder if I have these heads and this issue................would GM have to honor a head replacement for a defect on a 14 year old Avalanche with 172K miles on it?
rayra
Expedition Leader
Pretty much doubt it. Well beyond any warranty or assurance. I'm at 14yrs and 130k, I expect nothing.
well I went and looked, as anticipated, I've got the 706 heads. If I get up early enough to beat the heat, I might go pull the passenger valve cover and look for the identifying mark or any sign of coolant intrusion. Still no sign in the oil. I'm definitely going to take it a lot easier on the highway until I know one way or another.
The head number is on the bottom right sharp corner, adjacent to the valve cover as you look down on it from the side of the vehicle.
eta
hell if I have to pull the heads and I still haven't got around to the bottom end / oil pan gasket work, there'd be no better time to pull the guts for a rebuild. But I can't afford that in either inconvenience or cost.
well I went and looked, as anticipated, I've got the 706 heads. If I get up early enough to beat the heat, I might go pull the passenger valve cover and look for the identifying mark or any sign of coolant intrusion. Still no sign in the oil. I'm definitely going to take it a lot easier on the highway until I know one way or another.
The head number is on the bottom right sharp corner, adjacent to the valve cover as you look down on it from the side of the vehicle.
eta
hell if I have to pull the heads and I still haven't got around to the bottom end / oil pan gasket work, there'd be no better time to pull the guts for a rebuild. But I can't afford that in either inconvenience or cost.
Last edited:
This is a common problem if you can confirm you've got an affected truck. Put some dexcool approved stop leak and it will stop. My other truck had over 100k after use the stop leak and it never started leaking again. I never confirmed if I had the casting mark.
https://www.amazon.com/Genuine-3634621-Cooling-System-Tablet/dp/B000QIH3C4
https://www.amazon.com/Genuine-3634621-Cooling-System-Tablet/dp/B000QIH3C4
rayra
Expedition Leader
Well that's certainly good news / nice to hear. Beats hell out of changing heads or smoking my bearings.
I read a reference to those and that they were essentially ground walnut shell. I've used alumnaseal before to good effect on an old Chevy Luv motor that was developing a head gasket leak. inline four, aluminum head, iron block. Was a 'temporary' fix that held for over a year, until I found a different way to burn up the motor. I was hell on that thing back then. Did a hell of a lot of 'four-wheelin' with that one-legger. Learned all about momentum and power curves, mostly the hard way.
eta the more I look at this stuff, the more it doesn't look a damned bit different from the ground walnut shells that are sold as 'lizard bedding' in pet stores. And I got turned onto that as a cheap alternative to the crushed walnut shells sold for tumbling brass in ammunition reloading.
I read a reference to those and that they were essentially ground walnut shell. I've used alumnaseal before to good effect on an old Chevy Luv motor that was developing a head gasket leak. inline four, aluminum head, iron block. Was a 'temporary' fix that held for over a year, until I found a different way to burn up the motor. I was hell on that thing back then. Did a hell of a lot of 'four-wheelin' with that one-legger. Learned all about momentum and power curves, mostly the hard way.
eta the more I look at this stuff, the more it doesn't look a damned bit different from the ground walnut shells that are sold as 'lizard bedding' in pet stores. And I got turned onto that as a cheap alternative to the crushed walnut shells sold for tumbling brass in ammunition reloading.
Last edited:
rayra
Expedition Leader
http://www.thedieselpageforums.com/tdpforum/archive/index.php/t-3012.html
"7.4 VORTEC
01-22-2006, 05:55 PM
I met with Bars Leak at the Apex/SEMA show this last November just to ask the tech guys whats the best product in their lineup to use. I don't sell any type of sealants, but wanted to know whats the best system for a 6.5 TD Hummer. I originally "learned" about the pills from a Caddy STS owner who corresponds with one of the Northstar motor development engineers. These guys just love the Bars Leak pills. The same product can also be bought in powder form from Walmart in a clear tube. It's called Bars Leak Golden Seal. It actually looks a lot like dirt. In talking to the engineer at Bars Leak, it does appear that two of the major components are crushed walnut shells and ginger. The pill form is more concentrated and in my opinion easier to get into the radiator neck if its a tight squeeze.
I don't remember the exact amount, but the powder is not as dense so a little more is needed. But, in my opinion, I would not use any of the "aluminumized" type of sealants except in a dire emergency.
I use the "golden seal" product in all my cars as part of normal maintenance. I do drain and flush the coolant with distilled water every 2 years or so and add antifreeze and the bars leak golden seal. In talking about putting "too much" golden seal into the system, the engineer at Bars Leak said that unless you have other problems (clogged cooling tubes, etc), you'll never really see a problem. This is one of the things they actually tested. From talking to the engineer, many manufacturers add the pills to the cars as a normal part of the cooling system.
Bars Leak was one of the few companies at SEMA that actually had engineers working the booth to answer questions. (not just a sales guy) I was extremely happy with the engineers knowledge and the ability to answer my questions. This guy was very knowledgable regarding the problems of the 6.5 TD and Northstars Caddy motor. Within 5 days of the show, I had a complete engineering packet regarding the Bars Leak pills sent to my office. I would not have any reservations using the golden seal powder or pills. Very impressive company.
George"
"7.4 VORTEC
01-22-2006, 05:55 PM
I met with Bars Leak at the Apex/SEMA show this last November just to ask the tech guys whats the best product in their lineup to use. I don't sell any type of sealants, but wanted to know whats the best system for a 6.5 TD Hummer. I originally "learned" about the pills from a Caddy STS owner who corresponds with one of the Northstar motor development engineers. These guys just love the Bars Leak pills. The same product can also be bought in powder form from Walmart in a clear tube. It's called Bars Leak Golden Seal. It actually looks a lot like dirt. In talking to the engineer at Bars Leak, it does appear that two of the major components are crushed walnut shells and ginger. The pill form is more concentrated and in my opinion easier to get into the radiator neck if its a tight squeeze.
I don't remember the exact amount, but the powder is not as dense so a little more is needed. But, in my opinion, I would not use any of the "aluminumized" type of sealants except in a dire emergency.
I use the "golden seal" product in all my cars as part of normal maintenance. I do drain and flush the coolant with distilled water every 2 years or so and add antifreeze and the bars leak golden seal. In talking about putting "too much" golden seal into the system, the engineer at Bars Leak said that unless you have other problems (clogged cooling tubes, etc), you'll never really see a problem. This is one of the things they actually tested. From talking to the engineer, many manufacturers add the pills to the cars as a normal part of the cooling system.
Bars Leak was one of the few companies at SEMA that actually had engineers working the booth to answer questions. (not just a sales guy) I was extremely happy with the engineers knowledge and the ability to answer my questions. This guy was very knowledgable regarding the problems of the 6.5 TD and Northstars Caddy motor. Within 5 days of the show, I had a complete engineering packet regarding the Bars Leak pills sent to my office. I would not have any reservations using the golden seal powder or pills. Very impressive company.
George"
rayra
Expedition Leader
That image is basically upside down to how you view the heads on the motor.
Here's an internet pic of the failure
Here's a better pic of the castech logo's location. Unfortunately it it completely under the transverse bar / plate that underlays all the rockers. You'd basically have to pull the valve train to see the logo.
I fired up my truck just long enough to pull it into the driveway from the street. Only took a couple minutes to remove the passenger side coil pack plate - partly because after struggling for a while to remove its end bolt hard up against the firewall - had to remove the #8 coil pack to get to the plate bolt with any room to work it loose - I went ahead and left that bolt out completely when I put things back together. It's a stout plate and four other bolts (10mm) hold it to the valve cover. So this time the four easier bolts come right out in a jiffy.
Likewise the 8mm valve cover bolts were easy, as I'd only replaced the valve cover gasket sets a few thousand miles ago.
Off came the valve cover and I did catch a glimpse of some 'magic smoke' escaping. Didn't smell the sickly sweet smell of coolant, though. Probably oil vapor. Probably.
And after all that I found the dreaded CasTech logo.
So at this point it sure looks like the known low coolant issue. A mixed blessing / curse. After much reading last night, I'd rather it be this than a failed head gasket.
At this point my intent is to hunt down the preferred stop leak stuff. Tomorrow morning I'll drain off a bunch of fluid, get the stop leak well in there, top it back off and go drive the hell out of it for a while. I might pull the plugs to look for signs of a failing head gasket, rust, brown spotting, etc.
And after that test drive to 'set' the stop leak where it needs to be, I'll probably change the oil before my road trip, just to preclude any problem with lubricity.
Last edited:
That image is basically upside down to how you view the heads on the motor.
Here's an internet pic of the failure
Here's a better pic of the castech logo's location. Unfortunately it it completely under the transverse bar / plate that underlays all the rockers. You'd basically have to pull the valve train to see the logo.
I fired up my truck just long enough to pull it into the driveway from the street. Only took a couple minutes to remove the passenger side coil pack plate - partly because after struggling for a while to remove its end bolt hard up against the firewall - had to remove the #8 coil pack to get to the plate bolt with any room to work it loose - I went ahead and left that bolt out completely when I put things back together. It's a stout plate and four other bolts (10mm) hold it to the valve cover. So this time the four easier bolts come right out in a jiffy.
Likewise the 8mm valve cover bolts were easy, as I'd only replaced the valve cover gasket sets a few thousand miles ago.
Off came the valve cover and I did catch a glimpse of some 'magic smoke' escaping. Didn't smell the sickly sweet smell of coolant, though. Probably oil vapor. Probably.
And after all that I found the dreaded CasTech logo.
So at this point it sure looks like the known low coolant issue. A mixed blessing / curse. After much reading last night, I'd rather it be this than a failed head gasket.
At this point my intent is to hunt down the preferred stop leak stuff. Tomorrow morning I'll drain off a bunch of fluid, get the stop leak well in there, top it back off and go drive the hell out of it for a while. I might pull the plugs to look for signs of a failing head gasket, rust, brown spotting, etc.
And after that test drive to 'set' the stop leak where it needs to be, I'll probably change the oil before my road trip, just to preclude any problem with lubricity.
Sounds like a good plan. If it makes you feel better, the one truck I had this happen to (actually was my parents', but me being the car guy, when I came of age, all maintenance decisions was placed to me) had this start to leak around 90-100k miles. My parents simply topped off the coolant with distilled water every gas tank, and did this for ~50k miles. Only when I took over maintenance did I look for other solutions, and came by the stop leak stuff. Before sold, it was at 220k+ miles with no forseen problems from having the coolant leaking like that for many miles.
rayra
Expedition Leader
That's more excellent news, thanks. One thing I like about this community of older Suburban users is the sort of 'preview of coming attractions' it provides. It's all folks who are pretty much using their Sub as I do. So I'm always curious about the mileages and conditions of the troubles that occur. And it's no small part of why I started this topic, especially as I learned about some of the known issues with these drivetrains.
Got the Delco stuff at my local Chevy dealer, miraculously LESS than the expected MSRP, $4+. It's (5) 4 gram tablets, about the size of a stack of nickels. Basically sized to just fit down the gullet of the modern recovery tanks. 1-1.5g per quart of coolant capacity and instructions say just drop the pellets in. Book capacity says 16.7qts. So basically put the whole package in.
I went ahead and got two packages, will put the second with my roadside emergency stuff. Or maybe in the Tahoe. Will have to remember to look at that head casting number tonight.
Got the Delco stuff at my local Chevy dealer, miraculously LESS than the expected MSRP, $4+. It's (5) 4 gram tablets, about the size of a stack of nickels. Basically sized to just fit down the gullet of the modern recovery tanks. 1-1.5g per quart of coolant capacity and instructions say just drop the pellets in. Book capacity says 16.7qts. So basically put the whole package in.
I went ahead and got two packages, will put the second with my roadside emergency stuff. Or maybe in the Tahoe. Will have to remember to look at that head casting number tonight.
justcuz
Explorer
It would have been nice to know when I did my daughters Tahoe. Good thing is I did her heads at around 130,000 miles and when I pulled the heads the cylinders still had cross hatching in them.
LS engines are pretty damn durable.
Sorry about bringing this subject up, but the coolant loss needs to be addressed.
I think a pressure tester may force some coolant out when cold to expose the cracks. Mine had discoloration that was easy to see.
LS engines are pretty damn durable.
Sorry about bringing this subject up, but the coolant loss needs to be addressed.
I think a pressure tester may force some coolant out when cold to expose the cracks. Mine had discoloration that was easy to see.
Stryder106
Explorer
This thread is great - I just bought some of the AC Delco sealant off of eBay for $5. Amazon wanted $5 +$5 shipping, Jegs wanted $5 +$8 handling, and my local GM dealer didn't have any.
rayra
Expedition Leader
Well I gave a close look to the expected locations in the passenger side head while I had the valve cover off this morning, no clear sign. In fact overall the head was pretty darn clean for 130k mi. Should have taken a picture. And I'll probably inspect the driver side oil drains and pull the plugs too, maybe Thurs am. But maybe not until after this weekend's trip. Which might wind up being very foolish of me. But tomorrow a.m. I'm draining some fluid out, adding the pellets and some fresh coolant then I'm going on a 50-75mi jaunt on local highways. Then see how things are at the end and after it sits a bit. And then I'm changing the oil before the road trip. More cheap insurance.
I've still got an oil pan gasket change to make on this vehicle and had been intending to run a quart of engine flush thru it before I did so. But I've been waiting for the hot weather to break. It was a tiresome chore on the Tahoe, although not really that difficult. But I'm still leaking oil from my mistake of switching to synthetic. And I might not really need the flush, given how clean the top of the heads look. If it's that clean in the hot zone up top, not likely there's any sludge in the sump. I've been running either valvoline or penzoil in it since I got it 2yrs ago. Plenty of detergents in those.
Just annoyed that I'm not even completely finished with my storage platform build and just about to begin a bunch of electrical mods and have this plop in my lap. And find out about another known issue on these motors. I seem to be checking all the trouble boxes. Makes me worry about my plans for towing my neighbor's Evolution 2 popup camper this winter. I'm not even looking funny at my transmission.
/happy thoughts happy thoughts
I've still got an oil pan gasket change to make on this vehicle and had been intending to run a quart of engine flush thru it before I did so. But I've been waiting for the hot weather to break. It was a tiresome chore on the Tahoe, although not really that difficult. But I'm still leaking oil from my mistake of switching to synthetic. And I might not really need the flush, given how clean the top of the heads look. If it's that clean in the hot zone up top, not likely there's any sludge in the sump. I've been running either valvoline or penzoil in it since I got it 2yrs ago. Plenty of detergents in those.
Just annoyed that I'm not even completely finished with my storage platform build and just about to begin a bunch of electrical mods and have this plop in my lap. And find out about another known issue on these motors. I seem to be checking all the trouble boxes. Makes me worry about my plans for towing my neighbor's Evolution 2 popup camper this winter. I'm not even looking funny at my transmission.
/happy thoughts happy thoughts
Similar threads
