2004 5.3 Suburban Z71 4x4

[usamarshal]

Getting po171 and 174 codes. Also losing coolant, but unable to locate source of coolant loss. Had a 2000 Tahoe that had the same problem and had to replace the upper/lower intake manifold gaskets. I'm guessing I'm having the exact same problem with the suburban. Is this a common thing with the tahoes/suburbans? Anyway just want to see if everyone else thinks and if this is most likey my problem. Still getting good gas mileage and power....nothing is off...just getting those codes from time to time and losing coolant, but unable to find the leak. Thanks for any info/help.

[usamarshal]

Well...the check engine light went off...guess the codes aren't there after all...still pretty sure it may be a bad intake gasket...probably the lower gasket.

[migs_auto]

Just so's you know. According the Chevy Techs a batch of 2004 5.3's had heads that were prone to develop cracks. I know, I had one. Coolant problem started at about 75 K miles. Slow at first and it never really showed up in oil. Then engine started to burn oil. 1 qt every 2 k miles after never losing more than .5 qt per oil change. Finally brought it in (just barely still under extended warranty) and they replaced both heads. They pressure tested first and it held pressure. But, apparently they had seen this before and went with their instincts. New heads for a year now and haven't added coolant since.

[usamarshal]

The head gaskets?

Originally Posted by migs_auto

Just so's you know. According the Chevy Techs a batch of 2004 5.3's had heads that were prone to develop cracks. I know, I had one. Coolant problem started at about 75 K miles. Slow at first and it never really showed up in oil. Then engine started to burn oil. 1 qt every 2 k miles after never losing more than .5 qt per oil change. Finally brought it in (just barely still under extended warranty) and they replaced both heads. They pressure tested first and it held pressure. But, apparently they had seen this before and went with their instincts. New heads for a year now and haven't added coolant since.

[j cAT]

Originally Posted by usamarshal

The head gaskets?

some 5.3L engines where made by a contractor that screwed up..they leak coolant threw a crack into the oil drain back hole.heads have markings with covers removed to id the fabricator.

heads are dumped .

usually loss of coolant no DTC is the water pump gaskets ...this is when non dexcool is used , also if distilled water is NOT used with dexcool..


metal gets vaporized by volts in the coolant system ///coolant becomes acidic/conductive ............NOT GOOD !

[usamarshal]

Jesus....so if GM knows about this would they let the owners of these vehicles know? If I provide GM my vin number do you think they'll know if I got the shit heads or not? Right now I have no coolant in my oil.

Originally Posted by j cAT

some 5.3L engines where made by a contractor that screwed up..they leak coolant threw a crack into the oil drain back hole.heads have markings with covers removed to id the fabricator.

heads are dumped .

usually loss of coolant no DTC is the water pump gaskets ...this is when non dexcool is used , also if distilled water is NOT used with dexcool..


metal gets vaporized by volts in the coolant system ///coolant becomes acidic/conductive ............NOT GOOD !

[j cAT]

Originally Posted by usamarshal

Jesus....so if GM knows about this would they let the owners of these vehicles know? If I provide GM my vin number do you think they'll know if I got the shit heads or not? Right now I have no coolant in my oil.

GM will give you a notice about vehicle issues when a few owners have been Killed or injured. since this is a non safety problem you will never know about any defects GM has discovered ...

you ever get the gm notice about the DEXRON III ?

in about 2005/6 GM decided this fluid is costing them too much in warantee repairs gm now requires dexron VI !

GM does not license any products now that claim to be dexron III !

like I stated earlier ////coolant leak with no evidence of leak source is the water pump gasket area, could be water pump weep hole !

[usamarshal]

Will do man...anyway to see if there is fluid coming from the weep hole?

Originally Posted by j cAT

GM will give you a notice about vehicle issues when a few owners have been Killed or injured. since this is a non safety problem you will never know about any defects GM has discovered ...

you ever get the gm notice about the DEXRON III ?

in about 2005/6 GM decided this fluid is costing them too much in warantee repairs gm now requires dexron VI !

GM does not license any products now that claim to be dexron III !

like I stated earlier ////coolant leak with no evidence of leak source is the water pump gasket area, could be water pump weep hole !

[migs_auto]

I never saw coolant in my oil (milky oil, milkshake) but, when they took the valve covers off - it was the nastiest crap I have ever seen. I change my oil religiously with Syntec. But the crap I saw underneath the cover looked like I had never changed to oil. Dealer even accused me of it until I produced receipts and a diary. Really ticked me off but at least i was still under warranty (just barely). Good luck usamarshal.

[mishalah]

Originally Posted by migs_auto

I never saw coolant in my oil (milky oil, milkshake) but, when they took the valve covers off - it was the nastiest crap I have ever seen. I change my oil religiously with Syntec. But the crap I saw underneath the cover looked like I had never changed to oil. Dealer even accused me of it until I produced receipts and a diary. Really ticked me off but at least i was still under warranty (just barely). Good luck usamarshal.

Sounds like Toyota sludge. Strange. You'd better do some research on whether this is common or just a fluke.

[j cAT]

Originally Posted by mishalah

Sounds like Toyota sludge. Strange. You'd better do some research on whether this is common or just a fluke.

this is no fluke these heads are real ...they are costing owners big bucks ! If he makes the effort he will find the heads listed and pictures of the markings ID ing these defective heads.

when the dealer tech see's the mark they just trash them.

if synthetic oil is used the water will not mix with the oil. but the coolant will get injested into the intake , trashing the O2 sensors..then the cat converters get trashed..

[usamarshal]

I guess I'll ask the dealership about it...see what they say...is there anyway I can check for the markings/ID? Thanks again.

Originally Posted by j cAT

this is no fluke these heads are real ...they are costing owners big bucks ! If he makes the effort he will find the heads listed and pictures of the markings ID ing these defective heads.

when the dealer tech see's the mark they just trash them.

if synthetic oil is used the water will not mix with the oil. but the coolant will get injested into the intake , trashing the O2 sensors..then the cat converters get trashed..

[j cAT]

Originally Posted by usamarshal

I guess I'll ask the dealership about it...see what they say...is there anyway I can check for the markings/ID? Thanks again.

go here !

http://www.agcoauto.com/content/news/p2_articleid/148

[mishalah]

OMG!!! Any chance my '05 could be affected? Should we all give our VINS to the local dealerships and find out??

[j cAT]

Originally Posted by mishalah

OMG!!! Any chance my '05 could be affected? Should we all give our VINS to the local dealerships and find out??

If you read this article you will see that your vehicle may be affected ! not all engines had heads made by this contractor how many made ? GM top secret !

also GM will as usual will put the screws to you...should you have their defective product ! This is the type of proceedure [designed to fail] GM did to get themselves into bankruptcy...

did you check the water pump leak area ? weep hole/gaskets of the water pump ? Is your coolant clear pink or darker cloudy ? coolant should be tested for acid build up..if so ..


do you have an oil consumption problem ? or engine noises ? if so I would remove the valve covers and inspect for the defective heads..

you now have the documents needed to determine all this !