Head Change At 104k, Need Some Wisdom

gamc · January 2, 2010

Ok fellows I need some wisdom. I got bit by the leaky Castech heads at 104K on a 04 Sierra Z71. I'll have a set of replacement heads on Mon. My question is this, back in the day when ever you freshened heads on a well used bottom end you could expect oil consumption,is this still the case with these newer engines ? I have always run 5w-30 Mobil 1 and a quart of Lucas synthetic in this engine with no oil usage between the 5k change interval. I only noticed oil consumption about the time I suspect the heads started "weeping" at the rate of a pint per 1k. I figure I ran these POS heads about 4-5k before I pulled it down.

Would switching to a heavier weight help if it does turn out to be a problem ? What is the down side to running heavier weight with the "newer" style babbit material in the bearings ? I know these ?'s sound basic but I ran a diesel for 20 yr's and only went to a lighter truck about 3 yr's ago.

Thanks GKM

Nytemare · January 2, 2010

Ok fellows I need some wisdom. I got bit by the leaky Castech heads at 104K on a 04 Sierra Z71. I'll have a set of replacement heads on Mon. My question is this, back in the day when ever you freshened heads on a well used bottom end you could expect oil consumption,is this still the case with these newer engines ? I have always run 5w-30 Mobil 1 and a quart of Lucas synthetic in this engine with no oil usage between the 5k change interval. I only noticed oil consumption about the time I suspect the heads started "weeping" at the rate of a pint per 1k. I figure I ran these POS heads about 4-5k before I pulled it down.
Would switching to a heavier weight help if it does turn out to be a problem ? What is the down side to running heavier weight with the "newer" style babbit material in the bearings ? I know these ?'s sound basic but I ran a diesel for 20 yr's and only went to a lighter truck about 3 yr's ago.

Thanks GKM

I would say you will be fine man. I have done lots of head jobs on newer vehicles and the only time you get oil consumption, usually, is when the owner of the vehicle is too cheap to spend the 50 bucks or less on new valve stem seals. Invest in a good gasket set though...no use having to do it again in another 30-50K.

I would switch to a high mileage oil...I believe M1 makes one...and that's about all I would do... If you do see a little more than average oil consumption...than switch to an M1 semi-synth for high millage.

gamc · January 2, 2010

Ok fellows I need some wisdom. I got bit by the leaky Castech heads at 104K on a 04 Sierra Z71. I'll have a set of replacement heads on Mon. My question is this, back in the day when ever you freshened heads on a well used bottom end you could expect oil consumption,is this still the case with these newer engines ? I have always run 5w-30 Mobil 1 and a quart of Lucas synthetic in this engine with no oil usage between the 5k change interval. I only noticed oil consumption about the time I suspect the heads started "weeping" at the rate of a pint per 1k. I figure I ran these POS heads about 4-5k before I pulled it down.
Would switching to a heavier weight help if it does turn out to be a problem ? What is the down side to running heavier weight with the "newer" style babbit material in the bearings ? I know these ?'s sound basic but I ran a diesel for 20 yr's and only went to a lighter truck about 3 yr's ago.

Thanks GKM

I would say you will be fine man. I have done lots of head jobs on newer vehicles and the only time you get oil consumption, usually, is when the owner of the vehicle is too cheap to spend the 50 bucks or less on new valve stem seals. Invest in a good gasket set though...no use having to do it again in another 30-50K.

I would switch to a high mileage oil...I believe M1 makes one...and that's about all I would do... If you do see a little more than average oil consumption...than switch to an M1 semi-synth for high millage.

Thanks Mate, I run a lot of road mileage as much as 7-800 miles a clip and really want to run this truck another couple of years. I'm just really po'd about the heads though, I have overdone the PM on this rig and still got bit. The nagging worry is how long I ran the thing with coolant dilution in the oil. Da** !

Nytemare · January 2, 2010

If your really worried about it...drop the pan and replace all the bearings...depends on how much coolant was in the oil...we sometimes do this at the shop. If it was very little..the oil was basically 99% oil, and only had a little snot in it, I would run a liter (quart) of ATF through the crank case for 100 km or so, just to clean everything out. Basically dump your oil, fill it up minus 1 liter and top it off with a liter of ATF. Drive it like this for 100km than dump your oil again and fill it with new oil and a new filter....I would use some good Dino oil for the flush though....no use spending the extra cash on M1. Than when its all done put your M1 back in.

The shitty part is that some of the heads are defective...an no amount of PM can correct that.