2004 5.3 smokes on startup and burning oil

[nvsierra04]

I have a 2004 Sierra (Z71) has 222,000 on it. Anytime the truck sits for a couple hours or more it has a big cloud of white smoke come out tail pipe. It goes away and seems to run good. Been told it sounds like valve seals, but also since its high mileage and burning a quart about 400 miles its probably best to replace motor. Need some good solid advice. Rebuilts running between 3K and 4K.

[nvsierra04]

May actually be 1000 miles before i need a quart but that also seems a bit too much.

[txab]

Yep. Primarily valve guide seals. 1 qt in 1000 miles is not bad when you see guys in newer 900 series trucks burning that much in that kind of mileage.

 

You could always look into a junkyard motor for an upgrade. Or just replace valve guide seals and see what difference it makes

[nvsierra04]

Yeah i been lucky all this time i guess. I hear different things about the amount of oil burning...I think if i had to replace motor id bite the bullet and get a rebuilt though. Sounds like i should give the valve seals a shot and hope for some improvement. Thanks

[Doug_Scott]

You should make sure it is oil burning smoke you are seeing first. Does the smoke float away, or does it disappear like steam would? Generally worn valve seal or guides will give a puff of blue smoke on both startup and on older vehicles, deceleration. Try getting your truck hot, then go somewhere where you have lots of room and no other traffic. Put the truck in low gear with the shifter, accel up to about 4k rpm and let off the gas. Worn guides or seals will show oil smoke if you do this. Not likely to see it from drivers seat though, you may need someone to follow you, or leave someone on the side of the road and do a drive by.

 

At 225k miles, changing seals may not do much but remove some dollars from your wallet. Not sure what valve springs are like in the LS engines, but, if they have just normal coil type springs, including inner springs, you may be able to see if the seals are broken up. Not unusual for valve seals to get so hard they break apart from the slight movement of the stem in the guide. If you are lucky, you will see parts of the seals trapped inside the springs.

[nvsierra04]

Yes the smoke is a big puff that blows away. Seems that if i drive the truck about 20 miles or so then it sits for a few hours, the next time i start it i see the smoke. If i re-start it in an hour or less it doesnt. If the truck sits for the day it also has the smoke. I will try your suggestion also. I have talked to 2 recommended mechanics, and both say no guarantee replacing the seals will fix it. Best quote was 600 for seals or 3850 for a rebuilt motor w/ 3 yr warranty. 225K does change my thinking. especially since i lose a little coolant also.

Thanks - Any additional input is much appreciated.

[txab]

If you can't do the work yourself, then go the newer engine or rebuilt route.

[Doug_Scott]

Yes the smoke is a big puff that blows away. Seems that if i drive the truck about 20 miles or so then it sits for a few hours, the next time i start it i see the smoke. If i re-start it in an hour or less it doesnt. If the truck sits for the day it also has the smoke. I will try your suggestion also. I have talked to 2 recommended mechanics, and both say no guarantee replacing the seals will fix it. Best quote was 600 for seals or 3850 for a rebuilt motor w/ 3 yr warranty. 225K does change my thinking. especially since i lose a little coolant also.

Thanks - Any additional input is much appreciated.

 

At near quarter million miles, I doubt just changing seals will resolve it as well. Chances are high that the guides are worn, and they have likely either worn the seals oval, or broke the seals because old seals get brittle and a valve stem moving back and forth will make the seal flex past the breaking point.

There are a large number of replacement engine companies now. Right from GM all the way down to the old man running a local garage. Look for the biggest name, highest quality, with the best warranty, and highest torque you can afford to buy.

[nvsierra04]

Thanks for the advice. I think i felt a rebuilt would be how it ends up, but since it involves alot of money i wanted to get some valuable input from some others.

The GMC dealer i have dealt with before wants to do a leak down test for 100. I asked for a rebuilt quote and they want the truck in first. 2 smaller shops have given me prices between 3800 and 4000 with 3 yr warranty but GMC did tell me their rebuilt would be 100,000 miles. I want to see the quote in writing. Im betting it will be over 5K.

 

Thanks again i dont think ill waste money on valve seals.

[Mikeee]

As to a replacement, I found on the Internet, a rebuilt long block with 4 years / 1,000,000 mile warranty.

http://www.powertrainproducts.net/default.asp

 

Me, I'd probably trust a Goodwrench engine.

 

But then, it all depends on the the condition of the transmission and body as to what path I would take. Some people swear by $900 pulled engines.

 

[txab]

As to a replacement, I found on the Internet, a rebuilt long block with 4 years / 1,000,000 mile warranty.

http://www.powertrainproducts.net/default.asp

 

Me, I'd probably trust a Goodwrench engine.

 

But then, it all depends on the the condition of the transmission and body as to what path I would take. Some people swear by $900 pulled engines.

 

One million miles?

[Mikeee]

Yep ONE MILLION MILES or 4 years.

 

http://www.powertrainproducts.co/v/pdf/2013-warranty.pdf

 

That is about 179 round trips between NYC and LA. You would reach the mileage limit before you would reach the time limit.

[Doug_Scott]

I would be interested in seeing these "heat tabs" they have put at various locations on the block. You will want to read and fully understand the conditions of their warranty as well. You are required to document all maintenance, and to follow specific timelines. You are also required to use an actual business, as opposed to doing it yourself.

They are also very clear in the overheating part. If you don't catch it in time, and the engine overheats, goodbye warranty.

 

One of the first warranties I have seen that covers labour, and actually says they will pay flat rate per industry published guide.

[patriot]

Switch to synthetic oil and it'll burn a LOT less.

[nvsierra04]

I have been using the catrol high mileage / part synthetic. Should i try something like 10W 30 also ?