Chev 5.3 intake leak

My 2003 Avalanche with 72,000 miles started throwing engine codes saying "lean condition right and left bank". It was stumbling badly at idle and felt pretty anemic. So, off to my trusty mechanic I go. Verdict: warped intake manifold. Apparently this is common to this motor and year as the intake manifold is PLASTIC!!???!!! So after shellling out $850.00 for the "new and supposedly improved"(again PLASTIC!) intake manifold and labor, I questioned my mechanic as to why this happens. He said it's an overheating issue. I've never had the truck boil over, but it's gotten up to 230 ish pulling up some long hills. It probably got hot when I towed my boat from New Mexico to Utah for 12 hours as the problem surfaced about 1000 miles later. So now I'm gun-shy about towing long distances again with this truck. I wish there had been an aluminum replacement manifold available, but no one builds one. The plastic one weighs maybe 2 pounds. I'm going to be seriously PO'd if I have to replace another one. GRRRRRRR!!!!!

Re: Chev 5.3 intake leak

Warp huh, Did you get a straight edge and determine were it got warped???
If it only got up to 230f, I would think that warpage would not occour with the plastics they use today, But you just never know.
If you can not find were it has been warped then gaskets would have been my first guess.

Re: Chev 5.3 intake leak

Oh yeah it warped. You could clearly see it where it leaked past the gasket at the top of each port, no straight edge necessary. The ports looked cupped. I'd bet .030 at least. I didn't save is as a souvenier, I was too PO'd to bother.

Re: Chev 5.3 intake leak

I didn't know the 5.3's had the plastic intakes...good to know b/c I have that engine in my Tahoe.

I do know that every Chevy Impala in my work's fleet (40-45 of them) has had there's replaced at least once...seems to me it should be a recall issue due to a poor design or choice of material.

Re: Chev 5.3 intake leak

Making me glad I swapped my Sierra for an Expy last fall.

Re: Chev 5.3 intake leak

I replaced the intake manifold in my 5.3l 2 years ago. Before that I tried everything (inexpensive) under the sun to fix my rough idle at the stop light. It did indeed turn out to be a warped intake manifold, but my repair bill was only $350.

Re: Chev 5.3 intake leak

korygrandy said:

I replaced the intake manifold in my 5.3l 2 years ago. Before that I tried everything (inexpensive) under the sun to fix my rough idle at the stop light. It did indeed turn out to be a warped intake manifold, but my repair bill was only $350.

Click to expand...

???? The manifold parts cost was $525, how'd you get off so cheap?? My local Chev dealer quoted me $1375, I thought I got off easy!

Re: Chev 5.3 intake leak

Oooh...I had them put a used intake manifold in. It was a tiny shop so the guy must have given me a helluva deal on the labor. I thought it was rediculously cheap as well but your the first I told It was in the still of winter a couple years ago and the guy could have been hurting for business. The hassle I went through trying to diagnose the problem was very time consuming however so I didnt get off completely free and clear. I went through fuel pressure regulators, fuel filters, sensors...and all sorts of cheap little odds and end parts. I spent countless hours scouring the internet and talking to mechanics to try and figure it out. I dropped the truck off thinking I was getting shiny new heads, but thankfully I was able to return those when they discovered the true problem. I was skeptical about heads because it's not a common failure in 5.3l but I was willing to try it!

Re: Chev 5.3 intake leak

More likely a bad intake gasket & a DexCool issue, than the intake actually being warped. But I suppose it's possible.

Re: Chev 5.3 intake leak

Hope he put new knock sensors in when he had the intake off. Thats where they are and they go bad from the the extra heat. GM moved them back down on the block in 07 I think. Labor guide shows 2.4 hrs to replace Intake, and list price on new intake is about 650.00 from a dealer.

Re: Chev 5.3 intake leak

TilliamWe said:

More likely a bad intake gasket & a DexCool issue, than the intake actually being warped. But I suppose it's possible.

Click to expand...

Having had the manifold in my hands, it was warped at almost every port. Clearly distorted port plane, no straight edge necessary as said before. It's quite common if you Google it. The manifold doesn't have coolant chambers between cylinders, thus not a coolant issue. Plastic crap, hope the new one is improved. They checked the knock sensors also and gave them thumbs up, truck runs like new.

Re: Chev 5.3 intake leak

My 98' Buick with the V-6 did the same thing. First time, it ran around $1,400. Second time, a different shop charged. $1,100. Both times, coolant leaked into the cylinders and caused the engine to lock up. About 6 weeks after the second time, a wrist pin let go and the engine was ruined. If it caused hydrolock, be aware that the engine has been severly stressed and it might be time to get rid of it.

Re: Chev 5.3 intake leak

My 2004 Suburban had this at around 70K miles and they replaced the gasket to the tune of $450 and we are still good at 126K..