Replacing The Intake Gasket

**zachh1020** · 02-08-2009, 11:12 PM

Where is the EGR Valve located on the 4.8L engine and how can i test it?

UPDATE 2/9/09 - Looked for the EGR Valve, Couldn't find. I looked up some info, from what I have found, GM removed them in 2002.

**zachh1020** · 02-10-2009, 12:14 PM

Ok...Last night, my truck was running in my driveway, and I noticed my exhaust sounded different than normal. So I looked, and there was a quite a bit of water coming out of both my pipes. It was making puddles on the concrete. I could actually hear the water girggling as my truck was idling. It didn't smell like gas or antifreze. It was almost kinda black and mucky. My friend said that was normal, but I have NEVER seen this happen with my truck.

I didn't know if this could be related to intake issue or a whole other issue all together.

Thanks
Z

**Veinot** · 02-11-2009, 03:38 PM

There is no way for coolant to enter engine through intake on a 4.8 since there is no coolant in the intake. Also there is no way to actually check the MAF sensor. Borrowing a known good one is the best way. Usually the lean bank codes on these engines is from the MAF or the the position 1 O2S's. Swapping the O2's from side to side will determine if they are bad as the code will move to the opposite bank. Usually an intake problem shows up as a rough idle on cold start up. This can cause the lean code but 9 times out of ten its the MAF or O2S. But what do I know I've only been a GM tech for ten years maybe I need some more experience lol!

**zachh1020** · 02-11-2009, 07:07 PM

Wow. I'm glad someone was blunt enough to tell me what an idiot I am. Thank You! I appreciate the honesty.

Anyway, On That Note, We already replaced the MAF sensor and both O2 sensors last night to no avail. It is spitting out Right bank Lean and Left bank Lean. It NEVER put out codes for MAF or O2.

**kinglt1** · 02-11-2009, 07:30 PM

Almost 100% percent sure its the intake gasket. I just had it fixed on my 03 w/ 5.3 at a local shop for 225.00. There is a gm service bulletin out on it. The intake leaks internally around the bottom of the intake ports. It causes the engine to surge when cold at idle, but runs fine when you tip in the throttle. The pcm will throw codes p0174, p0171, right and left banks lean. Hope this helps!

**zachh1020** · 02-11-2009, 07:57 PM

That just described it perfectly! The RPMs dip real low, it almost stalls, and they surge back up. Those are the codes as well. Thanks.

**kinglt1** · 02-11-2009, 08:08 PM

No prob! Glad to help!!

**zachh1020** · 02-23-2009, 12:44 PM

This indeed fixed the problem! Me and a friend tore into it yesterday. It was much easier than I expected. I followed the Chilton book, and I didn't really have to label anything either because every elec. connector was different and every vacuum hose had its place. There was clearly discoloration on the block from the spray out in several places. My engine now runs better than before I had the problem. After the gasket, fuel line disconnector and thread lock it ended up being about $54.00.

Thanks to everyone for the help!

**mrfixdit** · 02-23-2009, 06:19 PM

You're not an idiot zachh you've just been taught that there is a fine line between confidence and arrogance, LOL

**k.daddy1** · 02-25-2009, 07:33 AM

It's also a common problem with the newer chevy's also. You won't see puddles on the ground or in the oil until the gasket has completely blown. You'll get a pin hole and the vacuum of the intake will suck in the coolant and foul the plugs. Especially on the passenger side. The smoke check won't do anything for the problems your describing. If you do tackle this task, make sure everything is very clean when putting back together.