2002 Silverado

Pallytankftw · April 9, 2015

Hi guys first time posting on this forum but I recently bought a 02 silverado 1500 4x4 with the 5.3 vortec with 74k original miles about 2 months ago. Over the past month ive experienced a couple issues,High idle on start up, one when I drive in grass, one when im towing an unloaded trailer it just feels like its losing power.Knocks on start-up that have gotten gradually worse and just the other day saw white smoke out of my tail pipes so I knew it was over, lifted my oil cap and sure enough the dreaded milky oil.

So my question to you guys do you think its an intake or a head gasket? I currently am 8 bolts away from taking my intake manifold off just haven't been able to get out there due to all this rain we are having where I am at.

Also how do I get all this crud out of my engine after I fix what ever problem it might be?

Carder09 · April 9, 2015

Probably the castech heads if I'm not mistaken. So new heads?

Doug_Scott · April 9, 2015

Do a search for castech heads and you will find lots of information on these heads. Your truck in the range of years that have seen bad cylinder heads.

Once you verify that there is coolant present under valve covers, you can be pretty certain it is the heads causing it. Replace the heads, and while it is apart, clean up as much of the engine as you can get to in order to remove as much of the sludge as possible. I think there is a removable cam cover tray you can remove as well. After you have changed the parts, and before starting the engine, drain the oil, change the filter, and put new oil and filter on/in engine.

Start the engine up, let it get hot, make sure oil is also hot, and then change the oil again. If it was me, I would not put an expensive oil in to clean out the inside of the engine, no need to. Use a low viscosity oil for the cleaning part as well. Not sure if they still sell it, but, if they do, you could also add Rislone to the oil. It is important to note that you do not drive the truck around for more that 100 miles on the first oil after assembling the engine.

Pallytankftw · April 10, 2015

I personally think its my intake, as I said once I get the time with work and rain I will take it off and see what happens, I'm not saying that its not the head gasket but the guy I bought it from didnt drive it. I think what happened was with him using dexcool it just sat and weakened the intake until I started using it as a daily driver, thats when I think it blew as its only on the oil fill cap, not the actual dipstick.

oldscsc · April 10, 2015

These engines use a dry intake manifold. It won't be the source of your coolant issue.

There is a known issue with Castech heads that will cause them to fail in the exact manner you're describing. Check them out before banking on an easy fix.

rdnkcpa · April 10, 2015

Sounds like a Castech problem to me, but hard to diagnose over the interwebs.

Lived the Castech nightmare.

Do the search, lots of good info on this site. Pull the valve covers. If you have the Dexcool snot under the valve covers and see the Castech logo stamped in the head, you need new heads.

Pallytankftw · April 10, 2015

Pulled valve cover to see if it was a castech head and one thing I noticed was the lack of sludge will pull rockers later to look for logo but I can tell you guys its a "706" head if that means anything.

Doug_Scott · April 10, 2015

Something else to consider is how the winter has been in your area. In areas that are below freezing for weeks at a time it is not uncommon to gather a considerable amount of condensation in the crankcase. It is made worse if your daily drive to work barely gets the engine warm, let alone hot. Condensation will only evaporate if the temp of the oil exceeds 212degrees F or 0 degrees C.

Good thing about condensation is that you won't get the same chemical reaction you get with glycol, so getting oil hot will not likely do any damage. Sometimes glycol mixed in oil will do some damage to main and rod bearings.

Pallytankftw · April 10, 2015

Just makes me wonder why I am getting a knock that gets progressively louder every week on startup. I'm gonna check my other valve cover and see how clean it is tomorrow

00Silverado4x4 · April 13, 2015

Did you get the other cover off yet? I have a feeling you have a head related problem, either cracked or blown gasket. You can get new heads pretty cheap from what I've seen online pricing so if you are capable, it should be a relatively easy job...I think.