2006 L33 Water in Oil

Chevrojayy97 · December 8, 2018

Hey guys, forgive me if this has been asked before, but the search forum feature was no help. I have a 2006 Silverado 5.3 (L33) that I bought as a beater with some body damage and small mechanical issues. I replaced the EVAP canister first thing before I registered the truck, and have a a new catted y-pipe and cat back exhaust on order from a hack job exhaust from the previous owners. I'm removing the rubbing 16x10's for stock sized wheels and felt like I was making great progress on this old truck. It just turned 165k miles, and i noticed the oil pressure was dropping at idle to below 20. I immediately pulled the stick and found a little water in the oil. I figured I have the dreaded Castech heads, and am glad I caught the issue early. I've always been against stop leak products, but I had read some good reviews on Bars Leak HG-1 and how it "supposedly" is formulated just for heads and not prone to stopping up radiators or heater cores. I've driven for a couple hundred miles and oil pressure and coolant is great. No leaks, tank is pressurized, and I'm constantly holding 210 degrees and 40 lbs oil pressure. I'm writing this new forum for 2 reasons.

1.) Was adding this to my cooling system a huge mistake? I'm hoping that it will last until spring and just get me through the winter until I can either get another truck or repair this one correctly. I'm still going to install the new exhaust and do some mild paint and body work to aid in resale on the truck. I don't want to sell someone a bad truck, but I don't want to spend a ton of money if it's a small issue that is truly fixed. I've read others are driving 50k miles with the HG-1 in their vehicles...

2.) Worst case scenario, if I need new heads, what are some good replacements? Are there any heads from other LS Powered vehicles that would make a good replacement?

Thanks in advance everyone.

sefiroxx · December 8, 2018

As for leak stop issue:
- run an exhaust gas test well. Vacuum stroke would pull in water while power stroke would expel gas through any hg failure
- the stop leak products are temporary. The GM tested version is also sold by bars leaks and utilizes walnut/etc ground shells. Other non organic products have a tendency to stop up vital passages.

Chevrojayy97 · December 8, 2018

Thank you for the advice. How do I run an exhaust gas test? Would that be like a compression test?

sefiroxx · December 8, 2018

Local auto parts rental or tool. Chemical test added to a sample of coolant fluid.

swathdiver · December 11, 2018

I do not think the L33 has castech heads as it is essentially a Gen IV engine with 243 heads and block. Bars leak has been in use for many many decades, good stuff. Do a compression test and leakdown test or just pop the heads and change the head gaskets.

L33 was the ultimate Gen III LS 5.3.

Mikebtte · December 12, 2018

22 hours ago, swathdiver said:

I do not think the L33 has castech heads as it is essentially a Gen IV engine with 243 heads and block. Bars leak has been in use for many many decades, good stuff. Do a compression test and leakdown test or just pop the heads and change the head gaskets.

L33 was the ultimate Gen III LS 5.3.

I am with swathdriver, change the head gaskets and call it good.

Supreme Pizza · December 12, 2018

Is your coolant currently leaking into the oil? After several oil changes, are you still showing water in the oil?

SierraHD17 · December 13, 2018

On 12/11/2018 at 11:00 AM, swathdiver said:

I do not think the L33 has castech heads as it is essentially a Gen IV engine with 243 heads and block. Bars leak has been in use for many many decades, good stuff. Do a compression test and leakdown test or just pop the heads and change the head gaskets.

L33 was the ultimate Gen III LS 5.3.

Quite a few of the 243 heads were also done by Castech. They have the same issues as the 706 castings did but it's just less prevalent so no one seems to know about it. He easily could have heads that are weeping. The MLS gaskets in those don't rot out usually but who knows.

swathdiver · December 13, 2018

4 hours ago, SierraHD17 said:

Quite a few of the 243 heads were also done by Castech. They have the same issues as the 706 castings did but it's just less prevalent so no one seems to know about it. He easily could have heads that are weeping. The MLS gaskets in those don't rot out usually but who knows.

Thanks, did not know that.

Chevrojayy97 · December 16, 2018

I am not sure which heads I have, I haven’t pulled the rockers yet to see if I have Castechs for sure. I’m assuming that I do based on other Castech related posts on this forum, and GM included the L33 in the TSB for Castech heads. THIS is the part that I find really weird, oil still has some milky look to it after driving it for a week, so I’m going to do another oil change and hopefully I will start seeing less water in the oil. Ever since I put the stop leak in, the coolant level hasn’t moved and the temp gauge is holding true at 210 degree. Oil pressure is perfect at 40lbs. If I had the dreaded Castech heads, wouldn’t I be losing coolant out of the tank? Tank is pressurized as well, which is what is puzzling me!? All the classic signs of heads or head gaskets just simply aren’t showing up, yet I still have water in the oil. Everyone I know asks about condensation on short trips, but I always let the truck warm up and usually drive it around 30-40 minutes per trip. Anybody know what’s up?