TJSZ

After changing serpetine belts this evening on my wife's stock 99 Z-28, I checked the oil and found something disturbing.
Pulled the dip stick and found rust on it about half way up.? Opened the filler cap and it had red powder like mess all in the cap. Also had some water, more like condensation, and yellow/red milky crap in the neck of the filler cap. The oil from the dip stick looks ok, no water or coolant visable. Anyone ever seen this before? Immediately I thought head gasket, cracked block, something major. The car is running great with 104K, not overheating, no smoke, etc. Never had any other problems before.
BTW, I perform more than regular maintenance, with good oil and filters. Last change about 2K ago and this issue was not present.
Any thoughts would be appreciated. I am stumped. May have to go to the dealer tomorrow for a leak down test and/or compression check.

Mike2kZ

iTrader: (3)

I have the same issue with my oil cap.. but it's never been a problem.. been like that since i got the car. Could be a bad O-ring?

TJSZ

Thanks for the vote of confidence Mike. Filler cap O-ring looks good. May be nothing more than condensation??
I have just never seen this before on a regularly maintenanced car.
Doing an oil change tonight to investigate a little further.

99PontTA

has the coolant level gone down in the overflow bottle?Are you using dexcool? I've noticed condensation in the oil filler cap but its been a milkly white...red or orange look to it would suggest dexcool mixed with it.I've seen a few engines with cracked blocks that ran ok but they used antifreeze.The oil looked ok but the inside of the oil cap would have you color of the antifeeze..example green milky look to it.Also dexcool leaking into the engine oil is going to become a strong acid and eat into everything fast.Does the oil dip stick look like a acid ate into it?If you do have a small leak it maybe possible to use a sealer in the antifreeze.One engine i remember had a large crack in the block in the lifter gallery area......we flushed it and used a block sealer...this worked for at least 50k.Have you switched oils recently...i've seen oil change colors from using different brands.

TJSZ

99PontTA, thanks for your input/advice.....
Yes, still using dexcool. Now that you mention it, the color of the muck in the oil filler cap is a very similiar red color. In the filler neck itself, it was more of a red/milky green/white mixture??? Have not noticed a drop in dexcool level but I will certainly check that again ASAP. The oil dip stick does have built up rust that will not wipe off. Hard to say if it is pitted, but certainly possible.
I have always used valvoline oil, but the wife did have it changed during the winter by a local shop. Hope they did not top off the antifreeze with non-dexcool, could explain the color variarions I am seeing in the filler neck?
Would a leak down test be in order to determine if I have an antifreeze leak?
Any advice on what brand of antifreeze sealer you used that lasted 50K?

99PontTA

additives in the oil may color the moisture you are seeing on the cap...i know i've seen mine look brownish-orange.The important thing here is to keep an eye on the coolant level....and you can't trust the overflow tank level because if there is a crack it may mess with the vacuum action needed to pull the anfreeze bk into the system at cool down.I would check the coolant levels in the rad and tank COLD everyday for a month...this will tell you for sure if you are using coolant.How often is this car driven? Do you live in a cool climate?I can tell you this much...if i seen rust on my dipstick and had done reasonable maintenance i would be changing to a diff brand oil!Unless the car sat for LONG periods...even then its suspicious.Think about what could could cause rust inside a engine that covered in oil?

We used K&W brand sealer...you 1st drain and flush the block with clean water ..no antifreeze..then add the K W then run the engine till its good and hot..then let it cool down,drain the block and add coolant...this worked very well.I'm sure GM has some sealer they use...noway an LS1 is leaving the factory without some kind of sealer in the antifreeze!ALL aluminum engine are notorious for small coolant leaks internally......but small leaks won't kill it....but if you suspect one be sure to step up your routine mantenance.The fact that you didn't see this before the last oil change is somethiing to consider carefully.....something changed...FIND IT.

TJSZ

Car is my wife's daily driver. We live near Memphis so winter is mild.
Keep in mind the rust is higher on the dip stick, actually a little over half way up. An area that I would not think would be emersed in oil all the time.
I agree that something has changed recently, want to find out ASAP. I will monitor the coolant level closely. I changed the oil today, and no water/coolant visable.
Actually, this is perfect. I now have a reason to drive the car on a more regular basis. I normally have to pry the keys out of her hand. lol She loves her Z-28.

99PontTA

if you saved any of the old oil you could get it analyzed and know for sure whats in the oil.........for now i think a careful watch of the coolant level should tell you alot.Good Luck