Bad fan clutch led to over heat, think engine got hurt?

[rob03tb]

Hi everyone, just a quick question to those who know the 4.2L. I had my plow hooked up, drove down the highway for 20min got off. two traffic lights and check guages chime rang. Looked and notice the temp gauge pegged at 260. Shut her down coasted and refired so I could pull into a gas station then shut it down again. Opened the hood to check things out. Coolant was bubbling out of the overflow. Started the engine and turned on high heat and the temp fell rather quickly back to 210. At first I thought the plow blocked the air flow and caused it to over heat. But the drive back home was fine. (35min). next day I find the tell tail yellowish crap under the oil fill cap. I wipe it off and check again every 24 hours. The engine runs fine, no issues. but I have been checking every 24 hours and wiping the yellow crap off. 3-4 times so far. Can't tell if the coolant level has changed. No sign of yellow crap on the dip stick.

What are your thoughts? blown head gasket? cracked/warped head? How durable are these engines to overheating? i'm sure I'm not the only one who has overheated one of these. A local mechanic stated the yellow crap is somewhat normal for GM engines, although I've never seen it on my 4.2 before. He said the 4.2L is nearly bullet proof and not to worry. What do you think?

I plan to monitor for a few more days then drain the oil into a clear container to see if there is any water in it.

1 day after it coded P1484. Found the SB for it so I'll check out the condition of the fan clutch harness.

Been driving for a couple of days and it trys to over heat only when the plow is on and the roads are wet. If they are dry then the fan operates fine.

I pulled over on the way home from work today due to the temp rising over 220-240 and the fan was spinning slowly. after tapping on the shroud, core support and other areas the fan turned on to the high speed. Must be the harness.

anyway thanks in advance for any suggestions about possible source of the water in the oil. Maybe the yellow crap on the oil fill cap is normal? I hope. Let me know if anyone has seen this on theirs. At least it will put my mind at ease.

[HARDTRAILZ]

Mine got hot a couple times a couple years ago n no issues since. You keep an eye on it and time will tell but but these are stout motors.

[v7guy]

The yellow stuff is just condensation more than likely.

There's been a fair mention of these motors being planned to be turbocharged by GM. Accordingly they're very stout NA.

[ErikSS]

No sign of yellow crap on the dip stick.

That's a really good sign. Keep an eye on that. You could run a compression test if your concerned.

[Iris_5]

Nice post! Even though I'm a lousy spammer and just got my ass handed to me by my web host.

[rob03tb]

Thanks everyone.

[Cable810]

Nice post! Even though I'm a lousy spammer and just got my ass handed to me by my web host.

Not trying to start the whole post whoreing

[rob03tb]

It's been about 3500 miles since I posted and wanted to follow up. I changed the oil back when I posted originally and poured it into a couple of clear soda bottles. Let it sit for a week and did not see any water/oil separation. I'm due for another oil change soon and if I find anything I'll post again. Since it's warm now, no more yellow residue on the cap. Must have been condensation as v7guy mentioned. Thanks for everyones input. This is a great site!!