Orange gunk in oil cap - is there something wrong with my engine??

[Stringer]

Hey me again, just got a 1996 C1500 4.3 and pulled the oil cap and seen this. Also, there looks to be water and vapor coming from tailpipe, and vapor from oil cap. Truck does not want to get up to temperature, despite replacing entire cooling system with new temperate sensor. I am praying this is not a big issue. Any ideas?

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[Stringer]

I changed the plugs and they looks fine, though were only in there for a very short amount of time. previous owner put rapidifire bs plugs in so i had to yank them. 1 plug was not even seated just floating around. def alot of vapor from tailpipe even after driving it around. i have a 5.3 next to it in the driveway, started it up and no vapor and never seen any shyt like this in my oil cap.

i was getting ready to throw some marvel mystery oil and seafoam in there and run it for a bit, then change oil with full synthetic high mileage (131k on odo) when i seen this.

Entire intake was super clean when i got it, but i took it to the next level.

 

[Caman96]

Gasket failure!

 

[Stringer]

i hope not! man that would suck. I just let it idle for a good bit, and pulled the oil cap and zero vapor now, i did this a couple times. i wonder if any of that had to do with emptying nearly an entire bottle of throttle body cleaner in there as i was cleaning that thing. Though i still have small amount oif water coming from tailpipe. i did not see any moisture or milkyness from dipstick, im gonna change the oil shortly. i did just add the mmo and seafoam. i did have to add a little coolant but that is expected as i just changed everything out and i heard an air gurgle as i was running the heater. I'll need to monitor coolant level from resevoir box. maybe the cap was just never cleaned in 27 years, ond only used for short trips? not sure what's going on, sure hope its not head gaskets. truck seems to be very well taken care of over the years.

 

[stutaeng]

Intake manifold gasket failure? Pretty common on these engines. They typically fail after the 100,000 mile mark, but some can go up to the 200,000 mile mark. I don't know if that could cause coolant to leak into the crankcase? I thought the coolant leak was usually external to the crankcase? But if the bottom of those ports of the gasket fail, I'm pretty sure coolant will fall inside the engine. I'm not sure about the steam from the tailpipe. Does it smell like coolant? Syrup-like smell?

Coolant Leaking From Intake Gaskets (GM 4.3L, 5.0L, 5.7L)

Intake gaskets leaking coolant and what to do to avoid a repeat of the problem. GM 4.3L, 5.0L, 5.7L engines.

troubleshootmyvehicle.com

I would think that if the head gasket is blown, the truck would run pretty bad, no?

I'm sure folks here with more experience than me will offer good advice on what you need to test to figure out the problem.

 

[someotherguy]

Typical on the small block Vortecs for intake gasket failure to leak into the crankcase, IMO. Sure seen a bunch of them with milky oil and then later bearing failure due to running them with the contaminated oil. Keep a close eye on it.

Richard

 

[1998_K1500_Sub]

I had an intake manifold gasket develop a coolant leak on my 1998 L31 Suburban around 200kmi. I noticed it promptly, as the engine oil started rising on the stick and the coolant level dropping in the puke tank.

Can't say I ever noticed crap on the oil cap like the OP did; I caught my problem early-on so that may explain why.

If you change the intake gaskets yourself, you might want to run a tap into the various threaded holes to clean them out prior to reassembly. But don't drop the tap down into the oil galley, through the distributor hole and into the oil pan, it will ruin your day. Don't ask me how I know.

 

[Stringer]

thanks for all the info! do you think i should order both the upper and lower intake gaskets? gonna look up the process now, hope its not too bad.

 

[stutaeng]

I think if you order the entire kit, it's a bit cheaper. I just did the lower on mine even though I ordered the whole kit.

Change your oil as soon as you can per Richard's comment.

 

[1998_K1500_Sub]

Change your oil as soon as you can per Richard's comment.

You might make a point to change it quite often for the next few thousand miles as the oil washes the crap / gunk out of the used engine you as-yet know little about.

Consider getting valve cover gaskets as well, if yours are leaking. Access to the covers is a bit easier once the other stuff's been peeled-back.