Head gasket replacement - My Turn?!

[Subzilla]

Greetings,
Tracing down some oil seepage on the 240k mile Suburban, I discovered the source to be the head gasket areas, mainly on the side of the engine toward the back (driver's side). With the engine running, little tiny oil bubbles were spitting out at the bottom of the head. The seeping has been occuring for the last 6 months or so but just recently got worse. There are no fluids mixing, no bubbles in the coolant but I've been pondering that maybe the additional exhaust smoke I've been seeing might be oil burning?? Can head gasket failure just seep oil as described and not affect the coolant stuff? How long can I drive it in this condition or is that too unpredictable?

[john8662]

The head gasket doesn't seal off presurized oil passages. The only source of oil that the head gasket is exposed to is on the top of the head where the pushrods pass through the heads to the rockers. I'd suspect that it could be a leaking valve cover. But your description sounds like (since you're getting a mist) a fuel leak. Check all the fuel return lines on the injectors, The one that usually goes to leaking is the cap at the end of the line on #8 injector. The fuel could look like oil if you have a leaky or oily engine in that location.

[Subzilla]

Thanks John,
The valve covers seem to be dry (I did those a couple of years ago). Why am I definitly seeing the tiny "pressure" bubbles coming from the bottom of the head? And why would I suddenly get more oil leaking? I'm talking about a small pancake size puddle on the ground when parked for an hour. I'm not trying to challenge your opinion but rather just trying to understand this stuff. I did just R&R the injectors last month and replaced all of the fuel return lines so I will check that.

[mdregister]

Subzilla,

I have a small coolant leak right where you describe; on the lower rear corner of the head on the driver side. Mine is definately coolant though. As soon as I get my engine hoist and stand, I am in for a head gasket swap as well.

Are you sure your oil sending unit or its fitting are not leaking. While looking for my coolant leak, I discovered my oil sending unit is leaking from the unit itself; right where the body of the unit is crimped together. I get a drip-drip-drip that has covered the whole area around the unit in oil.

Next time you are in the Wilmington-Carolina Beach, NC area, give me a shout and we can compare notes, drink beer and fish.

[john8662]

Subzilla,

I'm glad that mdregister pointed out the oil pressure sender. I've seen this leak too, I guess I got caught up in thinking passenger side head instead of drivers side. I've been messing with too many engines lately, it's all combining in my head!

[Subzilla]

Yea, I do have a small drip from the oil pressure sending unit but this oil is more on the sides of the engine instead of the back. Maybe it's ending up on the side due to wind turbulence?!? I also checked the vacuum pump as I had a major leak there a couple of years ago and it seems dry. But, again, I think I'm seeing those tiny bubbles coming from the bottom of the head! What is the cause of that? Thanks for the replies.

Mdregister, I do get "down east" to Wilmington occasionally. A few years ago,the family spent the night in Carolina Beach State Park, visited the aquarium, then headed up to my dad's place in Stacy for a couple of days of fishing. Love the coast and the Outer Banks! Gotta get this problem resolved before I can head back out there!

[mdregister]

I suspect the oil you are seeing on the corner of the head is from another source, such as the oil sending unit, and it is just "working" its way over to that spot and you have a head gasket leak that is causing the bubbling. I bet if you clean the area real good and run the truck as few miles, you will be able to see green coolant where you currently see oily bubbles, that is until the oil gets over there again.

Let us know what you finally determine.

If you have not been to the aquarium since it was rebuilt, I suggest you stop by the next time you are in the area, it is quite nice.

[Rod@Night]

I had the very same leak you are seeing with the bubbling on the Crivers side rear 2 weeks ago. Sence then I have reworked the heads and after talking to Felpro have reinstalled the 6.2 gaskets. I had on valve so far out of wack there was a slight inprint in the piston...another had a broken ring..GGirdle kit is in the mail but I had no visible cracks..Anyway to your question...After tearing stuff apart at this point , I believe the source of the oil on mine was the oil pressure sender..The oil was running down the side of the head and then getting bubbled by the leaky head gasket...Incedentally, that drivers side corner is at the corner where it is extremely hard to get the proper tork on the last head bolt because of cab frame..It all starts to make sence...After looking at the removed old style gasket and looking at the block surphase it made more sence..It will be another 10 days before it runs but I bet my problem will be solved...

[arveetek]

Originally posted by Rod@Night:
Incedentally, that drivers side corner is at the corner where it is extremely hard to get the proper tork on the last head bolt because of cab frame.. Rod makes a very good point that has been addressed here in the past, but I will bring it up again. When replacing head gaskets, it's a very good idea to remove the engine from the vehicle, so that you can put the engine on a stand and properly torque the head bolts. I know that it seems like an extra amount of work, but it's very important to torque the heads properly on the 6.2L. I know John Kennedy said that he would no longer replace head gaskets in the vehicle, for that very reason. It's something to think about.

Mark, I've heard of that exact same symptom before, of the oil bubbling out between the head and block. Everytime it's been mentioned on this board, most everyone else chimes in and says it's not possible. But, I believe you! ;) Like the others, I doubt it's actually oil seeping out of the head/block area, but it's probably just running down to that area, and possibly combustion gases are blowing it out. I've also seen diesel fuel leaks that bubble in that manner when the fuel runs down and actually begins to boil off from the heat, so I'd check really, really well for any fuel leaks that may be causing this before condemning the head gasket.

Casey

[Subzilla]

Ok, will definitely check all of the above. I do not have the time right now to yank the engine and replace the head gaskets (when is a good time??). Will replace the oil pressure sending unit, check the fuel return lines, clean the engine well, then check for oil streams again. I'll let ya'll know what I find.