Coolant in Oil - What Now?

[Justinj360]

Started the truck this morning (2004 GMC Yukon 5.3L Flex 206k miles) and immediately noticed a knocking sound (with doors closed and windows rolled up). That was unusual so I shut it off, got out of the truck, opened the hood, and looked for anything obvious. I noticed the coolant reservoir was low but it has been lately. I've been planning on changing the intake manifold gasket because I couldn't find any other coolant leaks... Did my time run out?
I checked the oil and saw that it had a few bubbles in the oil towards the top of the stick. When I went to wipe the dipstick it was noticeably sticky, not how oil should feel.
I've never had this issue before but I know it's bad news. It happened to my dad's 98 Suburban. So what are my options?

 

[swathdiver]

Well, you'll want to confirm that coolant is in fact in your oil and how it got there. Could be a headgasket or something worse, but often, you won't know until you open it up.

 

[Justinj360]

Well, you'll want to confirm that coolant is in fact in your oil and how it got there. Could be a headgasket or something worse, but often, you won't know until you open it up.

Alright. So is the engine salvageable then?

 

[swathdiver]

Alright. So is the engine salvageable then?

Well, let's say you have no rod knock and it just needs new head gaskets, yeah, put it back together and run it. If the coolant takes out the bearings, then you have to decide whether to rebuild that engine or swap in another. Hard to know from this side of the keyboard you know? hehe

There are some tools you can rent or buy that can help find the source of the leak. One is a radiator tester, the other is s compression tester and the other was mentioned on this forum farily recently. It was something I'd not heard of and unfortunately its name escapes me. Others will chime in, probably with better advice!

 

[SnowDrifter]

If you have a blown head gasket at 206k miles, I'd do a proper rebuild. Especially if you noticed a knock. It doesn't take much coolant in the oil to absolutely ruin its lubricity.

Drain it, send in for an oil analasys to check for coolant.

Go the auto parts store, look for a block tester. It goes on the radiator cap and will check for the presence of combustion gas via a color change

What heads do you have? There's a cracking issue on some that'll leak coolant into the oil

Check all other sources for leak. Heater core, water pump, radiator, hoses, tstat housing, heater core connectors, rear heater hoses, oil cooler in radiator

 

[Justinj360]

I ordered an oil analysis kit and I'll let you know the results. It'll probably take awhile. I guess that's about all I can do at this point. There's a million things running through my mind right now...

I do not know what kind of heads I have. They're the originals as far as I know.

 

[Doubeleive]

you can pull off your oil filler cap flip it upside down and see what it looks like, if it's milky it's probably bad news unless you only drive very short distances then it could be normal moisture

 

[Justinj360]

I had time to drain the oil at lunch but didn't have time for anything else. I sent the pics to my dad and he said without a doubt there's antifreeze in there. Judging by pictues online, it could've been a lot worse. I will check the underside of the filler cap. I do drive short distances to work.

 

[mattbta]

Google castech heads. You might have them.

 

[Tonyrodz]

I ordered an oil analysis kit and I'll let you know the results. It'll probably take awhile. I guess that's about all I can do at this point. There's a million things running through my mind right now...

I do not know what kind of heads I have. They're the originals as far as I know.

Easiest way--On the driver side, look all the way to the lower right(rear of the head) , you'll see a 3 digit # stamped on the head, that'll tell you what head casting you have--on the pass side that number is all the way to the right(front of the head)

 

[PatDTN]

Junk yard 6.0 swap time! Of course that's a gamble too.

 

[Justinj360]

Junk yard 6.0 swap time! Of course that's a gamble too.

I would love to have a larger engine! We'll see what condition this one is in first... Did they make a 5.7L for this year?

 

[swathdiver]

I would love to have a larger engine! We'll see what condition this one is in first... Did they make a 5.7L for this year?

Yes, the LS1 and LS6. Those engines were tailored for cars, vehicles 1/2 your trucks weight.

 

[Justinj360]

Yes, the LS1 and LS6. Those engines were tailored for cars, vehicles 1/2 your trucks weight.

So I could hypothetically order one of those crate engines from the dealer, swap them, and I wouldn't notice any differences besides more power? Why do you say they were tailored for cars?

 

[swathdiver]

So I could hypothetically order one of those crate engines from the dealer, swap them, and I wouldn't notice any differences besides more power? Why do you say they were tailored for cars?

Because their camshaft's rpm band is much higher than that for a truck. However, lots of people have put LS1 and LS6 camshafts in their trucks and were happy. If memory serves, the 5.3 loses about 40 ft lbs of torque down low and gains most of it back up above 4000 rpms. Lots of vids on youtube so you can judge for yourself.

 

[Justinj360]

Because their camshaft's rpm band is much higher than that for a truck. However, lots of people have put LS1 and LS6 camshafts in their trucks and were happy. If memory serves, the 5.3 loses about 40 ft lbs of torque down low and gains most of it back up above 4000 rpms. Lots of vids on youtube so you can judge for yourself.

I think I've heard that about the 5.3L with one of those cams as well. So are you saying it would be much better to go with a 6.0L instead of one of the 5.7L's?

 

[swathdiver]

Well, the LQ4 and LQ9 are truck engines so yes, they would be a better choice. Is the bottom end of your motor knocking?

 

[Justinj360]

Well, the LQ4 and LQ9 are truck engines so yes, they would be a better choice. Is the bottom end of your motor knocking?

Gotcha. I don't know for sure but it seemed like the knocking was louder coming from the wheel wells and not as loud from the engine bay with the hood open. That's what I remember anyway.

 

[swathdiver]

Gotcha. I don't know for sure but it seemed like the knocking was louder coming from the wheel wells and not as loud from the engine bay with the hood open. That's what I remember anyway.

Darn, the coolant may have gotten to the bearings and did them in.

 

[Justinj360]

Darn, the coolant may have gotten to the bearings and did them in.

Hey! We don't need that negative attitude around here!

Let's say that did happen... Would I be able to tell if that's what happened if it still makes the same knocking sound when I get it running again?