CAT 3306 Crankcase pressure?

[brendan1911]

Hi all, I'm really new to the forum. I work on an oystering boat, and our main engine is a CAT 3306. Today when adding oil, the oil bubbled back up into the funnel, and drained slowly back into the engine. Then we checked the CCV, and found that the line (1.5" line to a filter box) was plugged full of an oily/watery sludge, about the consistency of wheel bearing grease. Haven't checked the filter yet but I'm assuming it's plugged as well.

Obviously the plugged CCV caused the pressure, but what could've caused that? We have been losing water lately, but haven't found any in the oil. Obviously some of it is ending up in the CCV though. I'm just hoping someone here can shed some light. We may have to get a CAT tech, but their help has been spotty in the past, so any insight is appreciated!

 

[d9gdon]

Classic sign of coolant in the oil...if it has an oil cooler that would be the first thing to check.

 

[brendan1911]

We just did the oil cooler a few months back; it was leaking the other way, and we noticed a layer of oil on top of the coolant in the expansion tank. Will have to check that. Any chance that it would leak in the opposite direction now? i figured the oil pressure was higher than the coolant so it would go to other way, but there is no denying that there's water in the oil.

Just pulled the CCV filter; it was absolutely caked in sludge, and when we opened the filter box, about half a cup of coolant drizzled out...

 

[Nige]

If you stop an engine with everything at normal working temperature the coolant will still be under pressure so it can pass through a cooler (for example) into the lubrication system. When the engine is operating the oil pressure is obviously higher than what's in the cooling system so oil goes in the opposite direction. Oil in the radiator is the most common, but coolant in the oil is certainly not unknown.

 

[brendan1911]

Yeah, it has to be leaking. We pressure tested the coolant system and the pressure bled off pretty quickly. There's no coolant visible in the oil (we just changed it after the pressure test), but it may be leaking near the head and evaporating right away. We're gonna have to run it up to a shop. It's running alright, but we have the CCV going right into a bucket, no filter. She's got over 38,000 hours on her, so it may be time to do some work.

 

[kshansen]

Yeah, it has to be leaking. We pressure tested the coolant system and the pressure bled off pretty quickly. There's no coolant visible in the oil (we just changed it after the pressure test), but it may be leaking near the head and evaporating right away. We're gonna have to run it up to a shop. It's running alright, but we have the CCV going right into a bucket, no filter. She's got over 38,000 hours on her, so it may be time to do some work.

"Over 38,000 hours"? is that right?

I know if this engine is in a boat dropping the oil pan is most likely not going to happen too easy. Guess what I might try would be to drain oil and remove valve cover and pressurize the cooling system. Best if you could do that with an air regulator to keep it on full time then look every where you can see from the top for coolant running and keep an eye on the oil pan for coolant showing up there.

Just remembered I have had one or two 3306 engines where the water pump seal was leaking and letting coolant into the engine oil. There is a weep hole between the water and oil seals that "should" prevent that but some creepy crawly things like to seal up those holes. And if that pump has been on for 38,000 hours they have had lots of time to do that! Not sure if there is any chance you could probe around in there to clean it out. Sometimes the factory stuck a foam plug in there to keep dirt out but once that gets a coat of dirt on it it seals the hole right up. Would be nice if the pan would come off as then you could see coolant coming down from the front cover by the pump

 

[brendan1911]

Yep, just over 38,000. The oil pan can and probably will be coming
off.

We ran up about 40 miles to get closer to the CAT tech. We stuck the CCV hose in a bucket, and got a few handfuls of sludge and about half a gallon of coolant. The tech said it may be the head, because there's no coolant in the oil pan, so it must be leaking and evaporating quickly.

 

[Nige]

IMHO you can't guarantee it's the head unless you have reason to suspect that it is - maybe an overheating issue in the recent past or something like that might send you in that direction.
But until it is proved you have to suspect everything and TBH the first thing I'd be pressure testing would be the cooler unless you know something more of the history of the engine than you have already told us.

 

[Jonas302]

Check the water pump weep hole its a common issue had one in a grader doing the same thing even after I though I cleaned to hole need to really get up there and make sure it can drain I used a brake cleaner can straw then the coolant just poured out

 

[brendan1911]

Well actually, three weeks ago it DID overheat due to a stuck thermostat. However, this problem didn't pop up until today, and ran fine from then till now. Actually it still runs fine, it's just losing coolant through the ccv. We will be testing the cooler tomorrow, but we recently replaced the cooler because it was leaking and pushing oil into the coolant, so I doubt it would be going the other way now, since the oil pressure is higher there than the water pressure.

I'm still very surprised that we can't find any water in the oil. The stuff coming from the CCV is the normal milkshake oil-coolant mix that you'd expect, but there's no indication of water in the actual oil pan.

 

[John C.]

I don't recall but maybe someone here might. Are that any soft plugs in that head under the valve cover. Is this a direct injection engine or a pre cup? I've seen cracked pre cups put just a seep into the top of the head and when kept warm the breather catches most of the coolant. Was also wondering what type of antifreeze are you using? I would suggest an oil sample looking for lead in the engine oil as well as the coolant. I've seen a few hours on marine engines but never a 3306 with that much original time. Might be time to think about rebuild or exchange.

 

[kshansen]

From the sounds of it I be very careful starting this engine. Just thinking that if the head is cracked and leaking coolant into a cylinder it may hydrostatically lock up the next time you start it. If there is a way to crank the engine over a couple revolutions without it starting I would do that.

The thing that bothers me is why you have a half gallon of coolant in the CCV bucket but nothing in the oil pan. Never dealt with a marine application but I would think the CCV filter box would just be connected to the breather on the valve cover to catch the oil mist so it doesn't get in to the bilge. A half gallon of coolant is a lot to be coming out the breather but if the engine was working hard to go those 40 miles it may have just boiled it out of the crankcase and then condensed it in the CCV filter. I'd bet that if you were to drain the oil and then put say 10 psi air pressure on the cooling system for four hours then check the oil pan again it would have a very noticeable amount of coolant. No matter what is leaking, be it the cooler, a cracked head, water pump seal or rotted out core plug(I don't like the term freeze plug or soft plug because both are not that accurate to my thinking) that coolant if it is leaving the cooling system really only has two places to go. One being out of the engine, through the exhaust, intake or a hole to the outside. The other to be going to a different part of the internal engine and seems like all those possible places will end up in the oil system. Be it the oil side of cooler, the inside of a cylinder through a rotted out liner or through a cracked head. If it gets into one or more of the cylinders it will make it's way past the rings and into the oil pan, maybe not fast but given time it will.

 

[kshansen]

I don't recall but maybe someone here might. Are that any soft plugs in that head under the valve cover. Is this a direct injection engine or a pre cup? I've seen cracked pre cups put just a seep into the top of the head and when kept warm the breather catches most of the coolant. Was also wondering what type of antifreeze are you using? I would suggest an oil sample looking for lead in the engine oil as well as the coolant. I've seen a few hours on marine engines but never a 3306 with that much original time. Might be time to think about rebuild or exchange.

I guess a leaking pre-cup could leak coolant into a cylinder and past the rings but seems like that would likely let compression gases into the cooling system while running and show up as pushing coolant out of a pressure cap. I'm making the guess that this engine does not have a radiator as such but a water to water heat exchanger of some kind and is running coolant with some kind of expansion tank with a pressure cap like a radiator would have. Like I said I have no first experience with marine applications.

Also if this is by chance a pre-chamber engine a 3306 should have the chambers outside of the valve cover unlike say a 3408 where they are inside the valve covers.

 

[d9gdon]

If it got hot, it prolly did crack the head. Normally the coolant is going to sit on top of the piston where it cracked like Ken said. I'd pull that head real quick after I green lighted the cooler. If it's a pre-com engine, it likes to spider web where the chamber screws in after boiling.

 

[brendan1911]

Well the H.O. Penn/CAT guy came and basically said "I don't know what to tell you, it needs to be rebuilt." So the plan is to drain the pan, and pressurize the coolant system to see if we get water in there. He checked the weep hole on the pump and said it's fine.

Also, the coolant system is full of water, because we've been flushing it to remove residual oil from when the cooler went. So maybe that's why the water's evaporating before it makes it to the pan.

 

[Nige]

To remove the residual oil you need to fill the cooling system with water and a commercial dishwashing detergent such as Cascade. A heavily contaminated system could require 2 or more flushes to remove all traces of oil. After that you need to flush a couple of times with clean water and lastly fill with a recommended coolant.+

 

[brendan1911]

Cascade's what we used, and we're on our second run of water + cascade right now. My point was that maybe the water is why it's boiling off. Coolant has a higher boiling temp, and thus maybe if it were antifreeze it would be dripping down into the oil pan. It's a very large system, because the coolant runs down through the hull through keel coolers (basically a radiator under the boat, which uses sea water to cool pipes full of coolant).

All in all this is gonna be a pain. I'm the deckhand and the youngesy guy, so when it comes to deciding who needs to crawl under the engine, I tend to get first dibs. Only one way to learn though!

 

[brendan1911]

Well, the CAT guy said he cleared the weep hole. However after dropping the pan and seeing water drip from right under the water pump, I decided to check the weep hole with a small pick. Apparently his screw driver didn't go all the way in, because when I did that, a clump of crap came out, follwed by a ****** of water.

 

[Nige]

Immediately followed by an "Aw s**t" I bet .......

 

[kshansen]

Well, the CAT guy said he cleared the weep hole. However after dropping the pan and seeing water drip from right under the water pump, I decided to check the weep hole with a small pick. Apparently his screw driver didn't go all the way in, because when I did that, a clump of crap came out, follwed by a ****** of water.

So do I get the bonus points for suggesting that was one of the likely problems? See the last paragraph in post #6!

Maybe a free oyster dinner next time I'm in the neighborhood?