Twins with Twins, Anyone?

[kidturbo]

I put 36" drain hoses on the factory pan drain ports that I can hook up to a pump or vac setup. On my old boat I could run that hose out the transom drain plug hole into a bucket..

I got most of it cleaned out Sunday night. But being the bilge runs clear up to the cockpit door, it's gonna take a couple more bottles of dawn to get all of the oil scum washed out.. Problem is finding a place to park with nose high enough to drain. I need a forklift...

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[kidturbo]

Movin on up.. And that puts it currently fast as my original Duramax boat...

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[gmac32]

Out of the drain hole in the transom

 

[LBZ]

Where does this bilge oil go?

The oil I drain out the drain hole in the transom and into my normal pans that then gets poured into empty oil jugs same as everything else I change oil in. Then when I wash it out it gets drained into an empty used oil pail then everything goes to the waste oil collection site in town. That’s how I know it takes 5gal of hot water to clean it out lol.

 

[2004LB7]

 

[cdbright]

was waiting for the "get her on plane and pull the bilge plug from inside the bilge trick" hahahahahahahah

 

[kidturbo]

And here I thought that's why they made bilge pumps??

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[kidturbo]

Got all the oil all cleaned up, now we're dumping coolant in the bilge.. Thought it was just a pinched O-ring on the Stbd coolant reservoir, but after removing the O-ring spacer I put in there, inspected everything, replaced it,, to realize we have a crack somewhere....

So Dmax gurus, need some technical input.

Same engine that blew off the 16lb cap at 900hp on the dyno, is pushing coolant now above 30psi boost.. At 15lbs boost she makes maybe 4-5lbs in the coolant tank. Noting at idle.. But soon as ya bring the load on it, she's making 8-12psi in the system. Just enough to push past the o-ring on that tank, and spray coolant down on the belt, while never popping the cap. And according to the 1400-1500 EGT and 39lbs boost I noted today, we're only operating in the 700-750hp range right now.

Most of you will say where's the problem with that, just fix the O-ring leak.. And I would typically agree. However these engines are running Evans HD waterless coolant which, which doesn't boil unit 370F. Creates zero system pressure under normal conditions. Engine temps are both running running 180F.. In fact every gauge is so identical to the point you'd think your looking at same engine.. And when we moved the pressure gauge to Port engine, she makes about 1-2psi in the cooling system under same 39lb boost conditions.

Stbd also picked up on the blow by I noticed yesterday, which seems to be just some moisture / coolant vape escaping the crankcase upon closer examination. Once again, port side no issue.. So I brought my GM Master Tech back onboard today to confirm my thoughts. He agrees, we have a leak.. Most likely cracked in a runner, because it only happens under boost.

After the dyno runs, we ditched the LML head gaskets and went back to std Mahle C's thinking that was our issue. Today we made 3 runs of mile or two and did a head to head [pun intended] comparison between Port and Stbd under load. No doubt she's leaking, but where? We both feel it's likely a crack in an intake or exhaust runner since the issue only pops up when boosted. Tomorrow we're gonna yank both heads, and prep another set to replace em.

So what's the conscious?

 

[PureHybrid]

Heads are ported stock castings?

 

[kidturbo]

Bone stock, just springs.

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[DAVe3283]

I agree, cracked runner. Intake or exhaust, who can tell, you'll have to pull it apart and see. Could intentionally pressurize the coolant and see if you see it spraying in one of the runners.

I have some experience with cracked heads...

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[Stingpuller]

Back in the day I was fighting the same issue and it turned out being a crank in the cylinder. That was the original motor in my white truck that didn't have 6k miles on it. After 3 sets of head gaskets i pulled the motor down and the machine shop found it when honing the block. Hopefully not the issue.

 

[Fingers]

To this day, I have a crack in one of my heads in one of the exhaust runners that only shows up in cold, cold winter. I lose between 1-2 quarts. Not a drop in the summer. It only opens up during the warmup-cooldown cycles. 5 years to figure it out and I've been running that engine and heads for 8 since.

 

[Chevy1925]

cracked runner or cyl imho. you can see the cracks on the exhaust side pretty easy (been there), intake side daves thread is pretty good at showing. Cylinder means your pulling heads to verify. Being you have LMM heads (i think?), i have my doubts its the heads that are cracked but your situation is different than most too.

Mine was like jons for a long time but im sure the thermal expansion of me running 240* coolant temps and high exhaust temps finally did them in. all 8 runners were cracked. This was on old LLY castings though (known to be weaker).

 

[Bdsankey]

I'm on the same train as everyone else, crack in a runner or cylinder.

 

[JoshH]

Doesn't that thing have those water to air intercoolers? Possibly that's what is leaking? How easy would it be to swap them to rule that out?

 

[kidturbo]

Thanks much for the input everyone. We will hope for the best, and certainly do some heavy searching for the source before bolting another set of heads on it.

The blocks are very low mileage LML I got from DHD. Outa crashed trucks, so that's always a possibility. The slight moisture in the oil is concerning because it lends to not being a runner. I have a test kit from my BioD production days that does a definitive vale down to 0.1%. So will grab a oil sample before we tear down.

As for the charge cooler, it's on seawater side and not connected to the engine coolant. I was actually monitoring pressure on that system last few trips out to get the water pickup tubes height adjusted correctly. It's seeing about 20psi at speed, which is little lowers than I plan to run. But as with all the seawater cooled parts, if you spring a leak, the boost or drive pressure will most likely push air into that system, rather than water into the engine side. Unless it's a really bad leak, then you'll see water intrusion out the exhaust side at idle.. What had Mark and chasing a ghost on the dyno one morning, when it was actyally due to condensation from 40F water in our outside cooling tower setup.

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[kidturbo]

Beside the fact I smoked the autocal licensed to the ECMs last week and have lambda tables jacked way out down low, they are otherwise kicking ass.. Here is run from yesterday when we were comparing cooling system pressures. I let off at end when I looked back to see my helper DD with both feet on an engine and about to be sucked down a turbo.. lol

Source: https://youtu.be/qy9Sq4_A1Ds


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[Chevy1925]

she looks like she is just begging to go faster

 

[kidturbo]

Heads off, cyl walls look good with naked eye. Head gaskets show no signs of leaking, so guess we'll swap out the heads and hope for the best..

Sent a nice clean pair to machine shop today for inspection and swap springs. Plan is bolt em back on Sunday. I'll let the shop see if can find our crack. But I'll know the answer before them, pretty sure..

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