#%&@ Starboard engine again

[bobk]

Nalcool? Nalcool and distilled water is Ok as long as the concentration is correct. Too much Nalcool and it eats seals.

A DD mechanic in Florida changed the systems to Nalcool when he did flushes and changed a bunch of hoses etc, so I can only hope the level is correct, but it makes one wonder. I have Frank Butts from AP Marine coming to check/fix the problem. Frank is ex J&T and a DD-only guy with a great reputation.


I don't know about how to test it, but agree if this is 'just' an oil cooler leak, I sure don't want to get into head gaskets etc. I did notice that there was no vacuum/suction when I removed the cap on the expansion tank. And of course, the combustion gas test showed no leak into the coolant a couple of weeks ago.

Bob Kassal
Chateau de Mer
1981 48MY

[Genesis]

Oil cooler leaks aren't real common but they do happen, and they're a hell of a lot easier to take care of than ripping the heads off the engine only to find that's not where the problem is!

If the oil cooler is leaking you'll almost always get oil in the coolant as well as coolant in the oil - when the engine is running the oil pressure is much higher than the cooling system's, and so it will leak that way, while when shut down it's the other way until the cooling system cools off and the pressure is relieved.

[bobk]

Oil cooler leaks aren't real common but they do happen, and they're a hell of a lot easier to take care of than ripping the heads off the engine only to find that's not where the problem is!

If the oil cooler is leaking you'll almost always get oil in the coolant as well as coolant in the oil - when the engine is running the oil pressure is much higher than the cooling system's, and so it will leak that way, while when shut down it's the other way until the cooling system cools off and the pressure is relieved.

Karl, I already discussed this with the mech and he said the same thing.... with little to no oil in the coolant he tends to think it is not the cooler. I hope to know more when he gets to the boat tomorrow.

Bobk

[bobk]

The heads came off on Friday and there was a leak in a head gasket and Frank also said something about a burned seal. Frank also checked a bearing and found some problem so will be replacing bearings. The kits are out to identify the cause of the oil in the crap can. No word on that yet, but we might as well replace them at this stage.

Bob

[Genesis]

Burned seal on a 92 (presumably a liner seal) = overheated at some point.

The damage can happen quite a while before it starts leaking, but it will start leaking once it happens eventually.

"Never exceed" is 195F, and it really is "never exceed."

The head seals (Detroits don't have a conventional "head gasket" like a car engine) may have been compromised from the same root cause.

[bobk]

Interesting Karl. I never saw more than an indicated 185 degrees at the helm and those gages agree well with the ER gages, but wonder if the PO might have overheated it. He did have one heat exchanger replaced and the other cleaned. Could this also account for the oil running into the crap can?

[Genesis]

Probably not on the oil in the crap can, but possible. Depends on what was compromised where.

If the PO overheated the engine it's entirely possible the seals were compromised but didn't immediately start leaking. They reliably will though once that happens - it's just a matter of time.

You're not really better off with the dry-liner Detroits - they don't leak coolant into the oil like that, but they do crack heads (as do wet liner Detroits) and they do locally-overheat cylinder liners and warp the block, which makes a proper fitting of replacement liners trouble at best (and can turn the block into a throw-away at worst.) It's a hell of a lot easier to properly fit replacement liners on a wet Detroit - on the dry-fit ones there's a pretty-involved set of measurements you HAVE TO take before you order the kits or you'll get the wrong ones, and if you're out-of-spec for all of your choices you got big trouble. The shop manual has the procedure in it and it has to be followed to the letter or you'll have one of those famous "well under 1000 hours and it's dead again" rebuilds that goes bad on you.

Excessive oil in the airbox (which is where it has to go before it goes into the crap can) typically comes from one of three places - blower seals, bad oil control rings on one or more holes, or a bad center-section seal on a turbo. It can also be caused by really-excessive crankcase pressure (bad compression rings among other things) if your breathers are routed back to the intake, as is the case if you have Airseps.

The latter is easy to identify - you pull the air pipe from the turbo into the airhorn and it will be oily. If it's coming from the breathers the MIDDLE of the turbo compressor wheels will have crap on them - if it's coming from the center section they will not since the oil exits behind the compressor wheel. The first cause is easy to identify too, but dangerous - pull the airhorn and start the engine, then shine a light on the end plates of the blower. If it's leaking you'll see it. It's dangerous because if ANYTHING gets in the (open) top of the blower, it will be eaten - including arms, ties, engine parts, shirts, heads (yours) etc. - I got ripped a new one for suggesting this on Boatdiesel a couple of years ago, but it IS the definitive way to KNOW if the seals are bad in the blower.

The middle cause (badly worn or broken oil control rings) is usually only determinable FOR SURE by a teardown - you can't inspect them with the engine together as they don't up far enough to be visible in the ports during a stroke.

There are other places oil can come from but those are the "big three". For obvious reasons the middle one is the last one to be checked, as the other two require little or no disassembly.

In this case the engine is already apart so determining where it's coming from with reasonable certainty should be easy.

[bobk]

Fellow HOFers, the kits arrived yesterday and re-assembly began today. Sea trials are scheduled to be Friday. My insurance company is going to help with this. It appears a seal was not properly installed in the earlier rebuild (PO) and that led to the coolant intrusion. Sorry I can't be technically precise here... I'm a chemist. It's been a long wait, but we are anxious to get a cruise or two under our belts before we start south.

Walt, I have an old kit for you. How do I get it to you?

Bob
1981 48MY
DD6V92TA's

[saltshaker]

Glad to hear things are coming together.

[Walter P]

Bob,

Thanks. I'll call you about the kit. I'll probably drive over next week for it.

Walt