Detroit Diesel 12v 92s - Help Please!

Hi,

Ed,

These are the OP's own words.

Are you sure he is wrong?

If the level alarm is going off to indicate low level there is either low level. a bubble of gas around the switch or a faulty switch.

If the OP follows the simple instruction to leave the level a couple of inches below the filler and no more comes out this can be called finding its own level - something that we used to do in cars and trucks.

If it continues to push water out when starting with the level down as suggested the system is getting pressurised from somewhere hence a good suggestion was to get the DD Test Strips.

I don't believe this issue is covered in the CFRs.

Since I am not standing beside the engine and have not witnessed the condition the OP described, I am most certainly providing the benefit of my knowledge ... I strongly suggest a review of the DD documentation regarding approved coolants and additive packages before freaking out over the color of the stuff or dumping it. I also strongly suggest that the OP employ a knowledgable and competent DD technician to observe the problem before throwing parts at the engine or any other of the suggestions.

It should be obvious that the OP is not well versed enough to know when to stop trawling for an easy answer and call in the pros to help diagnose what may or may not be a problem. It might be the best $150 they guy ever spent and the education he receives will be worth far more than the price of a service call.

YOU HAVE TO USE THE DETROIT DIESEL COOLANT ADDITIVE OR ANTIFREEZE FOR 92 SERIES ENGINES!!!!!!!!!!!! Very Very important. If you don't get freezing temperatures you use water and the pink DD/MTU additive, if you do need antifreeze i think it's DD G92 antifreeze, but check with your Detroit Diesel dealer for the correct one as it's been a while since I've messed with the 92 series. This is very important with 92 series, otherwise you'll end up with blown head o-rings, and possibly water ingestion into the cylinders, and the coolant should be changed every 2 years with 92 series.

I didn't notice they were DDEC's. Yes, they do have a coolant level alarm. If, they're DDEC's then definately get overflow bottles. Once the system has purged the air out of it, you would generally only add fluid to the overflow bottles. I always add water once the coolant is at the proper mix, as the water evaporates, the coolant does not (provided you have no leaks). Definately get the test strips, and test the coolant you have to see where you're at. I'd recommend changing it anyways if you're uncertain of it's history with DDEC's. DDEC's will usually move a gallon or close to it of water between expansion at operating temp, and contraction back to outdoor air temp. That is my guess as to what is going on, but you cannot be certain. Are both engines doing this or only 1?

Per the OP, he's adding a gallon of water before he heads out. Could it be the engine is purging due to overfill ?

Correction, he adds water before he leaves the dock.

This is what I believe is happening. He's topping off before starting the motors, it purges the gallon due to expansion and he's back to adding a gallon. Therefore dilluting his coolant with water.

bingo!!!

Are you adding to both mains? If it's DDEC low water alarm, Where is the low water if the tank has expanded and spewed from the top purging water and air. A recovery system would really help remove any trapped air but I'm not Bingo on this yet.
Lets get at least some fresh caps on there. Check the seat inside the neck real good (may need mirror) And insure the neck itself is not deformed.
BTW, how is the sump oil looking?

Sometimes a part store will loan / rent tools. Call around and see if you can find a closed system pressure tester (radiator pressure tester). Pump it up a little one night, NO more than 8 psi. Let is sit overnight. report your findings. REMEMBER, NO more than 8 psi.

I'm out.

Change the caps with DD caps, as they are cheap anyways (on both) and you can alienate that anyways. It also can be the boats running attitude (angle) at cruise and the angle the engines are mounted in the boat (shaft angle) that's causing it to just hit the low water level at cruise. On the DD's the low water level alarm is not all that far down the tank. I would not change the coolant at this point. I would check with test strips or have the coolant sent out for testing (preferable) to see if there are any signs of combustion gases in it. Also pull an oil sample as well and have that tested. I would check coolant level cold and measure how low from the top with a ruler, run the boat for a few hours at cruise, come back 36-48 hours later and check the coolant level again after the motor is back to the initial ambient temperature. I would also check all over for any external coolant leaks as DD's have a lot of those 4" long rubber hoses between hard piping and they tend to leak somewhere.....

Also, another thing you can test is by taking the cap off (when ambient temperature), run the motor up to temp and if you have combustion gases getting in there you'll usually see bubbles in the coolant.

I'm not sure of the particular differences between the 12V71TI engines and the 12V92TA engines?

But ... I recently had one of my 12V71TI engines overhauled. I was experiencing coolant coming out of my radiator line (just below the cap).

After some exhaustive investigation, it turned out the new cylinder head was malformed and the "injector tube" was not properly seating. The coolant was getting into one of the air boxes. By pulling the airbox covers, the mechanic was able to see emulisfied oil at one of the injectors.

After replacing that cylinder head, all is well.

The water/coolant coming out next to the radiator cap seemed the same as the rest of the coolant. I had reservoir bottles installed. On the engine with the bad head, the reservoir bottle filled but would not "draw back in".

Dumb question: if the leak is on one side only and you suspect the radiator cap have you tried simply swapping caps from port to starboard to see if the issue follows the cap?

I have 12v92's with the recovery bottles. Even after you find and fix your issue, I would recommend installing them as others have recommended. Mine are mounted on the bulkhead forward of the engines. The tube running from the expansion tank to the recovery bottle runs up the bulkhead and acts as a sight glass for fluid level. I have stickers on the bulkhead that show where the fluid level should be for both cold and warm conditions.

This might be helpful, I have 6V92 TA's that are not DDEC. Stewart & Stevenson the Detroit dealer has more info on the coolant types. From the Hatteras forum:
DD 6V92 TA Coolant replacement

Yesterday I visited my local Detroit Diesel distributor to purchase replacement coolant for my two 6V92 TA engines. It has been a little over 2 years since the coolant was replaced. I had been using PenCool 2000 with distilled water only, since the boat only operates on the Gulf coast. To my suprise Pencool was not stocked anymore at the DD distributor. They recommended Detroit Diesel Power Cool 6000 if no freeze protection was required. I purchased the Power cool 6000 for $43.00 a gallon and drove to the boat to proceed with the replacement process. Has anyone else used this product?
Thanks,
Joe Signorelli
1985 422 Chris Craft Commander
Barbara Ann
New Orleans, LA