coolant issue on 12 v 92s

Why did you start another new Thread?


This is the third new Thread in 9 days for the same topic/subject.


Your update post should be a continuation of your prior Thread,
which should be an update post to the original Thread, dated 02-17-2014, 07:30 PM.


Thread #2: http://www.yachtforums.com/forums/technical-discussion/22481-coolant-blowout-12-v-92-a.html

Thread #1: http://www.yachtforums.com/forums/technical-discussion/22458-12-v-92-coolant-issue.html

It sounds legitament to me. However if he's yanking all of the injectors, and the tubes all look good, I would then do a compression test on each cylinder and see if there are any low ones and on which head, before yanking all of the heads off. But then again, if one is leaking it might not be a bad idea to inspect all of the heads. Was this the motor that was recently rebuilt?

What's the age since rebuilt? How many years? Was the other one recently rebuilt? Chances are it's the head gaskets (o-rings). It honestly is not a bad idea to have them all yanked (heads). The o-rings deteriorate on the 92's and then start leaking.

Until the three threads are merged, I will ask my question here:

Reading the other thread, Captain J and RCRAPPS suggested doing a few tests before going into tearing apart the engine, did you or your mechanic do those? What were the findings? If not, then, is the mechanic taking the route of "bigger bill"?

I ask because the guys were guiding you through an elimination process that would assist in pin-pointing the case and in my guess saving you a few bucks here and there, Captain J mentioned what you are doing now, but I would have liked to follow the simplest suggestions from the beginning till solving the problem or reaching the "Dark Side".

Thanks for sharing and I hope you get this over with soon!

Hi, Slow down, its going to get expensive.
You didn't mention what the the pressure was with the engine running, using the the pressure tester. As to seeing the the piston and liner conditions a good bore scope can be inserted through the air box covers. You see the fire deck of the head, pistons, and liners. Did you ever pressurize the cooling system with the injectors out?
Jim

I would, this might give you a place to start instead of throwing money at a problem that may not be there. Did the mechanic try running the engine with the tester on expansion tank? As to the overflow tanks, Are they the large 2 gallon type that DDA used or are they relatively small? Back n the beginning of this thread, you mentioned you pulled the cap off and there was pressure. What was the coolant level in the tank? It seems odd since there is no heating problem or coolant in the oil.
Jim

You asked, I'll answer.





Here's a question for you.

Is your mechanic a mechanic or a parts exchanger?

How good is this mechanic? I would do a compression test, if only to see what the compression is on all cylinders and how worn the motor is (rings/liners). With the injectors all out, it'll take an hour to compression test the whole motor. With 2700 hrs, if you have to drop the pan and have the heads off, just do a major overhaul. There's no sense in spending 60% of the money and having an iffy motor of questionable lifespan afterwards. If you ever go to sell the boat, you can at least say the Stbd was majored. It could be a cracked liner, but I'd point more towards an o-ring. But after compression test, if all cylinders are fine except 1 and pulling THAT head reveals it's an o-ring and the liner is fine, I'd just do o-rings on that head and let it ride instead of pulling everything. As the other poster mentioned. You can borescope D.D.'s through the airboxes without pulling anything apart.....I'd compression test 1st, then borescope, then pull heads in that order....if I was pulling the heads and pan, the motor is getting majored....no if ands or buts......If I was doing a major, i'd want someone that does them all of the time doing it, and not a simple mechanic.

Capt J is somewhat on the right path, but to do a compression test as per the service manual all the injectors must be installed except for the cylinder your working on. Reason being is that the engine is to be running at idle. For it taking an hour is nonsense, its going to be most of a day, Good Luck.
Jim

Coolant Issue on 12V-92s

Valid compression testing of a Detroit Diesel two-stroke engine requires the engine be running at nominally 600 RPM, and as warm as possible such that the mechanic can still handle the valve gear components and fuel injector of the cylinder(s) being tested. A starter cranking the engine over is of no value with Detroit Diesel two-stroke engines. No more than two cylinders should be tested (not running) at any given time, because the fuel injector has been replaced by the compression gauge. This requires disassembly of valve gear and removal of fuel injector on the cylinder(s) being tested, install compression gauge, start the engine and take compression data,
remove compression gauge, reinstall fuel injector and reassemble valve gear. Repeat this process until all twelve cylinders have been tested. A 12V-92 engine compression test of all cylinders will require at least eight man hours of labor to perform, even by the fastest technician. Been there, done that many times.