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OT- Does anyone here know a Detroit diesel "genius" I might could talk with ?

Milacron

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OT- Does anyone here know a Detroit diesel "genius" I might could talk with ?

This relates to my previous post about the mythical "engine rot" in a marine 12V71TA. I want to pin this down absolutely 100% as total BS (or not) before confronting the proclaimer of such and need backup authority from as high as it can get.
 
I don't know what you're talking about when you speak of "rot" on any DDA. These engines are very reliable, they simply need a good, comprehensive overhaul, if you are experiencing reliability issues. That means a total disassembly, cleaning and reassembly examining every part, repairing and replacing as necessary along the way. The bad part is that it is very time consuming to do correctly. The good part is that it is a lot of fun, very personally rewarding and lastly, parts for DDA motors are probably the least expensive of any diesel engine in their power class. I would not recommend contracting the job out to a shop. No shop can do this correctly without charging for the enormous time it will take. (Think cost) If you elect to do this, you will quickly realize just how well built these things are. If you elect to do this yourself, you should expect using about 60 days per engine to complete on a part time basis. That includes sending the heads out to a machine shop, exchanging the turbos for rebuilt units and time waiting for ordered parts. Poor maintenance, amateur assembly and unacceptable short cuts contribute to their undeserved criticism.
 
This relates to my previous post about the mythical "engine rot" in a marine 12V71TA. I want to pin this down absolutely 100% as total BS (or not) before confronting the proclaimer of such and need backup authority from as high as it can get.

I don't know any DD specialist but I saw the rot post and LMAO. it is 100% total BS. Anyone talking engine rot is a moron or a thief.
 
THey may be speaking of erosion in the coolant galleries or liners. I'm not that familiar with maritime applications but I know there is a cathodic reaction if a steel hull vessels' sacrificial zincs aren't replaced regularly.

The 855 FC and FFCs of various CPL Cummins engines would suffer erosion of the liners. It was variously explained as impact from the coolant hitting the liner or an electrolytic action and/or the former causing the latter. Never a consesus explanation. Various methods were used to counteract the effect. The water pump location was changed and a conditioner recommended. Over the years enough changes were made that the problem no longer exists to the extent it once did.

An out of frame overhaul generally, operant word generally, took about 60 hours shop time. Usually 40 for an in frame, again depending on the chassis it's in. A conventional tractor is a lot easier to in frame than say, a cabover refuse packer. Times get extended depending on machine work needed, line boring, cutting counter bores, flywheel reconditioning, etc.

The Detroit two cycle fuel delivery system is very complex. I think the GM engineers used the German doctrine of design which dictates that if ten parts could do the job well twenty would do it better and the corollary, taking a complex design and complicating it.

The fuel rack assembly on the Detroits noted are very difficult to get right. Specific procedures in the correct order have to be followed. Once properly set and necessary wear parts (usually ignored) replaced it was efficient. I can adjust valves and injectors, set timing, machine counter bores, etc. on an older 855 but lack the courage set valves and adjust the rack on a 6V,8V,12V or horror! a 16V. I saw a stationery 16V on a gen set with the valve covers off. I couldn't sleep for a couple of nights. Not as scary as seeing a completely disassembled 8V fuel rack, both sides apart in a parts washing bucket. DD mechanics are a unique breed. CAT and MACK motors with the Bosch pattern injection systems are a snap, except for the pumps.

I am speaking of the older engines not the modern electronically controlled hyper pressure computer controlled systems used by all manufacturers today.

CAT motors didn't have those erosion problems that I know of in automotive or construction applications. At least mine didn't. I had CAT power, 3406s and 3406Bs (all with retarders) for the last twenty years of my truck owning days. No problems with liner erosion or "rot" of any kind. I did however use their proprietary conditioner in the cooling systems and changed the coolant every two years or thereabout.

So.... I probably haven't answered the question adequately but I hope I stayed close enough to the topic not to have my post taken down. No references to A*****, Cr******** or CH***

Thanks for the opportunity to yak a little about truck engines.

Tony
 
There should be a "genius" here on PM, isn't there a "genius" for everything here on PM ? :rolleyes5:

That's a stupid question I 'spose, since this is most likely why you asked here. ;)
 
"Guarantee auto weld" of Cleveland did my excavators head (4-71 cracked, re-weld and rebuild)
(216) 431-1214 no website

They seem to do allot of DD, including in tugs and other boats (but only the freshwater of lake Erie I suppose)
 
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There used to be a show on National Geographic called "Big Fix Alaska". They followed around mechanics from Jim's Equipment Repair in Fairbanks Alaska. They did several repairs on 2 stroke Detriots, including marine applications.

I like that show. It was a little staged, but the fixes seemed legit. Probably why it didn't get renewed.

Anyway, it's just a shop in Alaska. I bet you could call them.
 
Never heard the term, but if a boat is kept in or near salt water then it will be exposed to salt. In salt water environments microscopic particles of salt linger in the air. These particles enter the engine along with the air supply and can be a source of corrosion. Salt-contaminated air (or in nightmare scenarios salt water) can also enter the engine via its exhaust system. Corrosion of the exhaust elbow is a common problem in all kinds of marine engines operating in salt water.

Also, there is something called "cold corrosion" that affects low-tuned diesel engines. Low-load engines are often used in designs which are seeking constant duty, high-efficiency operation as design objectives. When engines are tuned this way there is a tendency for condensation to build up in the engine and promote corrosion.
 
Never heard the term, but if a boat is kept in or near salt water then it will be exposed to salt. In salt water environments microscopic particles of salt linger in the air. These particles enter the engine along with the air supply and can be a source of corrosion. Salt-contaminated air (or in nightmare scenarios salt water) can also enter the engine via its exhaust system. Corrosion of the exhaust elbow is a common problem in all kinds of marine engines operating in salt water.

Also, there is something called "cold corrosion" that affects low-tuned diesel engines. Low-load engines are often used in designs which are seeking constant duty, high-efficiency operation as design objectives. When engines are tuned this way there is a tendency for condensation to build up in the engine and promote corrosion.
Your post falls into the category of "Hey everybody, look at what I know !" and is basically worthless to the actual issue at hand.
 
I have quite a bit of experience with DDA motors that goes back all the way to the early seventies and I can state that EVERY case of reliability issues that I have seen has been self induced by poor assembly, poor maintenance, incorrect repair, incorrect installation or incorrect configuration. Each of these areas are critical to the reliability and economy of use. There are hundreds of configurations and options for marine installations. Just because a boat manufacturer has installed a DDA in a hull is no guarantee that it was done optimally. This needs to be checked after every installation and rebuild. There are no short cuts here. This is especially true for oil, water and exhaust temperature checks as well as exhaust back pressure checks under operational load. I recommend permanently installed separate sea water thermometers at the heat exchanger inlet and outlets as well as a monometer at the engine exhaust manifold or turbo outlet. These provide assurance after installation, as well as early detection of issues before they become problems. Detroit Diesel has published an excellent installation guide line manual that I highly recommend reading.

Without knowing what issues Milacron is experiencing, I cannot made recommendations of course, but the guide line manual is a very good start. Overcooling can be an issue that needs constant monitoring. From memory, you should see approximately a 10 degree salt water temperature rise across the heat exchanger under load. It is not uncommon to see a bypass valve installed between the salt water pump and the heat exchanger for tuning purposes, as well as another salt water bypass valve between the heat exchanger outlet and the exhaust riser injection point to prevent excessive exhaust back pressure. Corrosion should never be an issue with a DDA either. The 71/92 series engines both use dry sleeves and the cooling cores for both the oil and water heat exchangers are made from a very corrosion resistant copper/ nickel stainless steel. Under no circumstances should the exhaust manifolds ever be cooled by salt water. They should be plumbed from the cylinder head water outlets at the back of the heads. I do also like to use the PH balancing fresh water filter option installed on the thermostat bypass line.
 
What exactly is engine Rot?

Marine Environment is harsh, if the wet exhaust is not designed properly and you get splash back of sea water onto the turbos things can get ugly fast.

Liner cavitation is mostly between the sleeves and due to tiny air implosion eroding a hole usually with wet liners.different coolants get different results.

Ditto on the engine application overloading is common on pleasure craft engines, they test them lightly loaded and most just pass then they ship them out and customer loads all his gear on board and instantly they are overloading the engines.

Or some service tech changes out the injectors and puts in 115's to get it to pull better on detroits obviously the exhaust temp goes up as well as other temp rises.

Pleasure craft have rating on duty cycle, constant use is commercial engine ratings are lower hp on constant duty.
Life of the engine is affected by hp rating.

Boat stands for Bring on another thousand.:skep:
 
Milacron,
I have just read your first "ROT" thread. I am sorry to hear of the wife's health issues. I am also sorry to hear that you are now selling the boat, but I can understand why. In that light, the improvements mentioned in my last reply are not applicable now in your case. However, I would not recommend an in place acid flush of the cooling system. There are too many different metals in contact to your cooling water that would not take kindly to the acid, specifically in the cylinder heads where there are copper coolant directors for each cylinder and the copper injector sleeves. You stated that the engines were rebuilt 300 hours ago, but as you can imagine, there are rebuilds and then there are rebuilds. Just how thorough your rebuilds were are anybody's guess. However, I think it is safe to say the yard guy that mentioned "ROT is full of BS. I think a simple engine flush once or twice is a good plan. It will cause no harm. If you elect to keep the boat, my previous recommendations will apply. Some rust flakes in the coolant is perfectly normal and should not cause any concern at all. Just another reason to use the optional coolant filters that I previously mentioned along with the correct corrosion inhibiting anti-freeze.

Those 12V71's are one of the very best marine engines ever designed and assuming a decent overhaul 300 hours ago, those engines aren't even broken in yet!
 
I have quite a bit of experience with DDA motors that goes back all the way to the early seventies and I can state that EVERY case of reliability issues that I have seen has been self induced by poor assembly, poor maintenance, incorrect repair, incorrect installation or incorrect configuration. Each of these areas are critical to the reliability and economy of use. There are hundreds of configurations and options for marine installations. Just because a boat manufacturer has installed a DDA in a hull is no guarantee that it was done optimally. This needs to be checked after every installation and rebuild. There are no short cuts here. This is especially true for oil, water and exhaust temperature checks as well as exhaust back pressure checks under operational load. I recommend permanently installed separate sea water thermometers at the heat exchanger inlet and outlets as well as a monometer at the engine exhaust manifold or turbo outlet. These provide assurance after installation, as well as early detection of issues before they become problems. Detroit Diesel has published an excellent installation guide line manual that I highly recommend reading.

Without knowing what issues Milacron is experiencing, I cannot made recommendations of course, but the guide line manual is a very good start. Overcooling can be an issue that needs constant monitoring. From memory, you should see approximately a 10 degree salt water temperature rise across the heat exchanger under load. It is not uncommon to see a bypass valve installed between the salt water pump and the heat exchanger for tuning purposes, as well as another salt water bypass valve between the heat exchanger outlet and the exhaust riser injection point to prevent excessive exhaust back pressure. Corrosion should never be an issue with a DDA either. The 71/92 series engines both use dry sleeves and the cooling cores for both the oil and water heat exchangers are made from a very corrosion resistant copper/ nickel stainless steel. Under no circumstances should the exhaust manifolds ever be cooled by salt water. They should be plumbed from the cylinder head water outlets at the back of the heads. I do also like to use the PH balancing fresh water filter option installed on the thermostat bypass line.

The 92 series are wet liner engines. This was a major problem when Detroit introduced the 6V92 engines.
 
What exactly is engine Rot?

:skep:
It's an illusion made up by a FOS marine yard mechanic.

.....which to be honest, I'm pretty pissed off about...as he is an older guy who gives the presence of the "wise old sage", such that at first I thought he might be right and was downright depressed about it as it would be a major expense to rebuild those engines (plus I would loose the sale of the boat)
 








 
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