Why do 692TA's overheat

[SeaEric]

Bob, On the Chesapeake, the Bay water temp stays up well into late fall, This serves as a heater for the engine room. Your engines will not freeze before you head south. If it got really cold, the domestic water system on the boat would be in some peril. I'm sure hoping that you get underway before that occurs.

The cooling system additives are a good question. The guys here (Karl) probably have the answer to that. I'm sure there are appropriate products available.

[MikeP]

Your situation is not at all unusual; my 8V71TIs did exactly the same thing. They would hold mid 170s at 1500 RPM but once RPM went above 1700, temps went up. You could not run at WOT for more than a minute or two without temps getting to the 195 range and heading upward. I cleaned the HEs and the intercoolers, replaced the coolant (looked like regular auto antifreeze) with Powercool/water 50:50 and now they will maintain low 180's at WOT for as long as you care to pay for the fuel. As Karl said, 50/50 is not necessary if you don't face freezing but we do (for one more winter!) and I don't care to be changing the coolant twice a year.

If this is the first time you will be cleaning the HE/ICs since you have owned the boat, I recommend you remove/disassemble them and, after inspection, dip them in the acid mix. You can use a 5 gal bucket. This provides a way to really inspect them and provide yourself with the comfort factor of knowing they are OK. It also ensures nice fresh gaskets and seals! After doing this, I would be comfortable from that point on with periodically pumping the acid through the system.

I used the solution of Muriatic acid, Oxalic acid, and water as specified in the DD service manual. The acids can be obtained at any hardware store. It is more agressive than ospho so if you end up using them instead, you need to be more careful (not that you wouldn't be careful with any acid).

Cleaning the HEs and ICs makes a tremendous difference!

[bobk]

You may have to get out the acid, I like to use a small recirculating pump and a bucket, do not use straight acid since it will attack everything it contacts, I use a diluted solution and it will eat the marine scale quickly anyway without affecting your engine components like pure acid does.

OK, I'm checking the strainers this morning. How about some guidance on the acid. One HE was replaced two years ago, the other was cleaned. About 70-80 hours on them since then. SO, I'd like to try the simple approach first. Where do I connect the acid inlet and outlet?

I'll also drain and refil with water plus additives. Where do I get additives?

Bob

[Genesis]

Call Saunders in Panama City FL if you can't find it locally. Talk to Bob - he knows what I used to run and can give you the Detroit number for it, which will let you buy it locally.

There's also a generic version that I like even better, as its cheaper...... but the shipping is likely to make that uneconomic if you can source locally.

ANY Detroit-centric shop should know what you're talking about when you ask about running distilled water with inhibitors. If they don't you need a new Detroit shop. BTW they may recommend against it but that's a CYA move because if you DO freeze with water + inhibitors in the block you're screwed. Note that Detroit specifically allows this combination in their shop manual - so for those who play the "that's unapproved!" game, tell 'em to stuff it - they're wrong!

Water has more heat transport capability than glycol, and due to what I consider to be marginal cooling systems on EVERY marine Detroit I've ever worked on you want every bit of margin you can get. If you talk to an HONEST mechanic he will tell you that THE #1 cause of short-time rebuild requirements on marine diesels is overheating.

My favorite H/E on-engine cleaning incantation can be found here: http://www.samsmarine.com/forums/showthread.php?t=1483

Note that if you've never had the H/E bundle out of the boat since you bought it AND you're running a glycol-based formula odds are good that you need to have the FRESH WATER side of the bundle cleaned too, because glycol has a habit of leaving deposits on the tube bundle over time. The only way to clean these is with a caustic dip or ultrasonic - and guess what - the "Twin Pack" is apparently no longer available due to EPA stupidity. As a consequence the only fix for this is to dismount the bundle and take it to a radiator shop - if you do my magic incantation and that doesn't fix it, that's your next move.

[bobk]

Thanks Karl. I'll be making up the adapters tomorrow and have at it. I have a J&T shop near me and they ought to have the lube/corrosion additives.

Bob