Coolant Questions

[z28jimi]

Well, I've decided to bite the bullet and replace both turbos. That will cure the coolant leak in the starboard engine, and hopefully eliminate the potential for the same type of leak in the port.
That means I'll be draining the old coolant, so it's a good time to start with a full charge of fresh stuff in both engines.

Here's where I need a little help.

I'm running DD 6-71 TIB's, and I know that each boat's cooling system is different, with different capacities, but can someone give me an idea of an approximate coolant capacity for these engines? At least that way I'll have a rough estimate of how much to buy.

Second, and probably the question that will generate the most discourse, is there a recommended coolant? I've been told by a local mechanic that he has used the xerex orange stuff for years with no ill effects, and I've seen where others swear that green is the only color there is.

The port engine is full of green stuff now, and the leaky starboard engine is filled with a combination of green, orange, and just about anything else with the word "antifreeze" on the label. How diligent do I need to be in draining and/or flushing that devil's mixture out of the starboard engine?

[SKYCHENEY]

I'd say green is okay for 71 series engines. If I weren't using that, I'd go with DD Powercool which is kinda purple.

Flush that mixture out well. Some of those antifreezes are not compatible with each other and make a muddy mess when mixed together.

[MikeP]

I think the purple is much prettier! But as noted, flush all the old stuff out as best you can before putting in new. If it's not premix, use distilled water with the AF.

[Vincentc]

If you keep the boat in FL, why use antifreeze? I've used distilled water and Pencool 2000 in a 20/1 ratio with no problems. I believe it is the recommended additive for 671's.

[z28jimi]

I appreciate the opinions guys...does anyone have an idea as to quantity?

[Genesis]

Daytona Beach? Run inhibitors and distilled water. Detroits, especially high-performance Detroits, are notoriously thin on reserve cooling capacity, have a low-pressure system, and overheats crack heads and do other ugly things. Distilled water has a material (10-15%) greater heat transfer capacity than glycol-based coolants (depending on the percentage of glycol you use.) This is an approved Detroit option, provided you're not in a freezing area; it is not "shade tree mechanic" speak.

Get every edge you can get on engine cooling; you have no need for freeze protection in that location and when the water you are floating in is warm it makes even more difference. (Around here it's not uncommon for the bays to reach the mid 80s which doesn't do your cooling system any favors either.)

As for capacity "best guess" is around ~6-7 gallons per engine, but that's a guess. Two 5-gallon buckets per engine should be sufficient for draining purposes. Make sure you get all the old coolant out - there are drains on the bottom of the elbow below the fresh water pump, the bottom of the oil cooler, manifold and drains in the block. Drain them all, then flush the block with clean water until it runs clear, then drain from all points again before refilling.

[Jim saco]

I'm up in rhode island and the Cranston DD service center has DD powercool unmixed for 10$ a gallon. I don't know what the price would be down there but for that price I wouldn't use anything else unless I was going to use only additives and distilled water as genesis suggests. I have 6v92's and they take 11 gallons total however a friend of mine has 671 inverts in a Bertram and they take 7.5 gallons.

[Hat52MY]

Being in FL you have a couple options:

1) Fully-Formulated Antifreeze. This comes in two forms: pre-mixed or a concentrate to be mixed with distilled water. See Approved Coolants List below for proper coolant selection.

2) Run distilled water with the add Supplemental Cooling Agents (SCA).

Below is documentation to help make an informed decision on the pros and cons. Really comes down to personal preference and dependency on warm or cold climates. I test the coolant every few months, using a test strip (similar to the ones for checking pool chemicals) which checks PH, Nitrite and Freeze Point.

Regarding the capacity, I have a book on the boat that lists the capacities for the different models. Will be up there this weekend, give me a ring and I will look it up.

Since you have it all apart it may be beneficial to flush everything (Coolant side & raw water side) before adding in the new coolant. Replace any questionable hoses and those radiator caps with the proper 7psi version - not 14psi otherwise you will have a whole new set of issues!

FWIW, I went with the Fully Formulated Antifreeze and glad I did. One month later the boat was in Jacksonville on the hard for a month for various services, no power on board. For a week of the month the temps never rose above freezing. I slept well knowing the engines were protected...point is, you just never know about mother nature.

Everything you wanted to know about Detroit Diesel Coolant Selections.....

Detroit Diesel Coolant Selections for Engine Cooling Systems - 7SE298
http://www.detroitdiesel.com/pdf/voc...Selections.pdf

Detroit Diesel Cooling Systems Technician's Guide - Inspection / Analysis / Troubleshooting - 7SE390
(can not find the PDF on-line but I have a downloaded PDF version if you want)

DDC Power Cool 93K217 Approved Coolants List
http://extranet.detroitdiesel.com/Su...int_93K217.asp

Penray Marine Information
http://www.penray.com/products/marin...7&navID=marine

[z28jimi]

Lots of good information. Thanks to all of you.

David, we plan to be on the boat this weekend. I'll give you a call.