When to change Coolant

[BadaBingII]

I have 2003 FWC 8.1 Merc V-Drives with low hours ( about 140 . ) When is right time to change the coolant ? It still appears very clean and has good Specific Gravity for freeze protection.

Mechanic says not to worry about it. I thought every 2 to 3 years was the norm for this.

Thanks for your input,

Jeff

 

[Alex D]

Merc specifies 5 years for the orange coolant which is basically a Dexcool water mix. That is the same interval recommended for cars (5 years or 10K miles). If you have the green stuff it should be changed more often, at least every other season.

 

[BadaBingII]

Thanks Alex

 

[stephane]

http://www.consumeraffairs.com/news04/2006/08/gm_dexcool.html

 

[Jimmy Buoy]

http://www.consumeraffairs.com/news04/2006/08/gm_dexcool.html

Since I have Dexcool as standard coolant in my 8.1's it also concerned me. Very scarry stuff about sludging up engine coolant passages and turning gaskets into goo!:wow:

However, if you continue to research the issue (as I have) you will find that Dexcool is NOT the problem for V8 marine engines.:smt001

1) The affected engines are certain GM V6's where the gasket material used was not the correct material to be used with the Dexcool long life coolant. It will turn THOSE gaskets into goo - and only on those certain GM's V6's.:smt009

2) For GM V8 engines such as the 8.1 Horizon, a problem is when owners are SCARED into changing over from Dexcool to regular "Green" coolant. The problem is that you are never able to totally remove all the Dexcool from the engine no matter how much flushing is done - some will ultimately remain. So... when you fill with "Green", it reacts with the left over Dexcool and can "gel" causing clogged passage, resulting in "hot spots" within the engine - NOT GOOD.:smt021

I decided to flush my system and refill with fresh Dexcool last spring. Happy to report that there are no issues with my engines to date!:grin:

 

[Alex D]

Yeah, I gotta do mine too. Have 375 hrs. and she's now 7 years old ... coolant looks still great in the expansion tanks though ...

How did you do it on your AJ ... space wise and getting to the block drains??

 

[tginz]

I change it annually and have made it part of my Fall maintenance list. I have found that the color is not so much the issue as the minerals and sandy stuff in the coolant when I drain it out. All of my diesels have coolant filters, but I have not found an effective way to install one on the boat engine. The "sandy stuff" most likely block casting sand circulates around in the system wearing away water pump components and who knows what in the heat exchanger. Like an oil change, it is cheap maintenance.

tginz

 

[Jimmy Buoy]

Merc specifies 5 years for the orange coolant which is basically a Dexcool water mix. That is the same interval recommended for cars (5 years or 10K miles). If you have the green stuff it should be changed more often, at least every other season.

Alex,

Let me tell you, it's NOT a fun job! :smt013

Getting between the engines on my Amberjack is a breeze due to the 13.5 beam. However, you can barely see the large hex headed drain due to the raw water cooling line/oil cooler on one side and other raw water lines block the outboard side as well.

With my first attempt I took the easier one off using a shallow socket (metric - 17mm?) with two 1/4" extensions and a 1/4" drive, while pulling on the hose to the oil cooler to get the angle straight. That was tough, so after draining I went to put the plug back in...:smt013 Easier said than done! Can't even get one hand in there and it's very difficult to get the plug lined up straight on the end on the socket while pulling at the hoses again. Just don't cross thread the plug! Patience is the key here. I had to just walk away from it several times before saying "if a mechanic can do this, I can do this" and went back for another go.

After filling the system with water I determined that there was plenty of coolant that did NOT come out with just one plug removed... so... :smt013 better do the other side too. Genny was in the way so I had to lay over top of the engine and feel my way around (could not see and work at the same time). It was actually easier on this side since I didn't have to pull on hoses to get the right socket to plug head angle.

Bottom line was that I fully drained the engine, filled it with the appropriate cleaner and ran the engine, drained again, flushed with water, drained, and finally filled with fresh Dexcool.:smt038

After talking with a local mechanic, he said that they just take the lower hose off the water pump to drain then just top it up with fresh coolant! That would leave about half of the old stuff in the engine!!!:smt009

By the way, I could tell by the look and feel of my plugs that they had NEVER been removed before!

You need to either be patient or stubborn to do this job IMHO. Good luck. :thumbsup:

 

[Alex D]

THanks Jimmy ... I only have a 11.5 beam and am hard pressed to believe I can get in there but we'll see. I am going to tackle this one later in the fall when it's nice and cool.

Thanks for you advice by the way!!