changeing antifreeze

[Dave66]

Have to change the anti freeze on both 7.4 merc inboards. I cannot find my manuals as to which long life antifreeze I should use and how much I need. Should I use the premixed long life or the one you mix yoursel.
Engine is a closed system. Manifolds,spacers and elbows are raw water cooled.
thanks for your help

 

[travis340]

I need to do the same with my 8.1's. The Merc manual says to use a 50-50 mix, which is what the premixed is. It gives me a capacity as well. My question is how to remove the old. I have an oil extractor, but that would only empty the reservoir. If I remove a hose it would drain into the bilge and would be difficult to clean up. How were you going to tackle this?

Thanks for any light you can shed.

 

[Asureyez]

First, find the petcock to drain the block, set up a funnel to hose to clean 5 gal bucket to drain. Dispose of shore side as per local regulations.

Check the specs in the manual for clean/flush/replace schedules

Most coolant is good for five years

 

[Dave66]

Since I am already in the water and can't drain it out the drain plug. I will use the shop vac to catch as much of it as i can before it hits the bilge. Whatever hits the bilge I can vacuum up later. Hope this helps

 

[jgoedd99]

Did this last year in the water with my two 7.4s and the generator. I tried to be as neat as possible, but pretty much ended up with a lot of antifreeze in the bilge. To drain antifreeze i removed the plug on each side of the engine and also removed the hose at the water circuilation pump to drain as much as i could. Empty the coolant resevoir too. If you have a hot water heater or cockpit heater, lift up those hoses to get coolant to drain back to the engine, so it will drain. This is also a good time to change thermostats and gaskets.

I hand pumped the AF from the bilge into a 5 gallon buckets and hauled it ashore. You have to do this before the bilge pump kicks on. I refilled engine with water and ran it till warm, and then drained that also into the bilge. I also pumped that into buckets and hauled ashore.

With the antifreeze i used DexCool and mixed it 50/50 with distilled water.

After that last rinse and drain, i hosed out the bilge and pumped that overboard.


Good Luck

JohnG

 

[Jimmy Buoy]

I've replaced the Dex Cool in my 8.1's.

The second hardest thing is to get a socket on the port and stb side block drain plugs. :smt013

The hardest thing was to get those plugs back in! There's just too much plumbing in the way of these things!! :smt013:smt013

My bilge area directly under the engines have NO limber holes, so any coolant spilled will not go to the bilge pumps. Must be a safety feature to prevent contamination of our boating waters. Sure makes it handy. Just let the block drain into the bilge, then use a pump to suck the coolant out and into jugs. A quick clean after and your bilge area is nice and clean.

Refilling the 8.1 is very straight forward since it is a self-purging system. The resevoir is the highest point of the entire system, so just check to refill as the engine burps while running. :thumbsup:

 

[whataride]

Please help me with the capacity in my Caterpillar engines. Thank you......

 

[rcknecht]

Change you raw water impellers at the same time... I pumped out antifreeze with a $2 hand pump from HF, then removed the lower hose on the Close Water cooling under the Heat Exchanger, to access the bolts onthe RW pump... When I disconnected the lower hose I drained the antifreeze into a bucket...

The OEM antifreeze is non-toxic, but I replaced mine with ethalene glycol... I would recommend using the pre-mixed otherwise you will need to buy distilled water. I used about a gallon for each engine... I would recommend you buy three gallons...