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Old 01-09-2022, 16:32   #1
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Blocked coolant drain

Hi all

Ive been working on my genny and need to drain down the coolant system. Unfortunatly its blocked with sludge, Ive taken the tap off and scrapped some out but not enough to let the coolant flow.

If I add vinegar and run the genny will this disolve the sludge enough to drain it? I dont want to try without asking as if it doesnt work I then have acid stuck in the system doing its funky thing!
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Old 01-09-2022, 22:06   #2
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Re: Blocked coolant drain

With respect, not enough info here for us to offer suggestions.
1) Make and model of genny?
2) Fresh water cooled?
3) The "tap" is that the cap on the coolant reservoir? Or is that a drain tap at the bottom of the (plastic?) coolant reservoir?
4 Is there sludge in the whole fresh water system?
NOTE: if your genny has alloy parts (like the head) doing an acid flush may harm those parts!!!!You really need to check with the manufacturer first!!!!


Without answers to the above, some general comments on flushing with acid:
!) If the coolant reservoir has sludge, and if it has a drain at the bottom, you can hose it out with fresh water from a dock hose while you hold a bucket under the drain. Suggest you do this first.
2) To do a proper clean of your entire fresh water coolant system, you need to use hydrochloric acid. Vinegar is simply not strong enough.

The best way to do this is to set up an active closed-circuit with an acid-proof centrifugal pump. You add hydrochloric acid to the water in the engine and circulate it for an hour or so. Then you flush out that water/acid mix. Just filling the engine with water/acid and letting it sit is the lazy way some people do it, but that will not get all the internal passages clean and remove all the sludge.

If you don't/can't set up an active closed circuit with an external pump, you could do the system flush by adding hydrochloric acid to the coolant water and running the genny for say 10 minutes. But I suggest you run this past the manufacturer.



Whatever you do, if you do an acid flush, you absolutely have to flush out the whole system with fresh water. To do this you'll need to disconnect 2 of the coolant system hoses and use one to introduce fresh water from a dock hose while the other dumps the water overside.
Again, without knowing how your genny is setup, its impossible to say which hoses to use for this procedure.
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Old 01-09-2022, 22:44   #3
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Re: Blocked coolant drain

Hi, thanks for the response.

In answer:

Its a Northern Lights genny
I use the normal 50/50 coolant mix.
To drain the system down there is a stop tap on the engine block, this is the one that is blocked with sludge and is preventing the coolant from draining so I assume there is sludge through out the coolant system.
As far as I know there are no aluminium parts but will put a call into the dealer.

My worry with adding any acid, either vinegar or the strong stuff, is if it doesnt disolve the sludge then I wont be able to get the acid out again....
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Old 01-09-2022, 23:05   #4
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Re: Blocked coolant drain

Quote:
Originally Posted by Olly75 View Post
Hi all

Ive been working on my genny and need to drain down the coolant system. Unfortunatly its blocked with sludge, Ive taken the tap off and scrapped some out but not enough to let the coolant flow.

If I add vinegar and run the genny will this disolve the sludge enough to drain it? I dont want to try without asking as if it doesnt work I then have acid stuck in the system doing its funky thing!
Hi, if you have access to compressed air then a good squirt with an air duster into the now open hole may well move the sludge and get things flowing. Much flushing will need to follow.
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Old 02-09-2022, 02:02   #5
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Re: Blocked coolant drain

Hello Olly75,
You can also stick a bent piece of wire into the hole in the block and use that to free up some of the sludge. While doing that, I suggest you find one of the fresh water cooling hoses that you can temporarily disconnect one end of. Then connect that to your dock water hose and force fresh water through the system. Connect a nipple to the place where the tap was and put a garden hose on that to get the water over the side or into a bucket. Uncle bob is right, it will take lots of flushing.

The sludge is the result of lack of maintenance over a long time. If flushing is done regularly, sludge won't build up AND your engine will run cooler because the water passages will be free of obstruction.
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Old 02-09-2022, 05:50   #6
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Re: Blocked coolant drain

This is not a joke but there is a product called Barnacle Buster that works really well. We had a licensed engineer show us how to reverse flush 850 hp diesels.
You need a pump like a water puppy and some buckets and make up some pvc adaptors to fit in your hoses after you disconnect them. Let it run for a few hours.
This stuff actually works . The engine temps were much lower and this engineer uses it between complete exchanger pull downs to keep temps perfect.
After the flush, the temps were just like you took the whole system apart and cleaned it. Its not a substitute but really helps between pull downs.
The above suggestions are fine too. Clean diesels last longer.
Happy trails to you.
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Old 02-09-2022, 07:42   #7
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Re: Blocked coolant drain

You should be able to (CAREFULLY) unscrew the tap, drain the system, clean the tap (or replace it) and reinstall.
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Old 02-09-2022, 14:11   #8
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Re: Blocked coolant drain

Tried the compressed air, low pressure and it bubbles up into the header tank but curiously no water drain out afterwards..

I will try removing the tap completly and dig aroumd with a piece of wire, and also pump out the heat exchanger remove the element and see if i can get a wire digging from the top.

If those fail i guess im unbolting the whole heater exchanger and digging from there.

Its ironic that by following the maintenance manual Im having this issue, from now Ill halve the hours between flushing. Also makes me concerned about the state of the engine cooling system!
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