Burping Coolant in Yanmar 6LYA engine

PocketAces · 05-10-2022, 02:58 PM

Hi, Is there a trick to "burp" the coolant. We took out around 15L and only got 8L back into the system before it was "full". Other than running the engine a while to move coolant around are there any other tricks to get rid of air in the system?
Regards, Tony
Pocket Aces 34T '08.

TowLou · 05-10-2022, 04:05 PM

Get a air compressor (i have had luck with a 2.5 gal 60v cordless dewalt) and a air lift its called to fill your coolant up. Best way to get coolant into all the voilds of the motor and can leak test it as well after you put a vacuum to the coolat system.

**Bacchus** · 05-10-2022, 04:52 PM

Did you pull / replace Tstat?
I replaced my coolant in my 08 MS 34HT w yhe tankard 6LYA and was able to fill will very close to the refill amount. I did pull mt Tstat & replaced w new. The Yan Tstats have a bleed hole in the plate to allow air yo escape. If it was replaced w other than the OEM that could be a cause.
I just filled ran it to temp and had to topnoff the oflow tank and good to go.

DavidM · 05-10-2022, 05:17 PM

Something similar happened when I added fittings and hose to circulate coolant through the hot water heater. Trawler builders rarely do that hookup at the factory.

I asked Tony Athens on boatdiesel at the time what to do and he said remove the fill cap and go out for a moderate load cruise, say about 1,800. Watch the engine temps and keep adding coolant as you go along and after a while it should stabilize. Then put the cap back in place and you should be good. It worked.

David

PocketAces · 05-11-2022, 12:53 PM

Thanks for the helpful replies. While we were waiting for feedback, we ran the engine for a few minutes to see if that would move the coolant around enough to allow us to top up. When we opened the cap, the coolant overflowed like crazy. (The air trapped internally obviously expanded!). So I will try a cruise as suggested, but leaving the engine to cool before topping up. It may take a while.
Also, I am thinking that once the engine warms up enough the thermostat will open allowing more complete through the system to flush the remaining air?
Don: Thanks for the suggestion re Bleed hole in thermostat. I will check this next time at the boat. (We still have the original thermostat, hence must be Yanmar)
TowLou: I am afraid I did not follow the post about the compressor. Anyway that is out of my league!
Thanks
Tony
Pocket Aces, 34T '08

DavidM · 05-11-2022, 01:16 PM

Take her out with the cap OFF! At moderate load the coolant shouldn't boil. Top off as required until it stabilizes. Keep an eye on the temp gauge so it doesn't get out of control.

David

**Bacchus** · 05-11-2022, 02:31 PM

Tony
When I was getting ready to do my coolant change an old hand mechanic told me about drilling a small bleed hole in the TStat but when I received the replacement I was pleased that Yanmar already had it built in.

TowLou · 05-11-2022, 07:39 PM

The tool is called a air lift. With compressed air and a venturi fitting it creates a vacuum in your coolant system. Works very well if you have acess to compressed air.

https://www.jbtools.com/uview-550000...xoCB_MQAvD_BwE

**Comodave** · 05-11-2022, 08:31 PM

Quote:

Originally Posted by TowLou

The tool is called a air lift. With compressed air and a venturi fitting it creates a vacuum in your coolant system. Works very well if you have acess to compressed air.

https://www.jbtools.com/uview-550000...xoCB_MQAvD_BwE

This looks very interesting. Have you used it on a boat? I found it on Amazon so I read the questions and reviews but none of them mentioned using it on a boat. I need to replace the coolant in my C series Cummins and was wondering how to get all the air out.

TowLou · 05-12-2022, 07:29 PM

Quote:

Originally Posted by Comodave

This looks very interesting. Have you used it on a boat? I found it on Amazon so I read the questions and reviews but none of them mentioned using it on a boat. I need to replace the coolant in my C series Cummins and was wondering how to get all the air out.

Im pretty sure any closed coolant system will work. You can keep a vacuum there to also check for leaks. Better with a bigger air compressor to. I did a 5 gallon coolant change on a JD motor paired to a 60kw alternator head I believe using my 60v 2.5 gallon dewalt pancake compressor. Took 3 cycles of the air compressor but 2 min or so had it vacuumed down to 25in. Just asks for about 2cfm at 90psi. My other place had a auto mechanic religiously use it on all vehicle coolant fills. No air pockets no overheats. Ive been trying out my pancake compressor in the field on days I have a extra hour to kill.

Burnt Norton · 05-13-2022, 10:38 AM

When using vacuum full technique, do you have to heat up the engine first? Joe do you deal with the thermostat?

**Comodave** · 05-13-2022, 12:00 PM

Ok, I ordered one of the ones in the link above but got it through Amazon for the free shipping. My neighbor used to be a diesel mechanic in the Navy. When I said I was going to change the coolant he immediately said get a vacuum system to refill it. So I did…

TowLou · 05-13-2022, 04:51 PM

Quote:

Originally Posted by Comodave

Ok, I ordered one of the ones in the link above but got it through Amazon for the free shipping. My neighbor used to be a diesel mechanic in the Navy. When I said I was going to change the coolant he immediately said get a vacuum system to refill it. So I did…

The air lift brand is the one I have always used and I saw the lead mechanic religiously use it on every coolant fill in the shop and just now been tryong it out as I had sucess on the road with the lil air compressor. I always use the cone atrachment it blocks the overfill spout to the resevoir.

Its pretty simple to setup and use. Get the needle in the green bout 25in of vacuum you may see your hoses collapse that is normal. Let it sit a few min to check for leaks. Attach the other fitting with the valve and screen at the end of the hose try to fill the hose up with coolant first you can with the mini ball valve on there. Then open both valves as let it suck the coolant in.

TowLou · 05-13-2022, 04:53 PM

Quote:

Originally Posted by Burnt Norton

When using vacuum full technique, do you have to heat up the engine first? Joe do you deal with the thermostat?

No need to. It will get around the thermostat. Just vaccume it down, be sure it holds a vacuum, then use the other attachment sick one end in a bucket of coolant and let her rip chip.

**Comodave** · 05-13-2022, 05:54 PM

Sounds easy but I have found that I am able to easily screw up simple things…

TowLou · 05-13-2022, 06:00 PM

Quote:

Originally Posted by Comodave

Sounds easy but I have found that I am able to easily screw up simple things…

We all do when we do something new. It takes a few tries. Like with the air lift I tried the little adapters they have to but they work if there is no overflow tube in the neck. I use the cone end in the radiator neck now since all the systems I fill have a overflow tube in the neck.

You can not harm the system with the venturi vaccume that it makes. Any questions feel free to ask.

**Comodave** · 05-13-2022, 06:05 PM

We are going to launch in a week and then I want to get started changing the coolant and servicing the aftercoolers. Can’t wait…

TowLou · 05-13-2022, 07:34 PM

Quote:

Originally Posted by Comodave

We are going to launch in a week and then I want to get started changing the coolant and servicing the aftercoolers. Can’t wait…

Dont sweat it getting every last drop out as well when you drain it. If you plan a regular schedule it will all dillute in the end. I hope the best of lessons learned.

Doodie99 · 05-13-2022, 08:16 PM

Quote:

Originally Posted by TowLou

The tool is called a air lift. With compressed air and a venturi fitting it creates a vacuum in your coolant system. Works very well if you have acess to compressed air.

https://www.jbtools.com/uview-550000...xoCB_MQAvD_BwE

I have used one and it works very well.

PocketAces · 05-17-2022, 09:37 PM

I have read the posts about the Air lift and such like. I don't have a compressed air, so consider this well above my skill level. I will see if there is a Youtube video to better explain.
I took the boat out on the weekend to try to "burp" the system. The first thing I noticed was that the temperature gauge was very slow to warm up compared to usual. Then about 15 minutes (of slow cruising) the temperature suddenly jumped to near max and the overheating alarm went off. I shut the engine down and drifted for about 15-20 minutes. Then the temperature showed normal around 180. So I restarted and everything was fine after that.
I am surmising that the trapped air was around the thermostat which thus was slow to warm up and when it finally opened up a bunch of hot water then flowed over it causing the alarm.
Hopefully I have not caused any permanent damage. I don't think so. But next coolant change in 2 years I will definitely try to bleed the air via the thermostat as suggested in this thread.
I did not keep the cap off as suggested. I was sure that would be messy. I am also wondering why this is the first time this as appeared to be an issue. I have had the boat for 12 years and several coolant changes.

Tony
Pocket Aces
Mainship 34T '08