Yanmar coolant drain

[Wilfred123]

Hi,

I am planning a coolant\antifreeze change on my Yanmar 4JH4AE engine. I have identified the coolant drain points on the engine and they appear to have a 'nipple' on them to attach a small bore hose to aid with a less messy change. Would anyone have any experience with this type of drain cock and would know what diameter bore hose I would need? I was thinking that 5mm or so would be more or less it.

many thanks in advance

 

[Mistroma]

I replaced the coolant on my 4JH4AE but it was a couple of years ago and the boat is more than a thousand miles away just now. I'll have a look for any notes I might have made. I seem to remember that there were 2 drain points, 1 near top at rear near the exhaust elbow and another on opp. side near the stop solenoid.

I remember having to drain and flush several times to clear all trace of the original green coolant. I can't remember the tubing I used but it was pretty run of the mill from B&Q or similar. I think 5-6mm sounds about right but my memory is pretty bad nowadays. You only need a very short length so no problem to buy a couple of different sizes (I suspect that's what I did).

It was an easy job, just took a fair bit of time but not at all messy. I seem to remember finding lots of confusing advice and scare stories about correct coolant so just stuck with Yanmar's own pink coloured long life stuff.

 

[noelex]

I just measured mine and it is an 8mm ID hose.

All the hose does is allow you to drain the coolant without it making too much of mess so it is not critical. It is just a push fit.

As has already been mentioned there are two drain points.

Yanmar strongly recomend the orange long life Havoline, or similar, coolant (the warantee is void in some countries if this is not used). Most Yanmar engines I see do not use this. It is expensive and difficult to obtain. You need to flush very very carefully if changing from another type.

 

[RichardS]

Yanmar strongly recomend the orange long life Havoline, or similar, coolant (the warantee is void in some countries if this is not used). Most Yanmar engines I see do not use this. It is expensive and difficult to obtain. You need to flush very very carefully if changing from another type.

I think the orange LLC / ELC / OAT stuff looks pink when it is diluted so is probably what Mistroma is also referring to.

Richard

 

[noelex]

I think the orange LLC / ELC / OAT stuff looks pink when it is diluted so is probably what Mistroma is also referring to.

Richard

Yes I agree pink is probably a better description. Apparently the days of colour coding the chemistry of antifreeze is over. So colour is no longer a realistic indicator of the type of antifreeze.

The recomended Yanmar antifreeze is Eyhylene Glyycol. The last time I checked only two types were specifically "approved" one is Havoline extended life coolant, which I have used since new. I think from memory the other was the Yanmar branded coolant, but there may be others by now.

 

[Mistroma]

I'm afraid that all my notes must be on the boat and so I can't give details of plastic drain hose. However, I'm pretty certain that the information below is pretty accurate. I started with green coloured coolant that was not long life, so easy to see if there was much left when filling with water. I'm pretty certain that I did 3 complete cycles before the green colour was pretty faint.

It is probably worth noting amount removed initially and amount of new coolant added. I know that the system is meant to take 6 litres but you will also have coolant in the hot water tank heating system (assuming you have one).

I flushed the system as follows (no rush as I was living on the boat at the time and had plenty of time):
1) Start with a cold engine:
2) Empty out header tank (it slides out of holder on my Jeanneau, so easy to tip it out and put back with lid on loosely
3) Start to drain via port side fitting, then open filler cap and leave to one side
4) When flow stops, transfer hose to starboard fitting and then drain from that point
5) Close both drains, fill with water, start engine and run for about 5 minutes whilst topping up with water
6) Replace cap and then run engine up to temperature
7) Stop engine and allow to cool completely (and I do mean completely)
8) Repeat steps 3-6 until water looks free of old coolant. I think that I repeated this at least 2 times.
9) Final coolant drain by repeating steps 3 & 4 (coolant should be clear) and close drain points
10) Fill with fresh coolant, then start engine and top up with coolant whilst engine runs for 5 minutes
11) Replace cap, tighten and run for 15-20 minutes checking drain points for leaks
12) Stop engine and top up expansion tank to bottom level
13) Leave engine to cool completely before lifting lid clear of expansion tank (stops contents syphoning out)
14) Release filler cap slowly and add more coolant if required. Replace cap and expansion tank lid.

Keep an eye on the expansion tank level for a while.

Apologies if this is too detailed but it was mainly to make me think it through in case anything unexpected popped up. The only thing that did come out of this process was the question of the calorifier circuit. I think that my water cylinder is close to the level of the engine block and I'm assuming that I managed to drain that at the same time as the engine. I do remember that I got more than 6 litres out and that the water eventually ran clear, so must have been happy with the situation. However, I can't remember the exact quantity (it will be written down somewhere on the boat).

Perhaps someone else has a better method of draining the calorifier (e.g. removing the feed/return hoses) in case you can only get 6 litres by draining.

 

[Wilfred123]

Hi,

Thanks for the reply's, the 8mm ID hose was perfect, got a short length on ebay for a pound or so.

And thanks Mistroma for the detailed instructions which I followed yesterday. All went to plan and I also managed to empty and clean out the calorifier circuit by disconnecting both the supply and return hoses from the engine, connecting the marina hose to one of the hoses and giving it a blast through. Then just a case of blowing down the hose to clear out the water. I did end up with an air lock in in the calorifier but this was resolved by lifting the hoses to a high point and filling the hoses with a funnel until water was flowing from both end of the hose indicating that there was no air left in the circuit.

Only real issue I had was that it was so cold at the marina yesterday that it was taking ages for the thermostat to open up so I will need another session to top off the coolant when its slightly warmer.