4BY2 How to Burp the coolant system?

[captstu]

Yanmar is now telling the mechanics working on our 2010 R25 the engine is overheating because we didn't "Burp" it?

1. Filled Heat Exchanger
2. Allowed it to settle
3. Refilled and ran engine with cap removed until it rose above 190 and the heat exchanger was hot.
4. Cooled and top off heat exchanger - maybe tablespoon???
5. Lubricated and replaced the heat exchanger cap - sure wish I knew how to do that the right way???
6. Ran engine - overheated with what looks like a "loss of coolant" incident since the heat exchanger was 1 quart low

What should I have done to burp the engine?

 

[scross]

IF Yanmar is correct and your low coolant level is due to "didn't burp" then that would be the exact problem we encountered after our 500 hour service. The mechanic should have measured the amount of coolant taken out (3 gallons) and made sure the same amount was replaced. That didn't happen and we took the boat with the coolant down 3/4 of a gallon. The mechanic told us that the coolant level at the top of the heat exchanger cap was full but that they didn't "burp" it to get out any trapped air.
Our "burping" process was to run the engine underway for 20 minutes at 2,500 RPM to get temperature up to 208 degrees. Then back to low RPM to get back to the slip. At the boat yard, the mechanic took off the heat exchanger cap with the engine still warm. You could hear air escaping from the cap as he removed it. He had us run the engine in neutral at 1,500 RPM while he filled the coolant into the heat exchanger through the cap opening with a pump and long hose. After he had put in about 1/2 gallon of coolant and put the cap back on, we took the boat out and ran it for 20 minutes at all ranges of RPM. It did not overheat. When back at the slip he took the cap off again (with gloves on) and filled another pint or so to top it off.
One thing the mechanic was worried about was the thermostat failing from the overheating (running over 210 degrees) because the major cause of thermostat failure (according to him) was running with high temps.
Not sure if all this is the Yanmar factory recommended "burping" process but this is what fixed our problem. Good luck!

 

[captstu]

Vicki and Al, Thank you. I've run it 30 minutes thru 3 overheat and cool down cycles. I'm trying to get the cap off, unfortunately the mechanic who filled it didn't put the cap on all the way so I have antifreeze everywhere.

He said, "Yanmar told him you must open the burp valve and bleed the air when refilling the coolant."

The shop is closed - I was hoping someone knew where the valve is located.

The service manual on the tugnuts site is labeled 4BY3, but is not the doc for our engine.

Guess I'll lose another weekend and call them o Tuesday.

 

[scross]

For what it’s worth: on page 55 of the Yanmar 4BY2 operations service manual, they show only one heat exchanger drain plug and one cap at the top of the heat exchanger.
I’ve heard of folks removing the drain plug, jamming a hose into the drain plug port and pumping coolant under low pressure back into the heat exchanger through the drain plug port with the cap off. That’s the process used to bleed air out of the brake lines in my airplane.
If there is only the one drain plug and the one cap then it seems like those are the only two choices you would have to fill the heat exchanger.
Please keep us posted on what you find out.

 

[YukonRon]

I’ve heard of folks removing the drain plug, jamming a hose into the drain plug port and pumping coolant under low pressure back into the heat exchanger through the drain plug port with the cap off. That’s the process used to bleed air out of the brake lines in my airplane.

Al, this reminds me of the process for filling the leg of an outboard with gear oil. A small handpump and hose is used with a screw fitting that goes into the "drain" hole at the bottom. The top "fill" plug is opened to allow the air escape, and the gear oil is pumped in from the bottom until it gets up to the top hole. No trapped air this way.
Just wondering if a similar setup could be rigged for coolant filling? Sounds like the setup you are describing.

 

[captstu]

Ron and Barb,

Good idea - if only I knew where the mystery air was trapped.

I tried removing the house heater, placing a T in the line and pumping water into the hoses to the house heater and hot water heater. That filled the system until water came out the heat exchanger cap - but the engine still overheated.

I think it is a leak - and the burping required for the 4BY2 is just like every other engine - fill it, run it, and fill it again until no more coolant is needed after a 2 minute run.

I ran it for 30 minutes yesterday and it took a quart - fine. Ran it again and it still overheated.

I think I'm filling the ocean, a quart at a time.

But, you may be right - tomorrow, I'll run it some more if I can get the heat exchanger cap off.

 

[knotflying]

On a thread a week or so ago someone was asking about the Phillips type screw on the ports side of the engine near the hoses that run to the water heater. Figure 24, part 14 identifies it as a screw vent. It is part of the cooling system so perhaps loosening that will help purge air.

 

[captstu]

I've seen that part. Didn't know what it was. Thank you!

 

[captstu]

Opened it, filled coolant. Still overheating w coolant in bilge.


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

 

[Andrew Custis]

All I have ever done is fill the engine up with coolant, go and run it until it gets up to temperature, let it cool back down and refill the antifreeze until it remains full. After that, I make sure the expansion bottle is set to the low mark to allow for enough expansion.

 

[captstu]

Andrew, Fill-run-refill is what I have always done also.

But, the Mastry person my mechanics (there are two now) consulted said the problems were: 1) the bottom was dirty - just painted and the boat goes to 14+ easily - and the engine needs burping. The screw is not at the high point of the cooling system - it is in the heater loop - so I doubt it makes any difference to this problem. The heater elbow I put in instead of the cabin heater gets to 140 degrees.

Now there is a quart or so of coolant in the bilge each time I run up to 3500 rpm for 5 minutes. I've tried pressurizing the engine by putting a T on the engine heater line - it holds pressure when cold. Next trick, I'll try pressurizing and run up the temperature until the pressure drops.

This time there was smoke - just a few wisps - coming out of the heat protector shield on the turbo. I think this is just assembly dirt compounded by the high engine temperature, but if pressurizing doesn't find the leak, I'll remove the shield and see if the cooling fitting onthe exhaust manifold that goes thru the turbo bracket is leaking. I'm thinking of part 17 on figure 11 of the parts manual.

I do appreciate your help and ideas. The mechanics can reach the parts I only dream about and are doing an OK job, bt finding leaks is largely hit or miss. and we are missing.

 

[Red Raven]

Stu, Maybe you can put a camera in there to capture what is going on at high rpms. Point it at the most likely leak points starting with the expansion tank. Just a thought. You could even set something up to capture it real time.

 

[Osprey]

On a thread a week or so ago someone was asking about the Phillips type screw on the ports side of the engine near the hoses that run to the water heater. Figure 24, part 14 identifies it as a screw vent. It is part of the cooling system so perhaps loosening that will help purge air.

Could you please post details of the manual to which you refer.

 

[captstu]

The manual Knot pointed me to for the bleed screw is:

This parts catalog is a first edition of the 4BY2-150, 4BY2-150Z, 4BY2-180, 4BY2-180Z Diesel
engine.
Parts catalog No. Date of issue Remarks
First edition 0CR10-G74700 Jan.,2009 No need

It is the latest version available - but is NOT the correct parts manual is some critical areas. The thermostat has been relocated and the parts shows in the manual are wrong for this engine - unless you plan to convert it to the older design as I did.

There is a corresponding service manual:

BY Series Service Manual, 4BY and 6BY P/N 0BBY0-G00102.

This manual is also wrong for my engine - it has extensive descriptions on how to remove, test, and service the same thermostat that is wrong in the parts manual.

I can e/mail you a PDF for each of these if you either e/mail me or PM me your e/mail address.

It is probably worthless to try to get the later version from Yanmar. My engine is overheating with an unknown leak, Yanmar certified techs worked for hours to remove the thermostat as described in the above docs.

Knot pointed me to the actual location of the thermostat on his engine - it is his album but I never thought to look until he told me. After several more hours, the certified mechanics, in consultation with Mastry, found the actual location and removed the t'stat that was defective. They declined to place it in that location (I agreed) putting it instead in the location shown in the manual noted above.

While the coolant is now correctly circulating thru the engine, it is still overheating - and we know for sure it is leaking coolant, but we can't find the coolant leak yet.

It is also worth noting that the bleed screw is no where near the highest point in the engine where air would normally collect. It is just a bogus idea with no possibility of effecting the problem I am seeing. Water came out of the bleed screw when I opened it and there was obvious water flowing thru the hose before I opened the screw - no matter, it is very easy to access, a rarity on this engine.