Losing coolant Yanmar 6lpa-stp

[Priceless]

Went to pick up my boat e today for the fishing season and noticed I was losing coolant on one of my engines. There is no sign of coolant on the white pads under the engine and have lost about an inch of coolant after Sea trialing last week. The engines are 2004 Yanmar 315's. They have been meticulously maintained they are 6L PA – STP's. My research has made the most obvious cause a leaky exhaust manifold. Also they have said to check the thermostat housing, the fresh water hose on the right side of the engine, a turbo exhaust, and a temp gauge sender. Any advice from the forum would be welcome I want to try and get this fixed so I can get on the water

[Navatech]

First, check your oil and make sure it's free of water... If there is water in the oil you'll see it immediately... It will be emulsified and look like "cafe au lait" (coffee with milk)...

Second, one inch over what I would estimate to be 2-3 hours isn't insignificant but it's certainly not a major leak... What I would do is do a very thorough check of the engine while it's running under load as a small leak may not manifest itself on the "diapers"... The leaking water may evaporate on the hot engine before being able to mark the "diapers"...

Is your turbo cooled?!... You might be loosing coolant there if it is... Look for white (steam) colored exhaust fumes...

[Priceless]

Oil looks good no evidence of water in it that was the first thing we checked. turbo is cooled will check the hose to the turbo make sure it's not leaking. Thanks

[Bruce]

A pressure check of the cooling system cold can confirm a leaking hose.
One area is the heat exchanger.

Is the coolant recovery tank losing fluid when it cools down? Is the fluid is sucked back into the engine? Does the tank gain much fluid when engine is hot?
A weak cap can allow excess fluid to leave but not come back. Cap can be checked.

In all the 6lp's I saw, never saw a bad manifold except for severe corrosion from electrolysis.

An upmost important task on yanmar engines is zinc replacement. There are a bunch that are not easy to see and are not serviced even by dealer lazy mechanics.

[Priceless]

Did a pressure test two weeks ago. Interesting I had a question regarding that we pumped it up to about 14 psi which with the the radiator cap was rated four and it held for a while and then slowly it went down after about five minutes with no visible leaks but not to zero. The zincs have been religiously changed every year by both the previous owner and myself. When you say a weak cap I am assuming you mean a radiator cap not the plastic That covers the overflow reservoir correct?

[Navatech]

Did a pressure test two weeks ago. Interesting I had a question regarding that we pumped it up to about 14 psi which with the radiator cap was rated four and it held for a while and then slowly it went down after about five minutes with no visible leaks but not to zero.

If the pressure goes down you have a leak somewhere... If your cap is rated for 4 PSI testing at 14 PSI is somewhat excessive... I normally test at double the rating of the system... But I leave the tester there for 20 minutes... And I don't give up on locating the leak unless the gauge stays put for the whole 20 minutes...

[Priceless]

Sorry that was a typo. The cap was rated for 14 psi and we pumped to 14.

[Bruce]

How far did the pressure drop?

[Priceless]

It dropped to about 10 after 5 minutes. I didn't know anything about pressure testing at the time, it was being done by a boatyard employee and I was watching but in retrospect it clearly showed we had a leak somewhere. After a quick tutorial from you tube and help from this forum and boat diesel I am more informed and educated. They are re pressure testing this am and checking for leaks. Also there is a test for exhaust in the coolant they will be doing to rule out head gasket issues. They are contacting Mack Boring and a few other Yanmar experts and hopefully will have an answer soon and a fix quickly. They think heat exchanger or exhaust manifold might be culprit. I'll keep you updated and I really appreciate all the advice. P

[Rawleigh]

Don't forget you have a factory Yanmar specialist here: Bruce!

[Navatech]

It dropped to about 10 after 5 minutes.

Definitely a leak somewhere... 14 PSI is just under 1 ATM so that's really not that high a pressure... I would test at 28 and definitely not lower than 21... And I would expect the pressure to hold for 20 minutes...

[Priceless]

seems it was a leaking cooling hose to the turbo. after fixing held pressure for 45 minutes.sea trialed and inspected under load and they will recheck oday

[micky]

A pressure check of the cooling system cold can confirm a leaking hose.
One area is the heat exchanger.

Is the coolant recovery tank losing fluid when it cools down? Is the fluid is sucked back into the engine? Does the tank gain much fluid when engine is hot?
A weak cap can allow excess fluid to leave but not come back. Cap can be checked.

Hi Bruce, I’m loosing coolant and can’t find a source. I fill the reservoir to the “full” mark. Start the engine, get it to temp and shut it down, coolant will go over the “full” mark while hot and the next day it is under the mark. I replaced the cap, the heat exchanger and checked all hoses and nothing. The other engine when warm, it will go over the “full” mark and when it cools off its right at the mark. I pressurised the system of the “bad” engine at 15 psi for 30 something hours and it held perfectly.

Any ideas to try?

Thanks

[micky]

I'm still chasing this leak. No visible leaks, turbo and exhaust manifold have been pressure tested, coolant pump is not leaking. Would it be possible that it is a head gasket leak?

[Tony Meola]

Are you getting any steam out the exhaust when you are running?

[micky]

No steam.

[Carl]

Damn…still have a thorn in your side.

I had coolant seeping out a hose fitting when motor was hot n running but dried up before dripping. It took awhile to find.

You said you changed the heat exchanger caps…did you swap, buy new or more important test them? I had motors not pulling coolant in after it cooled issue. I swapped caps twice, no change.

This year when pressure testing the motor to find a coolant leak I was waiting n waiting to see if pressure held n started reading the tester manual… huh, look at that this thing can check the caps. So I gave a try…both caps were bad. No wonder swapping didn’t help.

Isn’t there a way to test the oil n coolant to check for leakage? Analysis…as I’d expect major leaks would be obvious

Sorry Micky, I’m not much help here…but did bump your Posr.

Good luck

[micky]

All clamps have been triple checked and are tight. Both caps are brand new. I pressure tested the system a few months back when this issue started, I left 15 psi on the engine for 24 hrs and no loss of pressure, I also pressure tested the exhaust manifold. Three things that may be the issue, either coolant pump which there is no coolant trail coming out of the weep hole, head gasket or turbo. I'm removing the turbo this week to pressure test it. If this is ok, I'll have someone run the boat while I'm in the engine room looking at the water pump and all clamps.

Hopefully is not the head gasket.

[Tony Meola]

A head gasket should cause steam out the exhaust. I would also think you would see a pressure drop. Even a hose with a slow drip should create some pressure loss when sitting 24 hours. Is it possible your overflow tank has a leak?

[micky]

I may have found the leak, removed the turbo and on the exhaust side it has coolant residue, I tasted it and it tastes sweet, not salty. As you can see in the pictures, its coming from behind the blades and the riser has no water indications.

I will pressure test it tomorrow.

[Tony Meola]

Mickey

If you need turbos, there is an outfit in California that makes a number of OEM Turbo's, and they have an online website. Their prices are tough to beat. My friend just purchased two for his 4-cylinder Yanmars. Two were the same price of one from the Yanmar dealer.

https://turboturbos.com/?msclkid=995226 ... rbo+Turbos

They will also rebuild a Turbo if it is worth it.

[micky]

Are these OEM turbos or chinese? I've seen the Yanmar turbos from $5,500 to $3200. IHI turbos in the $2500 range.

[micky]

Pressure tested the turbo to 60 psi of nitrogen and it lost 5 psi in the first 10 minutes. Left it pressurized until tomorrow morning.

[Tony Meola]

They sell OEM and after market. Your choice. My friend bought two of the Yanmar turbos they were OEM. Free shipping and then if you send the old ones back, again free shipping, they will credit you with up to 10% of the original purchase price depending on the condition of your Turbo's.

My friend said their customer service is great.

[micky]

Ordered one of the OEM at 4pm and at 5pm it was already shipped.

[Tony Meola]

Good to hear. I hope you did compare prices just to make sure. But I think you will find it tough to do better.

[micky]

Turbo lost 5 more psi yesterday during the day and this morning it had lost another 10 psi. I ordered it from the website you posted, couldn't find it anywhere else for that price.

[micky]

I think I found the issue inside the turbo. A pin hole. I poked it and water came out so cut the turbo in half so I could see it better.

[Tony Meola]

Ugh! They would have given you s credit if you returned it to them intact. They even pay the shipping.

[Carl]

Micky- -

Maybe you would have seen a credit, but I'd think it was good to take a look and know why...that has to be worth something.


Tony-
As to a return, I think they want a usable core. A snailshell with a porosity hole should be kicked to the scrap heap...at least I hope it would be. No good way of fixing that.

[micky]

I prefer to know what the issue was before having a $150 credit.

[Tony Meola]

Not sure how they handle the credit. It says up to 10% on their website. So you might get nothing if they are trash.

Mickey
I hear you. I would feel the same way.

[micky]

Installed the turbo last night and was able to start the engine. As soon as it started I knew I had forgotten a plug somewhere as I could hear a leak so this morning I went and removed that plug from the old one and will install it on saturday.

[Tony Meola]

Mickey

Glad to hear you are almost there. A plug is minor. Let us know how she performs once you have everything working.

[micky]

I can finally confirm that the issue is solved.

[Tony Meola]

Micky

Good to hear. Now get out there and enjoy the fruits of your labor. You built a really pretty boat. You should be proud.

[Carl]

Nice job, now get out and enjoy her.