Yanmar heat exchanger service

[cardude01]

I'm finally going to do the HE service on my 4jh4-hte. I found this parts diagram on the Internet. Which gaskets do I need? I assume I will just remove the core and clean it? Also there is a bulletin that states some engines like mine had an internal deflector that may have been installed incorrectly so I want to check that out as well.

Any other special instructions I should know about? Any tricks to make this job easier?

This engine also has an oil cooler and trans oil cooler I think but couldn't find a parts picture for those. Do I need to clean those also?

 

[Moonstruck]

Bill, check the end caps of the HEs really good for rust and erosion. Some Yanmars have a lille piece in the center of the end cap that seems to have something to do with directing the water flow. I have replaced two end caps. Also remember that zincs are extremely important in Yanmar engines. Replace them at least annually if not before.

 

[Ski in NC]

Yes, you need to tackle the gear and engine oil coolers too. In fact, the clogginess in the two little ones is often the culprit due to their small size. Do all coolers in the sea water path.

Regarding coolant HX seals, the rings at each end of the bundle are usually all that need to be replaced.

Pay particular attention to surface conditions where those rings seat. Gots to be smooth to be leak free. Corrosion damage on the ends of the Al manifold is a common problem.

 

[FF]

On some heat exchangers a 22 rifle cleaning brush is a great tool.

 

[Capt.Bill11]

You'd be better off flushing it while leaving it on the engine if you can. You could flush the whole raw water cooling system at once that way.

 

[cardude01]

You'd be better off flushing it while leaving it on the engine if you can. You could flush the whole raw water cooling system at once that way.

I flushed it with Bbuster and it didn't seem to help. I must have a big blockage somewhere.

David on TF turned me on to this bulletin. I'm going to see if it's the problem.

 

[Pgitug]

I am not sure why most folks talk about using Barnical Buster when it comes to HE problems when you can visually see if there is a problem by just removing the HE end caps. What you can't see and what BB is worthless to clean is the "Coolant" side of your heat exchanger tubes. After time antifreeze scales the HE tubes with a clay like coating. Using NAPA's Diesel engine flush cleans off all the scale without any disassembly. My 54hp Yanmar was scaled badly after five years of annually flushing the old antifreeze out and putting in new. NAPA's Diesel flush took care of the over heating problem. A friend of mine used it on his 175hp Yanmar, which was running fine, and it dropped his engine temp 5 degrees in Florida summer waters.
It's the easiest and cheapest fix for a hot engine you will ever try.

 

[cardude01]

I am not sure why most folks talk about using Barnical Buster when it comes to HE problems when you can visually see if there is a problem by just removing the HE end caps. What you can't see and what BB is worthless to clean is the "Coolant" side of your heat exchanger tubes. After time antifreeze scales the HE tubes with a clay like coating. Using NAPA's Diesel engine flush cleans off all the scale without any disassembly. My 54hp Yanmar was scaled badly after five years of annually flushing the old antifreeze out and putting in new. NAPA's Diesel flush took care of the over heating problem. A friend of mine used it on his 175hp Yanmar, which was running fine, and it dropped his engine temp 5 degrees in Florida summer waters.
It's the easiest and cheapest fix for a hot engine you will ever try.

That's interesting. Thanks. I'll flush the coolant side before I take it apart I think.

 

[sunchaser]

Heard some good things about ultrasonic cleaning of HXers. Any experience going this route from TFites?

 

[Capt.Bill11]

I am not sure why most folks talk about using Barnical Buster when it comes to HE problems when you can visually see if there is a problem by just removing the HE end caps. What you can't see and what BB is worthless to clean is the "Coolant" side of your heat exchanger tubes. After time antifreeze scales the HE tubes with a clay like coating. Using NAPA's Diesel engine flush cleans off all the scale without any disassembly. My 54hp Yanmar was scaled badly after five years of annually flushing the old antifreeze out and putting in new. NAPA's Diesel flush took care of the over heating problem. A friend of mine used it on his 175hp Yanmar, which was running fine, and it dropped his engine temp 5 degrees in Florida summer waters.
It's the easiest and cheapest fix for a hot engine you will ever try.

That's a good point. And a good think to do unless you know your coolant system is in good shape. But I've seen far more over heating or running hot issues due to issues with the raw water side than the fresh water side of a marine engine.

 

[Pgitug]

That's interesting. Thanks. I'll flush the coolant side before I take it apart I think.

The process is easy. Drain the coolant. Fill with water and drain again until the water is clear. Add the NAPA Diesel Cooling System Flush per instructions. Then use your boat like normal for about ten engine running hours. Drain coolant and flush until clear. Fill with your PREMIXED antifreeze. Never add the antifreeze and then water and expect the engine to do the mixing. That will scale the tubes faster than you can say Oops. When you drain the flush, if your heat exchange was scaled, it will come out the color of coffee. Good luck and happy travels.

 

[sunchaser]

The process is easy. Drain the coolant. Fill with water and drain again until the water is clear. Add the NAPA Diesel Cooling System Flush per instructions. Then use your boat like normal for about ten engine running hours. Drain coolant and flush until clear. Fill with your PREMIXED antifreeze. Never add the antifreeze and then water and expect the engine to do the mixing. That will scale the tubes faster than you can say Oops. When you drain the flush, if your heat exchange was scaled, it will come out the color of coffee. Good luck and happy travels.

Is the Napa stuff OK with Yanmar?

 

[DavidM]

Do not use generic antifreeze in an aluminum manifold Yanmar- 4LH, 6LP or 6LY. Use Havoline Dexcool extended life antifreeze also sold by Napa stores.

David

 

[cardude01]

Do not use generic antifreeze in an aluminum manifold Yanmar- 4LH, 6LP or 6LY. Use Havoline Dexcool extended life antifreeze also sold by Napa stores.

David

Ok. Thanks for all the tips.

I have the O rings for the HE ready to go. Hope I can slide out that bundle without taking everything off the engine. Does the HE slide out from the front or back?

 

[Ski in NC]

Been a while since I was in one, but as I remember, it will slide out either end. But you need clearance ahead or aft for the whole thing to slide its entire length out. On some Yanmars, things are in the way and exhaust manifold has to come off to pull bundle.

 

[LarryM]

Do not use generic antifreeze in an aluminum manifold Yanmar- 4LH, 6LP or 6LY. Use Havoline Dexcool extended life antifreeze also sold by Napa stores.

It looks like Yanmar has expanded their list of approved coolants somewhat, but it is still quite specific. I received this memorandum from Mac Boring last year:

TO: MARINE DISTRIBUTERS
COOLANT ADDITIVES

After testing some popular coolant/anti-freeze solutions, we have reached the following recommendations. It was not possible to test all brands on the market, so there may be some solutions that are acceptable but have not been tested. However, caution is advised if using other than approved brands.

Regardless of the recommendation of the coolant/antifreeze manufacturers it is YANMAR'S requirement that the solution is changed every 500 hours (On the YANMAR Model 6LP 250 hours) or once a year whichever comes first. We do not recommend any other additives be added to the cooling system. Purified or distilled water mixed with the approved coolant/anti-freeze is the only protection approved by YANMAR. Concentrations of the Enix-ture should follow the recommendations of the manufacturer. The coolant/anti-freeze must be compatible with aluminum.



Advantages of this type of coolant:

• Improved water pump life due to reduced water pump seal wear resulting from fewer abrasive dissolved solids.
• Reduces hard water scale.
• Offers excellent protection against pitting corrosion caused by cylinder liner cavitation.
• Better heat transfer than conventional coolants with regular SCALE additions.
• No silicate gel formation during use or storage.
• Outstanding hot surface aluminum protection.
• Superior protection in high operating temperature conditions.
• Effective, long-term corrosion protection for aluminum, brass, cast iron, steel, solder and copper alloys.

The coolant/anti-freezes that have been tested and approved are shown below:

• Texaco Long Life Coolant Anti-Freeze both regular and pre-mixed Product codes 7991 and 7998. This product is available in gallon containers, drums and bulk. It is recommended that the cooling system be drained and flushed before filling. Only Texaco Long Life Coolant should be used for top-off. This product has a much longer shelf life than conventional coolants provided the integrity of the container is maintained. For additional information and availability contact Texaco at 1-800-782-7852.
• Havoline Extended Life Anti-Freeze/Coolant. Product code 7994. This product is available through Texaco gas stations, Procedures are the same as with Texaco Long Life Coolant Anti-Freeze.
• Dex-Cool Long Life Coolant. This product is available through GM service centers worldwide.
• Prestone Extended Life Coolant. Product code AF888. If the above coolants are not readily available, Prestone Extended life coolant is satisfactory.

 

[Pgitug]

Is the Napa stuff OK with Yanmar?

You have to remember that the Napa flush is only in the cooling system to clean it for 10 hours.

 

[cardude01]

You have to remember that the Napa flush is only in the cooling system to clean it for 10 hours.

It might take me awhile to get 10 hours of running time. Can it sit in there for a fee days/weeks or do I need to get it out fairly quickly?

 

[Pgitug]

It might take me awhile to get 10 hours of running time. Can it sit in there for a fee days/weeks or do I need to get it out fairly quickly?

That's a good question. Since the flush is designed to dissolve scale on your cooling tubes, if it were me, and it was, I put the flush in on Friday. Enjoyed boating around Friday, Saturday and Sunday. Then drained the cooling system on Monday. My 54hp Yanmar had gotten so bad that WOT was 3000. At 2500 I was over heating. After the flush I ran it at 2800 for over an hour and the temp never got above 178. Normal before was more like 190 @ 2300.

 

[cardude01]

Ok. I didn't think it sounded good to let it sit in there.

My Yanmar heats up at anything over about 2400-2500 rpm. At WOT of 3200 it gets to 200 pretty quickly.

At under 2400 it runs about 180-185.

 

[Pgitug]

Ok. I didn't think it sounded good to let it sit in there.

My Yanmar heats up at anything over about 2400-2500 rpm. At WOT of 3200 it gets to 200 pretty quickly.

At under 2400 it runs about 180-185.

That is just about where I was at with the over heating problem. I really believe you will be happy with your flushing efforts. I even had removed my core and physically touched and scraped at the scale. But I couldn't find an acid bath to remove it. After taking with the Napa folks I reassembled the HE and did the flush treatment. Talk about taking the hard way around a problem to get to the solution. But that's me. Anyway the end result was worth the journey. I just try and save others some frustrating steps.

 

[Capt.Bill11]

Ok. I didn't think it sounded good to let it sit in there.

My Yanmar heats up at anything over about 2400-2500 rpm. At WOT of 3200 it gets to 200 pretty quickly.

At under 2400 it runs about 180-185.

You are or have taking the heat exchange tubing bundle out to clean it correct? If so, the condition of the outer tube bundle will tell you if you really need to run coolant flush through the engine. Although doing it for one reason or another cant hurt anything.

 

[MurrayM]

That is just about where I was at with the over heating problem. I really believe you will be happy with your flushing efforts. I even had removed my core and physically touched and scraped at the scale. But I couldn't find an acid bath to remove it. After taking with the Napa folks I reassembled the HE and did the flush treatment. Talk about taking the hard way around a problem to get to the solution. But that's me. Anyway the end result was worth the journey. I just try and save others some frustrating steps.

Thank you!

 

[jimbeam]

When you say NAPA engine flush do you really mean the coolant flush not the engine flush for the oil I assume.

 

[firehoser75]

I do not believe in the BB flush technique of "raw water cooling (side) maintenance". It at best, looks after only a small part of what is needed to ensure a cool running engine. The flushing suggestion for the coolant side, is a good idea (using a compatible flush).

There are many "items" that can partially or completely block the small internal cooling tubes, and the most likely place (for blockage) is in the smallest components like oil cooler, tranny cooler, etc. Things like impeller pieces, shells, zinc pieces, as well as calcium/salt deposits are likely candidates and BB will not clear all of them.
Still, this (BB flush) is only part of the overall job. It is very, very important to KEEP the correct liquids in their correct locations!! In other words, it is bad news if you find saltwater in your engine oil, or tranny, or coolant, etc. Seals and O rings need to be changed, and the unit (eg. HX, tranny cooler, etc.) should be pressure tested to ensure no leaks - both internal and external. A BB flush does not do this! A BB flush could be used as a short term "fix" to lower temps to finish a boating season to allow the full servicing to be done in the fall?
You do not want an engine overheat. They have been known to cause extensive engine damage requiring major repairs. Cooling system preventative maintenance is a major part of preventing this kind of trouble, and is especially important for those with raw water cooled aftercoolers.
It's your boat, you decide how important this is (or is not).

 

[Dougcole]

It looks like Yanmar has expanded their list of approved coolants somewhat, but it is still quite specific. I received this memorandum from Mac Boring last year:

TO: MARINE DISTRIBUTERS
COOLANT ADDITIVES

After testing some popular coolant/anti-freeze solutions, we have reached the following recommendations. It was not possible to test all brands on the market, so there may be some solutions that are acceptable but have not been tested. However, caution is advised if using other than approved brands.

Regardless of the recommendation of the coolant/antifreeze manufacturers it is YANMAR'S requirement that the solution is changed every 500 hours (On the YANMAR Model 6LP 250 hours) or once a year whichever comes first. We do not recommend any other additives be added to the cooling system. Purified or distilled water mixed with the approved coolant/anti-freeze is the only protection approved by YANMAR. Concentrations of the Enix-ture should follow the recommendations of the manufacturer. The coolant/anti-freeze must be compatible with aluminum.



Advantages of this type of coolant:

• Improved water pump life due to reduced water pump seal wear resulting from fewer abrasive dissolved solids.
• Reduces hard water scale.
• Offers excellent protection against pitting corrosion caused by cylinder liner cavitation.
• Better heat transfer than conventional coolants with regular SCALE additions.
• No silicate gel formation during use or storage.
• Outstanding hot surface aluminum protection.
• Superior protection in high operating temperature conditions.
• Effective, long-term corrosion protection for aluminum, brass, cast iron, steel, solder and copper alloys.

The coolant/anti-freezes that have been tested and approved are shown below:

• Texaco Long Life Coolant Anti-Freeze both regular and pre-mixed Product codes 7991 and 7998. This product is available in gallon containers, drums and bulk. It is recommended that the cooling system be drained and flushed before filling. Only Texaco Long Life Coolant should be used for top-off. This product has a much longer shelf life than conventional coolants provided the integrity of the container is maintained. For additional information and availability contact Texaco at 1-800-782-7852.
• Havoline Extended Life Anti-Freeze/Coolant. Product code 7994. This product is available through Texaco gas stations, Procedures are the same as with Texaco Long Life Coolant Anti-Freeze.
• Dex-Cool Long Life Coolant. This product is available through GM service centers worldwide.
• Prestone Extended Life Coolant. Product code AF888. If the above coolants are not readily available, Prestone Extended life coolant is satisfactory.

Where in the world would someone find a texaco gas station these days? I can't remember when I last saw one.

 

[HTurner]

Where in the world would someone find a texaco gas station these days? I can't remember when I last saw one.

https://www.texaco.com/en_us/home/find-a-station.html