Heat Exchanger core extraction

[Geek_Guy]

Hoping for some details and opinions please.

Been trying to extricate the heat exchanger on my very old 3hm35f Yanmar. Several of the bolt heads on the covers were rusted away so badly that I couldn't attach any wrench to them. I have ground the remainder of the heads off and got the forward cover off. But the core won't budge. My Yanmar mechanic suggested that I try to take the whole thing off and he would attempt to get the core out and help get the bolts out. I was successful getting the exchanger off. When my feeble brain wondered why do I need the core out? I think I can likely get the bolts out as the ones that had a head came out reasonably well. So I can replace the gaskets in the covers.

He had suggested buying a new exchanger, but they checked and it's not available.

Thanks

[rognvald]

Geek,
Your above description indicates that your diesel has been poorly maintained. The question you need to ask is "why" you cannot remove the internal cooling cylinder. The answer is corrosion. I am not familiar with your exact engine but you should be able to remove the heat exchanger assembly from the engine and do a complete inspection of the cooling tubes. You then can soak the entire assembly in a solution of 10% muriatic acid and distilled water to free the tube from the heat exchanger body. If you are lucky, you will be able to clean the corrosion and reinstall. If not, replacement is the only option. I cannot believe there are no heat exchangers available for your engine. If that is the case, I would contact Yanmar and explain your problem. Finally, if your heat exchanger is in such poor shape, you potentially have problems elsewhere in your cooling system. You will need to check hoses, water pump">raw water pump, fresh water pump, thermostat, etc. I would consider using a commercial grade cleaner in your fresh and raw water systems before running your engine again and changing your antifreeze. Good luck. You may need it.

[neilpride]

Originally Posted by rognvald

Geek,
Your above description indicates that your diesel has been poorly maintained. The question you need to ask is "why" you cannot remove the internal cooling cylinder. The answer is corrosion. I am not familiar with your exact engine but you should be able to remove the heat exchanger assembly from the engine and do a complete inspection of the cooling tubes. You then can soak the entire assembly in a solution of 10% muriatic acid and distilled water to free the tube from the heat exchanger body. If you are lucky, you will be able to clean the corrosion and reinstall. If not, replacement is the only option. I cannot believe there are no heat exchangers available for your engine. If that is the case, I would contact Yanmar and explain your problem. Finally, if your heat exchanger is in such poor shape, you potentially have problems elsewhere in your cooling system. You will need to check hoses, raw water pump, fresh water pump, thermostat, etc. I would consider using a commercial grade cleaner in your fresh and raw water systems before running your engine again and changing your antfreeze. Good luck. You may need it.

+1 i remember free the old exchager in my old perkins in a soft bath with muriatic acid, just for few minutes and rinse well with fresh wáter , try if the core move and if not repeat again, usually dismilar metals between the aluminium case and the cooper core rings spacers cause salt deposits and corrosión , when assembly the whole unit, coat the interior aluminium with some kind of anticorrosive compound as well the end covers bolts ..

[a64pilot]

I'd try the muratic myself, if that didn't work I'd take it to a radiator shop where they can "boil" it in heated acid. That is how they clean the old brass and copper radiators.
However if your heat exchanger is like mine it is covered in a heavy plating of zinc, which the acid will work very vigorously to remove, so don't leave it in there long, especially if it boils like crazy with acid, cause that may confirm it is zinc plated.
I assume that is why my motor does not have zincs, cause there is a whole boat load of zinc in the exchanger?
I have a 4-JHE

[Geek_Guy]

Thanks for the info. However I'm still curious why I need the core out. I can clean the tubes with it in place. If I can replace the gaskets in each end. What else do I need it out for?

The inside actually looks reasonably OK.

Also I assume that I would have to replace the rubber gasket that is on the core??????? Also are there gaskets on the holes that allow the fluid to go into the engine?

[neilpride]

Originally Posted by Geek_Guy

Thanks for the info. However I'm still curious why I need the core out. I can clean the tubes with it in place. If I can replace the gaskets in each end. What else do I need it out for?

The inside actually looks reasonably OK.

Also I assume that I would have to replace the rubber gasket that is on the core??????? Also are there gaskets on the holes that allow the fluid to go into the engine?

Because salt deposits could be bad at all between the core and the case, and corrosión ...

[Geek_Guy]

Thanks Neilpride,

So the salt/corrosion would reduce the flow of heat between fresh and raw water? And/or the flow of water around the core......

[Geek_Guy]

Also thanks Rognvald,

Your list of items to work through is exactly what I'm checking. The exchanger was just first. There may be much more fun just over the horizon.

It has always fun cool, and for an ancient engine runs great.

Dave

[neilpride]

Originally Posted by Geek_Guy

Thanks Neilpride,

So the salt/corrosion would reduce the flow of heat between fresh and raw water? And/or the flow of water around the core......

Yes exactly, also you can presure test the core after clean up and check for pinholes , salt deposits usually mask leaks , you dont want after assembly the heat exchanger found how the coolant is gone ...that mean dissamble the heat exchanger again or worst , buy a new one...good luck.

[gjordan]

You can clean the inside of the small tubes with a small rifle cleaning kit/wire brush, but there will still be corrosion on the outside of the tubes that you cant reach with the core inside. This will slow the exchange of heat between the fresh and salt side. If you live in a state where the radiator shops still can actually boil them out, That would be the first step I would take. The mild acid treatment will do a reasonable job, but a true "boiling out" will get rid of all of the corrosion. Just some ideas for you. Good Luck. _____Grant.

[Cheechako]

Originally Posted by Geek_Guy

Thanks for the info. However I'm still curious why I need the core out. I can clean the tubes with it in place. If I can replace the gaskets in each end. What else do I need it out for?

The inside actually looks reasonably OK.

Also I assume that I would have to replace the rubber gasket that is on the core??????? Also are there gaskets on the holes that allow the fluid to go into the engine?

I think you need to clean it out, salt deposits, corrosion etc can eventually be a problem. Does yours have a zinc? Not sure how yours is assembled, but it could have orings on it also... they may be hard and brittle etc. They can also cause it to be difficult to get out. Does your Heatex have caps on both ends? Can you remove the other end and carefully drive it out?

[Geek_Guy]

(Previous post)I think you need to clean it out, salt deposits, corrosion etc can eventually be a problem. Does yours have a zinc? Not sure how yours is assembled, but it could have orings on it also... they may be hard and brittle etc. They can also cause it to be difficult to get out. Does your Heatex have caps on both ends? Can you remove the other end and carefully drive it out? ()

I understand the desirability of cleaning it inside and out. Thanks to the replies. Yes there is a zinc. Or actually I assume so as there is a large square nut on the side. Nut is an innie. Yes there are O rings, on the ends of the core. They are pliable and have not been leaking. And yes there is a cap on each end. I was able to get 3 of the 4 screws off the aft cap. The 4th didn't have quite enough head left for a good grip with the socket. But I then removed the entire exchanger. So I can work with it.

My 'cheap Dave' thoughts are that if it is impossible to get out. And I can't get a replacement, and it runs cool for now. A thought would be to put it back together and wait for it to start getting warm. Especially if the alternative is a new engine.

The Yanmar dealer in St Augustine checked on the full replacement and said it wasn't available. They have always been great and I don't have any reason to suspect their info.

[jimbunyard]

I've a slightly different take on it, especially given the non-availability of a new replacement.

If you or a radiator shop can't get the core out by boiling, before going to drastic measures (a press or similar arrangement), take the square cover holding the radiator cap plate on top of the manifold at the forward end off and have a look at the freshwater side of the tubes. If the antifreeze/water mix has been maintained, there may be no need whatsoever to disassemble the heat exchanger/manifold. If you can get both ends off and run the appropriate sized rifle cleaning brush down the raw water side (ID) of the tubes, that may be all you need. Beats messing up a non-replaceable core...

[mickelsen]

Originally Posted by Geek_Guy

Hoping for some details and opinions please.

Been trying to extricate the heat exchanger on my very old 3hm35f Yanmar. Several of the bolt heads on the covers were rusted away so badly that I couldn't attach any wrench to them. I have ground the remainder of the heads off and got the forward cover off. But the core won't budge. My Yanmar mechanic suggested that I try to take the whole thing off and he would attempt to get the core out and help get the bolts out. I was successful getting the exchanger off. When my feeble brain wondered why do I need the core out? I think I can likely get the bolts out as the ones that had a head came out reasonably well. So I can replace the gaskets in the covers.

He had suggested buying a new exchanger, but they checked and it's not available.

Thanks

Might try reaming it out in place with a threaded rod. 1/8 inch?

[baycruiser]

Originally Posted by Geek_Guy

Hoping for some details and opinions please.

Been trying to extricate the heat exchanger on my very old 3hm35f Yanmar. Several of the bolt heads on the covers were rusted away so badly that I couldn't attach any wrench to them. I have ground the remainder of the heads off and got the forward cover off. But the core won't budge. My Yanmar mechanic suggested that I try to take the whole thing off and he would attempt to get the core out and help get the bolts out. I was successful getting the exchanger off. When my feeble brain wondered why do I need the core out? I think I can likely get the bolts out as the ones that had a head came out reasonably well. So I can replace the gaskets in the covers.

He had suggested buying a new exchanger, but they checked and it's not available.

Thanks

I had a similar problem with diecon marine conversion .I boiled this for qiute a while in a acid solution I got from hardware store it was green in solution this was VERY successful after 2 treatments as I was concerned about heat affects .I did this with heat exchanger only in a 20litre urn ,This works on any salt encrusted problems The acid I used was not common but I thought it was the same as used in antifreeze but I am not certain of that .After having this experience tho I think I would consider going raw water cooled in future with a flushing attachment. I hope this is helpful good on you for having a go ...john