Heat exchanger corrosion?

[petdoc4u]

I have a Ford Lehman SP135 engine. Each end of the exchanger has a gasket, a cap and a bolt which holds to cap in place. Recently I have noted an accumulation of crusty blue/greenish material ringing the cap/gasket/exchanger. The zinc which bolts into the exchanger is healthy.
What does it mean and how can I fix it. Wish I could send a pic but the boat is far away.
Thanks in advance.

[Larry M]

Remove the bolt, end caps and rubber gaskets. Clean the ends of the heat exchanger and end caps being careful not to scratch either. Reassemble with new gaskets.

It's nothing to worry about. Its salt/moisture wicking around the heat exchanger ends and caps. The gaskets are cheap and you can even buy new end caps.

[Capt.Bill11]

What Larry said.

Plus don't forget the plastic washers that go on both sides of the bolt that holds the end cap on. And you can add a little Permatex to help seal the end cap.

Actually now that I think about it the washer that goes on the bolt on the inside of the cap between the cap and gasket is softer like rubber at I recall. The outer washer is nylon under a metal washer.

[Phil Fill]

Originally Posted by petdoc4u

I have a Ford Lehman SP135 engine. Each end of the exchanger has a gasket, a cap and a bolt which holds to cap in place. Recently I have noted an accumulation of crusty blue/greenish material ringing the cap/gasket/exchanger. The zinc which bolts into the exchanger is healthy.
What does it mean and how can I fix it. Wish I could send a pic but the boat is far away.
Thanks in advance.

Its probably salt wicking thru. However make sure you clean off the white coating on the zinc.

[sdowney717]

I sealed my Sendure end cap with Permatex Black, and no gasket. No leaks.
When the impellers tear apart, you got to open that up eventually to get out pieces, which a rubber gasket helps get you going quickly. Just Permatex, you have to wait a while.
On my rebuild, I opened up the heat exchanger and saw some impeller bits and pieces had been there about a year, but I never noticed any issues.

[dhays]

Originally Posted by sdowney717

When the impellers tear apart, you got to open that up eventually to get out pieces, which a rubber gasket helps get you going quickly. Just Permatex, you have to wait a while.

Why should the impellers tear apart? I always figured to replace the impellers long before they would start to fall apart. I think I am missing something again...

[Larry M]

Here's what the gasket looks like. They're about 3.75" in diameter but they are called 4" when you order them. They're pretty thick at 1/8". You can order from Fisheries Supply for ~$3/each (manufacturerers part #: SK5400). Before we changed to Al anodes, I had a problem with the zincs breaking off in the heat exchanger when checking them. I got in the habit of taking off the end caps every other zinc change to inspect the tubes and clean out the zinc pieces and installing new gaskets without any gasket sealer. Pretty cheap and easy.

[Wxx3]

Originally Posted by Larry M

Here's what the gasket looks like. They're about 3.75" in diameter but they are called 4" when you order them. They're pretty thick at 1/8". You can order from Fisheries Supply for ~$3/each (manufacturerers part #: SK5400). Before we changed to Al anodes, I had a problem with the zincs breaking off in the heat exchanger when checking them. I got in the habit of taking off the end caps every other zinc change to inspect the tubes and clean out the zinc pieces and installing new gaskets without any gasket sealer. Pretty cheap and easy.

Yep. What he said.

[sdowney717]

Originally Posted by dhays

Why should the impellers tear apart? I always figured to replace the impellers long before they would start to fall apart. I think I am missing something again...

Probably cause I let mine go to long.
It was either old age or it was a jelly fish sucked up against the hull.
I have had jelly fish do that and that does cause impellers to fail.

the one time my impeller disintegrated, there were jelly fish all around the boat. I had just started up after anchoring, within minutes engine overheat, no cooling, entire impeller disintegrated to the metal core.

Another time, running gen at the dock, I had jellyfish actually sucked up into my gen raw water thru hull, before the strainer. Undid the hoses and totally blocked, it was impossible to clear until I used the dock water hose to backflush it out.

[dhays]

Originally Posted by sdowney717

Probably cause I let mine go to long.
It was either old age or it was a jelly fish sucked up against the hull.
I have had jelly fish do that and that does cause impellers to fail.

the one time my impeller disintegrated, there were jelly fish all around the boat. I had just started up after anchoring, within minutes engine overheat, no cooling, entire impeller disintegrated to the metal core.

Another time, running gen at the dock, I had jellyfish actually sucked up into my gen raw water thru hull, before the strainer. Undid the hoses and totally blocked, it was impossible to clear until I used the dock water hose to backflush it out.

Never would have thought of that. I suppose another problem could be a floating plastic bag etc...

[Islanddreamer]

How often are you changing the zincs on the heat exchanger? New to me Albin 36 with a Lehman 120.

[kchace]

Originally Posted by Islanddreamer

How often are you changing the zincs on the heat exchanger? New to me Albin 36 with a Lehman 120.

It's really a good idea to check them every month or so till you get a feel for how fast they're wasting away. In my case I can get about 150 engine hrs on a set, but it does vary.

Ken

[Islanddreamer]

Thanks Ken. There are plenty of things I am discovering. Even though it has less than 3100 hours on it, I want to make sure I stay ahead of the ball.

Interesting to read the forum because things are popping up in my own boat as I am seeing them here.

[psneeld]

I check mine every 2 weeks when cruising steadily every day (30-50 miles/5-8 hrs a day)...sometimes it needs it in less than a month/100 hours...other times more.

[Islanddreamer]

Next question - for the Lehman 120 model 2715E where can I get replacement zinc pencils?

[kchace]

Originally Posted by Islanddreamer

Next question - for the Lehman 120 model 2715E where can I get replacement zinc pencils?

You can get them almost anywhere. They're nothing special, just a brass 3/8" NPT fitting with the zinc pencil threaded into it. The only thing you have to make sure is that they aren't too long. If you put one in that is a bit too long, the zinc will hit the internal boss for the bolt that holds the end cap, and as you tighten the zinc it can break off (inside). Ask me how I know this. The correct length for the pencil is 1 1/2" past the brass plug. That length is not nearly as easy to find as the 2" length. I usually just buy the 2" ones and cut a small piece off the end.

Martyr Marine Engine Pencil Sacrificial Anode

Ken

[Islanddreamer]

Thank you sir.

[Steve DAntonio]

Originally Posted by sdowney717

I sealed my Sendure end cap with Permatex Black, and no gasket. No leaks.
When the impellers tear apart, you got to open that up eventually to get out pieces, which a rubber gasket helps get you going quickly. Just Permatex, you have to wait a while.
On my rebuild, I opened up the heat exchanger and saw some impeller bits and pieces had been there about a year, but I never noticed any issues.

If you lightly coat, just a film, the gaskets on both faces with Teflon grease such a Superlube it improves sealing, and you may avoid the crusty verdigris, which is harmless. In a pinch, if you need to remove the end cap and you don't have a replacement gasket, the lube will often prevent the gasket from tearing. You can use this same technique on raw water pump gaskets. You should always replace these gaskets when removing covers, but again, in an emergency this may allow a re-use.

[Capt.Bill11]

Originally Posted by Steve DAntonio

If you lightly coat, just a film, the gaskets on both faces with Teflon grease such a Superlube it improves sealing, and you may avoid the crusty verdigris, which is harmless. In a pinch, if you need to remove the end cap and you don't have a replacement gasket, the lube will often prevent the gasket from tearing. You can use this same technique on raw water pump gaskets. You should always replace these gaskets when removing covers, but again, in an emergency this may allow a re-use.

I've done it that way for years. The only difference is I put Permatex #2 on one side and Super Lube on the other.

That way I've found the gasket stays sealed to the plate side with the Permatex and pulls off clean from the pump or cooler side coated with Super Lube. And is in the vast majority of the cases reuse able.

[sdowney717]

Originally Posted by Capt.Bill11

I've done it that way for years. The only difference is I put Permatex #2 on one side and Super Lube on the other.

That way I've found the gasket stays sealed to the plate side with the Permatex and pulls off clean from the pump or cooler side coated with Super Lube. And is in the vast majority of the cases reuse able.

I bet Rector Seal T plus 2 white teflon pipe dope would work sealing a gasket face to metal.
I have used it on all my hose ends including the exhaust hose, and so far no leaks and not sticking of rubber to metal. And when clamped with a hose clamp, no way to twist or pull off the hose, I have tried, they seal and stay on. And when clamp is loosened they slip off without sticking. With that Rector Seal, they also slip on easier.

I had some really bad stuck on rubber hoses when pulling down my engine for a rebuild. You can wreck a hose end for no good reason since it gets stuck while your prying on it, and the rest of the hose is in good condition. Large hoses are expensive so why waste money replacing good hoses because just the ends got stuck and removing them tore the ends up..