Heat exchanger gasket

[paulga]

The zinc pencil on the Lehman heat exchanger has shed some debris inside the tube. I want to open the end cap to clean out the debris. I remember seeing a post saying two different types of sealant or grease should be applied on the two sides of the gasket, but cannot find the post now. Can someone confirm what grease or sealant should be used on the two sides?

 

[C lectric]

Question. How do you know that debris has been shed? Zincs end up looking like that as they age and degrade. Clean the threads of the hole , get a new plug and reinstall the new zinc with something like Rectorseal #5 on the threads. Step up your change out intervals.

I won't suggest anything about a gasket seal.

 

[paulga]

Question. How do you know that debris has been shed? Zincs end up looking like that as they age and degrade. Clean the threads of the hole , get a new plug and reinstall the new zinc with something like Rectorseal #5 on the threads. Step up your change out intervals.

I won't suggest anything about a gasket seal.

There was corrosion around the zinc element. Some chunks fell inside when I wiggle it out.

 

[luna]

This might be the Thread you were looking for. Sealant on Heat Exchanger Caps?
You may also find it in the list of Similar Threads just below this post.

If the gasket is in good shape I would reinstall it dry.

If you do take this apart, which is likely a good idea so that you can assess the coolers condition, I would be prepared to clean the bores of the tubes. Not being a big fan of the acids typically used for this cleaning, once apart my next stop would be at the local Gunsmith's shop in an attempt to acquire the right brushes/tools to clean the tubes.

 

[Nick F]

My recommendation is to use a new gasket of you open it up. Why risk reusing th old one? The gasket is probably a piece of 1/16" nitrile sheet ( also called Buna-N) which you can easily cut yourself.
If the sealing surfaces are smooth, no sealant is necessary. Use Permatex aviation sealant if you must.
This is my personal preference - you will get lots of differing recommendations!
BTW, I agree with opening up the heat exchanger.

 

[paulga]

Thanks. I'll check it this weekend.
this is the thread I was looking for

Heat exchanger corrosion?

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...

www.trawlerforum.com

 

[paulga]

I removed both end caps. The gasket on the forward side is already warped. Is it due for replacement?
The part no of the gasket is 2d25, where can I purchase it?

The aft gasket is still flat.

Here is the inside of the forward cap.

The aft cap

The manual says to use 3/16 wood dowel to clean the tubes with twisting actions. But some holes are already plugged partially by calcium so the dowel may not fit in. How to clean these tubes?

 

[BruceK]

There will be more elegant solutions but rodding with a length of wire cut from a simple wire clothes hanger should help.

 

[paulga]

There will be more elegant solutions but rodding with a length of wire cut from a simple wire clothes hanger should help.

Is a small washer supposed to between the cap and gasket? I remember seeing it mentioned in more than one posts. But I didn't see a washer.

 

[BruceK]

Is a small washer supposed to between the cap and gasket? I remember seeing it mentioned in more than one posts. But I didn't see a washer.

Don`t know, but looking at pics there is a washer size mark in the center.

 

[boomerang]

An aluminum TIG welding rod is what I use to clean the tubes out in a heat exchanger. I prefer to use a material softer than the tube material so as not to score the tubes. Your tubes, from the picture, seem to be due for a reaming. Regarding reassembly, on our previous boat with a Lehman like yours, I used grease on both sides of the gasket on both ends and never has an leak issue. Just be sure the covers aren't overtightened soas to keep the slight dome shape to the cover itself.

 

[Nick F]

Is a small washer supposed to between the cap and gasket? I remember seeing it mentioned in more than one posts. But I didn't see a washer.

Not inside the cap. There must be some sort of seal to stop leakage around the centre bolt - not sure what is used on yours.

 

[paulga]

Not inside the cap. There must be some sort of seal to stop leakage around the centre bolt - not sure what is used on yours.

I see. The bulged center is an integrated washer.

 

[paulga]

An aluminum TIG welding rod is what I use to clean the tubes out in a heat exchanger. I prefer to use a material softer than the tube material so as not to score the tubes. Your tubes, from the picture, seem to be due for a reaming. Regarding reassembly, on our previous boat with a Lehman like yours, I used grease on both sides of the gasket on both ends and never has an leak issue. Just be sure the covers aren't overtightened soas to keep the slight dome shape to the cover itself.

Thanks
Is half turn using a wrench enough to tighten the bolt? Does it have a torque number?

 

[Nick F]

Not inside the cap. There must be some sort of seal to stop leakage around the centre bolt - not sure what is used on yours.

It may be that the sheet rubber main gasket also seals the bolt hole. The female thread in the heat exchanger body would have to be a "blind" thread (no hole right through) for this to work.

I looked at a Ford Lehman parts list and it does not show a sealing washer on the bolt. (So my statement quoted above is wrong!)

 

[paulga]

It may be that the sheet rubber main gasket also seals the bolt hole. The female thread in the heat exchanger body would have to be a "blind" thread (no hole right through) for this to work.

I looked at a Ford Lehman parts list and it does not show a sealing washer on the bolt. (So my statement quoted above is wrong!)

it was likely a blind hole as i remember.
do you mean if it is a through hole, there should be a separate washer outside the end cap, beneath the bolt head?

 

[Nick F]

it was likely a blind hole as i remember.
do you mean if it is a through hole, there should be a separate washer outside the end cap, beneath the bolt head?

I would say yes to your question. The washer would have to be made of something that would seal (that is, not just a plain stainless washer). Probably fibre gasket material or copper or nylon.

There are also special sealing washers that have a rubber insert in a plain metal washer.

 

[BB-marine]

I have a Yanmar 4LHA STP which has an exchanger that is the same or similar in design to the photo of the exchanger that you posted. The original question in post #1 was "what sealant or grease is used"? I use no sealant or grease to seal the gasket. I do use an anti-corrosion grease on the threads of the bolt. The gasket should be replaced each time the end caps removed. The exchanger used by Yanmar does use an o-ring to seal the bolt. The installation sequence is bolt, exchanger cover,-o-ring, exchanger gasket, exchanger. The torque spec is based on the bolt size 5/16 or 3/8. I torque the bolt at 15ft pounds 3/8" bolt. This is less than spec for the bolt stretch for a 3/8 bolt but the bolt is threaded into a bronze exchanger. This spec has worked for me.

I pull the exchanger covers every other year to inspect the tube sheet, for obstruction, debris and confirm good flow through all tubes. Anodes are replaced at the same time. If the boat is used in fresh water the anodes are replaced annually if the boat is in salt water every 6 months as worked for my use while owning this boat.

Most of the tube obstruction and build up is at the down stream end of the exchanger. It is probably a good idea to use a softer material rod for reaming the tube sheet. I have a heavy gauge coat hanger that has a polymer coating on it. I straightened it to be used for rodding the exchanger. In reality it is harder material than the bronze tubes. I have cleaned the exchangers twice after cleaning them when purchasing the boat in 2021 with no issues. I have two exchangers that use the rubber end cap gaskets, heat and oil and the after cooler uses o-rings. I do use Vaseline on the o-rings. I do not use grease, vaseline or sealant on the rubber gaskets. I have not had any issues with exchanger leakage. I removed the end caps in 2023 and the gaskets looked to be in good shape. The exchanger had about 10 tubes that had some build up. The engines were used mostly in salt water. I just cleaned and inspected this month. 90% of the use was in freshwater cruising Canada and the Great Lakes. The exchangers were clean with no obstruction. Gaskets again looked to be in good shape but I replace them.

The OP'ers exchangers look about the way mine looked when I first purchased the boat. I don't think the covers had ever been removed to inspect the tube sheets of the exchangers. The gaskets were deformed in appearance but I saw no evidence of them leaking other than a small amount of green powder around the exchanger to cover split line.
Good Luck with your repair.
Brian

 

[luna]

Obviously the existing gaskets have been reinstalled at least once before, as a result I would replace them.

If you have not sourced these gaskets yet from your friendly Lehman Dealer, it may be that you can get the gaskets and the gum washer (if you need it) from Sen-Dure. I would not be surprised that Sen-Dure supplied the original cooler, they did on my Cats. Lehman, like Cat, likely does not make coolers.

Have a look near the bottom of Page 5 on this: https://sen-dureproducts.com/Sen-DureCatalog.pdf

In order to clean out the tubes with the end caps off, (always a good idea so you can see whats going on) if the tubes themselves have an internal diameter of 3/16", 0.188" I would acquire a couple of 0.170" brushes like these: https://www.birchwoodcasey.com/products/bronze-bore-brush.html

At the same timeI would get enough extensions to reach through the tubes and a couple of bronze brushes at 0.220" just in case (an additional $4 investment) that I could chuck in the lathe and grind down to precisely fit, if I did not like the fit of the smaller brush.. Perhaps it's better to buy a kit, but they typically have brushes that are too big.

To clean the tubes, assemble the extensions & brush, then chuck it in a slow variable speed drill motor. You could do it by hand as long as you can spin the brush, but it will get tiresome.

I would orientate the cooler with the cleaner end high and put a bucket under the clogged end to capture the junk.

With a trigger bottle of water, wet one tube and insert the brush, then start it slowly spinning. Run the turning brush all the way to the low end of the tube (but not out) while you spray water down the tube. Do not force anything, your drive is made of brass and will fail if forced. Let the brush do the work.

Now, how do they say it? Rinse and repeat!

 

[paulga]

I would say yes to your question. The washer would have to be made of something that would seal (that is, not just a plain stainless washer). Probably fibre gasket material or copper or nylon.

There are also special sealing washers that have a rubber insert in a plain metal washer.

Is a gasket sealant also called grease?
When people say grease, they could refer to permatex ultra black/blue rtv silicone gasket maker, or permatex #3 sealant liquid. Are these sealant also grease?

 

[Nick F]

Is a gasket sealant also called grease?
When people say grease, they could refer to permatex ultra black/blue rtv silicone gasket maker, or permatex #3 sealant liquid. Are these sealant also grease?

I would say no. Grease is a very thick kind of oil. I saw people talking about using grease on the sheet gasket. I have seen grease used as a lubricant on some rubber gaskets. I think the rationale is that it lubricates the rubber and helps it to "accomodate" itself (or flow into the irregularities) when the gasket is compressed by the mating pieces being clamped together. Hope this helps . . .

 

[Cigatoo]

Grease is not necessary. If you want to grease it won’t hurt but use silicone grease. Available at any NAPPA store. Always good to have a tube on board. Silicone grease will not harm the rubber.

 

[SteveK]

I would put together dry. If it leaks replace gaskets. Those look like rubber which becomes less plyable over time. Gasket seal may work until it doesn't to spot seal. Best to use with new gaskets when called for.

 

[paulga]

Grease is not necessary. If you want to grease it won’t hurt but use silicone grease. Available at any NAPPA store. Always good to have a tube on board. Silicone grease will not harm the rubber.

Do you mean this silglyde lubricant ?

Superlube also has silicone grease: 92003.
Alternatively, does the superlube Teflon grease work?

 

[SteveK]

Does it say use as a gasket lube anywhere?

 

[Datenight]

I bought a .22 rifle cleaning rod with brushes at Wally World. Worked great.
Rob

 

[paulga]

Obviously the existing gaskets have been reinstalled at least once before, as a result I would replace them.

If you have not sourced these gaskets yet from your friendly Lehman Dealer, it may be that you can get the gaskets and the gum washer (if you need it) from Sen-Dure. I would not be surprised that Sen-Dure supplied the original cooler, they did on my Cats. Lehman, like Cat, likely does not make coolers.

Have a look near the bottom of Page 5 on this: https://sen-dureproducts.com/Sen-DureCatalog.pdf

In order to clean out the tubes with the end caps off, (always a good idea so you can see whats going on) if the tubes themselves have an internal diameter of 3/16", 0.188" I would acquire a couple of 0.170" brushes like these: https://www.birchwoodcasey.com/products/bronze-bore-brush.html

At the same timeI would get enough extensions to reach through the tubes and a couple of bronze brushes at 0.220" just in case (an additional $4 investment) that I could chuck in the lathe and grind down to precisely fit, if I did not like the fit of the smaller brush.. Perhaps it's better to buy a kit, but they typically have brushes that are too big.

To clean the tubes, assemble the extensions & brush, then chuck it in a slow variable speed drill motor. You could do it by hand as long as you can spin the brush, but it will get tiresome.

I would orientate the cooler with the cleaner end high and put a bucket under the clogged end to capture the junk.

With a trigger bottle of water, wet one tube and insert the brush, then start it slowly spinning. Run the turning brush all the way to the low end of the tube (but not out) while you spray water down the tube. Do not force anything, your drive is made of brass and will fail if forced. Let the brush do the work.

Now, how do they say it? Rinse and repeat!

what is the extension rod called? I only heard the thread size of 0.17 and 0.22 brushes are both 8-32.

due to the installation angle of the engine, the more clogged end of the HE is higher than the other end. HE is locked in place by those large pipes and hoses to the expansion tank, mixing elbow and trans cooler. I don't want to disconnect those hoses, so I'll clean shorter sections and rinse incrementally.

 

[luna]

Most gun cleaning extension rods that I have seen and used are made of brass, which results in them being somewhat delicate, particularly when driven by a lightly clutched slow turning drill motor.

Here is a set, Solid Rod Set with T-Handle Assembly. that is made from steel. It should be more robust, but could also cause harm if it whips inside the tube. It should not whip if you do this correctly.

There are times like these when you would be best to just go to the gun shop with all of the particulars of the job and see first hand what fits. This steel one may not fit as it says is used for guns 22 caliber and larger.

 

[Nick F]

I have a gun cleaning rod. I consider that it only removes the loose stuff and I would not think of spinning it with a drill - I simply work it back and forth by hand.

 

[luna]

If you only have the rod, I agree with you. Once you mount on the end of the rod the right sized bronze brush and spin it, things usually change quickly.