Heat exchanger gasket

[TJM]

Paulga, it is the offseason, removing the heat exchanger is not a big deal and will provide you comfort knowing that you did the right thing. The hoses will loosen up and wiggle off easy.

 

[paulga]

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.

maybe I can cut it myself. where can I buy this type of nitrile sheet?

 

[luna]

Nitrile, aka Buna-n, aka NBR is a good quality material to use for gaskets that are asked to resist oil or ethylene glycol at reasonable temperatures. If you want to step up in performance look to Viton or Teflon.

In this application you are sealing raw (salt, polluted) water at low temperatures and pressures. Neoprene, or cork/rubber sheet would work just fine.
Fel-Pro makes a number of suitable gasket materials that should be readly available on Amazon or ebay.

If you just have to have NBR (nothing wrong with that) Mcmaster Carr may be a reasonable source.

 

[paulga]

Nitrile, aka Buna-n, aka NBR is a good quality material to use for gaskets that are asked to resist oil or ethylene glycol at reasonable temperatures. If you want to step up in performance look to Viton or Teflon.

In this application you are sealing raw (salt, polluted) water at low temperatures and pressures. Neoprene, or cork/rubber sheet would work just fine.
Fel-Pro makes a number of suitable gasket materials that should be readly available on Amazon or ebay.

If you just have to have NBR (nothing wrong with that) Mcmaster Carr may be a reasonable source.

Thanks. neoprene does offer some low cost options. eg

Amazon.com

 

[Nick F]

Paaulga - the link you posted is "rubber" (not Buna-N, NBR).

Here is Nitrile sheet (it is available in different hardnesses. I recommend 60 or 70 (the units are Durometer of the A series)). I am not sure what thickness would be best - I suggest matching what the old gasket was - probably 1/16" or 1/8".

People have mentioned two other materials - silicon and Viton. Nitrile is the better choice (my opinion). Silicon is good for temperatures higher than what you have - it is also rather squidgy and sometimes creeps with time. Viton is required for some agressive chemicals for which nitrile is not suitable (not your case here). Viton is also harder and more expensive.

https://www.amazon.com/MATNIKS-Resistant-12x12-Inch-16-Protection/dp/B0C2262S5R/ref=sr_1_5?crid=1WRXPLK0P1OFB&dib=eyJ2IjoiMSJ9.O9dWQbcSBSeK9wUzWOCYWQN1MxB7JQjXao6jBIUZ8pQ1o3Ag5Y2LcLmsDWvuXsmhyl9vKjNFAfXM097OvynLRJ4Zdos6d_bB6KQCf1JKgXacqIMhOChjZQptz4XzPOlqGvD3hmR4pjUXYcLsoW465UzivQLPRmedSL7vj3ZF7jTKkZloOGzJ8cFAPvGW7jOax9nsOz-30-k7Sj9jB_-H1595n9uAXJvP1YPkroqTXPU.Edp7BNoi1gcoXkSddSILcV8rte5j8RuZlEFzQcxrVwM&dib_tag=se&keywords=nitrile+sheet+1%2F16&qid=1739018412&sprefix=nitrile+sheet%2Caps%2C213&sr=8-5

 

[BB-marine]

The gaskets are readily available from after market resources. Measure the size of the exchanger cap and order based on the diameter. Example a 4" diameter end cap from SeaKamp inc. is $5.50. There are many other resources. The material used for sealing exchanger end caps is Nitrile Rubber (Nitrile Butadiene Rubber or Buna -N). This can be purchased in sheet form if you want to make your own. Measurement the thickness. Most smaller diameter 3" or smaller exchanger end caps have thickness of either 1/16" or 1/8 material. 4" and 5" 1/16",1/8", 3/16". I purchase my gaskets either OEM when available or after market. Made up and properly sized. In a previous post I stated an opinion that the gaskets should be installed dry. Grease, sealants, silicone...... cause rubber sealing materials to slide when pressure is applied. If the mating surfaces, exchanger cap and exchanger shell are in good condition there is no need for a sealant. The Gasket does the sealing. The only grease application should be on the exchanger cap bolt threads.

Cleaning the exchanger, can be done with barrel cleaning brushes and or many other methods. Chemical cleaning in my opinion is the best way to clean exchanger tubes. In my case I used a coat hanger that had a polymer coating on it. This was to insure that each tube was clear from upstream side of the exchanger to downstream side. I now know that the raw water cooling can flow through each tube sheet tube. If I want the exchanger cleaner than that I would rather remove the exchanger and have it chemically cleaned or use a chemical wash that will clean the entire raw water cooling system in place. This is not a difficult process. I would use the directions on the bottle of a product designed to do this.
https://www.google.com/url?sa=t&sou...MQFnoECBgQAQ&usg=AOvVaw2nHZT8qR9EyYBrSF_r67vV

I have used this method in the past and have found it to be effective in cleaning not only the exchanger but the complete raw water cooling.
Brian

 

[av8r]

Paul
You’ve put a lot of time and effort into your boat projects and in trying to do things well, don’t change that now.
4” heat exchanger gaskets are easy to find, buy 6 to change them all and have 2 spares. I would recommend having 1 spare end cap in your spares collection, they can crack if over-tightened. Sendure is a good source.
Before attempting to clean the heat exchanger cores, consider that replacement is around $700 last I checked. A radiator shop can clean and pressure-test for way less, and then you only need 2 spare gaskets.
Brian at American Diesel sells water (coolant) hose kits with all the hoses, including the formed elbows. Boating is pretty slow right now, you have time to remove the exchangers and old hoses and replace with new. Then it’s done.

 

[paulga]

The bulged center that I saw earlier turned out to be a separate seal. The manufacturer said such a seal was probably added to stop leak but it should not be necessary. This extra seal has already left a mark on the HE over time. I'm going to sand the surfaces on the HE and the cap flat before reassembling.

The gasket is 1/16" thick. The bolt thread appears to be 3/8-16, it has a major diameter of 47/128" or 0.3672". What size drill bit should be used to make the center hole in the gasket?

 

[Nick F]

What size drill bit should be used to make the center hole in the gasket?

You can´t make a neat hole through rubber (nitrile) sheet with a drill. You should use a gasket punch. A larger hole can be made by hand with an X-acto knife if you are careful. For 3/8 bolt, make a 3/8 hole (the material is flexible).

1pc Round Hollow Punch Set Hand Tools Hole Punching Leather Gasket Carbon Steel | eBay

1pc Belt hole punch tool. Material: Carbon steel. It's made of high quality carbon steel. 25Pcs Red Fishhook Carbon Steel Treble Jig Hooks Fishing Hooks 2/4/6/8/10#. The color may have different as the difference display,pls understand.

www.ebay.com

 

[luna]

The small rubber washer is called a gum washer. Have a look at the lower right corner of page 5 of the Sen-Dure link in Post #19.
It is likely a Sen-Dure cooler.

 

[paulga]

The small rubber washer is called a gum washer. Have a look at the lower right corner of page 5 of the Sen-Dure link in Post #19.
It is likely a Sen-Dure cooler.

Thanks. I have sent the pictures of the HE to Sen-Dure for confirmation.

 

[Greg QS]

I use a piece of all tread sized for the tube. It helps grab and remove debris. I use this for general cleaning. You are way past this point. I would recommend to pull the cooler and take to a radiator shop and have cleaned. They will test it also. about 350-500 bucks. Then use the rods every 2-3 years.

 

[BobMc]

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

If you use anything metal like a gun cleaning rod, coat hanger, welding rod, etc, you risk damaging the tubes. Wooden dowels swell up and are difficult to use. Best is a plastic ros slightly smaller than the id of the tube. McMaster-Carr has 3 foot lengths that are perfect. Don't remember the diameter but they're cheap enough that you can order several to get the right fit.

 

[DavidNZ]

Hi all. I have just gone through a H/Ex refurb due to loosing coolant through the unit. Turned out to be a Brocken o-ring on one of the end caps. Mine is on a Cummins. To clean the tubes, as they were badly blocked, I talked to a radiator guy and he dropped it in a fresh water bath for a couple of days to loosen up the salt buildup. He also managed to clean out some of the tubes. I then took it home and set up bath using a large plastic bin and continued to soak and slowly clean out the tubes using wire to break open the clogged ands carefully and then a spray paint cleaning kit which I got from a hardware store which had a series of brush sizes. I could not find gasket parts (Cummins could not find anything that matched my h/ex based on my engine number) so I made from standard gasket material from the auto shop with high temp silicone gasket maker each side. Re assembled it all and installed back in my boat and all going well. This was all over the Xmas period here in NZ so everything closes down for weeks so couldn’t really get help from marine mechanics. We are currently cruising in the sounds at the top of South Island after crossing the cool strait and all going well. Before and after pics included

 

[DavidNZ]

I didn’t think of barrel brushes and so am going to investigate these for next time. Always good to read these posts as there are so many good tips, really appreciate them.

 

[Halinbrier]

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?


View attachment 161865

View attachment 161866
The aft gasket is still flat.
View attachment 161868
Here is the inside of the forward cap.

View attachment 161867

The aft cap
View attachment 161869

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?

Brian and American Diesel should be able to help you with replacement gaskets. We just ordered some for our 1992 GC 35 with Lehman 135s. 804-435-3107