Help: Heat Exchanger for Universal M-25 in a 1986 Catalina '34?

[Tashahacker]

Howdy fellow Catalina owners!

I need some help with an engine problem. My husband and I have discovered, just as we've reached Bimini, Bahamas, that our engine's heat exchanger is bad. We've not replaced this before and we're wondering if you might be able to help us with some resources to track down a new heat exchanger for a Universal M-25 diesel engine? I have no idea where to begin searching for one and we won't be able to move on from Bimini until we can get someone to FedEx us this part.

And another, related question: As our heat exchanger is now mixing salt water with the coolant and the salt water has made its way through the engine, do you know the best way to flush out the salt water properly once we install a new heat exchanger?

Your help is very much appreciated. Standing by for any and all suggestions...

Tasha (Turf to Surf)
s/v Hideaway

[Les Luzar]

Tasha,
You can contact Sen-Dure Inc, in Ft. Lauderdale FL. They manufacture heat exchangers. Phone number is 954-973-1260. Their web-site is www.sen-dure.com  Make sure that you purchase a 3 inch heat exchanger as a replacement. I am not sure if you have a 2 inch or 3 inch unit, but even if you have a 2 inch heat exchanger, you should replace it with a 3 inch upgrade for better cooling. My 1987 has a 3 inch HX. It will perform better. It is pretty straight forward to replace so you should be able to do this yourself. I do not know the part numbers so perhaps someone else can provide that for you. But at least you have a starting point. As you know, cruising is "repairing your boat in exotic places"!

Good Luck!

[Ron Hill]

Tasha : Follow Les's advice and get the 3" HX for your M25 engine!!
 
Don't know if it will help, but a Sem-Dure HX source also has another toll free # (800)282-0123.  Good luck!

[Stu Jackson]

1.  Heat exchanger source:

http://c34.org/bbs/index.php/topic,6920.0.html

It includes the selection of the 3 inch HX.

2.  Salt water in coolant:  drain the coolant, run fresh water through it, drain again, fresh water again, drain, new coolant.  Use distilled water with the coolant, your choice of using distilled for the second flush.  Don't use the engine petcocks to drain; you'll have to have disconnected the coolant hoses to remove the old HX anyway, right?   Just do it again. Check out the "Burping" link, like this:

http://c34.org/bbs/index.php/topic,4518.msg26462.html#msg26462

This is also in the "101 Topics" sticky.

The flushes should get rid of the coolant in the run of hose to the hot water heater.

Good luck, keep us posted.

[heliraf]

I'm not sure, but I think flushing the engine as described above will get rid of all the contaminated coolant from the engine, but it might not flush the old coolant in the hoses from the engine to the hot water heater.  Like I say, I'm not sure, but you might want to just disconnect those and flush them separately.

Also, while you're ordering a heat exchanger, I would also order some spare rubber gaskets for the ends, and some pencil zincs.  And when you install the heat exchanger back, I would add some thick rubber padding between the heat exchanger and the bracket, and secure it with at least three hose clamps.

All the Best

[Stu Jackson]

flushing the engine as described above will get rid of all the contaminated coolant from the engine, but it might not flush the old coolant in the hoses from the engine to the hot water heater. 

If you run the engine to circulate the flush water, it will have to go through the hot water heater loop since it is essentially a simple extension of the engine coolant loop.  By flush, I meant run the engine.  I can't think of a way to do that without running the engine.

...also order some spare rubber gaskets for the ends, and some pencil zincs.  And when you install the heat exchanger back, I would add some thick rubber padding between the heat exchanger and the bracket, and secure it with at least three hose clamps.

Good advice.  Since there are only two holes in the bracket, either two or four hose clamps make sense.

[Ron Hill]

Tasha : The RO (reverse osmosis) water in the Bahamas is as good as distilled water.
 
If they want an "arm and a leg" for "Prestone", just use RO water after the flush and add the "Prestone" when you get back. Just watch your engine temp.   A thought 

[Tashahacker]

Hi everyone! Thanks so much for this help... I've called the company in Fort Lauderdale and they're looking into making the part anew for us - it turns out these don't exist on shelves anymore?

In reading your replies regarding distilled water mixed with coolant, we've always just used tap water - is this bad?  What is the theory that goes with using distilled water?

Also, we have a concern about upgrading to a 3-inch and finding that the pipes don't fit the heat exchanger and then we find we'll need to replace the hoses. Our 2-inch has never had any problems and our engine has always run cool. So we were thinking the easiest thing would be to do a like-for-like replacement for ease and to know it will be just "plug and play."

Any thoughts on this? For those of you who upgraded to the 3-inch, did you find that you could use your old clamps and hoses or did you need to replace other parts to upgrade?

And if we've never had a problem cooling with the 2-inch, would it not be okay to replace it with another 2-inch?

Thanks again for your help. My prior mechanical experience involves only growing up working on my '73 Triumph Spitfire engine, so working with diesel engines is a learning experience.

I'm grateful for the resources and advice here :-)

Tasha

[heliraf]

I have the same model year boat as you with the same engine and the same 2" heat exchanger, and I have never had a problem either with cooling.  However, if I was going to the trouble of getting a new one, I would probably get the 3" one, "just in case" and because it seems to be an issue sometimes, as evidenced  by the amount of posts on the subject.  Also, I sail in the cold waters of southern CA, but in the warm waters of the Caribbean it might indeed be better to have the 3".  I would imagine a 3" one would not be mega bucks more than a 2" one either.  As far as the hoses and fittings go, this is not an issue.  The inlet and outlet pipes will be the same size.  I say, get the 3" for sure.

About the water to mix with the coolant, yes always use distilled water.  Tap water has too much stuff in it that affects the interior of the engine.  Distilled water for sure.  Or, just buy the coolant that is already premixed and says on it "do not dilute".  If you use coolant that you mix yourself, remember to mark the container with the unused coolant that is already mixed, so you don't end up diluting it further in the future if you need to use more.  I would also use distilled water for your final engine flush. 

[Ron Hill]

Tasha : Go for the 3" HX.

Tap water contains minerals that can leave deposits on the inside of the engine.  Use distilled water as it's "pure" water.

The new HX should have the same size hose fittings, but measure yours' to make sure.  I believe the size is 7/8".  You might want to use the old hoses as new ones might have a hefty $ trag and replace them when you're back in the U.S.

A few thoughts

[Stu Jackson]

Based on the link I provided earlier, the freshwater coolant hoses are 7/8" and the raw water are 5/8".  Same for both the 2 inch and 3 inch HXs.

[Tashahacker]

Hey Everyone,

Thanks again for all the help! In the end we were able to track down a 2" heat exchanger from Jerry's Marine in Fort Lauderdale and he was able to get it to us same day using a little known Bahamian airline for cargo - it only cost us $25 for shipping and we had the heat exchanger in our hands same day! Crazy!

Anyway, so I'm on to the process of installing the new heat exchanger. Thanks for the advice to upgrade to a 3" but as the 2" was readily available, we went with that. We've never had overheating problems with our engine, even in 80-degree waters, so this should be fine as a replacement.

I'm not on to the flushing part. I was the post about burping and will work through the steps. Should I be overly worried about the fresh water flushing of the salt water out of the cooling system? If I simply drain the system, then install the new heat exchanger, then put in coolant mixed with distilled water, "burp" it, then run the engine, should that be sufficient to wash the salt water out (since it never mixed with our oil)?

Any other tidbits of advice here?

Thanks again!

Tasha

[Tashahacker]

1.  Heat exchanger source:

http://c34.org/bbs/index.php/topic,6920.0.html

It includes the selection of the 3 inch HX.

2.  Salt water in coolant:  drain the coolant, run fresh water through it, drain again, fresh water again, drain, new coolant.  Use distilled water with the coolant, your choice of using distilled for the second flush.  Don't use the engine petcocks to drain; you'll have to have disconnected the coolant hoses to remove the old HX anyway, right?   Just do it again. Check out the "Burping" link, like this:

http://c34.org/bbs/index.php/topic,4518.msg26462.html#msg26462

This is also in the "101 Topics" sticky.

The flushes should get rid of the coolant in the run of hose to the hot water heater.

Good luck, keep us posted.

Hi there Stu,

This may be a dumb question, but how do you run fresh water through the engine without turning the engine on? Do I just bring a water hose into the engine compartment and attach it to a hose?

Thanks again,

Tasha

[Tashahacker]

Hey Everyone! The job is DONE! New heat exchanger installed... system "burped" - thanks very much for that link. It looks like we're all good! Thanks so much for your help... now we can head on out for the Exumas!

Sincerely,

Tasha (Turf to Surf)

[scotty]

Have a great trip!!