Is my heat exchanger bad

[glennj3]

My post regarding my carburetor changed to having overheating problems so I thought I would just post a new topic regarding this.
I removed my heat exchanger after doing a pressure test that would not hold more than 10 lbs.
I do not have any pressure testing equipment here so I just filled the internal or closes system hose with water, holding both equally elevated. The levels dropped equally and water was pouring slowly out of the end of the open exchanger (end caps removed).
So to verify, sounds like there is a hole inside allowing the closed system to be open to the pickup water.
If so, is it better to have it repaired or buy a new one. This one is only about 3 years old and looks very clean.
Thanks,

 

[stonyloam]

If it was coming out of both ends, I would think you have a tube with a hole in it. If it were coming out of one end I would think it was a seam between the inner and outer exchanger at the end. Try to identify which tube is leaking. Have the bad tube soldered shut at both ends and you should be good. I think you can loose up to 3 tubes in one section and still be OK.

 

[alldodge]

Agree with stony it can be repaired that way, but I would look real close at it. I would be leaning more to rebuild or replace then repair. The exchanger sprung a leak, and may do it again depending on how warn it is

 

[glennj3]

Thanks, I have been trying to ID for sure where the leak is located, don't think I can narrow down to which tube or tubes leak.
Mostly I want to verify with you guys, since it is difficult to get a strait answer from my mechanic over the phone.
HE has two large hose connections at each end, one large one small.
The two small should go to the same place as would the two large ones.
So if I close the end caps and fill the small hose which fill the small tubes, the water keeps dropping down. I closed off those two hose's, flipped the HE upside down and water poured out of the two large holes, which would be the antifreeze chamber, correct?
I think I should locate a shop that specializes in rebuild if possible or locate a new one.
Oh, there is a drain at the bottom of the HE, that would drain antifreeze? I was told a long time ago that to winterize the engine, I only needed to open the end caps from the HE which does the same as the little drain at the bottom. I always thought I was draining the river water at that time. So now I am confused as to how to drain the river water for winterization?

 

[tpenfield]

Got any pictures you can post. Fixing the HE would not be easy, unless you can easily get at the area that has the hole/leak. I would think you may want to just verify that the HE is bad and then get a new one.

 

[glennj3]

Sorry to bother you with all of those questions, I found on this site a diagram of the HE, water flow etc. now it all makes sense. But it does seem to have a larger possibility of getting trash clogged inside of the tubes!
Opening the end caps do in fact drain the sea water as well as the drain at the bottom. I will be looking for a new HE.
Thank you!

 

[FreeBeeTony]

You really need to pressurize the coolant side of the HE. You'll need to cap off the appropriate openings.
Then w/ the end caps removed you can spray soapy water on the open tubes and find the leaky one.
I did this last year and plugged the leaky tube w/ JB Weld. Pressure tested and all is well!

Hope this helps, you can probably rent a pressure tester at AutoZone for no $$$.

 

[HT32BSX115]

Hope this helps, you can probably rent a pressure tester at AutoZone for no $$$.

I would lean away from using JB-Weld to seal a heat exchanger........... with temp changes it would eventually lose adhesion with the copper. Soldering is a much better more permanent process.

You don't really need a special "Pressure Tester"

Just use a simple 0-30 psi gage available at any auto parts store. Then use whatever plumbing fittings you need to close off openings and connect a valve and an air compressor.

If the leak is in an area where the tubing is perforated due to corrosion etc....., no amount of soldering or JB-weld will fix it.

 

[glennj3]

I ordered a new one, just can't take a chance on patching this one up unless I keep it for a spare.
Thanks again.

 

[HT32BSX115]

I ordered a new one, just can't take a chance on patching this one up unless I keep it for a spare.
Thanks again.

Take the damaged one to any (real) radiator shop and they can probably fix it right up!

 

[stonyloam]

The exchangers really do not get clogged with trash very often because the openings for the water intake in the outdrive are small enough that any debris that comes in with the raw water pass through the exchanger tubes and do not accumulate. About the only time clogging is a problem is if the impeller is run to the point where it disintegrates and the larger pieces can clog the tubes. Any accumulation of trash should be found under the front cap, in the starboard set of tubes. The hoses are pretty simple: the farthest fore (in) and aft (out) are raw I water, and the farthest aft plug is the raw water plug. The inner hoses are coolant, and the farther forward plug drains the coolant. So if you fill the inner hoses with water, even under no pressure water should leak out of the offending tube.

 

[glennj3]

My new HE should be here tomorrow but I am still fooling with the old one. If I can locate a radiator shop i'll have it checked anyhow.
A little difficult to understand just what Sony said about the ins and outs. But what I said was, if I filled the two small hose sites (one most aft and one most fore) with the for and aft plugs in,water drains out of the two larger hose sites, which would be the internal cooling fluid. So I assume there is a fracture of tubing someplace allowing the two to mix. Bad thing?

 

[stonyloam]

OK this is how it works, the raw water from the outdrive comes in through the transom and a hose runs up through the water cooled voltage regulator then through a hose to the inlet in the front of the exchanger, travels through the starboard set of tubes to the aft of the exchanger, turns and comes back forward through the center tubes, then back aft through the port set of tubes then out through the farthest aft hose up to the exhaust elbow where it cools the exhaust on the way out. The antifreeze enters and leaves through the center two hoses. As the coolant passes through the exchanger a set of baffles circulates it around the tubes and cools it. So if you want to see which tube is bad just fill the center section, (either of the center hoses) and the water will either leak out of the bad tube or if the seam at the end is bad, from around where the tube section is joined to the outer case of the exchanger.

 

[glennj3]

Great Terry, very well understood! I think a seam is bad as water flowed out at the bottom at the end. I will check again to further isolate where it leaks. Still, I don't think any companies do repair work on them.
I got the new HE in today, tested it and all looked well. Put her on the boat, filled with antifreeze and fired her up with the muff on. Felt the hoses as she warmed up, all went very well, no overheating or leakage problems!
Changed the oil and now waiting for a trip to the lake for a good test run!
Thank you!

 

[stonyloam]

Great, have fun!