Over heat

M

Mule

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Mar 3, 2002
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7719
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74
Two weeks ago while changing the oil on my twin Crusader 5.7's, I noticed a small amount of antifreeze on the pad under my engine and around the overflow tank. Not much... Maybe a cup or less. I had added antifreeze a few weeks before cause I noticed the overflow tank to be a little low. So, I figured I added too much and it just overflowed a little.
Today while out for a quick little ride the engine overheated. I was able to get it back into the slip without the engine going over 220. When I looked at the overflow tank, it looks completely empty! I couldn't remove the cap because of the temperature but it looks empty.
No antifreeze on the pads or in the bilge and the raw water pump is working fine. I also, check the engine oil level and for contamination and found no problems.
Only thing I can think of is the thermostat or fluid level but if its the fluid, where did it go?
Any ideas??
 
A cylinder compression test and a heat exchanger pressure test will likely tell you if it the head gasket or H/Ex..
For that matter , just pulling the plugs to get to the compression test would likely indicate whether A/F was getting into the cylinders, plus in that case there would be more sweet steam in the exhaust . Failed head gasket would be much more likely to blow A/F out past the A/F recovery reservoir, but you said that didn't happen last run.
If it's just a leaky H/exch., you should be able to see and smell A/F in the exhaust wake but the exhaust shouldn't be particularly steamy ..if... the RW side is still flowing quite well . You can confirm that last by running the engine and seeing if you can still keep your hand on the top of the riser/elbows indefinitely. Good RW flow at idle and higher RPM will keep it cool or just warm , not HOT.
You can also try emptying one of the lower FW-side coolant hoses into a container and if there is any "coolant" in there to check, check by eye or coolant freeze-protection tester if it is diluted beyond normal 50%. I've seen some mechanics taste the coolant for salt water then spit it out and rinse , but I don't care for that as it is toxic.
Make sure you check to confirm oil level has not increased as that would add to the unfortunate possibilities.

Without more info , I'm guessing failed H/Ex. as the more likely suspect. Curious, have you been checking the pencil anode every month in season , and replacing when it looks about 1/2 gone as per the manual ? (The rest is very porous by then. ) That doesn't ensure very long life but it helps a lot.
 
Oil level was unchanged from where I topped it off when changing it. The engine ran fine during the run yesterday and my exhaust is underwater. So, hard to see any steam or AF smell.
At idle, it exhausts from a small port just above the waterline. I get some white "smoke" when at cruise speed but assumed it was just exhaust gas... Especially, since it is coming from under the boat!
The elbows were not hot, just warm. The RW pump is working fine.
I check and change the pencil anodes every three or four months...
However, the boat is 10 years old now and these things do tend to start happening about this time...
I'm puzzled as to why I found AF around the front of the engine prior to the overheat. Where would it have come from?
I plan to go to the boat and add water/AF later today and run it in the slip for awhile.
I'll report back afterwards.
I assum that I would need to remove the HE and have it professionally press tested?
 
AF near the front of the engine could be a leaking water pump on the engines closed cooling side. You might have a bearing/ seal going in the fresh water side of that engine.
Bill
 
I thought of that as well...
Not a drop from yesterday's run though!
I'll be rechecking everything later today.
 
In my older Carver, I found that the pencil zinc had given way and the fitting was actually leaking. REplace both and issue never returned.
 
Good thought... But no AF in the bilge.
Still, I'll check it out.
I double checked the oil level... Good.
No visible leaks anywhere, no AF in the bilge or on the pads under my motor.
Added about a quart of AF/water and ran the engine up to operating temp.
By the time it got to temp, the overflow tank was empty but was maintaining temp... Although, I didn't run it that long.
I checked the exhaust for color/odor, going so far as putting my hand in the water stream... No AF smell that I can detect.
I have a friend with a radiator pressure tester and will use that tomorrow to see if it holds pressure.
Another friend suggested I look at the block off plates on my risers but they are only about 1-1/4 old and I usually change them every three years.
I'll try the pressure test and then go from there.
BTW, the thermostat opened normally at about 160-162 degrees.
 
Just thought about it...
The pencil zincs would be on the raw water side!
 
The good news... I found the leak!
The bad news... It's the heat exchanger.
Pressurized the system and it bled down fairly quickly. Inspected for external leaks and checked for CO in the AF, which was negative (Whew!).
Decided to take the end cap off the heat exchanger. As soon as I did, I heard the leak and confirmed it by dipping a paper towel into the remaining water. It came out pink!
Re-pressurized and pulled the other end cap off, even louder on that side but definetely coming from the HE.
Now for the few questions I have...
1. Why is the HE corroded on one motor more than the other?
The leaking HE has about one-third of the tubes blocked by blue corrosion on one end of the HE (closest to the pencil zinc) while the other engine's HE has absolutely none! I checked it today and did a pressure check on it too (no leaks)
2. There was hardly any raw water in the HE's... Is that normal due to them draining back out when the engine isn't running?
3. The end gaskets look to be in excellent shape, should I replace them?
4. Anything I should be on the lookout for while changing the HE?
I'll keep you posted on the repair but I gotta find the best buy I can on the HE!
 
Have you owned the boat since new? If not, is it possible the other heat exchanger was already changed? Barring that, how intact is the bonding on the motor with corrosion? Grounding cable? Have you taken the other heat exchanger apart to be certain it is not on the cusp of the same corrosion?
 
quote:
Originally posted by jmeirhofer

Have you owned the boat since new? If not, is it possible the other heat exchanger was already changed? Barring that, how intact is the bonding on the motor with corrosion? Grounding cable? Have you taken the other heat exchanger apart to be certain it is not on the cusp of the same corrosion?

Click to expand...

I would agree chances are if the other hasn't been serviced it should be replaced as well.
Bill
 
I've owned and maintained the boat since it was new.
And I removed the end caps from the other motor and it looks clean with no corrosion. Additionally, I pressure checked too!.
The grounding system appears ok but I will be double checking the connections, etc.
 
quote:
Originally posted by Mule

The good news... I found the leak!
The bad news... It's the heat exchanger.
Pressurized the system and it bled down fairly quickly. Inspected for external leaks and checked for CO in the AF, which was negative (Whew!).
Decided to take the end cap off the heat exchanger. As soon as I did, I heard the leak and confirmed it by dipping a paper towel into the remaining water. It came out pink!
Re-pressurized and pulled the other end cap off, even louder on that side but definetely coming from the HE.
Now for the few questions I have...
1. Why is the HE corroded on one motor more than the other?
The leaking HE has about one-third of the tubes blocked by blue corrosion on one end of the HE (closest to the pencil zinc) while the other engine's HE has absolutely none! I checked it today and did a pressure check on it too (no leaks)
2. There was hardly any raw water in the HE's... Is that normal due to them draining back out when the engine isn't running?
3. The end gaskets look to be in excellent shape, should I replace them?
4. Anything I should be on the lookout for while changing the HE?
I'll keep you posted on the repair but I gotta find the best buy I can on the HE!

Click to expand...


That's good at least you confirmed the source of the leak. Also that the H/Ex is fairly easy to replace.

1) Who knows? Maybe the pencil zincs were used up faster on that side, could be RW flow difference due to any of several factors, could be a bonding issue, could be a manufacturing imperfection compared to the other H/Ex....?

2) Yes , the RW drains back. I never have any RW leak out when I check the pencil zincs each month.

3) I believe Crusader recommends not only replacing the end cap gasket after bundle inspection , but also the cap itself. That said, last time I ordered caps and gaskets I was sent ones that did not match and used all the old stuff with no problems.

4) You may not have any A/F left, but in case you do, I'd suggest you pull a FW side coolant hose off somewhere that is below the bottom of the H/exch and where you can drain it into a container for town recycling rather than draining into the bilge. The after the new H/Ex is installed and filled you might open the thermostat housing to help purge air. I can't remember if the '03 thermostat housing has a purge fitting built in with a hose back to either the fill tube or the recovery tank, but suspect it does.

FWIW, under warranty , I had the original FW cooling system on my '03 Captain's Choice 5.7's replaced with the improved '04-'05 style with 170* thermostat just above the new-type H/Ex and constant flow through the slick "Degas" recovery reservoir for best automatic purging.
 
Forgot to mention, if all is original on your '03 and it is Captain's Choice (not sure about the FW carbed Classic version) the Crusader part number for the H/Ex Ass'ly is RA147044. Even if you try to match up with an aftermarket Sen-Dure or Therma-flow(?) or other, that would be the reference I believe. You might also check with heatexchangershop dot com about repair if you are trying to find the cheapest solution.
 
Thanks Sandy.
The part number is RA147048. I'm not fond of the repair option just for piece of mind. I did find one on ebay that is used and the owner claims it is only 8 months old.
I have asked some questions of him before I decide on it or not.
This is the original equipment on an 03' MPI engine (Captains Choice) but I didn't look at the thermostat housing, I'll check it out.
I was caught off guard by the corrosion because I am quite meticulous with checking pencil zincs and general maintenance.
Thanks for the tip on emptying the system and purging.
 
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