Overheating

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Brad Young

We are sailing in Mexico.. we are currently having an engine over temp issue.
1) if we keep the rpm below 1800 it seems to run ok.
2)over 1800 rpm the temp slowly creeps up to at least 200, then I put her in neutral and rev engine  to cool her down.
3) when she is running hot, there is no steam in the engine compartment.
4) there is some gray soot (not black diesel) in the compartment below the head sink.

What I have done
1) pulled raw water pump look good, checked water flow to the riser and exchanger flow looks
Normal
2) pulled heat exchanger it was clean. We recently had it boiled at a radiator shop (2017)
Questions
1) is there a way to check flow on the freshwater (antifreeze) side. When looking at the antifreeze with the cap off there does not seem to be much flow
2) is there a way to see if there is a blockage riser?

Any thoughts would be greatly appreciated
Brad Young
Boat
Year 1986
Model C34
Hull# 84

KWKloeber

Brad

This is an M25 w/ 3" HX?

You have normal coolant level in the exhaust manifold?

You can remove the closed cooling system hose between the Hx and pump inlet, but you'd have coolant flowing that you'd have to catch/save/reuse (presumably.  If you hooked a water supply (not under pressure) to the inlet of the closed coolant pump you would (should) see water pumping through the block and out the 7/8" return hose to that pump. I'm not suggesting you do that - just answering your question.

You'll see some flow in the reservoir/exhaust manifold w/ the pressure cap off. If you rev the RPMs you should see the level being drawn down/go back up.

Perhaps your thermostat is not opening? If so you would have very little flow from the block -> to the exhaust manifold -> 7/8" to the Hx -> 7/8" back to the pump.  If the 7/8" hose between the exhaust manifold and the Hx is cool, then you aren't getting hot coolant flowing to the Hx. I realize that It's not easy getting at those locations. 

These might make might help you trace out the coolant flow.
https://groups.io/g/catalina30/wiki/Flow-directions-in-engine-cooling-hoses
https://groups.io/g/catalina30/wiki/Removing-the-Rube-Goldberg-valve-on-a-mk-I

Twenty years from now you'll be more disappointed by the things you didn't do, than by the ones you did.
So throw off the bowlines.  Sail away from the safe harbor.  Catch the tradewinds in your sails.
Explore.  Dream.  Discover.   -Mark Twain

Brad Young

#2
It is a M25 / with a 2 inch heat exchanger.
I do see a the coolant level move when I rev the engine.
I put in a new thermostat. I may take it out just to be sure.
Yes I have the normal amount of coolant.
Brad Young
Boat
Year 1986
Model C34
Hull# 84

scgunner

   Brad,

     Is it possible that you could have lost a vane off of the raw water impeller? If a vane has gotten stuck in the line it could be allowing enough water to bypass at low RPM to keep it cool but at higher RPM requiring a greater flow it could be restricting that flow causing it to overheat.
Kevin Quistberg                                                 Top Gun 1987 Mk 1 Hull #273

Brad Young

The impeller looks good. No parts missing. I have the heat exchanger off and soaking in a tube of muratic acid.
Brad Young
Boat
Year 1986
Model C34
Hull# 84

KWKloeber

#5
Brad

The remedy, quite simply, is to upgrade to the new(er) style 3" Hx. The 2"is undersized except for the coolest sea water.
The warning is all on the TechWiki -  see service bulletin #195.
http://c34.org/wiki/images/6/6c/Wb_searchable_service_bullletins.pdf

Otherwise keep the RPMs down (don't try to outrun any banditos. :shock: )
Twenty years from now you'll be more disappointed by the things you didn't do, than by the ones you did.
So throw off the bowlines.  Sail away from the safe harbor.  Catch the tradewinds in your sails.
Explore.  Dream.  Discover.   -Mark Twain

mark_53

#6
Quote from: Brad Young on March 21, 2019, 08:37:01 PM
We are sailing in Mexico.. we are currently having an engine over temp issue.
1) if we keep the rpm below 1800 it seems to run ok.
2)over 1800 rpm the temp slowly creeps up to at least 200, then I put her in neutral and rev engine  to cool her down.
3) when she is running hot, there is no steam in the engine compartment.
4) there is some gray soot (not black diesel) in the compartment below the head sink.

What I have done
1) pulled raw water pump look good, checked water flow to the riser and exchanger flow looks
Normal
2) pulled heat exchanger it was clean. We recently had it boiled at a radiator shop (2017)
Questions
1) is there a way to check flow on the freshwater (antifreeze) side. When looking at the antifreeze with the cap off there does not seem to be much flow
2) is there a way to see if there is a blockage riser?

Any thoughts would be greatly appreciated
What is the flow like coming out of the discharge?  Is there steam?  Have you checked the strainer on the raw water side?  Have you checked your freshwater pump?  What is the water temp where your at?

Noah

Brad - I know you are in cruise/crisis mode now but someday I would consider upgrading to a 3 inch HX.
1990 hull #1014, San Diego, CA,  Fin Keel,
Standard Rig

Ron Hill

Brad : Try "Burping" your engine heater hoses again - just to make sure that you don't have any air restricting the coolant flow.

A thought
Ron, Apache #788

KWKloeber

Quote from: Brad Young on March 22, 2019, 08:49:43 AM

heat exchanger off and soaking in a tube of muratic acid.


I'm sure if there was scale blocking it, you would see "immediate" evidence from the MA reaction.  Also, run a wire ("coat"hanger) thru each Hx tube to check for non-scale blockage.

Anything you can do in a pinch to cool down the Hx would help some until you can change to a higher capacity. 

If you have a washdown pump and can somehow rig up a nozzle spraying against or water running across the Hx and into the bilge it would help cool it down and help cool the engine coolant.  The same for a slight spray onto the exhaust manifold.  Anything in a real pinch.  Run the blower.  One time my bro was totally isolated/stranded and overheated -- the only liquid he had to use as engine coolant was beer.  It got him thru the pinch.
Twenty years from now you'll be more disappointed by the things you didn't do, than by the ones you did.
So throw off the bowlines.  Sail away from the safe harbor.  Catch the tradewinds in your sails.
Explore.  Dream.  Discover.   -Mark Twain

Ron Hill

Guys : In a real emergency to cool down the engine when you have to still run the engine; I turned on the hot water faucet in the galley and in the head!! This helped keep the temp down.

Another time I turned OFF the engine and sailed to the dock on the jib - furling in the jib as we turned 180 degrees into the wind.  My First Mate asked if we were going to practice this first!!  My reply was simply, "No this is just like a wheels up landing - no practice  " !!!  :thumb:

A few thoughts
Ron, Apache #788

Brad Young

Took heat exchanger off, looked clean but soak it in Muratic Acid, cleaned and inspected everything from the intake thu to the "Y" nipplle. We out on a nice long run 1 hour,  Ran at 2000 rpm and temp stayed at 165.  Untilll .....
I ramped up the rpm to 2500 rpm. Then the riser started to gush. Got a nice crack near the "Y" nipple.  When it rains it pours.

I have tried to enter into the tech notes but I can't get pass the longin.  As far as I know I am a member.  Any quick suggestions on taking off the riser? I got the bolts soaking in PBLaster.
Brad Young
Boat
Year 1986
Model C34
Hull# 84

Brad Young

As a side note: we came into the anchorage under sail and drop the hook. A little nervous with other boats around. Even though we had practice before.
Brad Young
Boat
Year 1986
Model C34
Hull# 84

KWKloeber

Again, the answer to your overheating is the 3" Hx.
Are you SURE you want to tackle the riser away from home? The can of worms and rattlesnake den can get very huge.
Twenty years from now you'll be more disappointed by the things you didn't do, than by the ones you did.
So throw off the bowlines.  Sail away from the safe harbor.  Catch the tradewinds in your sails.
Explore.  Dream.  Discover.   -Mark Twain

Brad Young

The riser busted. Need to fix here.
Brad Young
Boat
Year 1986
Model C34
Hull# 84