Overheating Issue

[JOHN COOKSON]

I replaced the wet exhaust hose but it now appears that my coil has gone bad.
Rekofa the Blue Whale
1979 C&C34

Take the distributor cap off and turn the engine until the points are closed. Pull the center lead out of the distributor cap while the key is on, and while holding the lead near ground(the engine) flick the points open and let them snap closed. A 1/2" blue-white spark is good.
If you do get a spark let us know. It means it is not the coil that is causing the problem. ( I presume no start?)
I don't like the idea of making the change to a EI when the engine is not running on points. You will just be introducing another variable.

TRUE GRIT

[BlueWhale]

Overheating Issue - Back at it

It appears that I left the ignition on and it burned out the coil. Should have it Monday or Tuesday.

[JOHN COOKSON]

Do you have a key or switch\push button ignition?
I have a key. The only time the key is in the slot is when the engine is being cranked or running. If I think I will need to start the engine again soon I leave the key on the bench near the ignition, never in the slot.

TRUE GRIT

[BlueWhale]

Overheating Issue

I've made it back to the boat and replaced the coil. That fixed the ignition issue. Unfortunately, replacing the hose from the manifold to the "muffler" did not solve the issue. It appears that water is flowing through the system but I'm still overheating and getting steam. I'm going to try removing the thermostat and see what happens. I'm assuming with no thermostat water will constantly go through the engine and should continually cool the engine, yes? I'm hoping I have not somehow damaged the engine and the issue is more than a block in the cooling system. I have one more hose to change as well.

Brian

[Ajax]

Blue-

Yes, remove the thermostat. This will open the system completely.

The question is- How *much* water is coming out of the stern? Is it a trickle or a gush? If you can hang a 5 gallon bucket from the stern, you can measure the output. You should get 3-5 gpm. So, if you fill up the bucket in a minute, or at least a little more than half full, you have adequate flow.

I just went 'round the rosemary bush with this issue myself.
I performed acid flushes and power flushes. What ended up happening, was the crud was pushed into the exhaust anti-siphon loop and formed a blockage.
However, let's not let my situation taint your troubleshooting process.

Let's start from the beginning-

A length of clear hose and a barbed coupler to join the various engine hoses with the clear hose would be helpful here. It helps you see the flow.

Remove the thermostat.

1. Disconnect the water pump output hose from the cooling jacket side plate and plumb it into a bucket. Start engine. Adequate flow? (3-5 gpm) Yes. Re-attach hose. No? Water pump fault.

2. Disconnect the T-stat housing/exhaust manifold crossover hose from the exhaust manifold and plumb it into the bucket. Start engine.
Adequate flow? Yes. Re-attach hose. No? blockage in engine block.

3. Disconnect exhaust cooling water injection hose from the aft end of the exhaust manifold, attach clear hose and plumb into bucket. (this verifies water is exiting the exhaust manifold cooling jacket) Adequate flow? Re-attach hose. No? Blockage in exhaust manifold.

4. Disconnect exhaust cooling water injection hose from the exhaust hot section water injection point (in other words, the other end of the hose) and plumb into bucket. Start engine. Adequate flow? Re-attach hose.
No? Blockage in anti-siphon loop.

If you have adequate flow (3-5 GPM) from all of these points, then your waterlift muffler is plugged or the exhaust hose from the muffler to the stern is collapsing or blocked.
You're only running the engine for 30 seconds to 1 minute at a time here, so you're not likely to do any damage. Following this procedure allows you to trace the entire water flow from input to exhaust.

By the way, you should ensure that your seawater fitting on the hull is not obstructed by growth before starting this procedure. If you've been sitting in the water, it may be blocked.

[JOHN COOKSON]

. I'm assuming with no thermostat water will constantly go through the engine and should continually cool the engine, yes?
Brian

As noted the first step is to ensure that enough water is being pumped out the stern.
But water can zoom around the engine and not through the engine VIA the bypass. This will happen if (A) the two stage thermostat is not working correctly (B) The water passages in the engine are so full of crud that the water is forced to go through the bypass. If you are still running hot with the thermostat out clamp the bypass which will force all the water through the engine. You can balance water flow through the engine and around the engine with an adjustable valve on the bypass.

TRUE GRIT

[BlueWhale]

Overheating Issue

I took these videos of the exhaust. Does this add any insight?

https://youtu.be/g1-MHV1grvM - Running hot

https://youtu.be/YK3AWn49JgQ - Running normal

Brian

[Mo]

Hi Brian,
I don't think there's enough flow there my friend. Something up there. If you'd like to give me a call 902 461 122eight. You have a flow problem so now we figure out what it is. You increased RPM and I can see the exhaust smoke and hear your RPM...your discharge rate didn't increase very much, if at all. You know, sometimes we can tangle with things and small variances in materials or parts can make a difference, my first thoughts on this is actually T-stat but I thought it was taken out. No need to clamp anything off...just have it out for now and pick up the rpms and see what it does. If the discharge rate increases in volume ...good for now...touch your fingers on the head with the engine rpms up and it should be warm with the T-stat out...should be able to hold your fingers there with no discomfort. Do that and let me know how it did...did the discharge rate increase, was the head warm and not hot. I have other things in the back of my mind and this doesn't mean all is well...but try that first.
[YOUTUBE]aoihuq_5sW0[/YOUTUBE] This is mine second start up for year 2013. That's pretty close to idle and if I throttle up she will drive water back 3 feet. The boat is in gear here to have a look for shaft wobble etc. The blue smoke is because I put motor oil in my top end every lay-up and it takes about 20 minutes to clear in spring.


Mo

[BlueWhale]

Overheating Issue

Hello Everyone,

I've finally had time to get back to the boat and this overheating issue. I worked through all of the steps up to #3. It appears that the clog is in the exhaust manifold. My next step is to remove the two elbows and clear out any gunk that may be there. Hopefully, that will take care of my overheating issue. Fingers crossed.

Brian

3. Disconnect exhaust cooling water injection hose from the aft end of the exhaust manifold, attach clear hose and plumb into bucket. (this verifies water is exiting the exhaust manifold cooling jacket) Adequate flow? Re-attach hose. No? Blockage in exhaust manifold.

[joe_db]

If you take the manifold off, you can get a radiator shop to boil it out.

Hello Everyone,

I've finally had time to get back to the boat and this overheating issue. I worked through all of the steps up to #3. It appears that the clog is in the exhaust manifold. My next step is to remove the two elbows and clear out any gunk that may be there. Hopefully, that will take care of my overheating issue. Fingers crossed.

Brian

3. Disconnect exhaust cooling water injection hose from the aft end of the exhaust manifold, attach clear hose and plumb into bucket. (this verifies water is exiting the exhaust manifold cooling jacket) Adequate flow? Re-attach hose. No? Blockage in exhaust manifold.

[BlueWhale]

Overheating Issue

Well, got both elbows off with the help of a little PB Blaster. The rear was pretty gunked up. I cleaned out both. I attached a hose to the rear elbow and ran the engine for about 50 seconds. I got almost five gallons! Problem solved right? No! Reattached everything, still with the thermostat out and she still darted to steam up. I doubt if the anti siphon hose is the issue because I just replaced it. It's either the muffler or the hose to the through hull. I know I'm almost there.

Brian

[sastanley]

Blue Whale, Ajax had this problem recently..I think his issue was the mixing elbow aft of the hot section. All these need to be checked to make sure they are clear. Everything flows downstream, so each and every hose/hardware junction can create a blockage.

During testing, and if you are on the hard, I'd eliminate the siphon break and go directly from the manifold to the exhaust connection..it is not needed during troubleshooting on the hard with the boat stationary. One less thing to catch debris!

[edwardc]

Blue,

You didn't mention if you had clamped-off the bypass hose in step 3. If you didn't, you could have great flow (through the bypass) but still be overheating due to a clogged block.

[BlueWhale]

Overheating Issue

Well, got both elbows off with the help of a little PB Blaster. The rear was pretty gunked up. I cleaned out both. I attached a hose to the rear elbow and ran the engine for about 50 seconds. I got almost five gallons! Problem solved right? No! Reattached everything, still with the thermostat out and she still darted to steam up. I doubt if the anti siphon hose is the issue because I just replaced it. It's either the muffler or the hose to the through hull. I know I'm almost there.

Brian

Well, it's the exhaust hose. I clamped off the bypass and still got good flow. I disconnected the exhaust hose from the muffler and attached a hose to it. I got good flow, about 4 - 5 gallons/minute. So, everything is good to the muffler. As soon as I put my finger in the exhaust hose I could feel a huge bubble. Looked inside and there it was. Now I need about 16 feet of 1 1/2 in wet exhaust hose. Then I have to contort my body to crawl into the tiny space in the hull to replace the old one. Any pointers? I plan to do this with the boat in the water.

Brian

[JOHN COOKSON]

When I did my exhaust hose replacement it was impossible to reach the barb at the distal or outboard end of the exhaust where it went through the transom. I smeared the inside of the new tube with TFP paste grabbed the proximal end and twisted it round and round* till it went over the barb, slid the clamps down the tube and was able to tighten them with a 1\4" socket. Hope this helps.

TRUE GRIT

* The twisting works because the hose is rigid