Broken down in Anacortes with cooling issue, help appreciated

[Heck]

We were cruising in the San Juan Islands for several days and everything was working fine with a healthy exhaust and temperature gauge down the middle, 170-180 degrees. Late one afternoon while anchoring the engine temperature gauge started climbing while also showing white steam from the exhaust. Boat is an 1989 Catalina 36 with a Universal M-25XP engine and is new to me so I have little knowledge of pre-existing issues.

First thing I tried was cleaning the intake raw water strainer which was kind of dirty so I thought that was that. Next day started motoring and after a few minutes engine started overheating again. We were in a bad spot due to conditions and to cut a long story short anchored in the closest protected shore and called for a tow. Eventually got to Cap Sante marina in Anacortes. Another long story for another day.

After getting to a dock I confirmed there was almost no water coming from the exhaust through-hull, just steam.

Things I have tried since then:

Raw water impeller. Looks in good shape and is intact and flexible although pump overall could be refreshed. Added some grease to center of impeller on cover side. I have an extra impeller but doesn't seem I can change it without a press. I have confirmed that water does come out of the pump however doesn't seem like it's a lot. Should the water volume increase with rpm?

Heat exchanger. I have the 3" Universal version. Took it apart and the section with the drain showed lots of zinc debris and blockage. Soaked it overnight in Coca-Cola. In the morning cleaned all the crud and ran lots of fresh water. There's now a good flow of water through every connection. Zinc is around 30% so needs to be replaced very soon as well as gaskets. No leaks.

Exhaust. Unplugged the hose that takes raw water to the exhaust manifold and put a hose there. Run water and confirmed it flows well to the exhaust through-hull.

Refilled the system with coolant and ran the engine for a while. Added coolant again. Repeated a couple of times until coolant level stayed consistent.

There's is now water coming out of the exhaust when the engine runs, however it does look like less than normal. When water comes out, every 5-6 seconds, it gets sprayed out, does not stream.

If I idle the engine at 1000 rpm and neutral the temp stays around 180F. However if the engine is under load the temperature starts climbing slowly but steadily and after you get to 190F steam starts to appear. Higher rpms will produce more frequent water discharge from the exhaust.

Any ideas appreciated! Mechanics are all at least a week out so I'd also love referrals to professionals that can help in the near future.Thank you!

[LeaseOnLife]

check your raw water intake and strainer. Yes there should be more water at higher rpms!

[IslandInfedel]

Does it appear there is any oil in the coolant or vise versa?

X2 on checking the raw water intake

[Sparx]

Check that there is no air leaking in at your raw water strainer.

[LittleWing77]

Geez does anybody read anymore?!

The FIRST thing the OP did was check and clean his raw water intake and strainer!

Sheesh!
LittleWing77

[jkishel]

From the description sounds like limited raw water flow. Yes, flow should increase noticeably with engine rpm. First check the raw water through hull. Close the seacock and remove the hose. Open the seacock with the hose removed. Water should jet upward several inches above the seacock. If not, run a long, thin rod or screwdriver down to clear the through hull. If the raw water through hull is clear, clean the strainer, be sure to check the inlet tube for blockage. Check flow at the strainer by opening the seacock with the strainer open, plenty of water should flow from the top of the strainer. If there is plenty of flow at the strainer, check the raw water pump, impeller OK, cover plate and gasket sealed. If all looks good, open up and check heat exchanger, passages open, no deposition on passages. Then remove and check mixing elbow for blockage. If all checks out and engine is still overheating, problem is in the freshwater circuit. Check coolant level, belt tension and thermostat operation.

[chris mac]

How is the belt tension? That would explain low flow and not increasing with rpm. Plus easy to check and eliminate.

[Snore]

Originally Posted by Heck

We were cruising in the San Juan Islands for several days and everything was working fine with a healthy exhaust and temperature gauge down the middle, 170-180 degrees. Late one afternoon while anchoring the engine temperature gauge started climbing while also showing white steam from the exhaust. Boat is an 1989 Catalina 36 with a Universal M-25XP engine and is new to me so I have little knowledge of pre-existing issues.

First thing I tried was cleaning the intake raw water strainer which was kind of dirty so I thought that was that. Next day started motoring and after a few minutes engine started overheating again. We were in a bad spot due to conditions and to cut a long story short anchored in the closest protected shore and called for a tow. Eventually got to Cap Sante marina in Anacortes. Another long story for another day.

After getting to a dock I confirmed there was almost no water coming from the exhaust through-hull, just steam.

Things I have tried since then:

Raw water impeller. Looks in good shape and is intact and flexible although pump overall could be refreshed. Added some grease to center of impeller on cover side. I have an extra impeller but doesn't seem I can change it without a press. I have confirmed that water does come out of the pump however doesn't seem like it's a lot. Should the water volume increase with rpm?

Heat exchanger. I have the 3" Universal version. Took it apart and the section with the drain showed lots of zinc debris and blockage. Soaked it overnight in Coca-Cola. In the morning cleaned all the crud and ran lots of fresh water. There's now a good flow of water through every connection. Zinc is around 30% so needs to be replaced very soon as well as gaskets. No leaks.

Exhaust. Unplugged the hose that takes raw water to the exhaust manifold and put a hose there. Run water and confirmed it flows well to the exhaust through-hull.

Refilled the system with coolant and ran the engine for a while. Added coolant again. Repeated a couple of times until coolant level stayed consistent.

There's is now water coming out of the exhaust when the engine runs, however it does look like less than normal. When water comes out, every 5-6 seconds, it gets sprayed out, does not stream.

If I idle the engine at 1000 rpm and neutral the temp stays around 180F. However if the engine is under load the temperature starts climbing slowly but steadily and after you get to 190F steam starts to appear. Higher rpms will produce more frequent water discharge from the exhaust.

Any ideas appreciated! Mechanics are all at least a week out so I'd also love referrals to professionals that can help in the near future.Thank you!

Ok we know the strainer is clear. And the impeller passed a visual check. Did you take BOTH caps off the heat exchanger? If not some debris could be on the capped side. So take both caps off and GENTLY run a wire hanger down each tube to clear it.

Now given that there was some crud in the heat exchanger that you removed, check the hose from the exchanger to the mixing elbow. My boat has a 90 at the heat exchanger that gets clogged if I don’t remove the second cap and flush the debris out. If you feel the need to flush the line, do so towards the heat exchanger ONLY when the caps are off.

Finally, check the connection at the mixing elbow.

If all of that is clear you should have as good a flow as the impeller is sending out.

[Cheechako]

Originally Posted by LittleWing77

Geez does anybody read anymore?!

The FIRST thing the OP did was check and clean his raw water intake and strainer!

Sheesh!
LittleWing77

Yeah, but does he know if the intake is blocked at the thru hull before the strainer? I've even heard of little fish getting sucked in. Or a plastic bag sucked in there?

OP: Possible partial plugged mixing elbow?
Possible hose failure so a flap of rubber sometimes blocks some flow? Especially any hose going to the exchanger.
How sure are you about temps and water flow before any issue? It's easy sometimes to imagine "there used to be more water flowing out the exhaust". Normal would be a surge of spray every 4-7 seconds or so. At higher rpm it should spray out pretty readily.
Do you know the engine didn't run at 190 at higher rpm before?
I remember often looking at exhaust and thinking: is that more steam than normal.?

[Heck]

I figured out how to replace the impeller with a new one so I did that. Then I turn on the engine and again no water at all coming through the exhaust.

I went to check the intake and removed the strainer cup completely. With the seacock open there's just a trickle coming in. Looks like there's some type of blockage on the through-hull, however it's not consistent. Any way to further investigate other than getting a diver?

[jkishel]

Originally Posted by LittleWing77

Geez does anybody read anymore?!

The FIRST thing the OP did was check and clean his raw water intake and strainer!

Sheesh!
LittleWing77

No, he said he cleaned the strainer. He didn’t indicate that he checked the raw water through hull.

[smac999]

Originally Posted by Heck

I figured out how to replace the impeller with a new one so I did that. Then I turn on the engine and again no water at all coming through the exhaust.

I went to check the intake and removed the strainer cup completely. With the seacock open there's just a trickle coming in. Looks like there's some type of blockage on the through-hull, however it's not consistent. Any way to further investigate other than getting a diver?

Jump in yourself... maybe a go pro on a stick. Probably too dark though.

[Uncle Bob]

Originally Posted by Heck

I figured out how to replace the impeller with a new one so I did that. Then I turn on the engine and again no water at all coming through the exhaust.

I went to check the intake and removed the strainer cup completely. With the seacock open there's just a trickle coming in. Looks like there's some type of blockage on the through-hull, however it's not consistent. Any way to further investigate other than getting a diver?

Do you have a deck wash system on board? If so then try backflushing the water intake, if not are you at a marina where town water is available?

[jkishel]

As I mentioned earlier, close the seacock, remove the hose from the seacock, then open the seacock. If the flow is pitiful, run a long screw driver, barbecue skewer, etc. down through the seacock/through hull until you clear the obstruction.

[Heck]

The seacock for the intake is a bit of mess and I'm not confident I should take it all apart without having replacement parts on hand. However after confirming that no diver was going to come for several days I grew bold and was able to remove the strainer mount.

Then I had clearance to get a water hose shooting right into the thru hull and with a few seconds whatever blockage was there was gone. Now when I open the seacock water gushes in, as opposed to a trickle. I started the engine and water gushes out, even at idle. Now a beer and a shower. Thanks everyone for your help.