Engine Overheats - Raw Water Problems - Help!

[Beersmith]

I recently purchased a 1975 Downeaster 38' Cutter, re-powered in 1994 with a Yanmar 4JH2E. It only has about 900 hours on the engine, but has been sitting unused for a few years now. I live in Orlando, FL but the boat is in Inglis, FL near Crystal River in the Big Bend area at the sellers dock. He is being kind enough to let me keep it there until I get it in shape to take it elsewhere. So I am limited to making weekend trips up there for now.

When we did the sea trial, the engine performed just fine. We ran it up and down the river for almost 3 hours with no problems at all. I had not taken her out since then (about a month) and have just been doing a lot of cleaning and work replacing the running rigging. Two weekends ago I decided it was time to take her out on the river (its on the Withlacoochee River) and show some friends a good time. Before we went out, I checked all fluids, cleaned out the raw water strainer and topped off the coolant. I noticed there was no rubber gasket or anything on the cap of the raw water strainer, just a metal plate. I didnt think much of it at the time, but now I wonder if there should be one.

The engine ran just fine for about an hour up the river. At one point, I revved it up to 2,800 rpms to see how it responded at cruising speed. Soon after my heart sank as I noticed steam (of course I first thought it was smoke and we were burning down) gushing out of the engine room. I quickly shut it off and had to release the anchor for the first time on the boat (something I needed to learn soon, but in less stressful circumstances).

The cap on the expansion tank for the cooling system had popped off and the cooling water was steaming everywhere. I also noticed that the air silencer had popped off and was hanging by a hose. I had checked it before we left and may have not secured it correctly. So I topped off lost coolant and let the engine rest for a while.

It was getting dark soon and we needed to get back. The engine cranked up just fine but after a short while the temperature was running high. Right before we got to the dock the cap on the expansion tank popped off and once again steam goes everywhere.

We had to go back to Orlando for the week so I did some research and stupidly realized that I didn't check if water was flowing out of the exhaust at all. I had also remembered that the belt was pretty loose, so those were first on the list to check when I came back. I would make sure to double check how I closed the water strainer.

So I go back to the boat this previous weekend. I tighten the belt after much hassle and checked to make sure the raw water strainer is tightly sealed. I then started the engine and first checked to see if any water was coming through the exhaust....none . So my guess is that the problem lies in the raw water circuit somewhere, correct?

I planned on checking and replacing the impeller, of which the previous owner already had a new spare. I soon realized that the impeller is in a hellish place where I can only fit one arm with barely enough room to move a tool. Removing the cover plate for the impeller was tricky, but I did it without loosing my cool. Then I realized that I would not be able to take the impeller out with any ease. I hoped to use the 2 screwdriver method to pry it out, but there was no way I could get two of them in there. I spent the majority of my day getting frustrated over figuring out how to get the impeller out, and didn't get much else done.

The only other thing I checked was to make sure there was nothing blocking the through-hull. I popped the inlet hose from the raw water strainer and was able to suck water through, so that was clear at least.

After leaving my dad asked if I checked to make sure the impeller was even turning after the engine was on...no, I didn't check .

The boat is old, but the engine is the one thing I was happy to have working fine. This completely has left me in the dumps emotionally, and then to cap it off I got cut to part-time at work this week amidst a bunch of lay-offs. Im lucky I still have the job, but loosing 20% of my salary takes away the extra money I was using each month to get the boat in shape.

So that is where I am. What steps should I take this weekend while I am there? I assume to make sure the impeller is even turning by running the engine with the cover off? Do I start to just pull hoses at various points along the circuit to see if water is flowing? Am I limited to buying an impeller puller or is there a cheaper tool I don't know about?

Any help isolating the problem would be appreciated. I hope I can get this done without paying someone to come out to the boat. I am willing to learn and do the hard work, but need some sage wisdom.

Thanks!

[Tellie]

The word my daughter dreads to hear from the old man applies. "patience"
Some engines because of either design or proximity to other boat components do not lend themselves to easy access. It may take some time the first time but it usually is a lot faster the second time. If you cannot get to the impeller you may have to remove the water pump. This is something you as a boat owner have to learn to do yourself anyway. I would think the first person to ask would be the person you bought the boat from, where you state that you still store the boat at. I'm sure he's replaced the impeller a few times before himself. If it was working fine a month ago and worked fine for over an hour when you went out, you either have an obstruction which you've ruled out, and air leak or the impeller is bad. Bet it's the impeller.

[Pblais]

You might want to also follow this thread. It's all information that you could use:

http://www.cruisersforum.com/forums/...low-29149.html

[Tellie]

Beer Smith, read over this article. You'll owe me a six pack of that home brew.

The All-Purpose Impeller Puller

[Beersmith]

Thanks for the replies so far. The previous owner is out of the country for a few weeks so I can't ask him for any advice. But I know that he mostly paid others to work on the boat.

Originally Posted by Tellie

Beer Smith, read over this article. You'll owe me a six pack of that home brew.

The All-Purpose Impeller Puller

Thanks for the article! It seems to me, however that the guy in the article has even more space to operate than I do. My impeller is in the exact same location, but I do not have a hole on the side to access it like he does. I have to go to the back of the engine and reach through to access it. I don't think I can fit a 10" handle for pliers in there with any space to actually work the tool and pull the impeller out.

[Tellie]

Damn, gotta buy my own beer again.

Hey wait, that guy in the article owes me a few beers I never collected on.

[gonesail]

the yanmar should be in good shape if it is a 1994 model. you need to check the impeller and i would ask the previous owner about it too. sounds like you already checked the raw water supply line from the thru hull. it is possible that the mixing elbow could be clogged.

[boden36]

There should be a gasket or O ring on the lid of your raw water strainer, as it is on the suction side of your system and will pull air if not sealed. Check around to see that you did not accidentally drop it somewhere when you had it apart. Regards, Richard.

[JiffyLube]

The raw water pump on our Pathfinder is pretty hard to get to also, but I took the time to think this problem out, and went to Sears to get a couple of Craftsman tools just for this challenge. After completely removing and replacing the pump and impeller a couple of times, I'm glad I invested in the special tools to make the job easier. Maybe you need to look at spending some money on pump pulling specific tools.

[mesquaukee]

Disconnect the hose from the mixing elbow.
Start the engine and see if you have a good flow. If not remove/open the pump.
If yes place your thumb on the hose and see if you have good pressure, real pressure like a garden hose. An impeller pump is a constant volume pump, flow remains constant irregardless of pressure. Rember there is a fair amount of pressure in the exhaust that this pump has to overcome.
If you can slow it down or stop it your impeller is worn out which is readily seen when you open the pump. The body or more specifically the cover plate and the end of the body can be worn down. Check for scoring of the cover plate, in a pinch it can be flipped over. You can also mill (or carefully file) down the body to get a tighter fit end to end of the impeller.

[Beersmith]

Thanks a ton for all of the responses. I have a good checklist of things to check out this weekend.

[Beersmith]

One thing I am sort of confused about: how do I prime the raw water circuit after opening parts and letting air in?

[wallandj]

I'm with Boden. Carefully, reassemble the raw water strainer and there should be a rubber gasket under cleanout cap.

I have rubber gasket on mine but its hardened with age. If I don't put the strainer basket in just right and set the cap just so, then it will suck air and the raw water flow is reduced.

[fareweather]

If your layout allows it, disconnect a hose in the raw water circuit at a high point and either suck on it till you get good flow or if you're not into that kinda thing get a small shop vac and pull water through the system.

I also blow out the system till I am bowing bubbles on the outside of the boat to make sure there are no obstructions before I suck.

[Tellie]

Originally Posted by Beersmith

One thing I am sort of confused about: how do I prime the raw water circuit after opening parts and letting air in?

You shouldn't have to prime it. When you replace the impeller put a little GLY silicone grease on the impeller. This will help lubricate the vanes when you first start the engine. If your system is right it will pick up the prime quickly.