Overheating engine detectives needed!

[NatySailor]

I have an early model A4 and the water pump finally gave up the ghost (after 50 years, as far as I know!) Had my mechanic install a new pump (a Westerbeke 295625), which seemed to work great initially. I had never seen such a robust flow of water coming out the back of the boat.

After just a few short trips though, I now have almost no water coming out the back of the boat and my engine was badly overheating the other day. (Fortunately, gentle and favorable winds allowed me to sail back to my slip)

Around the same time, I also had a raw water strainer installed as well as a temperature gauge. Along with the overheating incident, my new Groco raw water strainer started to leak badly and my temp gauge wasn't working either. I also noticed that the water in the intake hoses was quite hot when the engine was overheating.

Today I tried bypassing the raw water strainer by running a long hose to a bucket of water, but the draw from the filter was too weak to pull water into the engine (had it worked, I planned to do an acid flush). The hose was 8' long and I tried placing the bucket in my cockpit (about 2-3 feet above the engine), as well as on my cabin sole (same level as the engine).

Does this array of symptoms mean anything to you A4 experts out there? If so, I'd love to hear your thoughts!

Dennis

[hanleyclifford]

That robust flow may have dislodged a lot of crud in the cooling jacket and delivered it to the bottleneck. Have a look at the discharge fitting on the manifold; remove the hose and actually take the fitting out of the manifold.

[JOHN COOKSON]

Either the pump is on the fritz or you have a blockage somewhere between the intake and output.
Blockage: Start at one end or the other (intake or output) and work your way to the other end of the cooling system until you find the blockage.
Pump: Check it out and be sure it is pumping like it should.

I did pick upon a hint of the problem. The temp gauge stopped working. Maybe that is where the blockage is - right at the sending unit. Here's what I did when I had the same problem: Took the temp sending unit out and put a nipple in its place, attached a hose to the nipple and aimed the other end into the bilge, started the engine and blew the KRAP out.

TRUE GRIT

[NatySailor]

Doesn't seem to be a blockage...

First of all, thanks for all the input-- really appreciate it!

Spent a few hours on the boat today and things are pointing to the my new water pump not working, which is hard to believe (and infuriating... that sucker was $500+)

First thing I did was check the impeller -- looked fine (by the way, do I have to change the gasket now that I opened the pump up?)

Second - I read something somewhere about someone having to prime their pump to get it to work, so I tried pouring some water through a hose into my pump before starting. Then I started the engine, which sucked not at all as before, and after a minute or two actually started to backflow hot water back up my temporary hose!

Third- I attempted to do a pressure flush of the engine. I couldn't find the aft drain plug mentioned in the Moyer manual (note: I have an early model engine, so most of the photos and diagrams in that book do not apply to me). What I was able to do was pull out the sending unit for the temperature gauge near the exhaust outlet and plug a hose into that. Then I pulled a couple of the bolts from the water jacket side plate. Turned on the hose gently at first, and clear water came right out through the side plate bolt holes. Turned it on my forcefully and more water came out, with a little bit of gunk but not too much.

Since water was able to flow through the engine backwards pretty easily, seems like the pump --- were it working -- should be able to move some water through the engine in the forward direction.

So am I missing something, or do I have a bad pump? Is there a more direct way to test if the pump is working?

Thanks again!
Dennis

[JOHN COOKSON]

First of all, thanks for all the input-- really appreciate it!

Spent a few hours on the boat today and things are pointing to the my new water pump not working, which is hard to believe (and infuriating... that sucker was $500+)

First thing I did was check the impeller -- looked fine (by the way, do I have to change the gasket now that I opened the pump up?)

Second - I read something somewhere about someone having to prime their pump to get it to work, so I tried pouring some water through a hose into my pump before starting. Then I started the engine, which sucked not at all as before, and after a minute or two actually started to backflow hot water back up my temporary hose!

Third- I attempted to do a pressure flush of the engine. I couldn't find the aft drain plug mentioned in the Moyer manual (note: I have an early model engine, so most of the photos and diagrams in that book do not apply to me). What I was able to do was pull out the sending unit for the temperature gauge near the exhaust outlet and plug a hose into that. Then I pulled a couple of the bolts from the water jacket side plate. Turned on the hose gently at first, and clear water came right out through the side plate bolt holes. Turned it on my forcefully and more water came out, with a little bit of gunk but not too much.

Since water was able to flow through the engine backwards pretty easily, seems like the pump --- were it working -- should be able to move some water through the engine in the forward direction.

So am I missing something, or do I have a bad pump? Is there a more direct way to test if the pump is working?

Thanks again!
Dennis

Try swapping the inlet and outlet hoses on the pump. I think you will be a lot happier.
Or the pump rotation is opposite the engine rotation.

TRUE GRIT

[NatySailor]

Try swapping the inlet and outlet hoses on the pump. I think you will be a lot happier.
Or the pump rotation is opposite the engine rotation.

TRUE GRIT

Thanks, John, but the pump worked before so I don't see how that could be the problem. It also was installed by a pro (switching the hoses is definitely the kind of thing I would do, however)

My theory about the water coming back up the pipe was that the water in the engine just heated up and expanded, like the mercury in a thermometer.

[romantic comedy]

Hook the garden hose to the engine, then run with the pump unhooked. You can play with the pump. Hook it to a water source and see if it pumps. Still may be a restriction.

[tenders]

Gosh I would not put city water pressure into the engine, especially if you have a waterlift muffler. Suggest instead installing a hose spigot near the bottom of a 5 gallon bucket, and attaching a hose to the spigot with the bucket filled and placed well above the engine (as in, on the cabin top). The vertical head of the water will prime the pump, if that is the problem, and will probably be enough to test for a blockage with the impeller removed, the pump impeller plate and gasket reinstalled, and only the pressure from the vertical head pushing water through the engine.

You can use the bucket with the spigot to refill your freshwater tank the next time you're on a mooring or anchored out.

[Easy Rider]

Re-read post #2 and check to see if the fitting is plugged. Remove it from the manifold for a proper examination. It's a known location for Krap buildup if you're raw water cooled and it's easy to clean if it's plugged? On another note, to confirm if your new pump is working or not you could disconnect the discharge hose from the pump and then crank the engine over and if the pump is still working, which I suspect it is, there should be water coming while it's being cranked. As others have already mentioned I wouldn't recommend hooking up city water directly to the engine. Let us know what you find.

Chuck

[NatySailor]

Thanks guys, will check that bottleneck.

I am a little surprised and confused by the two comments not to attach city water to the engine. Isn't that exactly the procedure outlined in the moyer manual for flushing out the raw water cooling (right after acid wash). They even sell a special kit for doing this.

Fortunately I only did it for a few seconds, so hopefully I didn't #*$#$&* anything up!

[tenders]

I just reread those sections in the Moyer manual. He says to flush one section out at a time with many portions of the system open, like the thermostat housing. This is different than forcing city water pressure throughout the engine, which is what I think we're concerned about.

[edwardc]

That's right. Flushing an open system will result in very little pressure buildup. The fear is that city water pressure, which is supposed to be no more than 80 PSI but is often higher, will be too much for any sections of the water jacket that are rusted thin. A closed or blocked system will quickly build up to the full pressure in the water main, exerting hunderds of pounds of force on the walls of the water jacket.

[joe_db]

If you want to run the engine with a hose (city water) to observe the pump output, do the following:
Get one of those $5 shutoff valves for the end of the hose.
Use another hose hooked to that to connect to the engine.
At the valve on land, turn the water on to be more than a trickle, but not much more. Something like the water only shooting an inch or two horizontally.
Turn the $5 valve off and connect the assembly to the engine.
Start the engine.
Turn the valve on to feed the much reduced water pressure

[NatySailor]

The Saga Continues

Hi guys -

I'm always happy to come home and see new posts from you all.

Following some of the advice here, I pulled my water pump hoses to isolate the pump from the engine and the pump works fine. So that's great.

Then I took a piece of wire and dug around in the pipe which connects the water pump to the water jacket side plate. It did seem pretty cruddy in there, but I soon was able to pass something the size of a narrow screw driver into the opening.

Hooked the hoses back up, started the engine.... and still no water to speak of passing through the engine.

So at this point I pretty clearly have a clog somewhere in the system. So now what? I can't do an acid flush if no water at all is moving through the engine, and the advice here is not to attach and hose and apply lots of pressure. But if I attach a hose and apply just some pressure, how is that different from the pressure already exerted by the water pump?

Or perhaps I should just try to remove the water jacket side plate and clean things up manually? Not sure how hard of a job that is....

D

[Easy Rider]

Ok, so before you take the side plate off try disconnecting that hose between the thermostat housing and the manifold and crank her over. If no water exits the thermostat housing then the blockage is in the block. If water does discharge out the thermostat housing then the blockage is downstream and if this happens to be the case then the exit fitting at the top rear of the manifold is the next suspect. We'll get to the bottom of this eventually. It's just a matter of elimination until the location can be narrowed down. Again, keep us posted. The suspense is killing me!

Chuck