I love this forum...rubber in the 90 degree fitting

[RobH2]

Hi all,

I was having severe overheating issues after rebuilding the top end of my engine with all of your fantastic helpl. I power flushed, acid flushed and did everything. Still...overheating.

I spent 3 hours reading posts here last night and today I pulled the waterpump. I bought the boat a few months ago and as such have no idea what transpired prior to me buying her. Lo and behold I took the exit 90 degree fitting off of the pump and found this... see photo attached. Gee...do you think that was my problem? I'm betting so...



You guys are great...Thanks...Rob

[tenders]

Those look like broken-off pieces of the vanes of a water pump impeller.

[rigspelt]

Impeller bits? Let us know if that fixes this pesky problem.

[thatch]

Good news, Bad news...

Robh2,
The good news is that those pieces most likely caused your overheating problem. The bad news is that your engine won't know what to do with all of that nice cool water!...
congrats, Tom

[67c&ccorv]

Now that you have done all that work - have you changed your impeller yet?

[RobH2]

Now that you have done all that work - have you changed your impeller yet?

Duuh, yea...now my engine is an air conditioner...

[sastanley]

Nice work Rob.

I am getting to ready to rely on the A4 to get the boat back to the marina to haul & put the stick back in...No alternative there!!

[marthur]

We had the same thing, but only discovered it after rebuilding the water pump. The increased pressure blasted impeller bits out of all kinds of unlikely places. If you have found these three, better check all of the hoses and especially all of the fittings, thermostat cover, etc...

[RobH2]

Will do.

So far though all is well. Ran her hard yesterday with a 25 knot headwind at full throttle for about 45 minutes and the highest temp was just a needle's width over 180.

[RobH2]

Hey 67c&ccorv, I wasn't being a flippant by my "duuh" remark. What I meant was, yea, better do that for sure. When I read it out loud it sounded wrong. Sorry for bad wording...

[67c&ccorv]

Hey 67c&ccorv, I wasn't being a flippant by my "duuh" remark. What I meant was, yea, better do that for sure. When I read it out loud it sounded wrong. Sorry for bad wording...

Hey no sweat - just wanted to make sure all the bases were covered.

You can bet that somewhere out there in the Atomic 4 history someone has discovered the very same piece of impeller in their cooling system but didn't think to check the impeller in the water pump!

[RobH2]

Elation turns to disappointment. I now have runaway temperature problems. Also, I'm getting a lot of steam in 70 degree weather.

I pulled everything off today and found no more lodged impeller parts. My thermostat is 3 weeks old (Moyer aftermarket kit with spacer and ball valve). I tapped my exhaust flange today and measured the back pressure. It was .5. That's within range I believe. I did a Muriatic Acid flush last week. I also have it sitting in a vinegar bath tonight. I did a high pressure flush two days ago. I rebuilt the head last month so I know all the block ports and head ports are clear. I also pulled the water jacket plate behind the alternator when I did the head and cleaned it out. It had minimal detritus.

I've read about everything on Cooling on the site by now I think. My suspicion now is that maybe my impeller is not the right height. I replaced my original impeller to be proactive with an impeller I found on the boat. Having had the boat only a few months, I've found a lot of spare parts, none of which I purchased. It's completely plausible that the previous owner purchased inferior replacement parts and I'm now sticking them in. What alerted me to water pump issues is that I had a hard time sucking the vinegar in. My bucket was the same height as the flywheel. The pump only had to pull the vinegar up about 12”, out of the bucket and into my “T” at my raw water thru-hull. I actually had to use one of those cheap drill attachment pumps to push the vinegar along the hose. How strong a suction does the water pump create anyway? How much elevation should it be able to draw?

I was thinking about drilling the hole in the water injector inside the water jacket side plate but can’t find a thread telling exactly what to do. I’ve found someone saying they did it but can’t find specific directions. If anyone has that link I’d appreciate getting it.

I still don't know why I have so much steam all of a sudden. I checked the torque on my head and it was fine. All of the bolts were 35 ft/lbs. Could I have blown my new graphite head gaskets in a runaway overheating?

[ndutton]

It had minimal detritus.

Minimal detritus. Nice, I like that.

You may be on to something with the poor draw by the raw water pump. I routinely flush with fresh water through a T on the pump intake. With the engine at idle I'm guessing I draw 4 gallons out of a bucket on the cabin sole in about 60 seconds. Yours sounds way less than that.

If you're not blocked either before or after the pump, it must be the pump itself and there's not much to it other than the impeller.

[RobH2]

It must be the impeller. I pulled the water pump last week and inspected it completely. I replaced a slightly scored shaft two days ago but not the seals. If the seals were bad I'd expect weeping water but have none. I don't think I pump more than 1/2 to 1 gallon per minute if that. Today it stopped completely which is why I assisted it with a drill pump.

Baltimore Sailor wrote about a slightly dimensionally imperfect impeller. It sounds plausible that I have that issue. I may have a gap between the impeller and the cap plate which I assume would kill the pump force pressure in the chamber that has the exit hole.

I can't wait until I can stop working on the engine and actually do some sailing.

I'll report back in a day or so.

[tenders]

It could also be a worn shoe inside the pump--that's the cam that's inside the pump housing that helps compress the impeller vanes through part of the impeller rotation.

There's a slight chance the pump housing itself could be worn. You have no idea how badly it's been treated over the years.

I realize you've already sunk some bucks into it with the shaft, but if you want to fix this problem fast I'd suggest replacing your pump with a new Moyer pump, then deciding if the old pump is worth further troubleshooting.