Is My Impeller Bad? Mercruiser 228

[Kola16]

My engine is overheating and I am trying to track down why. Below are the pictures of my impeller. The video is of the outdrive hooked up to a hose running at idle and WOT. What do you guys think, is that how much water it should be pumping or should it be more? The outdrive is an old MC-1. Fresh-water-cooled. The overheating happened all of a sudden, 4 miles from the boat launch. Now it happens on the hose too. I will be changing the impeller regardless, but I would like to know if there is something else I should be checking.

Thanks all!

 

[Bt Doctur]

Imperller is totally wasted, and the pump base is also damaged from overheating. If the video is of you on a hose the high rpm destroyed the impeller. On a hose your limited to about 1500 rpm max or impeller gets destroyed

 

[Kola16]

Imperller is totally wasted, and the pump base is also damaged from overheating. If the video is of you on a hose the high rpm destroyed the impeller. On a hose your limited to about 1500 rpm max or impeller gets destroyed

Good to know. I have run it on the hose at high RPMs many times over its life. Will not do that any more I guess haha. Just ordered an entire new pump kit. Thanks!

 

[kenny nunez]

How does the temperature read above 3500 on plane?

 

[Scott06]

Are you using an OEM merc impeller /housing or aftermarket OEM is worth the money

 

[ROY WILLIAMS]

the picture is a breakdown of the impeller ...then inspect the outdrive and change the impeller ,,, parts are worn ...
I have a 1978 wellcraft suncrusier bought it in 1986 still running it today .

 

[Bondo]

Imperller is totally wasted, and the pump base is also damaged from overheating. If the video is of you on a hose the high rpm destroyed the impeller. On a hose your limited to about 1500 rpm max or impeller gets destroyed

Ayuh,...... Ya got the last lap outa that one,.....

While it's all apart, Back-flush the system, from the T-stat housin',....

 

[Kola16]

Okay long story. It is still running hot.

The overheating was not because of the impeller, although it was good to replace it thanks all. The engine threw the belt that runs the water pump and the alternator. That is why it overheated. I did replace the impeller and housing though (aftermarket, bought it before I read your post Scott, whoops). So I put the belt back on tight and went to the lake. Ran great at idle at about 170 degrees F after warming it up. As soon as I throttled down to get out of the hole it threw the belt again. WTH? It has never done that before. Put the belt back on and same thing. Stays on at idle, but throws the belt when I hammer down. When I put the belt back on it would idle at about 170 F. I noticed the harmonic balancer pulley and the water pump pulley were not aligned. Weird that it has never really been aligned to my knowledge, and I have ran this engine for 200 or so hours and it has never thrown the belt.

So I take the boat home and install a spacer in between the harmonic balancer and the harmonic balancer pulley. New belt too. Now the water pump pulley and the harmonic balancer pulleys are aligned. So I take it back to the lake. The belt stays on fine this time, but the engine is running hot. Creeps up to 205 F. I have a digital temp sensor and an analog, and both agreed the boat was running hot. The pulleys seem to be vibrating/shaking maybe? The heat exchanger on the front on the engines hanging over the pulleys seems to vibrate, which I do not remember it doing before. The boat seemed to run fine though.

Any thoughts? The thermostat is new as of a month or two ago.

 

[Kola16]

Update: I just put 3 quarts of antifreeze in the system. Now it is running back at 170 F (digital gauge) at 1500 RPMs on the hose. And my IR temp gun at the thermostat housing says 170 F on my gauge is actually 155 F. That is the outside of the thermostat housing and manifold of course, but that is what I want to see! Weird because I know I topped off my system before heading to the lake the second time. I do not have an overflow tank. My heat exchanger dumps antifreeze straight to the bilge through a tube. Maybe I should get one...

 

[flashback]

How old is this rig? A little more specific info is good, unless I missed it.

 

[Kola16]

How old is this rig? A little more specific info is good, unless I missed it.

It's in the title and my bio sorry haha. Bits and pieces. My brain scatters. Mercruiser 228 is a 1979 system that was originally a carbed 305. Now it is a 350 with throttle-body injection, but still the MC-1 outdrive. Fresh-water cooled.

 

[flashback]

A lot of folks here need the specifics to help you, I'm not one, but what you just shared will open some eyes.

 

[Scott06]

It's in the title and my bio sorry haha. Bits and pieces. My brain scatters. Mercruiser 228 is a 1979 system that was originally a carbed 305. Now it is a 350 with throttle-body injection, but still the MC-1 outdrive. Fresh-water cooled.

When was last time heat exchanger was cleaned. Most heat exchanger /fresh water kits use a bravo style belt driven pump on older mc1 and alpha gen one set up i believe. You need to move more water through the heat exch than raw water. Did it ever work with this heat exch or did you put it on during the engine swap.

i think normally a through hull is used for the engine driven pump and the drive pump is kept to cool the drive , they cut the water hose between bell housing and transom

 

[ROY WILLIAMS]

It's in the title and my bio sorry haha. Bits and pieces. My brain scatters. Mercruiser 228 is a 1979 system that was originally a carbed 305. Now it is a 350 with throttle-body injection, but still the MC-1 outdrive. Fresh-water cooled.

I had my suncrusier eng and I fixed the heat exchanger ..flushed out that water and did antifreeze 75% and 25% distilled water ...the caps removed and I did the 2 tubes leaks , using the silver solder ... then I inspect the zinc drain plug port sea water .. then I take the sea water plug out port and in the fall..drain it out of the heat exchanger ..

 

[Kola16]

I have run this cooling system for about 200 hours and never have had an overheating issue. So 200 hours ago would be the last time it was cleaned. The FWC was installed by a boat mechanic when I did the engine swap. The only raw water I have coming in is the impeller in the outdrive. No other pickup. I just ran it on the hose for 15 minutes and it ran cool. I let it cool down, opened the cap on the heat exchanger and it was low again so I added just under a quart again. I will see if this continues, but it is running cool now that it has coolant. There is no water in my oil, so I am going to have to figure out if it is just air bubbles in my system, or if there is a leak somewhere, but I do not see any leaks so far.

 

[Scott06]

I have run this cooling system for about 200 hours and never have had an overheating issue. So 200 hours ago would be the last time it was cleaned. The FWC was installed by a boat mechanic when I did the engine swap. The only raw water I have coming in is the impeller in the outdrive. No other pickup. I just ran it on the hose for 15 minutes and it ran cool. I let it cool down, opened the cap on the heat exchanger and it was low again so I added just under a quart again. I will see if this continues, but it is running cool now that it has coolant. There is no water in my oil, so I am going to have to figure out if it is just air bubbles in my system, or if there is a leak somewhere, but I do not see any leaks so far.

pressure test it with a radiator type tester if u loose a qt in 15 min its going somewhere

 

[ROY WILLIAMS]

I have run this cooling system for about 200 hours and never have had an overheating issue. So 200 hours ago would be the last time it was cleaned. The FWC was installed by a boat mechanic when I did the engine swap. The only raw water I have coming in is the impeller in the outdrive. No other pickup. I just ran it on the hose for 15 minutes and it ran cool. I let it cool down, opened the cap on the heat exchanger and it was low again so I added just under a quart again. I will see if this continues, but it is running cool now that it has coolant. There is no water in my oil, so I am going to have to figure out if it is just air bubbles in my system, or if there is a leak somewhere, but I do not see any leaks so far.

open the heat exchanger caps front . rear then see if the water drips out to the sea water area .. I fixed it ..but ?

 

[flashback]

It's in the title and my bio sorry haha. Bits and pieces. My brain scatters. Mercruiser 228 is a 1979 system that was originally a carbed 305. Now it is a 350 with throttle-body injection, but still the MC-1 outdrive. Fresh-water cooled.

That's what I get for using my cell phone. My bad, apologies

 

[Kola16]

Weeeeell, I took the spark plugs out, and sure enough, there was plenty of water in the port side cylinders. I still haven't seemed to find water in the oil though.

I am going to pressure test my heat exchanger while I have it out (why not). Should I also pressure test the block where the coolant goes through? Would I use the pressure tester at the water pump inlet and outlet once I have the heads back on?

Also is there anything I can spray on the pistons and inside of the heads to decarbon inside the cylinders while I have them apart?

That's what I get for using my cell phone. My bad, apologies

No you were right. I started the thread as a, "is my impeller okay..." but it has turned into a lot more now

 

[Scott06]

I am going to pressure test my heat exchanger while I have it out (why not). Should I also pressure test the block where the coolant goes through? Would I use the pressure tester at the water pump inlet and outlet once I have the heads back on?

os it water or antifreeze. Do you have a half or full closed system?

i would pressure test the af side while its still together