How to backflush impeller debris?

[liquidlew]

I've been reading old posts on overheating and think I might have to backflush my system. How do you do it? Hook up a garden hose to the incoming hose to the thermostat housing and back out thru the outdrive? Does the lower unit or whole drive need to off to do this? I am going to check first to see if I got good incoming water. I just replaced impeller and housing, all new hoses, new thermostat, new water circ pump, new manifolds and risers, new spark plugs and dist cap and rotor. Did not have cooling problem prior to changing everything but it was due. Have only ran it once on the muffs and the temp goes up slowly and doesn't stop. Checked new thermostat and it is working.

 

[liquidlew]

Re: How to backflush impeller debris?

I also had the thermostat housing cleaned out, could the check balls be too loose or too tight when I put it back together? I tried to get it the same tension it was before I took it apart.

 

[HT32BSX115]

Re: How to backflush impeller debris?

Howdy,

I replaced my raw pump and housing on my Bravo before I tried it and even though the previous owner said he replaced it I had a sneaking suspicion that he might not have found all the pieces

I did find pretty much ALL the remnants of a previous pump failure all crammed up into the oil cooler. They were fairly large pieces so it didn't appear that they would completely block water flow but they did hinder it...

A lot of Mercruisers have the oil cooler and power steering cooler (if installed) down stream of the raw pump.....so if the raw pump disintegrates the pieces go into the oil cooler. The oil coolers have small holes in them. It's unlikely the pieces can get past it. You would probably find pieces of your impeller there if it broke up.

You may have to remove the raw water line and oil cooler to get to it though....the stuff may be so crammed in there that flushing water in the other direction may not dislodge the pieces.


Regards,


Rick

 

[liquidlew]

Re: How to backflush impeller debris?

Thanks! Yeah, my oil cooler is on the lower port side near the front of the engine and I will check that out later today after work, along with a checklist of other things. Sure hope it's something somewhat simple. I am getting some water to the engine, lossened the drain valves and water came out of the block, all hoses get hot except for the 2 upper riser hoses, they sayed cool and the risers did not get warm at all, thats way I was wondering about the check balls also. I will keep looking...