No water flow after muriatic flush

[systemek]

Greetings Afourians! Last month I performed a Muriatic acid wash. This resulted in a healthy increase in running H2O discharge immediately after reattaching the hose fittings. I left the boat for 3 weeks, started her up and to my horror, there was only a few sputters of H2O discharging from the exhaust (yes the raw water through-hull is open ) I would normally suspect a bad water pump, but the fact that it happened directly after the flush makes me suspect a correlation between the two. Any thoughts? Thanks!

[Al Schober]

Yeah, sounds like you have a blockage. I'll assume raw water cooled, but I have no idea of your exhaust system. Do you have a thermostat installed? I'd suggest removing it until you get this sorted out.
Start disconnecting pieces of the coolant system and see if you can blow air through them. ie: can you blow air through the discharge hose from the manifold? Can you blow air through the manifold itself? Anyway, you get the idea - find the blockage and remove it.
Not really surprising after an acid flush - no telling what you loosened up. Perhaps a dead carp, long happy in the recesses of the block, got washed into the exhaust manifold.
Find it, fix it, be happy.

Al

[systemek]

Thanks Al. Raw water cooled it is. I will take your advice and start the process....although, the boat is in the salt water so its probably more likely a halibut than a carp......

[ndutton]

The first hose I'd disconnect is the pump output. This will determine pump function or not and indicate whether to look upstream or downstream.

I had a funny situation years ago. The head wouldn't draw sea water so I started chasing the failure point. When I removed the hose from the thru-hull there was a little fish looking at me. Little guy swam right up into the thru-hull and got lodged in there.

[Mo]

Look outside the boat first. If is was sitting, marine life could have moved in the through hull area. Thermostats also cause problems ... if you are getting steam out of the exhaust along with the decreased water it is likely the thermostat.

The acid wash and corrosion issue is not going to happen if you did it right. Once you do the acid wash and run the engine with non-acidic water that acid is diluted and gone in minutes.

[Bold Rascal]

The flush was a success!

Unfortunately all that rust and scale has now been freed to move around and is probably connecting someplace.

As suggested, start looking where it makes the most sense and work thru it systematically.

You might also want to go beyond just removing hoses, Especially that water discharge fitting on the exhaust manifold. All my loose scale and crud collected and blocked right there.

[chiron]

I just had a sudden loss of water and after checking everything I found the problem at the thru-hull. A chunk of something got lodged in the fitting before the filter. Removed hose and jambed a coat hanger in there nice and simple. I would first make sure you are actually getting water to the pump and then work your way from there.

[vabiker23518]

Ditto to Maurice and Chiron

this spring I had overheating issues...it appeared that I had good water flow at the stern exhaust, but with a load I was getting 190 temps on my FWC Columbia 8.7. I took the hose off of the thru hull and flow was slow...took it apart and had a small fish crammed in there!

[gclayton]

I had not water flow at my exhaust. Started troubleshooting at the thru hull. Even when it was open no water flowed through. After removing it (with the Admirals finger in the dike) the handle had sheared off from the ball in off position. Waiting on the part.

[systemek]

This is all very great advice. Seems like the fish scenario is more plausible than I ever imagined. Getting to the boat this week to apply this sage advice. Cheers!

[Dave Neptune]

NO or LOW FLOW!

Whenever the flow begins to slow, first check your strainer if so equiped. If a strainer is missing go to the exit fitting on the manifold and remove it. That is the most restrictive area in the cooling system and the most likely to collect debris at the end of the system. It is an easy check, probably the most common restriction found in the A-4 and it is an easy check before you start looking for plugged lines. If you find the passage under the fitting clean, then start at the beginning ~ the intake side of the pump.

Dave Neptune

[systemek]

Thank you Dave! Perfect timing, as I am doing the troubleshooting this week. That really helps.

[smaarch]

I find the answer here

same problem
after flushing with acid ...no water flow
I disconnected each fitting starting with the thru hull working my way up stream.
As per Dave's suggestion, the problem was the very last fitting that ties into the exhaust aft of the manifold....of course..
cleaned it out and I've been running at a rock solid 160 under load all summer.

[systemek]

Followed all the advice here and I ended up solving the problem by replacing the gasket in the water pump after isolating the problem there. Does anyone know if muriatic acid can degrade gaskets? Thanks again for all the advice......

[JonnyQuest]

Excellent discussion here.

Good point about clearing out the exhaust lines before performing the flush to avoid a later blockage issue. I am due for a muriatic acid wash but have concerns that it might eat away the protective coating of rust and scale on the inside of my A4

Seriously though, how common is it for an acid wash to eat through and expose corrosion holes throughout the systems? Some reassurances/prodding is required before I decide to perform the flush.