Time for an acid flush? How?

[mpahl]

So I pulled my A4 last fall, took it all apart and put $5-600 into it over the winter, dropped it in and it ran great for a solid 75 hrs of running time on a trip from the chesapeake up the coast, through NYC, up the hudson, up the champlain canal, and home to the northern end of lake champlain. Since entering the lake, it's started running very warm. The whole way up, I ran it b/t 135 and 165, controlling the temp with a ball valve in the thermostat loop. Now it's running at 195-205 in the lake with the ball valve totally closed, never going much above idle speed. Water flow *looks* like it always has, but it's hard to really tell. The lake water is very warm, which I'm sure has something to do with the problem, but it doesn't explain the whole thing.

So my first plan is to do an acid flush, but that's difficult b/c the exhaust on my boat (1977 Oday 27) is right at the water line, so it's not gonna be easy to keep the acid from going into the lake. My thought is to disconnect the hose from the manifold to the exhaust T and find an electric pump to pump lake water into the T while the acid goes into a bucket in the boat. Will that work? I could also do the same trick (disconnect the line from the manifold to the hot pipe) and pump the acid in and then back out using my trusty hand crank... With out the engine running I wouldn't need the water flow the cool the exhaust.

Is there any easier trick I'm missing?

[Mo]

Hi,

You still need some circulation to the head to keep it cool so I'd open that by-valve a bit. Do you use a thermostat? How does the water ejected out the stern look...is there any steam.

-check for partial obstruction on intake thru hull valve.
-check strainer if you have one.
-check impeller
-remove the t-stat if you have one and run it with the valve about 1/2 open and see what happens.

...also check oil for level and water (water will turn it greyish). Hot heads lead to head gasket replacement so try to avoid that.

If no improvement after those checks:
- pull apart the water lines (close your thru hull) and check all elbow and joints (that you can get at) for debris.
- check exhaust manifold (I have never seen the manifold blockage myself, however, I seen it discussed on here).

If you want to do the acid flush you might want to do it sooner than later. That said, if it was cooling so well earlier in the trip I'd be thinking there is debris caught up somewhere that needs removal and acid flush may or may not help on that. Below is a video of my output....no T-stat in mine and by-valve open 1/2

http://www.youtube.com/user/mmullaley#p/a/u/1/zn_ioeGigQQ

Hope that helps.

[edwardc]

So I pulled my A4 last fall, took it all apart and put $5-600 into it over the winter, dropped it in and it ran great for a solid 75 hrs of running time on a trip from the chesapeake up the coast, through NYC, up the hudson, up the champlain canal, and home to the northern end of lake champlain. Since entering the lake, it's started running very warm.

Based on the abrupt onset, I'd say you have some obstruction from debris, rather than a general narrowing dur to corrosion. Have you checked the pump impeller? Its all too common for one or more vanes to disintegrate and the pieces to lodge in an elbow somewhere in the cooling system.

Another trouble spot is the intake strainer and any inline strainer you may have on the intake line. Something as simple as a paper towel here can cause hours of frustrating troubleshooting.

...So my first plan is to do an acid flush, but that's difficult b/c the exhaust on my boat (1977 Oday 27) is right at the water line, so it's not gonna be easy to keep the acid from going into the lake. My thought is to disconnect the hose from the manifold to the exhaust T and find an electric pump to pump lake water into the T while the acid goes into a bucket in the boat. Will that work? I could also do the same trick (disconnect the line from the manifold to the hot pipe) and pump the acid in and then back out using my trusty hand crank... With out the engine running I wouldn't need the water flow the cool the exhaust.

Is there any easier trick I'm missing?

Disconnect the outlet line from the manifold, and the inlet line on the cooling side plate. Without a thermostat. you can use a hand or electric pump to circulate the acid from a bucket, through the engine, to another bucket without starting the engine at all.

[dvd]

Mpahl

I had almost the same issue with mine last time I went on a long cruise. Motored for probably 6 hours everything was fine and engine started to heat up by going to about 200 then quickly dropping down to about 180. I replaced the old brass dinosaur T-stat with the moyer T-stat kit with the new T-stat housing, T-stat and spacer and also at that time installed the by pass kit which you already have.

So if you havent already done the T-stat kit I would definitely recommend it.

dvd

[CalebD]

Vinegar vs Muriatic Acid

As usual all previous comments make sense to me. Sudden onset = look for obstruction or clog from impeller vane(s) and whatnot in cooling fittings and hoses.
I can only add that you do not necessarily need to use Muriatic acid (Sulphuric Acid?) to flush the cooling passages. I have had some luck using 1 gal. of white vinegar a couple of times a year as a cooling system flushing agent.
The last time I did this (a few weeks ago) I ran 1 gal. of vinegar into the block by squeezing the cooling hose leading to the T-stat with a vice grip. I left it in there for about 6 hours and when I started her up again and checked the exhaust there was a grey particulate in the water. The next time I do this I should try removing the T-stat to try flushing the head as well.
Vinegar or acetic acid is much less acidic then Muriatic acid and is safe for a lake like Champlain or the Hudson River where I usually sail. That is why I leave it in the cooling passages for a longer time period as it is not as reactive and therefore works more slowly. I leave the vinegar in the engine for much longer then the 15 minutes that is recommended in the thread below.

Every time you eat salad you probably ingest some vinegar.

Does vinegar flushing the cooling system work as well as the pressurized Muriatic acid flushing procedure outlined here at the MMI forums? http://www.moyermarine.com/forums/sh...hing+procedure
I'm really not qualified to say and I have no idea if it is as effective. All I know is that dumping 1 gallon of vinegar into the Hudson is not harmful to the environment and can be done while the boat is in the water. I could not say the same thing for dumping sulfuric acid into the river, although, it too would dilute (like the 'X' million gallons of raw sewage that local municipalities have dumped into the river this summer).

http://www.dnainfo.com/20110725/harlem/raw-sewage-flow-into-hudson-continuous-problem-experts-say

http://www.lohud.com/article/20110811/NEWS02/108110425/Ossining-sewage-spill-prompts-new-Hudson-River-health-warning?odyssey=mod|newswell|text|News|s

Sorry, didn't mean to grouse but aint I lucky?

[ndutton]

I think I read around here that Don once said by the time muriatic acid has made its way through the engine it's pretty much neutralized anyway.

And if I remember my college chemistry correctly, I think muriatic acid is in fact hydrochloric acid.

[CalebD]

...
And if I remember my college chemistry correctly, I think muriatic acid is in fact hydrochloric acid.

Neil,
I am sure you are correct that Muriatic acid is mostly hydrochloric acid (HCl) rather then sulfuric acid.
The extra chlorine introduced into our river might help keep the bug count down in water tests, who knows?

I wish I had taken an organic chemistry course after physical chemistry. I also wish I had taken Auto Shop.

[jpian0923]

We need a backflush pump for RWC A4s.

[mpahl]

All sounds good. I'll start by diving on the strainer this weekend (easy enough- I go swimming pretty much every time I'm out, I'll just bring a mask). Then check for obvious obstructions in the lines or elbows by pulling the line before the T and checking the flow with the engine running. If that looks good, I'll flush the engine with a bucket of acid and an electric pump (I should have thought of that).

I wish there was a cheap GPM gauge that could be used to ensure proper flow... It's so hard to tell by observation whether the right amount is coming out the exhaust.

[Administrator]

We need a backflush pump for RWC A4s.

Well, guys?

Bill

[ndutton]

Suggest you read this thread
Why I Don't Like External Strainers
particularly post #1 by Maine Sail. It's the best treatment on the subject I've seen and echo's my opinion exactly. I got rid of my external thru-hull strainer at last haulout in favor of an internal raw water strainer that I can clean from inside the boat.

[hanleyclifford]

Suggest you read this thread
Why I Don't Like External Strainers
particularly post #1 by Maine Sail. It's the best treatment on the subject I've seen and echo's my opinion exactly. I got rid of my external thru-hull strainer at last haulout in favor of an internal raw water strainer that I can clean from inside the boat.

Good link, Neil. I have the slotted scoop style external strainer that is removable from the outside by six machine scews. The key to using one of these is to carefully paint inside and out without clogging the slots. In addition I have my 3800 gph washdown pump plumbed into the salt water cooling circuit so it can be used as a "backflusher" when needed. FWIW

[smosher]

I also had an issue with the sea strainer and it was solid and couldn't be cleaned. I had a nagging problem with water flow and high heat that I eventually tracked down to a clogged thruhull on the sea strainer. Sometimes it worked fine, other times it reduced the flow of cooling water to the point of the engine getting to 180 - 200 degrees. I ended up replacing the sea strainer with a regular 1/2 thruhull and an internal strainer. haven't had a problem since.

I am amazed though on how much debris gets sucked into the strainer.

Steve

[hanleyclifford]

I also had an issue with the sea strainer and it was solid and couldn't be cleaned. I had a nagging problem with water flow and high heat that I eventually tracked down to a clogged thruhull on the sea strainer. Sometimes it worked fine, other times it reduced the flow of cooling water to the point of the engine getting to 180 - 200 degrees. I ended up replacing the sea strainer with a regular 1/2 thruhull and an internal strainer. haven't had a problem since.

I am amazed though on how much debris gets sucked into the strainer.

Steve

Yeah, the solid type that cannot be cleaned and painted should be discarded.

[ILikeRust]

And if I remember my college chemistry correctly, I think muriatic acid is in fact hydrochloric acid.

You are correct.