My A4 adventures

[Surcouf]

and if applicable, do not forget to close your cooling water seacock when doing compression test... or it could become a true wet test...

[Ando]

A few questions/suggestions re: elevated heat:

1. If installed, please remove the flow sensor until after troubleshooting is complete.
2. How old is the water pump?
3. Have you acid flushed this engine?
4. Is a bypass valve installed? If yes, try removing the thermostat and closing the bypass valve.

Yes, flow sensor is installed
Water pump is brand new
Yes, muriatic acid wash was done recently
Yes as to the bypass valve. Ok I’ll try removing the thermostat and closing the valve and report back.

But as to wet and dry compression testing as advised by Dave Neptune, I recall we did a dry compression test at the start of the season and at that time compression was as follows:
1. 115
2. 95 sparking stopped
3. 100
4. 100
And I will be doing a wet and dry compression test after going over the steps above

[Ando]

Update

Flow sensor removed and replaced with straight water line. Found a couple small barnacles inside the flow sensor.

Removed and checked both manifold input and output barbs (the input is a 90 degree barb but it was clean).

Removed manifold and high pressure washed it.

Oil changed

Dry compression test results (from 1-4): 105, 100, 100, 100.

Wet compression test results to follow (I will be using MMO).

I have not removed the thermostat yet. Planning on running it after the wet compression test and seeing what the temp is at to see if the flow sensor removal did the trick.

[Ando]

See comments directly above.

Wet compression test results (I put MMO in each cylinder first, which wasn’t the best idea...should have put it in each individual cylinder prior to testing because the other three cylinders shot out MMO in the first test):

Wet test 1: 200, 120, 120, 115

Just to be sure
Wet test 2: 165, 118, 120, 115
*test 2 was done without placing any more MMO in each cylinder (ie I put MMO in each then tested each cylinder twice and so the MMO was probably all shot out during the first test of the first cylinder).

[Ando]

See comments above

I’m not sure what “fouled” spark plugs look like, but here are mine:

[Ando]

See comments above.

Water flow is way way way better now. Now my temp gauge isn’t working, but I still have my temp gun and at ~15min of running time it reads between 160-190 at different point along the head, the manifold reads between 100-120 and the connection to the exhaust reads around 400.

Edit: the temp gauge IS working, but only when the engine is off does it give me a reading lol. When it’s on, the pointer falls to below 100. So weird, right?

[ndutton]

Please save the flow sensor as-is for me (tomorrow afternoon?).

[Ando]

Please save the flow sensor as-is for me (tomorrow afternoon?).

Yes, sir. I’ll be here.

[ndutton]

Forensic examination of the flow sensor showed a minor amount of detritus inside but nothing that restricted its movement, encumbered its function or affected its flow. I do not know if removal from the boat dislodged anything that might have been inside, just reporting the condition as I received it.

Do you have a raw water strainer installed (I think I remember you do)? What size is your intake thru-hull? Does it have an external strainer?

[Ando]

Forensic examination of the flow sensor showed a minor amount of detritus inside but nothing that restricted its movement, encumbered its function or affected its flow. I do not know if removal from the boat dislodged anything that might have been inside, just reporting the condition as I received it.

Do you have a raw water strainer installed (I think I remember you do)? What size is your intake thru-hull? Does it have an external strainer?

Thank you, Neil.

I do not have a raw water strainer installed.

Re the size of the thru-hull intake: I have to go back and double check, but if I recall, it is 3/4”.

As for the external strainer, I do have this:

[roadnsky]

As for the external strainer, I do have this:

Ando-
Assuming you are currently in the water as opposed to on the hard, I would take a swim and check that external strainer.
Those are notorious for filling and clogging with stuff. Especially sea life.

It could absolutely be limiting your intake of cooling water.

[roadnsky]

Flow sensor removed and replaced with straight water line. Found a couple small barnacles inside the flow sensor.

Neil-
Please note this comment back in post #138

Ando-
The fact there were barnacles inside the flow sensor would lead me to believe they are also living in that external strainer as well.

[ndutton]

That's why I retrieved the sensor for closer examination. When I opened it up there were no barnacles inside, only a few minor specks of greenish growth, none of it hard. Because of the condition of the sensor I immediately started thinking something else might be restricting the flow. Sensor autopsy pics attached.

[Ando]

Here’s a pic of the barnacles I found, one (blurry in the foreground) and one in the back).

I had my diver double check the strainer a couple weeks ago and myself put a rebar down the thru-hull from the top that same day.

Thru-hull is, in fact, 3/4” btw.

[ndutton]

That barnacle could certainly affect the flow but was not present when I got the sensor. I would like to see three things happen:

1. Remove the external strainer. Depending on the design it may mean a complete thru-hull replacement.
2. Addition of a raw water strainer instead. It is easily cleaned out inside the boat.
3. A fresh water flush of the engine when cleaning up the boat after a sail. With a flushing Tee and valve installed, it's a 5 minute process.