penta aqd40a over heating troubleshooting

[dragoon]

In an engine with an otherwise ok cooling system, removing the thermostat will cause a longer warm up time.

What ever you do, don't run your engines long at higher temperatures - the 40As were known for head failure - the pressed in cups in the head could come loose and fall into the combustion chamber with catestrophic consequences.

Good luck - I know what a pain it is to rectify cooling problems on these engines.

Cheers,
Paul

 

[dragoon]

For lower loads issues you can put your hand on the exhaust elbow or the seawater pump housing to understand if the seawater flow is the issue or not. The pump housing should be "cold" and the exhaust elbow a bit warmer but still ok for a quick and light touch.
.

This is good advice. It will certainly provide some feedback as to whether you flow on the raw water side or not. Please do this and let us know.

 

[symondo]

Stupid question - another 1...

This exhaust elbow - i assume this is at the rear of the engine heading towards the outdrive?

if it was blocked, i assume it would be - cold? so no hot water running through it?

 

[dragoon]

Stupid question - another 1...

This exhaust elbow - i assume this is at the rear of the engine heading towards the outdrive?

if it was blocked, i assume it would be - cold? so no hot water running through it?

The exhaust elbow exits the turbo - on my TAMDs it is a 90 degree curved pipe, about 3-4 inches across. If the exhaust elbow is blocked, it will heat rapidly as the hot exhaust gases are not mixed with cooling water. The elbow should be coolish to the touch when everything is working correctly. The mixer pipe that supplies the cooling water will likely be cold.

 

[symondo]

Ok

So to clarify.. If said part is hot... I have a blockage if cool raw water side is ok so look to the fresh water system...

 

[dragoon]

Ok

So to clarify.. If said part is hot... I have a blockage if cool raw water side is ok so look to the fresh water system...

Yes, basically that's it. It may not be a 'blockage', but no flow - could be caused by incorrect operation of the sea water pump also.

 

[symondo]

Yes, basically that's it. It may not be a 'blockage', but no flow - could be caused by incorrect operation of the sea water pump also.

Had an interesting afternoon, i think i have found the issue.

I closed the seacock to said engine to inspect the impellor...

It was bone dry.

I checked the other engine to see how it was meant to be which leaked water as i had expected it to from whatever was in the system

I then figured if thats dry theres mo water getting to it, upon inspection of the sea cock, i realised the handle which was turning was not actually turning the valve. So i assume its been closed causing lack of raw water cooling.

I took a set of grips and managed to re tighten the handle to operate the valve.

I checked this by taking the lid off of the weed filter and turned the engine over, and appeared to have flow pouring from the top. Resealed the filter and also checked the fresh water which looks to be circulating ok.

After about 10 minutes of idling at about 1000rpm, the guage still showed cool which it didnt last week. I could also feel the exhaust was cool enough to touch like the
Working engine.

I havent taken it out today, the weather has been pretty rubbish but im hopeful this may have resolved the issue

Also cleaned a lot more of the engine bay up