Overheating KAD32

Charge Air Cooler

Is anyone familiar with the Charge Air Cooler - it has been suggested as the leak detection kit has indicated that the pressurisation is not caused by burnt gasses escaping ie head gasket or liners
 
FlowerPower said:
I thought the charge air cooler was saltwater cooled?
Click to expand...

Correct!!

This is a very interesting post but as I mentioned many times there is normally a story to it, so I have my usual questions for the OP.

Did this overheating happen over a space of time?
Was it after any work had been carried out?
Were there any 'incidents' that could have started the line of events causing the problem?

Can you understand where I am coming from, there are obvisouly no major problems as the engine works OK at full chat.

I have to admit I agree with VolvoPaul about using the laser thermometer (I love using mine) to compare one engine against the other, just as RIN did with his engine, although that was a switch chance, (that's another story!!) I don't think this is your problem as you have actual coolant loss.
I assume you are not overfilling the tank, I only have about a inch or so of coolant in my tank and that works for me.

Let us know how you get on.
 
Hi Peanuts

The problem began last June on a trip over to Yarmouth, motored from Haslar to an overnight stop in the Hamble first for a meet-up with friends and pick up extra crew then next morning intended motoring to Yarmouth but the alarm went off as soon as I entered Southampton Water, quickly back to the Hamble and opening up the engine bay confronted with a bilge full of coolant- Seastart came out and we thought all was good. Shot to Yarmouth no problem. Next day dropped off friends in the Hamble and identical spot back in Southampton water off goes the alarm, same thing bilge full of coolant. I returned to Haslar on one engine.

After several other checks by marine engineers we had our two week Summer Break - off to the West country, however the weather turned on us and forced to head into Poole - as soon as we brought down the speed in the marina the overheat again happened and again coolant forced out of the system.

Had volvo engineers to the boat and thought be better to return to the Solent, all went well, stopped in at Newtown Creek for lunch then all OK until we slowed down outside of Cowes - off goes the alarm.

Eventually back to Haslar on one engine - getting quite proficient now at driving a single engine powerboat.

More enineers and more tests and still none the wiser.

Can take the boat out - run her at 3k revs or above for an hour - no problem, even if we up and down the revs she performs well - then as we bring down the revs and start running back into Portsmouth at our 10knots speed she pressurizes, pumps out the coolant and overheats.

This weekend I bought a leak detection kit which duly tried, the chemical didnt change colour although there was plenty of pressure blowing through the test kit.

I also bought one of the infrared thermometers - brilliant. All showed though temps of 72oC -75 (intercooler and exhaust riser) the heat exchanger at 17oC

Completely stumped
 
Hi
So, the way I read this is that during a run at 3k RPM (ish) everything is OK, as soon as you drop back you get the coolant overspill, do you get a temp rise first then the overspill?

The way I am thinking is that during the 3K RPM part everything is at the correct temp, as soon as you throttle back the seawater cooling flow rate drops, the engine has heat soak and becomes hotter and the coolant boils up. The question you (and in fact all of us) are asking is what part is causing the problem?

I expect you have written this before but if you were to cruise at the 10 kt speed that the engine normally boils off at without having gone to the 3K RPM before does it overspill then?

I expect I will end up with more questions for you but this will do for the moment.
 
Hi Peanuts

I've had the problem both when setting off on a journey when running from cold - and when dropping down to a 10 knots after having a run out. In both cased this does not happen all the time - I've been able to motor out several times from Portsmouth without issues on the outward journey - only materialises on the return leg and vice versa.
 
Hi Peanuts

re the Raw water - the heat exchanger remains cool to touch throughout and therefore I'm assuming raw water system is functioning OK
 
barney365 said:
Hi Peanuts

re the Raw water - the heat exchanger remains cool to touch throughout and therefore I'm assuming raw water system is functioning OK
Click to expand...


Dont supose the thermostat is only opening so far?, but insufficient for the released heat soak,

Perhaps it jams against some crud or is not bigenough when open, or gets an air space round the capsule and therefore shuts rather than opens.

17 c for the header tank sounds v cold, compared to our sabres, unless you mean the end caps. Would be tempted to remove thermostat and go for a quick blast to see what happens.
 
Hi David

Thermostats have been replaced albeit I have run without them but problem still manifests itself

When checking the heat exchanger with the infrared thermostat we were at 17oC
 
barney365 said:
Hi David

Thermostats have been replaced albeit I have run without them but problem still manifests itself

When checking the heat exchanger with the infrared thermostat we were at 17oC
Click to expand...

I take it the lost coolant is not gettng contaminated with sea water? (possile to leak some via the heat exchanger ,then the lowered level boils out?)

It is almost as if at a certain revs something is cutting the fresh water pump flow. perhaps some old gasket etc being lifted up.

dont supose the drive belts,pulley or impeller slipping?
 
Last edited:
Hi David

Not sure about sea water contamination - however raw water pumps swapped over between port and starboard and still persists.

The fresh water pump has been taken off and this has meant that all the belts have been re-set - again problem persists

cheers

Paul
 
Boy, you've got a lot of us thinking hard on this one.
I'm struggling to understand whether overheating causes the expansion and loss of coolant, or pressurisation causes loss of coolant which in turn causes overheating. I assume its the first scenario and overheating comes first.
I'm not sure of your setup, but i am assuming raw water is taken in through the leg and delivered to the engine that way. What else changes as you throttle back and slow down? Is the leg trim changed and could this pinch or collapse an intake hose?
 
barney365 said:
Hi David

Not sure about sea water contamination - however raw water pumps swapped over between port and starboard and still persists.

The fresh water pump has been taken off and this has meant that all the belts have been re-set - again problem persists

cheers

Paul
Click to expand...

does it happen off load at the rpm for the speed?
 
Hi Phill

I've burnt out so much grey matter in the last year but also have learnt a bit on boat engines ....

The process in short is the raw water enters at the base of the legs, and through a strainer before being then passed through the heat exchanger which in turn cools the fresh water which then cools the engine .

The throttling back doesnt affect the trim

Cheers

Paul
 
Have you checked the temperature difference across the heat exchanger of both sea water and coolant at the critical point of over heating? there must be a temeprature drop/increase. If it is overheating it is because the heat is not being taken away due to blockage inefficiency etc.
If it is becoming pressurised and dumping coolant that is a different story.

http://suffolkyacht.com/Yacht-engines/temperature-testing.html

this may help
 
At least with two engines and a temperature gun, you should be able to compare temperatures from the good engine with the other and hopefully find where the problem is. Sounds more like a restriction of the waterway now.
God luck in your search.
 
You must log in or register to reply here.

Other threads that may be of interest

Jon magowan
White Smoke from my Engine
Replies
11
Views
464
Ian_Rob
I
W
  • Locked
KAD32 Injector and sleeves
Replies
0
Views
112
Wobbo
W
B
How does a tacho get RPM and engine-hours data, and how to fix faulty readings?
Replies
16
Views
441
Babylon
B
O
“The Dog that Didn’t Bark:” Yanmar. 4L HASTE.
Replies
2
Views
274
oldgit
O

Share this page

Top