KAD running hot

petem

petem

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Joined
16 May 2001
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Location
Cotswolds / Altea
www.fairlineownersclub.com
Our KAD44's are running a bit hotter than I'd like. It's been very hot (air and water sea water temperature but I doubt that's the issue).
  • We had the cooling system flushed, stripped and cleaned in the spring.
  • The exhaust elbows were changed with the Turbos, four years ago.
  • We don't have a lot of fouling where we are so I doubt the intakes are blocked.
Where do we go next?
  • IR thermometer?
  • A different mechanic noticed some scoring on one of the impeller cover plates. Could that be a cause?
  • Do I need to ask the mechanic to do a raw water flow test?
Thanks.
 
I would check the temperatures with an IR meter, the vp's own meters may for one reason or another be wrong. Measure temperatures at several points at close distance from the engine
 
NBs said:
I would check the temperatures with an IR meter, the vp's own meters may for one reason or another be wrong. Measure temperatures at several points at close distance from the engine
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Thanks, that's probably what we'll do.

Running the boat with the engine hatch open (and exposed belts) isn't something that I like doing but I guess we have no choice.
 
I understand, it's not comfortable, but be careful not to wear loose clothes.

On my old boat 2*kad44 one thermometer started showing almost 10C° different temperature and the IR showed about the same temperature for both, so I did nothing about it. It could be a sensor failure or corrosion in the connections or something else.

It may also be a thermostat problem, but you will know that after the IR measurement.
 
Going back a bit now pre 2014 when I had KAD 300s . Similar thing happened.
Turned out ( after IR gunning etc ) it was the gauge wiring loom . Not the actual VDO gauges but the wiring harness from the temp sensors to helm .

Can’t recall the exact fix ….VP tech messed with the loom to gauge wires ? Vaguely recall the pins on the unbiblical were corroded so increased resistance thus sent false readings ….? Something along those lines .

Yes we went through the same list of parts too before rounding on the loom .
 
Had this theme recently on my kad44 /dp-e ( we discussed here ) . Can you report your indicated temps during trolling ( lets say 1500 rpm ) and cruise at +3000?

Mine are 80-82 trolling and 90-93 at cruise .

Adressed this to a ( i think ) reputable vp dealer in netherlands and talked to a mechanic .
Before i write down here what he recommended please post your temps first .
 
Point an IR thermometer at the cylinder heads and the thermostat housing. Stick some black insulation tape on them first for a better reading off the black surface.
It could well be just gauges reading high but better to check given everything else has been gone through a few years ago.
 
Farmer Piles said:
My KAMD44 reads about 40-60 at 1400rpm, about 90 at cruising - 3000 - 3200rpm. Told by the service engineer that it's about right.
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40-60 can't be right even at a 1000rpm on a river we see 80-82deg. Currently I'm investigating high temps too as I see 92-94 at 3000rpm, but thats on the ECU data feed not the analogue gauges which seem to read 2-3deg less and use different sensor positions I believe.
 
I know this is very obvious, but.... impeller?

I only say so because just this weekend, our stbd engine started reading around 92 degrees at 3400RPM. I pulled up, replaced the impeller and boom... back to the late 80's on both sides at 3400RPM (I wasn't in a position to go WOT).

On a side note, I only use genuine impellers... previously I bought aftermarket and temps started to rise. I put back the (used) Volvo impellers (I do appreciate that they're likely Jabsco, but in the blue box) and boom, temps back to normal.

2 x KAD300, BTW
 
alt said:
I know this is very obvious, but.... impeller?

I only say so because just this weekend, our stbd engine started reading around 92 degrees at 3400RPM. I pulled up, replaced the impeller and boom... back to the late 80's on both sides at 3400RPM (I wasn't in a position to go WOT).

On a side note, I only use genuine impellers... previously I bought aftermarket and temps started to rise. I put back the (used) Volvo impellers (I do appreciate that they're likely Jabsco, but in the blue box) and boom, temps back to normal.

2 x KAD300, BTW
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It's a good shout. I'll check when the impeller was last changed.

As I said in my original post, a different mechanic to our usual chap noticed some scoring on the cover so I'll investigate that as well.
 
petem said:
It's a good shout. I'll check when the impeller was last changed.

As I said in my original post, a different mechanic to our usual chap noticed some scoring on the cover so I'll investigate that as well.
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Sure it'll do no harm to replace them, not the end of the world €€ wise and worst case, you have some spares!

In my old age of mid 30's, I tend to just buy the tools that are needed and a few years ago, purchased the Volvo 'impeller puller' which is basically just a bolt within a bolt, but the impeller shaft on the KAD300 is too long for this, so, in my opinion, the next best tool to have if this Knipex: https://www.screwfix.ie/p/knipex-smartgrip-water-pump-pliers-10-250mm-/641hl

That Knipex is actually so handy, I think i've 3 of them now, kept in the shed, the car toolbox and the boat.... of course it's usually helping others than myself, but it's great to have the tools to be able to help people, when in need.
 
petem said:
Our temps are very similar to this.
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i was told by a vp mechanic that ~90 at cruise is about normal for a kad44 . The tstat is fully opened at 93 so anything up to this is normal operating , the max permissible and alarm threshold is 100 .

He said that beyond an obvious impeller check and strainer cleaning i should grease the strainer cap sealing area to make sure its a perfect sealing without any air sucktion . Ir checking is also recommended

To rydlyme the heat exchanger might be an good idea but they will not do it because a result cannot be guaranteed . If , they will clean the heat exchanger manually . Rydlyme only as a diy job .

Not sure if to trust him but its now the second vp mechanic who told me that (verfied) 90 and even a touch above is a non issue as long no alarms .
 
aerobat said:
i was told by a vp mechanic that ~90 at cruise is about normal for a kad44 . The tstat is fully opened at 93 so anything up to this is normal operating , the max permissible and alarm threshold is 100 .

He said that beyond an obvious impeller check and strainer cleaning i should grease the strainer cap sealing area to make sure its a perfect sealing without any air sucktion . Ir checking is also recommended

To rydlyme the heat exchanger might be an good idea but they will not do it because a result cannot be guaranteed . If , they will clean the heat exchanger manually . Rydlyme only as a diy job .

Not sure if to trust him but its now the second vp mechanic who told me that (verfied) 90 and even a touch above is a non issue as long no alarms .
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Thanks, that's reassuring. Perhaps for this winter I'll just replace the impellers and the impeller covers (there's a company in Sweden that sells them for £20 or so).
 
petem said:
A further thought on this. Do they thermostats ever fail? Could it no longer be opening fully?
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Yep, thermostats can fail in this way.

They can also fail fully closed, and the engine will overheat quickly . Or fail fully open and the engine will take ages to warm up/never get to normal temp.
 
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So there are lots of possible causes.
Did anyone mention raw water hose delamination leading to internal partial collapse?
 
Momac said:
So there are lots of possible causes.
Did anyone mention raw water hose delamination leading to internal partial collapse?
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I think that's a good shout.

Replacing the hose on the starboard engine would be relatively easy. I assume the boat needs to be out of the water (sterndrives)?

Replacing the one on the port side might require a bit of dismantling (calorifier and battery boxes).
 
The fact that both the engines are running hot (not just one) would be a clue I would think. I would say it's highly unlikely that something like a thermostat or delaminated hose has failed in both engines in the same way at the same time.

I don't know what it could be, but you're going to need to go back to first principles.

My gut feel (if both engines affected equally) would be some kind of fouling, either in the stern drive intakes, or in the heat exchangers.
 
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