Overheating KAD 42 again!

[Keithleask]

Hi all again, I posted a couple of weeks ago about my overheating stbd engine, well after removing all the hoses except from the leg to the raw water strainer and checking for bits of impeller etc , removing and cleaning the heat exchanger, I did not remove the exhaust elbow as these were new about six months ago, replaced raw water pump for a re built one, I put it all back together today and ran the engines up. I tied up securely and put some drive on to load up the engine up a bit. The gauge eventually ( after an hour or so) went up to 150o , the port engine stayed solid at 125o. Felt the raw pump ( it was getting hot previously) and it did get warm for a short time then went cold like the port engine and stayed like that. I did hear that on these KAD 42 s that the stbd engine runs hotter than the port engine because of the caorifier, is that correct ? I also noticed that the drive dog behind the raw water pump was quite badly split and was wondering if this might have been slipping and adding to the problem. I have ordered new ones,
The manual says these engine should be between 165/195o , I am still not convinced that I have sorted the overheating though cleaning out the exchanger was probably overdue anyway, anyone have any more views on the above ??? Thanks ,

 

[wofforduk]

Only third party info here, from my parents boat - they had one engine overheating a lot. they used brick cleaner and all sorts to clean their heat exchangers out, and i think this cured their problem. it was the calcuim build up that caused it , so just flushing the exchangers might not be enough?

 

[A_8]

If the exchanger needed cleaning the oil cooler is probably more critical, its a lot smaller and if like on the 43 sits between the pump and the exchanger so any"****" that gets through the pump most likely gets stuck in the oil cooler. Its passage area is also smaller so any buildup will affect water flow more than the same buildup in the exchanger (i think)

 

[scubaman]

Do you have a reason to suspect that bits of impeller might be astray?

I once blew an impeller due to raw water blockage (a kamd300) and the engine kept overheating until i opened the intercooler top lid. I found a handful of impeller bits blocking the water flow. Everything ran fine after that.

 

[rlw]

From personal experience with AD41's and kad 44's the calorifier does not cause the engine to run warmer but does cause the engine with the calorifier to warm up slower and cool down slower. At cruising speed temps were the same. I would recommend to buy an infrared hear gun voor 100€. I once wasted time & money chasing an overheat problem that did not existon my Portofino 31. In the end it was bad grounding. From memory oil sensor read lower and temp sensor read higher with added corrosion resistance. I had 10°C difference on the dail but thermostat housing temp was identical/. With my Martinique 38 limped in with what I thought was an overheat. In the end it was a spade connector on the dail that shifted coming of a wave. Pushed it back on and temp dropped 10°. I now start with an independent temp measurement if any trouble occurs. Also helps compare bits of engine when you have twins.

Good luck
Rob

 

[Keithleask]

If the exchanger needed cleaning the oil cooler is probably more critical, its a lot smaller and if like on the 43 sits between the pump and the exchanger so any"****" that gets through the pump most likely gets stuck in the oil cooler. Its passage area is also smaller so any buildup will affect water flow more than the same buildup in the exchanger (i think)

Looks like I might need to do this as well then , a real Sxx to get to , thanks for the input!

 

[Keithleask]

Yes I had an impeller break up got a lot of bits out but sure I never got them all! The impeller was only changed the previous autumn so I was surprised it broke up so quickly unless of course I had another blockage somewhere! I suppose I need to look at the oil cooler and inter cooler as well then ? Thanks for the help

 

[Keithleask]

Rob thanks good points and all noted, glad you resolved your problem easily I will invest in a heat gun it might save a lot of heartache and I am sure it will come in useful again. One other thing I am unsure about is on the turbos there is a lead with a spade connector that is clamped purely to the turbo housing under the hose and jubilee clip. Any idea what this is for? I have no exhaust temperature gauge and cannot see them on the wiring or workshop drawings ?

 

[rlw]

No idea. I have never come across this. It sounds like an aftermarket exhaust sensor.

 

[Barleycorn]

After my recent disaster when my impeller broke up I am considering fitting something similar to this between the pump and heat exchangers. A lot quicker to clean the broken bits of impellor out of this than to strip down the oil and cooling heat exchangers. Would that be a good idea, or may it restrict the water flow?
I would have to make sure that the filter in this is coarser than the Vetus basket filter feeding the pump.

http://www.ebay.co.uk/itm/1-1-4-BSP...853?pt=LH_DefaultDomain_3&hash=item5d2f08d665

 

[Keithleask]

Hi it looks a good idea we use these quite a lot on plant rooms for heating and circulating pipe work would need to check the glitters though but looks a good idea for catching impeller bits !!

 

[A_8]

After my recent disaster when my impeller broke up I am considering fitting something similar to this between the pump and heat exchangers. A lot quicker to clean the broken bits of impellor out of this than to strip down the oil and cooling heat exchangers. Would that be a good idea, or may it restrict the water flow?
I would have to make sure that the filter in this is coarser than the Vetus basket filter feeding the pump.

http://www.ebay.co.uk/itm/1-1-4-BSP...853?pt=LH_DefaultDomain_3&hash=item5d2f08d665

I think the filter area is to small and will make your system very sensitive to blockage. Perhaps if you get a bypass valve in there as well so that you can keep running the engine if the build up suddenly gets too much but that will still most likely get you into trouble more often than if you kept your system as is.
I am on 10 years ownership on my current 2 engines, many more miles than most and have never had broken bits of the impellers come loose, what do you guys do?
I think changing them every 1-2 yrs keeps you out of trouble.

 

[Keithleask]

Only had the boat a couple of years and never thrashed the engines, as stated earlier the engine overheated on sea trial, the seller changed stats , impeller, and it ran perfectly on second sea trial. Then had the impeller break up , less than two years old. Think a big contributory factor with the break up was I had the boat on the hard for several months doing upgrades and should have removed the impellers but didn't. When I re launched the port engine sprang a leak from the raw water pump seal so I re built the pump and fitted a new impeller so cannot be sure this one would have not broken up as well had I not fitted the new impeller,

 

[Momac]

I am on 10 years ownership on my current 2 engines, many more miles than most and have never had broken bits of the impellers come loose, what do you guys do?
I think changing them every 1-2 yrs keeps you out of trouble.

I have kad32's in my present boat - single kad32 in the previous boat. I have replaced raw water pump impellers every annual engine service regardless of condition - in part not wishing to take any chances with a single engine. I find it difficult to move away from the same philosophy even now I have two engines. Never had an impeller problem in 7 years and almost 700 engine hours. There is always some very minor sign of perishing at the roots of the vanes after a year but I expect two years would probably be okay - exactly as you suggest.

If the brass plate on the pump is worn it might affect pump performance . A 'speedseal' plate is said to be an improvement.
http://www.speedseal.com/

.

 

[Keithleask]

Interesting about the plate, thanks,anything that helps,will check thus out !

 

[Double Vision]

My old Sunseeker with Kad42s had this problem on one engine. After replacing the impeller, removing and cleaning all the coolers, cleaning and inspecting the pipework the problem turned out to be a bad earth to the Temp Gauge. worth just running a new wire direct from the nearest good known earth ( -ve 12V) that you can find and the other end to the terminal with the black wire on the back of the dial.

 

[Keithleask]

Thanks, I have checked the heat exchanger , replaced raw water pump with a good spare, replaced the impeller, cleaned the after cooler and oil cooler all clear. There is pressure in the fresh water header tank, much much more than the port engine. I have a couple of new stats to try and I ordered a coolant gas analyser to check if I am getting any combustion gasses in the freshwater which will probably point to a blown gasket or cracked head! I have no mush on the rocker box filler or on the dipstick, the history of the engine is it overheated a couple of years ago then again few weeks ago when the impeller broke up, I don't know if the last overheating may have blown the gasket or not, I turned the engine off straight away. I ran the engines up on the pontoon on Saturday and with a bit of load on them the port engine stayed steady at around 125o and the stbd went to 175o left them running for an hour. I think with more load on out on the water it will overheat again am dreading the thought of taking the head off etc! Need to check the freshwater circ pump first though then I think I am out of options ??

 

[Double Vision]

I know the early Kad 42s had head gasket problems and most of them were replaced with a modified gasket in the mid 90s. Yours may have slipped the net. Not too much of a prob to do. They are just a big pushrod engine but the heads are bloody heavy! Get the coolant analysis done to confirm it before getting the big socket set out though. I have a little laser temp thing I bought on ebay for around £25. worth getting one and pointing it on the thermostat housings to confirm the gauge is correct?

 

[Keithleask]

Yeah, I am getting a heat gun from my mate tomorrow just so as I can confirm the stat housing temp is confirming near enough the gauge temp. Those heads look really lumpy, am trying to get my head around what is probably the inevitable, I just need to be 100% sure what caused the overheat so I am not just replacing the gasket / head if the problem is still there somewhere , ie circulating pump, blockages in the water jacket etc!

 

[baylabayla3288]

Did you resently rebuild the raw water pumps. If so, pls check that you have used the right cam for the Kad 42. The re-build kits from Volvo comes with 2 cam sizes in the box, a smaller to be used with 200 hp diesel and the larger with the KAD 42. If you use the smaller cam the engine will ower heat under load.