Engine overheating
Printed From: myHanse.com
Category: Hints & Tips
Forum Name: 325
Forum Description: 352 Hints, Tips and News
URL: https://www.myhanse.com/forum_posts.asp?TID=9398
Printed Date: 27 March 2026 at 03:29
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Topic: Engine overheating
Posted By: Fiona
Subject: Engine overheating
Date Posted: 07 January 2016 at 15:16
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My engine does overheat sometimes. But only at low rpmīs . I can run the engine at 1800 rpms for hourīs on end without overheating. But going from 1800 rpm to a 1000 rpm results in overheating after just a few minutes. Under sail and just need to charge the batteries for a while I have the motor running a little over idle and after just 10 minutes itīs overheats. I suspect that it could be that the expansion bottle is mounted to low relative to the freshwater heater. I have now moved the expansion bottle (see pic below) from the original mountīs on the engine to the side wall of the engine room, but since itīs winter and the boat is a shore, I havenīt made any tests yet. http://imageshack.com/f/p5z5oJFyj" rel="nofollow">  I have replaced the impeller and cleaned out the cooling fluid, the old impeller was undamaged so there was no rubber parts clogging up the system... It would be interesting to know If anybody else have had this problem? Cheers! Magnus
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Replies:
Posted By: Mark_J1
Date Posted: 07 January 2016 at 19:41
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Thermostat replaced? Has the impeller ever failed? Might leave a partly clogged heat exchanger. ------------- Hanse 400e "Grey Goose" Hull #31 |
Posted By: Perttu
Date Posted: 07 January 2016 at 22:04
Hi Magnus, I have had exactly the same issue with my 355. Root cause is what you have discovered so I'll never start the engine on port tack. I am planning similar modification to get rid of the issue. Local Volvo guys are confident that issue will be solved then. - Perttu ------------- Check my sailing videos - http://www.youtube.com/user/l11483?feature=results_main |
Fiona wrote:Posted By: High Time
Date Posted: 07 January 2016 at 22:26
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Maybe you are not getting enough cooling water flow at low revs. I can think of 2 reasons this might happen. Firstly, your water pump or impeller may be defective and not pumping effectively. However, you have recently changed the impeller and cleaned the pump so maybe this is not the problem. Alternatively, you may have a small air leak in the sea water intake circuit before the pump i.e on the suction side. The most likely cause of this is a poor seal on the lid of the sea water strainer. If air is entering here the suction is reduced and hence the flow of cooling water is also reduced. I had this problem on a previous boat and finally replaced the poor Volvo strainer with a better designed system from Vetus. ------------- Roger High Time (415 #038) |
Posted By: Fiona
Date Posted: 08 January 2016 at 08:11
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[QUOTE=Mark_J1]Thermostat replaced? Has the impeller ever failed? Might leave a partly clogged heat exchanger.[/QUOTE] Hi as I said the impeller never failed. Cleaned out the whole system. If it was the thermostat, would it run ok @ 1800 rpm??? Cheers! |
Posted By: Fiona
Date Posted: 08 January 2016 at 08:15
Air leak might be a cause... If moving the expansion tank I will look in to that as the next step. But Perttu`s comment makes me think I am on the right track. Under sail, my overheating experience is on the port side tack... Cheers
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Posted By: Sea-U
Date Posted: 08 January 2016 at 10:41
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I had a Volvo 2002 for many years. Had much problem with growing inside in the saildrive. When I changed the rubber seals I cleaned of caurse. Then the problem was gone for a few years. The last season I had it, I disconnected the hose and connected it to a washbasin outlet. I could then run full revs with no problem. -------------  Sea-U is a 370e #532 located SW Norway
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Posted By: Nilandhoo
Date Posted: 08 January 2016 at 12:23
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Hi Magnus, We have a D1 30 on our 325 and the Volvo maintenance manual recommended cleaning the heat exchanger last year. We spoke to the local Volvo engineer who advised us not to dismantle the unit but to use RydLyme. This stuff descales the system and cleans out the heat exchanger. This may be worth trying if you are having overheating problems at low revs. http://www.rydlyme.co.uk/index.php/en/ Regards Paul ------------- Hanse 325 'One Life' |
Posted By: Fiona
Date Posted: 08 January 2016 at 12:41
Thanks for the tip. Even though I donīt think the problem is on the sea water side (I am in the Baltic sea, more or less fresh water) It could be worth to rinse the heat exchanger. How do you use this product? Cheers!
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Posted By: Nilandhoo
Date Posted: 08 January 2016 at 13:02
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Magnus, From memory you need to dilute it and pour it into the strainer then run the engine and leave it for 24 hours before flushing the system through. I think there are instructions on the container but if not let me know and I will check next time I'm down at the boat. Cheers Paul ------------- Hanse 325 'One Life' |
Posted By: Perttu
Date Posted: 08 January 2016 at 15:45
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Hello, To add to this. This occurs only if you start the engine on port tack. This http://www.bavariayacht.info/forum/index.php?action=dlattach;topic=673.0;attach=683;image" rel="nofollow - photo illustrates the problem. On port tack I am getting the overheat alarm very quickly after the start and the engine is not even warm at that stage - as said it can occur almost on idle revs after few minutes... If the engine is started on starboard tack it runs normally and I can even tack and no overheat occurs. - Perttu ------------- Check my sailing videos - http://www.youtube.com/user/l11483?feature=results_main |
Posted By: Fiona
Date Posted: 08 January 2016 at 16:41
Perrtu! Your picture really convices me that this is the root of my problem. When I think about the fresh water heater on the star board side, it's evident that the expansion tank is the lowest point of the cooling system. Mine also overheat almost instantly when on the port tack. It will be interesting to see if the relocation will do the trick. Will get back to you in this matter. Cheers! |
Posted By: Bruno
Date Posted: 09 January 2016 at 02:13
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My suggestion may be odd but check also your hot water tank circuit and coolant level. At lower revolution, your coolant is more solicited. ------------- Bruno Hanse 400, 2010 Hull 660, Canadian flag sailing Lake Champlain, VT USA |
Posted By: samuel
Date Posted: 09 January 2016 at 08:06
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last year I noticed a reduced flow of water & i kept having toclean the filter. However, never having had a filter problem before I decided this winter to remove the exhaust elbow. The water inlet hole was clogged to within 6 or 7 mm diameter. I now suspect that this caused a back pressure on the pump so slight problems such as small amounts of weed in the filter had a greater effect It may be that at different angles of heel the pump has to work harder .This may lead one to start looking in the wrong place ------------- Daydream Believer- Hanse 311- No GBR9917T- Bradwell Essex |
Posted By: Perttu
Date Posted: 26 January 2016 at 17:52
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Hello, I did visit the Dusseldorf boat show yesterday and checked Volvo installation on various different boats, including Hanse. With every boat expansion tank is located either above the engine or then moved to the other side of the engine so that it will be always level with heat exchanger. - Perttu ------------- Check my sailing videos - http://www.youtube.com/user/l11483?feature=results_main |
Posted By: Zwerver
Date Posted: 24 April 2016 at 20:46
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I had the same issue with my 325. Has been solved by changing the location of the coolant storage vessel on top of the Volvo Penta. I brought it up a few centimeters ( to the side of the compartment and reconnected. The problem seems to be that when motor sailing under an angle , the coolant forms sometimes an air lock whcih restricts the flow in the internal cooling system |
Posted By: Martin&Rene
Date Posted: 27 April 2016 at 17:52
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I have had problems getting the seawater to run through the engine when I first put the boat back in the water. One solution I now use is to run the engine at high revs immediately after starting as only then does the pump seem to prime. The seawater pump has to pull a vacuum so that the water will flow through seawater strainer and I should think the problem will be worse on the tack that places the seawater strainer at the higher level. ------------- Martin&Rene Hanse 341 Dipper Wheel steering, 3 cabin layout, normally based in Scotland |
Posted By: Martin&Rene
Date Posted: 28 April 2016 at 17:59
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Extra thought, before you start re-arranging items. When you start the engine to run slowly to charge the batteries when sailing, check there is a good flow of water coming out of the exhaust. The first flow of water can be just the water coming out of the exhaust waterbox, what you need to see is a continuous flow of water. If there isn't, then run the engine on high revs for a short period and hope this gets the whole system fully primed. Another extra thought, the alternator output and battery charging rate increases significantly the faster you run the engine, so running it a low speeds is not achieving too much. ------------- Martin&Rene Hanse 341 Dipper Wheel steering, 3 cabin layout, normally based in Scotland |
Posted By: Fiona
Date Posted: 24 May 2016 at 14:20
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Did some testing. When I went to a regatta last year the engine overheated after going from my port and to the starting point of the regatta when i lowered the rpm from 1800 to 1000 rpm. I attended the same regatta this year and did the exact same thing, going from my port to the starting point at 1800 rpm and lowered to 1000 rpm, result = No overheating this time. I will give more feedback when I have more experience, but it looks promising. How ever I still have some small leakage of freshwater, but itīs so little it is hard to tell where it origins... Cheers! //Magnus
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Posted By: Sylvie
Date Posted: 09 June 2016 at 14:18
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thanks for the advice everyone , i have now moved my coolant header tank up 20cm unto the white bulkhead in the engine compartment and have motorsailed on port tack in 12 knots of breeze going upwind with full sail at 2000rpm and have had no overheating problems whatsoever, unlike before see photo
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