Protecting that Volvo from overheating
Printed From: The Fishing Website
Category: General Forums
Forum Name: The Boat Shed
Forum Description: Discuss all things boating.
URL: https://www.fishing.net.nz/forum/forum_posts.asp?TID=127606
Printed Date: 04 Jun 2026 at 6:36am
Topic: Protecting that Volvo from overheating
Posted By: ABT
Subject: Protecting that Volvo from overheating
Date Posted: 27 Mar 2018 at 3:54pm
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Well, I've had my Vindex 3000 (powered by a 2005 Volvo KA42) for a few months now and everything is going great, but I sometimes feel nervous that the overheat warning systems are pretty basic, and you don't watch the temperature gauge close enough all the time for that to be a reliable option. I have an overheat alarm, but how can you be 100% sure that's working until it actually happens? I thought it would nice to have a temperature gauge with an alarm built in, but that doesn't seem that easy to find. This water flow alarm from Aqualarm looks interesting: https://www.boat.net.nz/product/aqualarm-kit-with-panel-and-buzzer/" rel="nofollow - http://aqualarm.net/cooling-water-flow-c-2/ I'd be interested to know what others might have done as it can't hurt to have multiple types of overheating warning systems. |
Replies:
Posted By: SaltyC
Date Posted: 27 Mar 2018 at 5:38pm
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I have 2 AD41P 200hp Volvos and trust the temp guage and overheat alarms. Have had the alarms go off pretty quickly when an impellor has failed and also when the raw water pickup has been blocked (through legs ... plastic bags grrrrrrr). I have checked my guages against the actual engine temps with a heat gun and they are accurate to within a degree as far as I can see. I installed these motors new in 1998 and haven't found the need for additional warning devices. Just my 2c
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Posted By: Tagit
Date Posted: 27 Mar 2018 at 5:40pm
| That unit looks like it only reads loss of water flow. Won't help if you have one of the many other causes of overheating. One thing you could look at is an exhaust pyrometer. This will pick up pretty much all the causes of an overheat. |
Posted By: SaltyC
Date Posted: 27 Mar 2018 at 5:43pm
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I should add I do monitor the temp gauges closely as they come up to temperature each time. I watch the temps rise and then the thermostats open and allow the coolant through the heat exchangers and the temp drop back down to normal operating temp. Just confirms each time that everything is operating correctly.
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Posted By: Don18025
Date Posted: 27 Mar 2018 at 11:18pm
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You should consider a preventitive maintenance programme of the cooling system. No doubt you are doing this with regular water pump impeller changes. Here are some ideas to avoid the engine overheating. Your motor is 13 years old, when were the heat exchangers last cleaned and tested? What is the condition of the cooling hoses and their clamps? Hot water system leaks in diesels cause a lot of call outs for Coastguard. Changing the engine coolant regularly. Water intakes clean and wide open. Do you clean your water filter often? |
Posted By: widerange
Date Posted: 28 Mar 2018 at 6:38am
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hot tip for owners of those "generation" engines, When was the rubberised V drive for the raw water pump last replaced? If you answered ,don't know or more than 12 months, I suggest you do this before running the engine again
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Posted By: Steps
Date Posted: 28 Mar 2018 at 7:33am
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Dont know about Volvos and such Old school SB chevy yes. The SB chevy has a water sensor on plug on the side of the block, and often another plug in the valley cover. As a warning light/ buzzer is a on/ off sensor and the temp gauge a resistance sensor are different and unique to each. The usual is to run 2 sensors , one for warning light/ buzzer the other for gauge. I believe there are duel type sensors available, thu I have never played with one. Oil pressure is far simpler.. a T fitting off the engine oil pressure port.. A pressure sensor in each spare port of the T.. one on/ off that goes to buzzer/ warning light, the other to gauge, be it electrical or capillary. I would be surprised if the volvo has only 1 port going into the water jacket.
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Posted By: ABT
Date Posted: 28 Mar 2018 at 3:00pm
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I like the idea of a pyrometer as another form of monitoring. This kit from EGT Digital looks quite good as it has the alarm function as well: http://thesensorconnection.com/gauge-pyrometer-kits/gauge-kits-marine/egt-digital-dpg-sd-series-pyrometer-gauge-probe-kit-marine-en" rel="nofollow - http://thesensorconnection.com/gauge-pyrometer-kits/gauge-kits-marine/egt-digital-dpg-sd-series-pyrometer-gauge-probe-kit-marine-en My current temperature gauge is not in my line of sight when helming and has slightly faded glass as well, which is why I would like something extra. Would there likely be an existing port to screw the probe in to, or would I need to drill a hole?
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Posted By: Tagit
Date Posted: 28 Mar 2018 at 3:16pm
| They normally get fitted after your mixer so you would probably need to make a hole. Put up a picture of your exhaust system from the turbo down to where the exhaust goes overboard if you can. |
Posted By: Garry 23041
Date Posted: 29 Mar 2018 at 7:50am
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The Alarms seem reliable but I can understand wanting a back up. On mine I changed a few things beyond the important maintenance Don and others stress' Marine engines are made in a cube so they can fit tight spaces. Once fitted if you want you can tweak that. In terms of cooling I have my K&N style large flow air filter on a short flexy hose mounted away from the engine a little so it gets gobs of air. With water I put a through hull in and have a much larger supply of raw water as far as the first engine pipe just below the pump. I got rid of the top of pump sea strainer which if it leaks or you drip it gets salt water on the engine and fitted a nice big sea strainer just after my new through hull. The through hull is nice also because I can shut off raw water when I turn off the bats after each trip which I like on a moored boat... I feel like the boat is well set up in terms of cooling now it has a little built in obsolescence. |
Posted By: Durban
Date Posted: 30 Mar 2018 at 10:35am
| The heat sensors is an open circuit once the sensor is activated by the thermal plate it becomes a closed circuit and engauges the earth to send the power to what ever you have an alarm or what ever . being a open circuit i dont see a problem connecting the kill wire to a sensor you fit on the motor as it gets activated by the thermal plate when it overheats it engauges the earth[ the boady of the sensor is the earth ] this will then instantly cut the motor and save you from a seased motor if you deaf and cannot hear the alarm . the ignition switch works on the same princiapal it connects the kill wire to the earth when you switch off . |
Posted By: ABT
Date Posted: 18 Jun 2018 at 3:18pm
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I didn't expect to be asking this question so soon, but if the engine got hot because the raw water seacock was closed (I won't go into it yet as to why, but it wasn't my doing), and the engine was shut down reasonably quickly after noticing the temperature gauge moving up - what should you be checking to make sure everything is okay? There was lots of coolant overflowing from the cap. Is it normally okay to open the seacock and start using the engine again if it's staying cool, or is it likely the impeller or something else is already damaged? Q1: Do most boaties leave the raw water seacock open or closed when berthed? Q2: Do you inspect that it is open before each trip? or only after someone else may have been on the boat? From what I experienced I still think the temp gauge and alarm is too late in this case in alerting me. Something should have alerted me when I idling slowly out of the marina, which is why I started this thread to begin with. Would of the exhaust temp shown something was not right earlier? I hate having a crash course in learning thse things....
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Posted By: Garry 23041
Date Posted: 18 Jun 2018 at 4:07pm
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I did this last year when I dropped a pulley. so hot it melted the hard plastic pipe from circulation pump to manifold! look and see if your manifold has changed color? is it a bit brown now or worse black. mine was slightly brown and my motor is good as gold still. your raw water impellor needs to be changed and you can tighten your manifold bolts as they can loosen from the heat (expansion contraction). run it up and watch for leaks for a while..... I always close my seacock on the mooring. if you want you can make a start checklist and a shutdown checklist and use that for a while..... |
Posted By: Tagit
Date Posted: 18 Jun 2018 at 4:44pm
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I think good advice from Garry above. Do the impeller and inspect for scoring inside the pump. Make sure you get all the impeller pieces out if it is broken.
Personally I don't close the seacocks unless I was leaving the boat unattended for a long time. If you inspect them regularly they are a low risk item. Sounds funny that you got hot enough to be dumping coolant without an alarm? If it is just set too high you can possibly get another one with a lower set point and just swap it out. Did you note what temp was on your gauge? |
Posted By: Garry 23041
Date Posted: 18 Jun 2018 at 5:21pm
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doesn't sound like it got super hot..... good point on the alarm being off. my alarm worked fine but it was a bit willing out and I had a guy in a wheelchair onboard and some other hassles so I made a bad choice..... |
Posted By: Bounty Hunter
Date Posted: 18 Jun 2018 at 6:30pm
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i leave my keys on the raw water strainer - which reminds me to open the salt water intake before turning the ignition. sighting exhaust water flow before moving off should become a subconscious habit in time as suggested above - a check list for getting started and closing up at the end of each trip might be something to develop. i have been considering one for myself ------------- No disintegrations! |
Posted By: ABT
Date Posted: 18 Jun 2018 at 8:12pm
The temp gauge went up a long way but I'm not sure where it stopped as I was too busy concentrating on slowing down, turning it off, and then checking the engine - and cursing a bit.
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Tagit wrote:Posted By: ABT
Date Posted: 18 Jun 2018 at 8:14pm
On a stern leg is there any visual check that water is coming out when in the marina? Seems hard to tell with the exhaust bubbling away.
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Posted By: Garry 23041
Date Posted: 19 Jun 2018 at 9:46am
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no you cant see abt. I had a mate who fitted a telltale on his and it shot a small jet of water overboard midships so he could glance from the helm... something else to go wrong though I reckon |
Posted By: SaltyC
Date Posted: 19 Jun 2018 at 9:52am
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ABT, You are right it is not easy to see whether you have cooling water flow through a stern leg. If you have reasonably easy access to the front of the motor an easy check for cooling water flow is to check the temperature of the front cover of the impellor housing with the back of your fingers. If there is limited or no flow this plate will heat up very quickly after the motor is started, It should always remain "cool" to the touch as the motor comes up to temp.
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Posted By: Garry 23041
Date Posted: 19 Jun 2018 at 10:42am
| true that saltyc good method. |