Pending catastrophic engine overheat?

[MickJ]

Engine is a Volvo AD31. I've been ignoring a possible temperature issue, am I being wise?

When I bought the boat in July, the temp would settle at 82 degrees @3350rpm. 61 hours later, it settles at 86 degrees @3350rpm. I had put this down to increased drag due to weed etc, but the following 3 cooling system issues are telling me not to be so sure...

1- I'm loosing a very small amount of coolant. There's no obvious leak, and during a recent 40 mile trip at full cruising speed, we lifted the engine bay and couldn't see anything wrong. However, there was the usual small puddle of coolant in the bilge at the end of the trip (although not enough to push the header tank level below MIN).
2- When stressing the engine (on the edge of planning with increased weight etc), the temp needle keeps flicking past 90 degrees momentarily (no longer than a second). I can actually hear the needle 'pinging' as flicks up and down.
3- The engine is 5yrs old, and it seems its only since I've had it that the paint has cracked and fallen off the hoses.

Any thoughts? I had a major service in July, the impellor etc was replaced.

Many thanks...


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[[2068]]

Hmm, I had similar issues with an AD31-XD.

It turned out to have several problems, the main one being a leaking cylinder head gasket. In your case, you need to find the source of your leak - it's not easy to spot leaking green fluid on an engine painted green, but it can be done by feeling around for damp areas after running, or running with the engine hatch open under load (careful !).

Also, the heat exchanger that was getting clogged up. These can be cleaned at at reasonable cost if you can drain the cooling system and remove it yourself (do NOT use any kind of acid, whatever people tell you)...

Overheating issues on these engines don't normally go away without some kind of intervention.

hope this is of some help.
dave.

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[tcm]

86 degrees is not a problme imho -but keep an eye on it.

i think the coolant leaks shows they (someone) filled it chock full. UNder 90 degrees is ok. the paint crackling shows you are using it, unlike the previous owner. The warmer seawater at the monet may account for the small temp change. Or the themrstat may be on the way out. Of the extra coolant reduced running temp. 86F wd not trigger an ooer from a surveyor i think.

But i think you are right to keep an eye on it, as it is changing. But not right to consider ripping the engine apart. A thermostat allows more/lesss water to flow around, and if it's busted that could cause it. there's an impeller which draw water in, and that could be busted. A service (and it might be time for one) wil show what's what, but ithink it unserious.

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[MickJ]

Many thanks, I'll just keep an eye on it for now then.

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[scottie]

water level

it is not unusual for an engine to find its own capacity and blow out the excess
this can appear as a leak situation but if the same ammount is required to top up the system every time and with not topping up it remains constant leave at that level
this is more likely with a calorifier fitted


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[Col]

That would be my answer too. Don't looses sleep, but keep an eye

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[oldgit]

Temp gauges on my 40As have risen approx 5 to 6C this summer compared to last winter .

<hr width=100% size=1>Two boats please one here n one in the Med

 

[stamfordian]

Don,t think you have anyhing to worry about ,i have had the same thing on my small boat with a ford fsd with bowman heat exchanger, the first 3 times i started it from cold as soon as it reached 60 degrees the cap would blow and water everywere,in use i have ignored this and the level in the header has settled to about an inch below the fiiler neck,the engine runs between 80 to 85 degrees and has stopprd leaking(yes i did buy a new pressure cap inthe process),if you have a oiltemp guage monitor this ,it will give yoou a better indication of possible catatropical events that might take place,as for cracking of hoses...do cars come with paiNted hoses ...no thats cos they flex too much{smile} many times,
seriousy regards t.B

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[[2068]]

I still think you need to find where that coolant is escaping from. If it's from the expansion tank blowing off a bit, you should be able to see. And it should stop blowing out once the level has reached maybe an inch below the max mark, unless you keep topping it up.

If this is the case, then fine.
else...

nag nag nag...


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[MBJB]

I've been told that ill fitting injector sleeves can also cause this problem. Under load, the cooling system can be overly pressurised which can lead to lost coolant. No idea if it would affect the temperature though.

On mine, the giveaway is the slight residue from the leaking injector(s). Having said that, under the loads my engines normally operate at on the river, it isn't a problem - only when some welly is applied.

I still need to fix it though. Hope your problem is cheaper to sort out....

Mike

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