Overheat and coolant escaping?

[Andy Bav]

First time out in 2 weeks today. Tick over up to 1500 revs ok. Pootle around the bay ok. Up the revs turbo kicks in all ok for a minute or so then over heat, 104 degrees. Drop revs cools back to 85 in 30 seconds up revs, after a minute temp shoots up so back off again. Do this for 3 or 4 times to limp home. look in engine bay and liberal "spattering" of coolant. Cap on tight level.hasn't dropped noticeably...

Any ideas and should I try again tomorrow or leave it for an engineer on Monday?

 

[powerskipper]

sounds like you have a particle blockage, check filters, when running is the impeller housing staying cold. If on an outdrive , lift the leg and give the intakes a good scrub, if weeded up they might be restricting the amount of water being able to get pulled into engine.The coolant escape is caused by the water heating up more than there is room for, ie above normal running temp.

 

[enterprise]

Hi Andy,
Is it on both engines?, are the intakes clear of fouling
could be impeller missing a few blades or partial blockage on the raw water side, both easy checks.
Hope it's sorted soon

 

[superheat6k]

Interesting that you are losing coolant, but haven't noted a drop in the level. I found this issue when a heat exchanger became punctured (not the overheat symptom). This overheat as described is very rapid, and pressuring the FW system at higher power - not good news. My suspicions would be a blown head gasket.

What engine ?

 

[FalconSteve]

Hi Andy, also worth checking thermostat on the fresh water side. If it's impractical to boil it in a saucepan, take it out and reattach the housing and see if the overheat is cured in the water.

Steve

 

[Andy Bav]

Interesting that you are losing coolant, but haven't noted a drop in the level. I found this issue when a heat exchanger became punctured (not the overheat symptom). This overheat as described is very rapid, and pressuring the FW system at higher power - not good news. My suspicions would be a blown head gasket.

What engine ?

Thanks. D4 260.

Not sure if "controlling" overheat helped or not. Watched a fairly orderly rise in temp from 85 through to late.90's.and backed off, hence possibility for "expansion" of.coolant..

There seemed to be some coolant around cap, which made me.think.I didn't tighten it enough when doing checks, but it was on tight... Thankfully less.than.a.year old so.warranty issue... Hopefully..

 

[[2068]]

I think you can probably forget about blown head gaskets on a newish D4-260.
Start with the simple stuff first, and follow the sea water circuit around.
Intake, impellor, strainer, then heat exchanger.

A minor overheat will always cause a bit of coolant to be ejected: this is a symptom, not the cause.

 

[Andy Bav]

If an escape of coolant is normal I'll have another go tomorrow.

Timed over heat, worked @85 for roughly 50 seconds before temp started to climb.. Wondering if time will increase if blockage gradually clears - if that's what it is..

Thanks for all comments.

 

[Momac]

I don't have the same engine but I do have diesel inboard+outdrive........
Only couple of times I have had an overheat it has been some debris on the leg intake - maybe a polythene bag or the like. Stopping the engine has cured the fault. But if your fault persists you may have something stuck on or growing in the leg intake . I assume you have checked the raw water filter.
If the raw water impeller is damaged it could be fine at slow speed but not sufficient at higher speed.

 

[Andy Bav]

I don't have the same engine but I do have diesel inboard+outdrive........
Only couple of times I have had an overheat it has been some debris on the leg intake - maybe a polythene bag or the like. Stopping the engine has cured the fault. But if your fault persists you may have something stuck on or growing in the leg intake . I assume you have checked the raw water filter.
If the raw water impeller is damaged it could be fine at slow speed but not sufficient at higher speed.

Always wash raw water filter as part of daily checks, but after yesterday's run out there was a shrimp looking creature in it which suggests some sort of flow, but question is I guess whether we picked him up en route or if he was part of a bigger blockage that is starting to work its way through.... Had an overheat about 6-8 weeks ago which local Vp dealer could replicate once, but cleared through use, so tried same myself, but with no succes...

A bit alarming as have 85 y.o. Mother with us who.has never been on a boat before @?#

 

[superheat6k]

On reflection I have misinterpreted your initial description of a liberal amount of coolant leaving the engine. So yes does sound like a partial blockage in the raw water system, or partial pump failure. If you check the pump impellor check also that the shaft doesn't turn freely - a friend of mine had both pump shafts sheer on his D6 engines at about 1 year old.

 

[Andy Bav]

On reflection I have misinterpreted your initial description of a liberal amount of coolant leaving the engine. So yes does sound like a partial blockage in the raw water system, or partial pump failure. If you check the pump impellor check also that the shaft doesn't turn freely - a friend of mine had both pump shafts sheer on his D6 engines at about 1 year old.

After sticking in beach mode and chipping away at growth etc, took her out for a blast and behaved impeccably.... Think I may have found a new part of routine maintenance... Mum's (and mine) minds at rest.

Thanks for all suggestions and saving the weekend B-)

 

[Andy Bav]

Thought you may.be interested to hear the conclusion of this saga.

I spoke to VP today and they said that if the coolant gets too hot, there is a pressure release mechanism around / under the filler cap that sometimes allows for a "burp" of coolant, which is released from a clear pipe, behind and beneath the filler.... And into engine.compartment...