I would suggest putting an hour aside to watch a whole series of Barnacle Buster youtube videos. There is a problem with the cooling system somewhere out of sight. Don't necessarily have to use Barnacle buster as it's very expensive for just a mixture of phosphoric acid, I use Metal Gleam which is about $35 for 4 litres and is enough to flush 20 engines and scrub down a dozen yachts.
Clean the cooling system and see if the problem persists.

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Saskia II said..

garymalmgren said..
I'm back on board tomorrow to work though this, so i'll keep everyone posted.

Steve

How'd ya go, Steve?

gary

Hi Gary, all seemed fine when I raced a fortnight ago. Motored at 1800rpm for an hour both to the start and return to the Marina, then it happened again last Thursday! Left the marina, pushed the revs up to 2100 and 20 mins later engine shutdown..... had to quickly set sails and attach the anchor (racing so not allowed to have it set up on the bow roller). went below and dipstick had not blown out but coolant was boiling again. We raced and on the sail back i topped up the coolant and she started again fine, 1500rpm back to the berth..... have noticed the paint has darkened around one of the cylinders too. Mmmmm......

Mmmmm indeed. What colour is the oil again? If it's milky, you've blown a head gasket. If it's not, you may still have blown the head gasket into the water jacket, creating additional pressure into the cooling system. The discolouration of the paint on the one cylinder would perhaps suggest that's the culprit.

Headgasket failure will either discolour the oil or show bubbles in the heat exchanger. If the engine runs an automotive coolant you might also smell a sweet smell at the exhaust. Not starting easily might also indicate a head gasket problem.

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mixture of phosphoric acid, I use Metal Gleam ..... to flush 20 engines

I assume this means you use Metal Gleam to flush the entire engine block plus heat exchanger. Sounds like what I need.

Though given that it is an acid, is it safe for the typical marine engine block - aren't there rubbers or seals or stuff that can be damaged by an acid flowing through the block ?

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Karsten said..

mixture of phosphoric acid, I use Metal Gleam ..... to flush 20 engines

I assume this means you use Metal Gleam to flush the entire engine block plus heat exchanger. Sounds like what I need.

Though given that it is an acid, is it safe for the typical marine engine block - aren't there rubbers or seals or stuff that can be damaged by an acid flowing through the block ?

Metal gleam is harmless to everything except rust and calcium. It does etch aluminium but has no effect on cast iron blocks, copper and brass or any seals. I don't even wear gloves though it does sting if you have a cut. Watch out for your eyes though!

So, i finally made it back to the boat after a few busy weeks and, after a lengthy conversation with a marine engineer, who suspected a faulty thermostat I ordered a new one, a spring and a new gasket and set to work dismantling 'the beast' as garymalmgren so aptly called her! This involved disconnecting the battery, draining the cooling system, removing the alternator, disconnecting all the cooling pipes, removing the relay box and the exhaust elbow before i could remove the heat exchange unit. As Ramona suspected it was a problem with cooling system, a completely blocked thermostat, so blocked i had trouble getting it out. Full of green crusty gunk! I then completely cleaned out the heat exchange, installed the new thermostat, spring and gasket, reassembled and started her up. Within 5 minutes the coolant started the heat up in the exchange, i put the cap back on and ran the engine for 20 mins. the engine block was hot to touch, as was the heat exchange and all appears to be working fine. Prior to changing the thermostat I had run the engine for 20 mins and the exchange did not warm up at all, so I believe the problem has now been sorted, except for the failed alarm. Next job will be to test the sensor and replace it if necessary. Happy to say I went out on Sunday and ran the engine at 2000rpm for 45mins with no issues! Thank you all for the advice and guidance, it has saved me over $600 in repair costs. I will start a regular flush of the system with Metal Gleam from now on to hopefully avoid the problem again. Looks like it's time to get back to twilight racing tomorrow! Steve

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Saskia II said..
So, i finally made it back to the boat after a few busy weeks and, after a lengthy conversation with a marine engineer, who suspected a faulty thermostat I ordered a new one, a spring and a new gasket and set to work dismantling 'the beast' as garymalmgren so aptly called her! This involved disconnecting the battery, draining the cooling system, removing the alternator, disconnecting all the cooling pipes, removing the relay box and the exhaust elbow before i could remove the heat exchange unit. As Ramona suspected it was a problem with cooling system, a completely blocked thermostat, so blocked i had trouble getting it out. Full of green crusty gunk! I then completely cleaned out the heat exchange, installed the new thermostat, spring and gasket, reassembled and started her up. Within 5 minutes the coolant started the heat up in the exchange, i put the cap back on and ran the engine for 20 mins. the engine block was hot to touch, as was the heat exchange and all appears to be working fine. Prior to changing the thermostat I had run the engine for 20 mins and the exchange did not warm up at all, so I believe the problem has now been sorted, except for the failed alarm. Next job will be to test the sensor and replace it if necessary. Happy to say I went out on Sunday and ran the engine at 2000rpm for 45mins with no issues! Thank you all for the advice and guidance, it has saved me over $600 in repair costs. I will start a regular flush of the system with Metal Gleam from now on to hopefully avoid the problem again. Looks like it's time to get back to twilight racing tomorrow! Steve

Hi, have to ask, did you do as suggested and chemicaly flush the entire engine, particularly after finding that gunk, or just put it back together again with the new thermostat?

Hi Uncle bob, i have not yet flushed the whole engine with Metal Gleam yet, just with fresh water, and soaked and scrubbed the heat exchange completely clean. I plan on flushing the engine this weekend.

Steve

Well done Steve, it must feel good to finally have the problem sorted. Love the green sludge pics, more please when you do a flush.

I ran the engine for an hour yesterday at 2200 rpm , pushing into 15 kts against a 2kt tide on the way to the start line for twilight racing and she was happy as Larry ! Pleased to say we had a win too.

Hi Steve
Congratulations on getting the engine back on the road and the win. 5.8 knots!!

I was waiting for someone else to comment on the green jelly like gunk that has clogged up your thermostat.
Ramona posted information on removing calcium build up on engine internals. The vid he posted especially dealt with a heat exchanger.
That calcium build up is in the primary (seawater ) side of the cooling system.
Your green gunk is not calcium and not on the primary side.
It is on the enclosed (coolant) secondary side.

You have been lucky to catch the problem at this stage and avoided a serious and expensive engine failure , but there is still a problem lurking.
The green gunk is degraded coolant and more of it is still in the secondary cooling system, especially in the lofin tubes of your heat exchanger.

Sorry to say, it means. off with the exchanger and a really thorough flush through the tubes.
Then a flush of the engine block to remove as much of the jelly as possible.

I looked for reasons for this type of breakdown of the composition of the coolant and the culprit seems to be mixing two different type of coolant
But that is not gospel.
If you have added new coolant to the jelly already inside it would seem that it will eventually turn to gunk too and you will be back to square one or worse.

Gary.

Yes, the green stuff is coolant that has been contaminated by non compatible coolant. Always pays to top up with exactly the same coolant. The freshwater side will need a flush and then fill with coolant.

Good work Gary.

Hi all, when i pulled,it all apart I removed the whole heat exchanger unit from the engine block then the brass exchanger,from the smaller block I had removed and soaked and scrubbed it and flushed the inside of the removed block with high pressure until I could see no more. I also completely drained the internal cooling system, removed all the hoses and cleaned them out too. Then I took the pressure hose into the cabin and flushed the engine block as best as I could. Put the whole lot back together and filled with new coolant. The green gunk was more crusty than jelly like and I suspect salt water has made its way into the coolant sometime in the past. I have only had the boast for two years and the engine is 9 years old so not sure how well it was maintained previously. I have records of it being serviced but that doesn't mean much, as when i had a service last summer it was a changed of all filters, new oil, impeller check and throttle adjustment, but no more. A test and a tick of approval from the Volvo authorised mechanic, all for the bargain price of $900 ! Hate to imagine what this job would have cost me had I left it to the experts. I plan to remove and check the thermostat again in a few weeks, just to see if anymore crystals have started to block it. I am not loosing any coolant, nor does it overflow so I believe the clamps on the elbows to and from the exchange are sealed.

Leaning, learning, everyday ! Happy sailing

Steve

Just make sure you top up the engine coolant with exactly the same coolant each time. Those crystals are from an incompatible coolant

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Saskia II said..
Leaning, learning, everyday ! Happy sailing


... when i had a service last summer it was a changed of all filters, new oil, impeller check and throttle adjustment, but no more. A test and a tick of approval from the Volvo authorised mechanic, all for the bargain price of $900 !

Steve

Well done - always learning!!

Get yourself a manual & there should be some YouTube vids on how to change oil & filters & impeller & do it yourself next time - it's not rocket science!!
I replace my impeller every service as opposed to check it - they're not expensive & it's cheap insurance. You always have a good spare as well.
After I do my service I always get new filters, fuel & oil, & impeller to have ready for next time & I then always have spares.

All very interesting, I've been told not to mix coolants, an I guess it's a colour coded thing, don't mix the red with the green ?
Lazz, I change oil, oil filter, fuel filter and transmittion oil every 100hr, also clean the heat exchange which entails a change of coolant, and I thort that was a bit obsessive, how many hours do you change that impeller at ?

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woko said..
All very interesting, I've been told not to mix coolants, an I guess it's a colour coded thing, don't mix the red with the green ?
Lazz, I change oil, oil filter, fuel filter and transmittion oil every 100hr, also clean the heat exchange which entails a change of coolant, and I thort that was a bit obsessive, how many hours do you change that impeller at ?

Yeah, changing the impeller every 100 - 150 hours or yearly (or thereabouts) is probably a bit obsessive but I reckon it's cheap insurance!!

A timely reminder then, just checked the maintenance log ..... 300hrs / 4years since the impeller was changed, we are due for a service will flip a new impeller in while I'm at it

Thanks for the advice Ramona and Lazzz, i'm an ok petrol motor mechanic (read chef! ), had an EH Holden once and did everything myself. I did download a workshop manual prior to the thermostat repair and will now do my own servicing as it doesn't seem too hard. I do carry spare filters and both impellers on board and it's coming up to a year now so a service is probably due. Ramona, when yo say don't mix coolants do you mean colour or brand? I have used Nulon and Penrite premixes. Should I just stick to one brand? I have checked the labels and they seem compatible?

Steve

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Saskia II said..
.... had an EH Holden once and did everything myself.

Steve

Now you're talkin!!!!!!
Beautiful car, mine was red, because they were the fastest!!! Bored out to 192ci, triple SU's, extractors blah, blah blah - was pretty quick in 1972. Loved it

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Saskia II said..
Thanks for the advice Ramona and Lazzz, i'm an ok petrol motor mechanic (read chef! ), had an EH Holden once and did everything myself. I did download a workshop manual prior to the thermostat repair and will now do my own servicing as it doesn't seem too hard. I do carry spare filters and both impellers on board and it's coming up to a year now so a service is probably due. Ramona, when yo say don't mix coolants do you mean colour or brand? I have used Nulon and Penrite premixes. Should I just stick to one brand? I have checked the labels and they seem compatible?

Steve

Colour has nothing to do with it. The colour is often different with long life coolants. Different coolants are mainly for modern aluminium block engines and have different chemicals. The problem is usually from people putting the best, most expensive stuff in their engines with out flushing the coolant system first. The old and new don't mix and the results are a jelly or crystal mix. I use Penrite in all my cars and one engine is cast iron and the other two all alloy. Most coolants now will handle both but different companies use different chemicals so choose a brand and stick with it. Certainly, don't top up with a different coolant.

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Ramona said..

Saskia II said..
Thanks for the advice Ramona and Lazzz, i'm an ok petrol motor mechanic (read chef! ), had an EH Holden once and did everything myself. I did download a workshop manual prior to the thermostat repair and will now do my own servicing as it doesn't seem too hard. I do carry spare filters and both impellers on board and it's coming up to a year now so a service is probably due. Ramona, when yo say don't mix coolants do you mean colour or brand? I have used Nulon and Penrite premixes. Should I just stick to one brand? I have checked the labels and they seem compatible?

Steve

Colour has nothing to do with it. The colour is often different with long life coolants. Different coolants are mainly for modern aluminium block engines and have different chemicals. The problem is usually from people putting the best, most expensive stuff in their engines with out flushing the coolant system first. The old and new don't mix and the results are a jelly or crystal mix. I use Penrite in all my cars and one engine is cast iron and the other two all alloy. Most coolants now will handle both but different companies use different chemicals so choose a brand and stick with it. Certainly, don't top up with a different coolant.

Thanks Ramona, your advice, and that of others, has been invaluable! ( actually more than $700 in value

Cheers, Steve