Merry Fisher 805 cooling problems

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ianmac955i

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Hi Every one,

This is my first attempt on the Form,

I am in need of some help, I own a Merry Fisher 805 circa 2004 with 680hrs on a Nanni 4.390 tdi. last year it started dumping its coolant into the bilge only when I take the engine to full power. Eventualy this resulted in a cracked cylinder head and was replaced at huge cost. Only 25hrs latter it has started again ie dumping the coolant into the bilge, it will be a matter of time before I will have to change the head again. I have fully checked the cooling system and it appears ok. Any Ideas please help :(
 
Try 'minting' the engine.
Then cover pipes, manifolds. heat exchanger etc etc with Talc!
Drive flat out with an observer (with ear protection!) to peer/crawl about the engine bay to spy where the coolant is leaking from.

My first thoughts are the end caps of the heat exchanger as a point of leakage , maybe the exhaust gaskets too.

Coolers and heat exchangers etc suffer from electrolysis.
A 6 year old boat could have this kind of problem.
Especially when connected to shorepower in some Marinas.
Even when seemingly all anodes etc are suitibly set up.
Then again, could just be a pin prick in a pipe !!

The source of the coolant Must be found!

Good luck
K
 
Doubtful that the head is shot in so few hours. So it's one of two "things". You had a leak last time that resulted in you overheating the engine and cracking the head, you've fixed the head, but the leak is still there. Or the head just cracked and it has not been correctly fixed. Changing the head on your engine should also mean changing the fixing bolts. With a new engine they need to be checked after 20hrs, so it might be wise to do so after a rebuild. Your engine is based on the 3.0 litre D-4D Toyota Land Cruiser engine, so most of the service/repair parts can be sourced from Toyota dealers or motor factors.

To find out which, without a big headache, find a garage or competant marine engineer local to where the boat is kept and get them to check for combustion gases in the cooling system. If you're a little bit mechanically minded/competent yourself, get one of these and do the test yourself, it's very simple to do :

http://cgi.ebay.co.uk/UNIVERSAL-BLO...iagnostic_Tools_Equipment?hash=item1e5a54966e

If the test shows positive for combustion gases, it's a head off job. You'll need to find the source of the combustion leak. Cracked head, cracked block or leaking gasket.

If the test is negative, you need to find the source of an external leak. A prime suspect for an external leak is the raw water cooling pump. If it leaks, you can reseal it, but check the bearings are not worn, if they are, they can also be changed. A pair of bearings and both seals can be acquired for about a tenner.

If you don't fix it and continue using the engine, you kill it. A bare motor is around 10k !
 
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If you can get hold of a pressure tester, that will save you having to crawl about in the bay with the engine running, simply fit to header tank and pressurise, then examine engine for leaks. If none are found and the gauge still drops then I would suspect the head is defective, or it could be something as simple as the header tank cap having a weak spring or worn sealing ring. Another way to check for combustion in the jacket is to watch the water in the header tank, if you see fine needle bubbles 10 to 1 the head gasket is shot. Also since the refit does the temp get high? could be the thermostat. Lots of reasons but start with the pressure tester.
 
omega2 said:
If you can get hold of a pressure tester, that will save you having to crawl about in the bay with the engine running, simply fit to header tank and pressurise, then examine engine for leaks. If none are found and the gauge still drops then I would suspect the head is defective, or it could be something as simple as the header tank cap having a weak spring or worn sealing ring. Another way to check for combustion in the jacket is to watch the water in the header tank, if you see fine needle bubbles 10 to 1 the head gasket is shot. Also since the refit does the temp get high? could be the thermostat. Lots of reasons but start with the pressure tester.
Click to expand...

John, the simple combustion gas test above categorically determines whether it a combustion leak or a water leak, beyond any doubts at all. If it passed the combustion gas test then your advise above is good, but for me, especially given the engines history, the combustion test is the first step.
 
ianmac955i said:
Hi Every one,

This is my first attempt on the Form,

I am in need of some help, I own a Merry Fisher 805 circa 2004 with 680hrs on a Nanni 4.390 tdi. last year it started dumping its coolant into the bilge only when I take the engine to full power. Eventualy this resulted in a cracked cylinder head and was replaced at huge cost. Only 25hrs latter it has started again ie dumping the coolant into the bilge, it will be a matter of time before I will have to change the head again. I have fully checked the cooling system and it appears ok. Any Ideas please help :(
Click to expand...

Hi I surveyed the same model of boat and engine last week, this one only done 70 hours.

The d4d engine is very simple, but do you have an expansion bottle from the heat exchanger,most jap engines have these, yanmar etc, so if not fit one and see if that cures it, reason is that its syphoning out once it starts to pour out, if it goes to a bottle then it can be contained.

Heads and engines that overheat only do it for a reason so id also be looking at the whole installation and check its right for the job.

If its overheating its for the usuall reasons, impellers, blocked intake etc, exhaust probs, block or melted silencers.

However if and I say if, the whole installation is wrong, ie too small exhaust, wrong water intake hose and skin fitting size then its never going to work properly, so id get an expert to take a look.
 
volvopaul said:
Hi I surveyed the same model of boat and engine last week, this one only done 70 hours.

The d4d engine is very simple, but do you have an expansion bottle from the heat exchanger,most jap engines have these, yanmar etc, so if not fit one and see if that cures it, reason is that its syphoning out once it starts to pour out, if it goes to a bottle then it can be contained.

Heads and engines that overheat only do it for a reason so id also be looking at the whole installation and check its right for the job.

If its overheating its for the usuall reasons, impellers, blocked intake etc, exhaust probs, block or melted silencers.

However if and I say if, the whole installation is wrong, ie too small exhaust, wrong water intake hose and skin fitting size then its never going to work properly, so id get an expert to take a look.
Click to expand...

It isn't fitted with a header tank in an 805, the heat exchanger is the highest part of the cooling circuit.
 
More info is needed really and any suggestions are going to be educated guesses.

Sounds to me like the cooling system is getting pressurised by escaping combustion gases. Was the new head correctly torqued down and re- torqued after a period of settling? Were new head bolts fitted?

Can you see any signs where the coolant is escaping from? What sort of amounts are we talking about? If it's only a small amount it can be difficult to detect the leak, but larger amounts are more obvious. You need to get it hot and have a poke around to determine where it's comnig from.

Is the engine actually overheating?

My guess is it's blowing it out of the filler cap due to over pressurising, either due to combustion gases getting into the cooling system or a blockage. Don't forget to check for leaks from the calorifier.

If you're not sure, and in view of the potential costs involved, probably best to get a trustworthy engineer to take a look.

You don't say where you keep your boat, a forumite may be able to point you in the right direction. I'm intrigued as to how a MF 805 can be 'circa 2004'. If it is 04 I think it may be one of the first to have that engine, but I might be wrong.
 
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Philiz said:
<snip>

You don't say where you keep your boat, a forumite may be able to point you in the right direction.
Click to expand...

I meant to ask where he was Phil. If he's anywhere sensibly local to me or my boat, i'd be happy to call in and carry out a combustion leak test and have a nose around. I'm a mechanic (not a fitter or a technician :)) by trade and i also have an 805, so i might be able to help.

I'm intrigued as to how a MF 805 can be 'circa 2004'. If it is 04 I think it may be one of the first to have that engine, but I might be wrong.
Click to expand...

The Nanni was introduced during 2003.
 
Merry Fisher 805 Cooling

Hi Folks,

I,v been away all day and only just read your reply,s.

The new head was torqued down as per the manufacturesrs reccomendations with new strech head bolts. It appears that the coolant is being dumped out of the header tank breather, and only when the engine reaches full boost on the turbo. It will happily run at 2000rpm all day and never overheat (80 DEG) no more. I realy appreciate your efforts and sugestions. The boat spends most of its life in the Calidonian cannal in the Highlands.
 
Hmm, that's 500 miles away, so i'm afraid i won't be popping down for a look lol

I'm sticking with my guess that it's got a head gasket leak, or similar problem. Of course, it might just be a simple header tank cap faulty.

As i'm sure you already know, this engine should happily sit at 3,000/3,200 RPM all day long. My advice would be to pop a new cap on the tank first, just to be sure. Then, i'd get the kit i linked to earlier and check for head gasket leaks. I'd almost dare to bet £50 that it'll fail the test. It's really easy to do Ian, you just have to run the engine up to temp, put some fluid in the tester and hold it in the top of the header tank, where the cap fits. If there is a leak, the fluid changes colour, simples.

So, so sum up :

a) Fit new cap
b) Test for combustion leaks
c) If it fails (b) you could try checking the bolt torques, they need to be checked at 20 hours on a new engine.

If all of the above fails, the head needs to come off.

If it passes the combustion test, you know the head can stay on and need to look for other problems.

A cheap test that takes 60 seconds to carry out will narrow the possibilities down immensely.
 
ianmac955i said:
Hi Folks,

I,v been away all day and only just read your reply,s.

The new head was torqued down as per the manufacturesrs reccomendations with new strech head bolts. It appears that the coolant is being dumped out of the header tank breather, and only when the engine reaches full boost on the turbo. It will happily run at 2000rpm all day and never overheat (80 DEG) no more. I realy appreciate your efforts and sugestions. The boat spends most of its life in the Calidonian cannal in the Highlands.
Click to expand...

Sounds like you're getting an increase in pressure in the cooling system at higher revs allowing the coolant to blow past the pressure cap. As PG says, almost certainly combustion gases passing into the cooling system causing the pressurisation, possibly cylinder head gasket (you didn't say if you nipped it down after settling in). Was it determined why the original cylinder head failed? Was the cylinder block face checked for trueness?
As PG says, start simple, replace the pressure cap first, easy and cheap, then do the combustion gas test.

You're too far away from me too! Anyone up there who can help?
 
Merry Fisher 805 Cooling

Once again,

Thanks for your help, I will start with the header tank cap and follow on from there. But I am sure it will be a head off job again. I hope it isnt cracked as last time, Nanni £1400, Toyota £700 no contest. Being a good Scot every penny counts.

Cheers Ian
 
ianmac955i said:
Once again,

Thanks for your help, I will start with the header tank cap and follow on from there. But I am sure it will be a head off job again. I hope it isnt cracked as last time, Nanni £1400, Toyota £700 no contest. Being a good Scot every penny counts.

Cheers Ian
Click to expand...

Keep us posted Ian. I doubt the head would crack after just 25 hours, if so i'd be wanting some warranty work done.
 
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