Sanity check

[pappaecho]

I started my 4108 today, having bought the boat in Novemeber last year. It always starts on the button. However, there is a loss of coolant from the fresh water side, which ends up in the exhaust... nice blue type antifreeze cooling water from the raw water pump.
The first thought is blown head gasket, even though there is good compression on all cylinders. Any body think of other causes, as I will rip off the head tomorrow, and so if the head gasket is OK, must look for other reasons like head or heat exchanger faults

 

[tugboat]

If the fresh water coolant has transferred to the raw water system the prob will be in the heat exchanger. A tube or tubes gone or maybe just a gasket. You'll need to take off the end cover and then eliminate each possibility.

 

[LeytonC]

Which type of heat exchanger have you got? I have the Bowman one that sits infront of the engine with a seperate water cooled manifold - and i had to replace the tube stack last year, so dont panic they are still made. In fact I went to Bowman in Birmingham and they made me 1. Also Bowman can supply the rubber seals as well.

Hope this helps ;-)

 

[kandoma]

the compression needed to start a diesel engine is so high, (compared to a petrol engine) that the blown cylinder gasket does not apply to diesel engines. Either it starts or it does not start. If it starts, then the gasket should be ok.

Peter

 

[ShipsWoofy]

Sorry but I disagree with this.

I had a diesel Citroen BX which had a hairline fracture between no.2 and no.3 cylinders. This also destroyed the head gaskets, but it always ran. The main symptom was that it emptied the radiator in around 30 seconds as the pressure was getting into the water jacket.

There was no loss of power to the engine, it would just overheat as it had no coolant.

Not trying to split hairs, but nothing is so simple in reality.

 

[boatmike]

I would agree with Tugboat. Before you start disturbing the head check the heat exchanger stack. This is very much easier to check than taking the head off and is the likely cause if the engine is otherwise OK.

 

[boatmike]

So do I. Unless the leak affects all cylinders and is very bad the engine can start and run with a head gasket leak. I have indeed seen a fair number of pistons and con rods destroyed by a hydraulic lock on one cylinder caused by water when the engine fired on the other cylinders.

 

[oldharry]

Much more likely the heat exchanger. And I agree also that a blown head gasket does not make much difference to a multi cylinder diesel start and running, although it may well sound a bit different, and the power would be down. The fact that you can see uncontaminated coolant in the exhaust points to heat exchanger too. If enough coolant to be visible is escaping, then it is unlikely to have passed through the combustion chambers without wrecking the engine by hydraulic lock.

 

[angelsson]

Hi all,
As usual lots of help at hand here, I have a 4108 but without a heat-exchanger fitted for providing hot water for galley and shower. Is it possible to fit one to my unit? It is fairly old but runs sweetly, starts first time and no smoke. Also not had it long and have used the spare filters ie, oil and fuel, that came with it, is it best to use Perkins originals or are other makes as good? Advice on where to source either would be appreciated. have tried the Perkins site but not found anything helpfull.
Thanks,
Mike

 

[tugboat]

I make no claim to being a whizz with engines (just the opposite actually) but think I must be missing something here. Surely if there was a head gasket problem the freshwater coolant would blow out the pressure release cap into the engine bay/bilge rather than appear in the raw water outlet. I thought engine systems were properly designed to have different pressures in them so that cross contamination didn't take place in the wrong direction in the event of a component failure. I realise of course that there might be a weak spot somewhere due to wear and tear. Signed- confused of Devon! /forums/images/graemlins/confused.gif

 

[paddywackcocker]

I would be inclined to agree with the heat exchanger idear. If the head gasket was faulty to the point of a noticable amount of coolant being ejected you would most definetly have starting/hydrolock problems, as it would be a water jacket to seal ring problem and allowing quite a bit of coolant into the cylinders. It is possible to have head gasket problems and still have perfect start up and run but as above, due to the high presures involved with the a compresion ignition engine you would have water jacket presure, to the point of the presure release letting go.
All that said there is another idear to think on (just incase the exchanger tests OK, and no over the norm presure with temp buld up) there could be a crack on the exhaust port of the cylinder head. As the engine will normally stop in the same place (never got to grips with that bit but seen plenty of ring gears that do) if the crack was on the cylinder with a closed exhaust valve then this could bleed off serficent coolant into the exhaust system itsself giveing the synptoms, but not known as fault with 4108. Any way I would start with the exchanger and you should be able to have a good look at the ports as you remove it. Any way, better get back to my knitting

 

[pappaecho]

Thanks to all who replied - the fault lay in the heat exchanger and not the head gasket as diagnosed originally.
The previous owner ( now deceased) has made up a gasket, on the end of the heat exchanger, which is supposed to blank off the end of the cooling waterways, and has then the exhaust pipe offtake bolted onto the end of the heat exchanger. The owner had carefully perforated the gasket to allow fresh water to mix with saltwater!
One other problem the engine has no dipstick! That is to say there is a hole which is empty. Even the surveyor missed that one!

 

[oldharry]

Yes tugboat you are right in thinking that it is unusual for coolant to enter the combustion chambers normally. It can happen though if an engine is cranked without starting, or if the engine fires, but not on the affected cylinder, when coolant can be sucked in on the induction stroke. In the case of a very bad leak (again unusual, but not unheard of), enoughy water can enter to stop the piston reaching the stop of its stroke. Water will not compress at all, so the energy has to go somewhere - usually bending or breaking the con rod, which may then go through the side of the block! This is more normally seen if water is ingested through the air intake of a running engine - with instant and catastrophic results!

For there to be enough coolant in the exhaust of Pappaechoes engine for the colour to be clearly identifiable means that quite a lot of coolant is escaping - and too much for the head gasket to be the cause without other major problems arising.