Overheating

[spannerman]

I have never ever seen a raw water intake as you describe and without a strainer. On all of the installations I have done I always fit a scoop type inlet with a built in strainer, same as you find on production boats. I am certain your problem is the flat intake is going into negative pressure as the speed increases and the raw water pump can't suck against it so your seawater flow dwindles and you overheat. If its possible to fit a clear section of hose somewhere in the raw water system you may see the flow falling off.

 

[Murv]

Don't tell me the heat exchanger is the same, hideously expensive tube stack setup as that bloody CAC?! *Sigh....*

Yes, thermostat is fine, it's brand new although there was nothing wrong with the old one as I discovered when I tested them side by side. But, fitted the new one anyway as a precaution.
The clear tubing is a great idea, the only lengthy section that isn't copper though is large bore with an acute bend but it may be worthwhile to monitor flow if I can find something.
Sounds as if a scoop would be a worthwhile upgrade anyway then, easily fitted when it comes out if I can find one.

New impeller is on its way. Apparently its a very good pump, although obsolete now, only Lancing now make them. Should arrive tomorrow so may be able to fit it by the weekend.

Get yourself one of the heat laser gun thingy's that will show the temperature at any area that you point it on the engine. This should identify the possible source of the problem.
I picked up one on Ebay.

Sorry, missed your post. One is on its way, they look exceedingly useful.
Quite honestly, it only took the words laser, gun and ebay and I was off a-clicking...

 

[omega2]

You may only require the rubber end caps! take them off and take a look at the tube stack, the raw water runs through the small holes and the fresh water surrounds the stack.

http://www.asap-supplies.com/marine/marine-heat-exchanger-tubestacks

if its anything like your CAC THEN CLEAN IT, and rod through the small holes.

 

[Murv]

You may only require the rubber end caps! take them off and take a look at the tube stack, the raw water runs through the small holes and the fresh water surrounds the stack.

http://www.asap-supplies.com/marine/marine-heat-exchanger-tubestacks

if its anything like your CAC THEN CLEAN IT, and rod through the small holes.

Superb, thank you, I will do that.
Thanks very much for the link, although it's just made me realise that there's yet another dreaded tubestack in the oil cooler!! There must be more value in copper in that boat than the thing is worth!

 

[superheat6k]

In addition to checking the heat exchangers are all clean - Rydlyme is the best stuff apparently, steam in the seawater cooled exhaust suggests insufficient flow, so perhaps broken bits of old impellor, or heavy crud build up - try squeezing the rubber pipes to check for a crunchy feeling rock build up.

+1 for a temperature gun and key point is the water temp just before the injection point, then downstream of the injection bend at a suitable metal pipe part. On my boat this runs quite cold, and even in high Summer stays below 45 C. Large volumes of steam would require the sea water quite a lot warmer.

On my VP TAMD60C it is vital to get rid of airlocks in the fresh water circuit, especially at the turbo charger, but don't know if this is an issue on your Ford unit.

 

[Murv]

In addition to checking the heat exchangers are all clean - Rydlyme is the best stuff apparently, steam in the seawater cooled exhaust suggests insufficient flow, so perhaps broken bits of old impellor, or heavy crud build up - try squeezing the rubber pipes to check for a crunchy feeling rock build up.

+1 for a temperature gun and key point is the water temp just before the injection point, then downstream of the injection bend at a suitable metal pipe part. On my boat this runs quite cold, and even in high Summer stays below 45 C. Large volumes of steam would require the sea water quite a lot warmer.

On my VP TAMD60C it is vital to get rid of airlocks in the fresh water circuit, especially at the turbo charger, but don't know if this is an issue on your Ford unit.

Thanks for that, I'm looking forward to having a play with the temperature gun, I imagine it will be very useful.
Good to know some approximate target temps as well, I was fairly sure that clouds of steam couldn't be right.
I just hope that the water pump will come off without too much of a fight, although I suspect it's going to be a real struggle.

 

[omega2]

Superb, thank you, I will do that.
Thanks very much for the link, although it's just made me realise that there's yet another dreaded tubestack in the oil cooler!! There must be more value in copper in that boat than the thing is worth!

Once you are happy that the water ways are clear then you know where to start, in your case you had no idea where to look, as stated the raw water system could be full of crud and bits of impeller, remember what you found in the CAC??

 

[lynall]

If you havent got a seacock on the raw water intake you will need to clamp the hose somehow, before removing impeller.

 

[Murv]

Hopefully this is the main problem.
The cam is broken, and before the lug snapped off it looks as if it's gouged the middle of the impeller.
In addition, somewhere along the line one of the screws that holds the front plate on has broken off, so someone has stuck the screw head over the hole with a bit of sealant.
Unfortunately, the large screw that holds the cam is turning to dust and won't come out, so as it's outside my area of expertise of repairing things with a lump hammer, I'm going to see if Cleghorn will repair it.

 

[rafiki_]

Hopefully this is the main problem.
The cam is broken, and before the lug snapped off it looks as if it's gouged the middle of the impeller.
In addition, somewhere along the line one of the screws that holds the front plate on has broken off, so someone has stuck the screw head over the hole with a bit of sealant.
Unfortunately, the large screw that holds the cam is turning to dust and won't come out, so as it's outside my area of expertise of repairing things with a lump hammer, I'm going to see if Cleghorn will repair it.

Looks like you found the root cause of the problem, well done. It is amazing what some people will do to bodge something up!

 

[Murv]

Thank you! will be nice if it is the cause.
I've uncovered a few interesting bodges along the way, another recent one was the row of holes drilled through the thermostat. I did wonder why it took so long to warm up before it overheated!

 

[omega2]

Holes in thermostat not uncommon, maybe the wrong one, check specs before you buy another, now you are learning the art of spanners take all the raw water bits off and clean them, it is not rocket science (as some on here would have you believe) re the deflector take the pump off, close the intakes first, then try again to remove the screw or even drill it out, the new deflector will have a new thread in it, so order a screw as well, the pump body (were the false screw is fitted) will accept a new screw, if you use a sealant, if not then there is enough meat to retap the thread, or even fit a larger diameter screw, Order new parts from jabsco shop, the pump number will be on the face plate. In essence you will need impeller, back plate, front plate, deflector, gasket, and screws.

http://www.jabscoshop.com/marine/pumps/bronze-engine-cooling-pumps/

do the gearbox oil cooler while your at it. Do not fret over this minor set back we all have 'happenings' but it's nice to be able to fix things without calling in the guru;s, look what one of them did to the Beatles. LOL

An after thought! the CAC will need inspecting again, could have bits of impeller in there.

 

[Murv]

Holes in thermostat not uncommon, maybe the wrong one, check specs before you buy another, now you are learning the art of spanners take all the raw water bits off and clean them, it is not rocket science (as some on here would have you believe) re the deflector take the pump off, close the intakes first, then try again to remove the screw or even drill it out, the new deflector will have a new thread in it, so order a screw as well, the pump body (were the false screw is fitted) will accept a new screw, if you use a sealant, if not then there is enough meat to retap the thread, or even fit a larger diameter screw, Order new parts from jabsco shop, the pump number will be on the face plate. In essence you will need impeller, back plate, front plate, deflector, gasket, and screws.

Thanks for the advice, I'd assumed that the holes in the thermostat were factory, but on closer inspection they're rough and not a manufactured job. Presumably an attempt to keep the temperature down?
It certainly runs no hotter with the new thermostat, just gets up to temperature a lot more quickly.
I will clean the heat exchanger, but need to get some assistance at the boat first. It comes off complete with the turbo so it's incredibly heavy, not a one man operation when stuck in the bilge!
I appreciate what you're saying about removing the screws, but I just don't have a steady enough hand for jobs like that. The screw, in particular, holding the front plate is tiny. I could try and drill it out, then replace with a nut and bolt but if I damage the body, I'm stuffed and there's very little room for error.
Problem is it's an obsolete pump. Lancing make them in batches of 20, they're not, apparently, made by anybody else and were only fitted to the FSDTI engine to cope with the extra heat from the turbo.
A similar sized pump is around £500.00, I've no idea how much a direct replacement is from Lancing but I think it's a far cheaper option for me to get it repaired professionally than to damage it myself and then have to replace the pump.

EDIT: Quick pic showing the broken cam, not even sure there's a backing plate in there?

 

[omega2]

No need to remove heat exchanger, just remove the rubber end caps, the crud will be obvious, rod through the matrix, and if you like just tap with a wooden mallet on either end to see if you get movement, I expect you will, although you could be tight on complete removal in situ, re the pump as I said the deflector is tapped to accept a new screw, so all you need do is drill away the old head, the ones in the face will need drilling and re tapping. You will find (hopefully) a back plate when you have the deflector out. Finally any numbers on front plate or send the full number stamped on the body not qite readable from picture. If not confidant take the body to a local engineer I am sure they would help, BIG FIRMS ONLY SELL STUFF, they have no idea about fixing or repairing, "Oh that bit? it will be in bin number 532" and no we aint got one. LOL

 

[Murv]

Right, gotcha, thank you. I thought I'd have to remove the thing which is not an easy job! I shall give that a go then
I see what you mean about the pump now, I thought the body was tapped as well as the cam plate. So, it's only the head that needs to come off.
I shall give it a cautious go, if not, there's an engineering firm down the road that I can try.
Thanks for the help, it's much appreciated,

 

[kashurst]

Hi Murv
on the pump in your photo it appears to be made by Jabsco with a part number. Try ASAP Supplies or Aquafax for spare parts. I suspect given the number of cooling issues you have found so far it would be well worth the effort of cleaning everything out. Don't panic about the intercoolers they usually come apart OK with patience and just need a few seals to restore them. Don't be tempted to reuse the old ones as internal leaks are not a good idea. I think a scouped inlet with a filter would help a lot too just to make sure.

 

[omega2]

Have you got one of these in your system?

http://www.asap-supplies.com/marine/remote-bracket-mounted-water-strainers-plastic

if not get one. try it before you fit a scoop inlet strainer. as they are prone to collecting foreign objects (plastic bags) and are not easy to clear when at sea.

 

[Murv]

Thanks very much both.
Yes, there is an inlet strainer in the system, it wasn't long ago that I discovered it. Obviously I've now cleaned it out, but it was surprisingly clear as I had hoped to find a few carrier bags blocking the thing.
A forum member has very kindly offered to look at my pump, and drill/tap where necessary in addition to replacing worn parts.
I'm going to try just running it with the rebuilt pump and see how it goes.
I'm reluctant to fit a scoop if not required because there is an awful lot of debris floating in the Medway, it also sits on soft mud at low tide so would suck through a globfull on every start up.
I'm also a little reluctant as I have all the receipts from the owner who repowered her, he spent a small fortune on the project and I don't think he would have omitted a scoop if it was needed.
If, however, it does still need one, I'll look into fitting one when it comes out.

 

[billskip]

Probably way off here, but I just noticed that you have a 50:50 antifreeze mix. Antifreeze is not as good a coolant as water - you could be loosing a possible 10-20% cooling capacity over a straight water (no anti freeze, not recommended) coolant at high revs. Could matter if system is already on its limits.

mmmm you sure about that?

 

[talltim]

Hi Murv

Glad to see your getting to grips with owning an older boat

In reply to others 50/50 antifreeze mix is fine just don't mix types ie longlife and normal

On mud like you I prefer a straight though skin fitting as this can be rodded clear if need be, I used to find a good sharp blow down the pipe clear most things but as you said the Medway can contain all manner of things

ASAP for pump spares, as Omega said regarding cam, broken cover screws usually com out easy enough with pliers.