Leak from heat exchanger

[redbreast]

Hi all, wonder if you talented people out there might shed some light on a small leak i have just found on my AD41 Volvo Penta 1991 deisel engine Its starting from around the back of the heat exchanger. Any thoughts ? Cheers

 

[lazyliz]

Don't know this engine, but when my Monterey 250 with Yanmar deisel was 11 months old the brazing on the heat exchanger for the power steering fluid inlet and outlets broke away. The raw water water filled the bilge, the float switches on the bilge pumps failed and raw water entered the engine via the dip stick hole. Result - one knacked engine, which Yanmar replaced with a new unit.
Just as well as a new unit retais at £19500.

 

[Peanuts]

It might be of some help if you knew if it was antifreeze or saltwater. When you say the back of the heat exchanger do you mean at the end of the unit furthest away from the front (under the expansion tank) or is it behind part of the body (tube)? I assume it's not seeping along from the expansion tank itself. I have known the seals at either end of the unit to have some corrosion build up under them causing a slow leak, taking the end off, cleaning it up and refit with new seals (with a bit of help from hylomar) usually sorted out the problem.Of course this might not be it but I hope it could be.

Steve

 

[oldgit]

The heat exchangers on the Volvos are a fairly simple and easy job to do if you are that way inclined.Getting the thing off and dismantling it is a fairly straightforward job,worst bit is remembering how it all goes back together(Hint a digital camera is very useful).A search of the net will produce several sites showing exploded views of the offending item.
All the "O" rings and rubber seals are available at your local VP dealer,if you want to save a little cash try Keyparts or Coastal rides for stuff with a bit of a discount.

 

[robinstall1]

Is there a small screw in the exchanger for emptying the water for the winter chills, I have on mine but it was brazed over and due to the fact this was lying on its mountings it started to leak again and undergone another weld. May be well investigating this as you might only need to tighten things up

 

[Kawasaki]

On My previous Ford Mermaid eng the end caps had corroded badly.
New "Body" and end caps were needed.
On My current boat , Volvo TAMD 30A The caps were just starting to show signs of corrotion.
I removed them to inspect.
The Yard who used to look after the eng for the previous owner (the yard went bankrupt) had bodged with gaskets and Hylomar type stuff.
I managed to save the job by cleaning and making the faces good.
I fitted new O rings and treated them with vasoline.
That was 2 years ago and so far so good.
Check these anyway.
It might not be the source of Your drip but it makes sense to check them.
The body of lots of heat exchangers are made of an aluminium zincy stuff.
Combined with Copper/ Brass end caps electrolysis is a prob.

 

[redbreast]

Stars that you are. there is white powder in the area and on one of the vertical joints. There is a rubbery solution eminating from one of the joints.
Question: can i take this unit apart while the boat is in the water or do i need to hoist it on to the hard ???

 

[mjkinch1]

I had a problem with my hose from teh engine pump to the heat exchanger which was the hose coming loose under pressure and spraying some water out, and I had the tell tale white salt crystals around the area. Took it off cleaned it up (gets crusted with salt in it) and its fine now.

I did mine on teh boat, but remember the stop cock for the water if you have one?

Hope you sort it

Martyn

 

[ChrisKaye]

I have the same engines, spent all my hols a couple of years back taking apart and cleaning /rodding (careful not to damage core, I used gun barrel brush) out the cooling system on one of my engines. No need to take boat out can be done in situ. I just use wooden bungs to stick down open pipes and clamp em just in case.
Like oldgit says lots of O rings, so replace them all ! also big rubber O ring when you take cap of back end of heat ex replace him too. Also Im sure there is an anode there as well so good time to replace him as well. Lots of silicone grease when u put back togeher
I always use wire wool to clean up all the connections the

 

[Tim777]

I think the leak you describe is possibly coming from the square ended brass fitting which holds the pencil anode? Remove while aflloat (a little sea water will come out) and renew the anode and grease the brass sqare headed holder and refit. This is if you have salt water deposits on the bottom of the back plate of the exchanger Check the jubilee clips on the 2 sea water rubber pipes are ok. I have just taken apart the exchangers on my AD41A engines and refitted so PM me if further probs.