Volvo heat exchanger problems

[AdrianPetts]

My Volvo MD2040D has developed a leak of coolant from the heat exchanger. It seems that a hairline crack has developed around the base of the filler neck, the part that the filler cap fits onto. At first I thought it might be a problem with the filler cap but after replacing with a new, and expensive, Volvo replacement the problem still persists. On close examination one can see small water bubbles being blown out around the joint between the filler neck and the housing body. This is leading to a loss of coolant which runs down the engine block and into the bilge. About one third of a cupful is being lost per hour. Absolutely nothing is coming down the expansion overflow tube, which I have checked to ensure its not blocked.
Has anyone experienced similar problems? Is there a fix short of a new heat exchanger housing? Is the filler neck part of the housing casting or is it somehow fitted, by pressure of screwing, to the housing body?
This is not a case of salt water entering the fresh water system and being expelled through the overflow. I have had experience of that previously and the symptoms are very different.
All positive advice greatly appreciated.

 

[Heckler]

My Volvo MD2040D has developed a leak of coolant from the heat exchanger. It seems that a hairline crack has developed around the base of the filler neck, the part that the filler cap fits onto. At first I thought it might be a problem with the filler cap but after replacing with a new, and expensive, Volvo replacement the problem still persists. On close examination one can see small water bubbles being blown out around the joint between the filler neck and the housing body. This is leading to a loss of coolant which runs down the engine block and into the bilge. About one third of a cupful is being lost per hour. Absolutely nothing is coming down the expansion overflow tube, which I have checked to ensure its not blocked.
Has anyone experienced similar problems? Is there a fix short of a new heat exchanger housing? Is the filler neck part of the housing casting or is it somehow fitted, by pressure of screwing, to the housing body?
This is not a case of salt water entering the fresh water system and being expelled through the overflow. I have had experience of that previously and the symptoms are very different.
All positive advice greatly appreciated.

Just guessing now but the neck has probably been sweated or pressed/ rivetted in to place. Silver soldering comes to mind to fix it although Araldite would probably fix it. For the tooth suckers, when I was mechanic ing in the paddocks I remember looking at one of Mike Hailwoods Honda engines, he had had something let go and Nobby ? had a spare crank but not crank cases. He had rebuilt it with Araldite to hold the busted crankcase bits together!
S

 

[VicS]

My Volvo MD2040D has developed a leak of coolant from the heat exchanger. It seems that a hairline crack has developed around the base of the filler neck, the part that the filler cap fits onto. At first I thought it might be a problem with the filler cap but after replacing with a new, and expensive, Volvo replacement the problem still persists. On close examination one can see small water bubbles being blown out around the joint between the filler neck and the housing body. This is leading to a loss of coolant which runs down the engine block and into the bilge. About one third of a cupful is being lost per hour. Absolutely nothing is coming down the expansion overflow tube, which I have checked to ensure its not blocked.
Has anyone experienced similar problems? Is there a fix short of a new heat exchanger housing? Is the filler neck part of the housing casting or is it somehow fitted, by pressure of screwing, to the housing body?
This is not a case of salt water entering the fresh water system and being expelled through the overflow. I have had experience of that previously and the symptoms are very different.
All positive advice greatly appreciated.

Id think the filler neck is probably just expanded into the heat exchanger body .

Nothing to loose I think by trying a bit of a bodge.

two things i would do.

Try sealing it externally with an epoxy repair paste. I am sure the Americans would use JB weld.. It's a metal filled epoxy. You'll find it available from Amazon even if you cant find it in high street shops.

Ideally I think do it when warm but it must be dry so getting it dry and warm might be difficult.

Secondly I would consider a radiator leak sealant such as Radweld or Bars Leaks ( both available from Halfords) to tackle it from the inside...... perhaps do this first then if it stops the leak it should be nice and dry to try the JB Weld round the outside of the joint.

http://www.amazon.co.uk/diy/dp/B0006O1ICE

 

[RichardS]

Just guessing now but the neck has probably been sweated or pressed/ rivetted in to place. Silver soldering comes to mind to fix it although Araldite would probably fix it. For the tooth suckers, when I was mechanic ing in the paddocks I remember looking at one of Mike Hailwoods Honda engines, he had had something let go and Nobby ? had a spare crank but not crank cases. He had rebuilt it with Araldite to hold the busted crankcase bits together!
S

I araldited my BSA crankcase halves together with Araldite as vertically split cases on British bikes were the work of the devil. I figured that I could always get it apart if I needed to with a blow torch as Araldite won't stand very high temperatures.

Richard

 

[Bobc]

Use this stuff

https://www.google.co.uk/shopping/product/12963720041425150573?q=chemical+metal&biw=1366&bih=610&bav=on.2,or.&bvm=bv.95039771,d.bGg&tch=1&ech=1&psi=1KV0VY2DEIKXsgGjmYGACQ.1433707989094.3&prds=paur:ClkAsKraX93sGqrV69KWrwGVxQUNm4oEfUWVemIyUmyGiI01XKHFXDg7uAxpsgjY5vXtNRbGjBtdTSmLW7TpVHPUzzDZhCT4ywXZkSC2cx-UeNXX5beuli-qchIZAFPVH71NDKzysWkbXsrSHwstW2KTFV-8jw&ved=0CAoQqSs&ei=2qV0VYG7EoG4sgH7pa7QDQ

Get any paint off and get it clean (give it a go round with some wet&dry. This stuff comes in a stick (2 colours). You just nead it together with your thumbs and then squish it around to make a fillet. Sets rock hard. I've used it to mend coolant systems (aluminium ones).

Best of luck

Bob