Water leak between water jacket and combustion chamber - Model 20

Hi All,

I filled the radiator on my Model 20 Hup for the first time and water quickly started leaking out of one of the priming cups (from the thread where it screws into the cap). Obviously this is not good!! There must be crack or corrosion between the wall of the water jacket and the combustion chamber. Is there any way of fixing this? It seems to be worst on No.3 cylinder.

Any suggestions very welcome...

Thanks and regards,

Andrew.

I'd like to know the cause of this. The plugs the primer cups screw into are solid cast iron, I think, and the base of each primer cup is above the intake valves. For coolant to exit the primer cup threads, wouldn't the whole interior of the block have to be flooded? I'd remove the leaky cup and plug to see what's there. Perhaps a crack in the cylinder head threads? Also be sure you don't have water in the cylinders.

Phil

Hi Phil,

Yep - I think the whole combustion chamber was full for this to happen. Luckily the priming cup was not screwed in too tight or I may not have even known. I have now pulled the block off and it looks like it might be a pin hole in the cylinder wall. The block is at an engine shop and they will pressure test it properly early next week and see if it is repairable. Otherwise I may have a very expensive boat anchor ....

Will keep you posted.

Regards,

Andrew.

Andrew,

If the "pin hole" is in the cylinder wall, have a sleeve installed and when you run the engine for the make ure you install a product called IRON TIGHT.This is used in big engines that run WET SLEEVES. It will seal up any small weep that may occur between the sleeve and the cylinder. Don't give up! This is not a huge problem. Mike

Sorry to hear bad news.

Please keep us posted on your progress .

Good luck.

Ken

Hi Everyone,

For those interested in my tale of woe, the block has now been repaired with a sleeve being inserted. Where the stud that holds the water pipe on top of the block is, the stud must have been seized or broken and someone drilled out the old stud and put a thread insert in. When drilling, they went way too deep, into the combustion chamber. So, hopefully I'm back in business!

By the way, what is the trick to getting the bonnet rod out? It looks like it is threaded at both ends - when I turn it, it loosens off one end but tightens on the other? I got the blocks off without removing the bonnet but it would be a lot easier to put the blocks back on with the bonnet (hood) off.

Thanks for the "keep positive messages".

Cheers,

Andrew.

Hello Andrew, It sounds like you are refering to p/n 752 the dash to rad. tie rod.?

If I remember right you will need to loosen the rad. bolts then turn the rod into the rad. as far as it will go ,rock the rad. forward and hopefully the road will clear the dash.

Ken

G,day to all especially Andrew. Perhaps you have your engine cylinder block back on but if not be sure that the rust in the other bores is not nearly the same. Take an open end spanner and tap inside the cylinder in the water jacket region. If nearly through you will hear the change in the note. You might like to fill each block with hot muriatic acid for an hour. This will quickly clean out most of the rust . Kill the acid with sugar soap, dish washing liquid will do, and flush it out with hot soapy water. Look for rust stains in the cylinder and tap in that area. Letts hope there are none but if there are better to sleeve them now. Check that the bloke that fitted the sleeve cut the champfer on the bottom the better to fit the rings. Happy Hupping Max BURKE Nulkaba 2325 Australia

Hi Max and everybody,

Happy New Year! Max - yes the sleeve has been chamfered to fit the rings so all good there. Thanks for the tips about checking the other block as well. I have the other block off as well and will have it properly pressure tested shortly to make sure it doesn't have the same problem as it's neighbour. One things thing the engine guy who put my sleeve in recommended was that I fill the void below the stud that holds the water channel to the top of the block with a two part epoxy to reinforce the sleeve and make sure no water leakage occurs into the combustion chamber. I put a piece of wire down this void and it is quite deep - can anyone tell me if the void area below this stud actually has water circulate through it or am I Ok to fill it with epoxy?

Cheers,

Andrew.

G,day to all and Andrew.

I could not recall if the stud is into a blind hole so I checked a block that I have sleeved but not yet bored. The hole on this block goes down into the water cavity and is "Botomless". I would allow that filling the hole will fill the water cavity and as Hup 20 are famous at running hot this would not be a good idea. Perhaps some blocks were a bind hole here. .If this is so in your case, remember to cut a hacksaw cut up the thread of your stud so as not to cause a hydraulic lock when you set in the stud with Nutlock or simular. I would run a drill bit down the hole to determine if the "blind" is rust. Pop down to Revheads or Pep boys and get a worm drive style hose clamp. Get a wide one as used on air cleaner connections. Use this as your ring clamp and open it to get it off. Happy Hupping Max BURKE Nulkaba 2325 Australia