1967 990 engine block

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ollek
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Joined: Tue Apr 10, 2012 1:20 pm
Location: South West Finland

Re: 1967 990 engine block

Post by ollek » Wed May 22, 2019 10:21 am

I do not think there is any need for discussing this. Just do as the sealant manufacturer recommend, remove the thermostat as they have a reason for doing so.

Gard
Posts: 244
Joined: Sun Apr 06, 2008 2:25 pm
Location: Fairfax Vermont USA

Re: 1967 990 engine block

Post by Gard » Wed May 22, 2019 12:29 pm

I would guess if you put the sealant into the radiator it will not circulate thru the engine until the engine has been worked hard and the thermostat has opened. In cooler weather this may take awhile. Perhaps putting the sealant into the engine directly, like at the block heater hose would be an option, then by the time the thermostat opens the engine would already be sealed? I think ollek is probably correct, trust the instructions.

I am curious about the welding or brazing options, this must involve draining the coolant and preheating the entire engine to some extent? Is it best to strip down the block completely? I once brought the cast iron yoke from a cement mixer to a weld shop, they put the entire thing in a furnace then brazed steel plates on the side, then allowed it to cool in the furnace for a day or so. I can only guess getting the engine block clean enough to weld or braze would be a bit of a trick.

Attached is a photo of the plate I bolted over a crack many years ago I have not seen any sign of leakage.
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ollek
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Location: South West Finland

Re: 1967 990 engine block

Post by ollek » Wed May 22, 2019 2:03 pm

I thought that I would not make any more comment here, but I just can not keep my fingers of the buttons. You do not have to guess anything, there is a by-pass facility between the front of the cylinder head and the water pump suction side. This prevents overheating in hot spots of the engine during the warming up time. The connection also, in combination with a tiny hole in the thermostat flange, help getting air out of the system. Some sealants can block some of the moving parts in the thermostat if there is air in the system. Removing the thermostat will give a free flow of coolant trough the engine and the radiator.

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cobbadog
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Re: 1967 990 engine block

Post by cobbadog » Thu May 23, 2019 6:50 am

Yes Gard, you can weld using a specific rod with only a small amount of preheating but as I mentioned you do short runs and then peen it. Keep this up until you have welded the crack. In my case with the broken lug I "V" the area to be welded as deep as possible from both sides because I had access to both sides and using LPG gas flame warmed the area to be welded and did the short runs. On run down the middle at the bottom with 2 runs over that and finally a 3 row over that as well. Allowed to cool slowly out in the full sun and it has been good ever since. As described to me by the professional welder by doing short runs and peening it this procedure gives best results for using that rod.
Yes if you can always heat the complete job but in this case unless the block is out and completely stripped down then all surfaces re machined it would not be practicable. You could bronze or braze the crack in place and again "V" it out to give as much clean metal first and it is advisable not to grind it out but to chisel it. Grinding cn seal the pores of the metal and you will not get the same penetration as when you chisel it.
Some welders have even suggested using a MIG welder and still get good results. I have not tried this but going by those who know not all agree on that idea.

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bedwards1966
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Location: North Yorkshire

Re: 1967 990 engine block

Post by bedwards1966 » Sat May 25, 2019 10:19 pm

There are different methods available to weld or braze cast iron. One method - which most seem to think is the only method - is to heat it up, weld it and cool slowly which is obviously a lot of hassle, particularly with an engine block.

It can be welded cold with a stick welder using the correct rods, but it must be kept cool and peened between weld beads while it cools. This method is very successful and can be done without having to strip and remove the engine, provided there's adequate access to the crack.

There are people who just weld it with a MIG, people who get it hot and weld it with a MIG, people who will use rods other than the correct high nickel content type and sometimes these methods give success, however anybody who understands anything about cast iron knows that these methods have a very high risk of causing further cracking and are not a proper fix.

Gard
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Joined: Sun Apr 06, 2008 2:25 pm
Location: Fairfax Vermont USA

Re: 1967 990 engine block

Post by Gard » Tue May 28, 2019 1:22 pm

Thanks for the additional information, bedwards and cobbadog

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