Tapping a thread into a cast iron block

Has anyone had experience into tapping a thread into a cast iron block? I have an RD28T, which i am converting into an RD28eti. the coolant return on the RD28eti is in the block with a thread tapped into the rear of the block. the RD28T has a flat area, but no thread tapped in. any advice on tapping this tread in would be appreciated.

i have put the photos below.

Sorry, forgot to mention that the coolant return is for the turbocharger.

1. Work SLOWLY. Cast is not homogenous and the drill may try to wander
2. Generously centre punch the point you want to start and drill a small pilot hole, say about 5mm
3. Drill at a slow speed and ease the swarf out by pulling the drill out regularly
4. Increase the dia of the Drill in use until you get too the correct tapping size
5. A good quality sharp tap is the trick in cast. You can use no lubricant for cutting the thread but I prefer a very light lubricant (kero in the old days) like WD40.
6. Back the tap off a turn or two every 1/2 to one turn to keep teh threads clean and if you fell a lot of material getting caught up pull the tap out and clean it and the hole with some compressed air or whatever.
7. Refer to Rule number 1 and it all should go pretty easily for you.
8. If you do balls it up a Helicoil can usually put you right again. Indeed some people tap for a helicoil in the first instance and put the fitting into the helicoil

Quote:

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Originally Posted by the evil twin

1. Work SLOWLY. Cast is not homogenous and the drill may try to wander
2. Generously centre punch the point you want to start and drill a small pilot hole, say about 5mm
3. Drill at a slow speed and ease the swarf out by pulling the drill out regularly
4. Increase the dia of the Drill in use until you get too the correct tapping size
5. A good quality sharp tap is the trick in cast. You can use no lubricant for cutting the thread but I prefer a very light lubricant (kero in the old days) like WD40.
6. Back the tap off a turn or two every 1/2 to one turn to keep teh threads clean and if you fell a lot of material getting caught up pull the tap out and clean it and the hole with some compressed air or whatever.
7. Refer to Rule number 1 and it all should go pretty easily for you.
8. If you do balls it up a Helicoil can usually put you right again. Indeed some people tap for a helicoil in the first instance and put the fitting into the helicoil

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This is very good advice also to help find the tap size you want and you can get 3 diffewrnt types of that tap a starter worker and finisher tap for easy of tapping I'd use a starter and then the regular one. always use tapping cutting drilling fluid cleaner cut.
Make sure you drill 1 to 2 mm smaller than your thread or you wont have any steel to tap

Have you thought about just running the turbo coolant return to somewhere else in the cooling system ?

May be easier to make up a hose/pipe than stuff around drilling the block ?

I have thought of that, but where? does anyone here know where would be the best position to put a return coolant flow?

Hi Greg,

I'm not sure where you are but there are mobile thread repair guys that will come out to you.

Might be worth the call out fee seeing as you have the broken glow plug and require a thread in the block.

Rodney

I am situated on a farm north of Canberra. you dont know the company name of anyone that does this service?

Give this mob a call & see what they can do for you.

http://www.yellowpages.com.au/act/ca...2-listing.html