Tapping cast iron

If the engine is running, I'd expect the turbo to be hot enough to dull your tools, apart from being most hazardous to work on. My employer does engine conversions: we left an engine running overnight on the dynamometer: someone slipped in & took a picture in the dark. The turbo & exhaust manifold were red hot! I still have a copy of that photo. Me, I'd bit the bullet & take thing off, work on it at the bench like a gentleman.

I think I'd feel most comfortable with it removed. I'd just have to work up the patience (oxymoron) to do it.

Wayne D.

I would presume you immediately do the drilling after starting from a cold start. The turbo should take a lot longer than the few minutes drilling would take to get hot enough to be an issue, particularly sitting at idle.

I would personally be more comfortable working up to the tap drill size in a few steps than drilling that relatively large hole in one shot. At least starting with a center drill for a pilot hole and starting taper would be good.

I would get the tap and tap drill as a quality set if possible. For sealing I'd think a light coat of a suitable high temp gasket maker would be good.

Since it's post-turbo, the only issue you'd have would be getting the swarf caught in your engine's muffler or catalytic converter.

If you're trying to work on it when it's hot you'll have to consider the change in hole/thread dimensions caused by thermal expansion.

If I were you, I'd take a good look at just how difficult it'd be to get the turbo off and, as you stated, do the job with your mill.

Otherwise, I'd see if it'd be possible to pull the plumbing off the turbo's exhaust and stuff a rag in the hole to catch the swarf.

If I were to be installing an EGT sensor on my Cummins I'd go pre-turbo and go through the exhaust manifold so as to have a better idea of just _when_ the turbo was about to get fried.

This is downstream from the turbine housing correct? If so just coat the bit with heavy grease to catch most of the chips. Then do the same with the tap. Step drill it so you get a nice hole. Any swarf you lose into the hole will just get blown downstream into the catalytic converter and not be a problem. This is a common thing to do when you add EGT sensors or do an EFI conversion and need to drill the manifold or the head pipe. I wold make VERY sure of the turbines position before you drill, some of them extend down a bit into the outer end of the scroll.

I'd save the removal grief & do this underhood. I'd probably use a total of 3 different sized drill bits. Put a ring magnet like those in speakers around the proposed hole to catch the swarf. You'd only allow a very minimal amount of dust in your system.

No need to have the hole perfect. Also no great worries about tapping hot and having the hole/threads change size when cool.

Why not? It's a tapered pipe thread. If 7/16" is the right drill for that thread (and I don't have a chart handy), the large end of the taper will be cut to greater than that. As to the hot vs. cool size, just let the cast iron cool down before you install the part. It won't thread in as deeply as it would have into a hot casting, but that's all. If that's a problem, thread it deeper cold.

John Martin

I don't actually have the directions yet, just the info the sales person gave me. I'll get that in the middle of next week. So I don't know if it goes in pre or post turbo. Just looking at it, it would appear to go right on the turbo housing just where the it connects to the exhaust manifold. I'd have to guess that the exhaust coming out of the main pushes down on the blades, then turns and goes to the back of the truck. The scroll is in front of that. How some of it works is starting to make sense.

Thanks, I'll have to check that I don't hit anything on the inside.

Wayne D.

How'd you know this was a Cummins? Looks like 4 bolts off of the exhaust manifold, a clamp in front and back. 2 of the bolts are in the back and have to be gotten from underneath. They said removing is difficult only because of accessability. They probabaly mounted the turbo prior to putting the exhaust manifold.

Wayne D.

however hard it is, it can't be harder than removing the turbo from an Audi TT - that was a real total absolue (place curse word here) nightmare - daughter broke a timing belt - well OK, we can fix that - just pull the head - but to get the head off you gotta remove manifold to turbo bolts and one stripped (don't ask, removing the head is non-trivial - a motor mount goes through the middle of the timing belt, for example) - anyway, I cut the bolt with a air driven cutoff and got the head off, and then was so tired that when I went to unscrew the bolt it unscrewed easily and then I dropped it right into the turbo where no amount of fishing with a magnet would get it out (turns out it isn't magnetic, but I didn't realize that at the time) - taking the turbo out (with the head off) took about 2 1/2 hours - with the head in place I just can't imagine how long and how difficult it would be - and putting it back was worse - there is no room, the transmisison for all wheel drive is underneath it, and there are oil AND water lines (2 of each) going into it, plus a mounting bracket that you can't see and have to unscrew by feel, plus ....

so, trust me - don't do what I did..... and be glad you have more accessability than on the TT.

Wayne wrote in news: snipped-for-privacy@wsd1.gateway.2wire.net:

I drive an '03.5 RAM 3500 with the 305/555 HO CTD.

If you're *not* a member of the TDR site/fora then I'd strongly suggest that you visit their site: and browse through the fora that apply to your model.

Their quarterly magazine is full of good technical advice on all aspects of the care and BOMBing of the Cummins ISB engines.

For the benefit of those unaware of the term, BOMB is an acronym for "Better Off Modified, Baby!".

When a Cummins is BOMBed, especially for towing, an Exhaust Gas Temperature gauge is extremely highly recommended lest you fry the turbocharger.

See? It's an elementary exercise in Logic.

While my preference is for a pre-turbo installation, a post-turbo installation offers the advantage that any dust/swarf would simply be blown out the exhaust pipe since it would not pass through the turbocharger.

Those with catalytic converters and/or particulate filters might have an issue with "stuff" collecting there so, if yours has either or both, disconnecting the exhaust pipe at the turbocharger before starting the engine and letting it run for a couple of minutes will be a simple step to clear the deritus. The pipe can, then, be re-attached as soon as it's cool enough to handle.

BTW, while you're installing the EGT sensor and gauge, why not also install a Boost sensor and gauge as well?

Just 2 comments:

1. In my experience, cast iron DOES "powder" when cut.

1. If you haven't tapped with a pipe tap before, just be sure to test the hole as you tap it, so you don't tap too deep. I don't know the exact specs on the holes, but some fittings vary in actual size. If you tap too deep, the fitting can bottom out before it seals well.

Pete Stanaitis

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Wayne wrote:

I may look those up later. I'm getting what Banks recommended for what I'm towing. The sensor is going to go wherever their directions say. Diesels are new to me, but I've been learning. I got the last of the (not ultra) low sulpher engines.

Methinks I'll get an automotive shop to do the removal/installation. I'll do the drilling/tapping

Wayne D.

Good to have verification on #1. Haven't done any pipe taper tapping yet. So how deep to tap is a concern for me. I'm not sure how tight the fit should be until the shoulder hits. I'll practice with some scrap AL first. I don't think I have any cast iron around (old water pump or whatever).

Wayne D.

Wayne wrote in news: snipped-for-privacy@wsd1.gateway.2wire.net:

You might want to have them do the drilling/tapping while they're at it.

That way, if something goes _wrong_, it'll be _their_ expense for the replacement part(s).

FWIW, the Banks package is both overrated and overpriced - especially when one considers that a "programmer" can provide the same (or better) results for a fraction of the co$t and have the advantage that when you take it in for warranty work you can simply reload the OEM programming. This becomes important when a "fix" involves "flash"ing the Engine Control Module [aka engine computer]. This way, when the technician looks at the programming it'll be pure stock.

Re-programming only takes a few minutes and doesn't involve any hardware.

Tapping cast iron is not too difficult, especially if you are using sharp tools. One thing you might want to consider is to do it on the vehicle, cold with the engine off. You can rig compressed air to flow in to the tail pipe and that way the air pressure will blow the swarf out.

You can loosen something along the way to allow a little pressure to escape. I think about 10 to 15 PSI should do the trick without blowing anything.

I see what you mean. I found some cast iron elbows and drilled by hand. It drilled quite easily. Of course I didn't make a straight hole.