D'OH! Bonehead coolant leak, what to do

[madpogue]

1985 F250, Dealers Diesel reman 6.9 NA with aprx. 50,000 miles. Early model year (11/84) truck. Back-story - Since the truck is an early '85, but with a replacement engine, I've been wondering if the engine is the "old" or "new" design, wrt. whether it's safe to run the block heater. It's based on the engine number on the top of the block, just behind the IP. Well, DD puts THEIR engine number on a brass plate, riveted to the block, RIGHT over the original IH number. Gee thanks guys. I contacted DD to see if they had any database info on the reman job based on the number, and got a reply that no, they don't. They suggested (well, I suggested, and they concurred) that I should drill out one of the rivets, rotate the plate and see if I could read the original number underneath.

Welllllll.... just as I got the rivet head drilled out, the drill just kept going, and suddenly I get a nice pink stream going straight up. Pink because I'm running Fleet Charge anti-freeze. Those rivets must've gone RIGHT into the water jacket, because I was using a cheap drill bit on a cordless drill, no way I could've gotten through the iron of the block that quickly. In any event, I lost maybe a cup or two of coolant, and I drilled it out enough to get a #6 bolt with some Gasoila thread sealer in there. But the hole isn't tapped or anything, the bolt is just threaded 1-2 turns into the hole. Started it up, and it's holding, but I don't trust it.

So, have you stopped laughing? So what to do now? My general plan is to tap the hole and plug it. But I'm wondering what sort of plug to use. Just a bolt, with some thread sealer? Or more of a plumbing plug type device? Any thoughts on thread size/type?

So where's the smiley of the guy with a bone going through his head?.......

Gory details:

 

[riotwarrior]

K a simple fix, find a 1/8' pipe tap and the correct drill bit, drill tap install two pipe plugs with some thread sealant...NOT TEFLON TAPE...don't get me going on that *****....and you will be golden.

 

[madpogue]

Are you saying two pipe plugs, referring to the other rivet? I was thinking of leaving it, but yeah, maybe since I've already done this much damage, I might as well drill out both.

And +1 on the teflon tape; that's why I have a tube of Gasoila.

Thanks for such a quick reply man; appreciate it.

 

[icanfixall]

The 1/8 inch pipe tap requires a drill bit the letter "R" and is 03390. The 1/4 inch pipe tap drill bit requirement is 7/16th inch bit. Might want to coat the bit will heavy grease to collect as much metl as you can. Try a drill and tap in a test piece of cast iron before you drill the block and attempt taping it. If you screw the tap too deep in the drilled hole you will never get a good seal on the plug to block threads.

 

[Garbage_Mechan]

Personally I wouldn't drill out the currently likely about 1/8 diameter holes to the size for 1/8 pipe plugs. I would just go to the machine screw that uses a drill size the same or close to the one you have now, tap to that size, use a little blue locktite on the treads.

 

[OLDBULL8]

A #6 is a pretty small screw, you could easily break a tap off that small. Go up to the hardware and get a 10-32 or 10-24 couple of stainless bolts, drill and tap for that size, or any tap size you might have around that size, seal the screws and screw the plate back down.

 

[madpogue]

^^^^ That's my dilemma; I don't want big gaping holes, yet I don't want them so small I might break off the tap or the bolt. I was wondering about 1/8 NPT; I mean, it's called "1/8", but it's obviously a LOT bigger than an actual 1/8 drill hole. Indeed, that's what it's drilled out to now. I'm leaning toward a smaller solution; that space isn't very wide, and therefore I don't even know the dimensions of the water jacket. Part of me is concerned that a too-large hole will start cutting into the "sides" of that space.

Fortunately the Ace Hardware in my neighborhood is one of those old-school places with narrow aisles and wood floors (the old black dog died last year), and guys working there who know what they're talking about. Maybe they know of a tap that's not so likely to break off, or a technique for avoiding it.

And if I opt to drill out the other rivet and take the plate off, it's staying off; the screws, bolts, plugs, whatever will be just there to re-seal the water jacket. I can't believe they drilled all the way into a water jacket just for that plate.

 

[icanfixall]

You can find a 1/16 tap for pipe threads I think. But really nothing wrong with a machine screw thread in the water jacket. Look at any chevy block.. EVERY head bolt enters the water jackets so you MUST use a thread sealant or you get a leak past the threads.
An 1/8th inch bolt drill bit is the same for 8-32 or 8-36 threads. Its a size 29 drill bit which is .1360. your already at 1/8th inch and thats .1250. Use a thread sealant on the machine screw threads and you will be fine. Even RTV will hold.

 

[madpogue]

Hmm, just found a set of these gizmos: http://www.amazon.com/Greenlee-DTAPKIT-6-Piece-Combination-Drill/dp/B0041FIR1E - gimmick?

 

[IDIoit]

^^^
DO NOT USE THAT ON CAST IRON!
that garbage is for thin stuff.

#25 bit (.1495) and a 10-24 allen head. donski
X2 on sealant and not teflon

 

[madpogue]

Allen head bolt is a good idea. But 10-24? Dare I drill it out that big?

I figured those Greenlee contraptions were for thinner and/or softer applications; just wanted to confirm.

 

[PwrSmoke]

OK, you got good advice here about the hole... but what about the original engine number? You'll have to get back to that eventually?

 

[IDIoit]

if youre not comfortable with drilling it out to #10, go #8.
but 8-32 is a pretty fine thread to be tapping into cast.
it can be done, but were talking about less than 50 thou here if a #6 fit.

#10 is where you get a coarser thread. much easier and safer IMO.

.1495 on the drill and tap it to 10-24.

and use a stainless allen.
http://www.americanfastener.com/tap-and-drill-size-chart/

if you feel safer with a NPT, you can hog it out, but the less you drill, the better off youll be....
http://www.engineershandbook.com/Tables/npttap.htm

 

[madpogue]

Okay then, I'm thinking 10-24 is a good balance/compromise, size-wise. Now to see if I can source the tap, drill and plugs/bolts locally....

 

[IDIoit]

Okay then, I'm thinking 10-24 is a good balance/compromise, size-wise. Now to see if I can source the tap, drill and plugs/bolts locally....

any hardware store has them.

i actually had to go buy this bit and tap for one of my machine fixtures. spent 9 bucks on the drill and tap, the screws i had on hand, but those are less than a dollar.