How to remove plugs from manifold?

[Trekka]

Below is a picture of the exhaust manifold on my 4-108. Coolant runs through it. I would like to remove the two half inch bronze plugs, on the side and top rear, as well as the large plug, top forward, which has a return on it.

I have been straining and straining to get these to move. I used PB Blaster a few days ago and again tonight. They don't budge even with me hammering on the wrench.

Suggestions?

I would like access to the inside for cleaning, and the manual says that if the coolant system needs to be bled to prevent air pockets, to loosen the top two plugs when filling.



This forum has been great on advising me in this refurb. Any suggestions welcomed.

[Stillraining]

Air impact gun for blank plugs with a square socket as far as the ones with nipples you might try heating the surrounding manifold but they are bear cats and have had to be drilled out carefully I know.

[GordMay]

Originally Posted by Stillraining

... you might try heating the surrounding manifold...

The JUDICIOUS application of heat to the area around the bolt (manifold) often frees “frozen” parts.

[never monday]

they were set with locktite. The small tube is designed to bleed air back to the header tank at the thermostat. If this has always had a clean coolant mixture in it. It shouldn't need cleaning.

[Chief Engineer]

You are starting to make this project way too hard.

[Ex-Calif]

Heat, heat, heat, heat heat. Then using a suitable guide tube drizzle ice water on the center of teh plugs while applying lot's of torque.

Repeat if necessary.

[delmarrey]

I deal with these on a daily basis, almost.
Cast iron is one of the worst items to extract pipe plugs from.

First, get the right size 4 point socket (or 8 if not available). Pre-heat right around the plug to about 400-700º as fast as possible then put a long breaker bar on it with a cheater bar and force it out. If the head strips off, you never would have gotten it out anyway.

Now you'll have to drill and tap the thing out. and still not EZ, the threads will still want to remain. The method I found best is to drill close to the tap hole size, then take a carbide burr (rotary file) shaped to a sharp cone and grind in the hole until you start to see the tips of the thread. Then take a sharp pointed tool, like a scribe and start picking the threads out. Once you get most of them out you then take the right size pipe tap and clean the threads.



It's not an EZ job but if those plugs HAVE TO come out that's the only way it'll happen. Corrosion has welded them in! I've done so many I lost count years ago.

Good luck!!!!

BTW-replace the plugs with a SS or bronze. The difference in metal keeps them from welding together.

[Inthewind]

I have often had success using a pipe wrench. Get a good sized one and make sure you get a good tight bite on the plug being carful not to strip it. I usually try the pipe wrench after wrenches and sockets failed to work. They have an amazingly strong bite when used properly.

[delmarrey]

Originally Posted by Inthewind

I have often had success using a pipe wrench. Get a good sized one and make sure you get a good tight bite on the plug being carful not to strip it. I usually try the pipe wrench after wrenches and sockets failed to work. They have an amazingly strong bite when used properly.

A pipe wrench will ruin the square. Once it's messed up, one might as well get out the drill. If the square twists off there is no other wench that would have worked anyway!

[Inthewind]

Originally Posted by delmarrey

A pipe wrench will ruin the square. Once it's messed up, one might as well get out the drill. If the square twists off there is no other wench that would have worked anyway!

All I meant to say is sometimes as a last resort they work. I tend to have to disagree that it would strip the square, if done right with a tight solid fit they are very secure. (it would have to be a high quality pipe wrench). The eight point socket would strip it before the pipe wrench would in my opinion. It's worth a try and what ever works, right.

[Ex-Calif]

I'd go air hammer and heat before a pipe wrench. The teeth on the pipe wrench will always leave a mark if the kind of torque we are talking about is applied.

This is a torque problem. Long arm (bigger lever) gives you the advantage. However, the wrenching flats of the plug are not built for the kind of torques required to overcome what is likely corrosion. Cooling systems are devils for corrosion. The pipe wrench is a popular choice because the tighter you pull it the tighter the grip. But that grip can cause damage.

The air hammer does not apply too much torque but does provide the vibratory effect needed to perhaps break the corrosive bond.

At some point, as Del points out, it becomes a machining job.

[Trekka]

This has been very informative. Thank you. I think upon consideration of all points that I shall leave this alone. That the dangers of proceeding more aggressively outweigh any possible benefits.

Given that the top forward plug has a retrun line in it to the reservoir I think that should take care of any air pockets and negate a need to bleed through the plugs. As for cleaning the manifold, I shall do that with pressure water through the in/out on the front, and then with some sort of flush when the whole coolant system is connected and I run the engine for a while.

Thanks again, guys. Much appreciated.

[delmarrey]

Wise decision!!!!