Hot Rod Forum banner
1 - 1 of 17 Posts

· Registered
16,533 Posts
Hi guys,

I am creating this post in hopes of getting some solid advice. So here's the deal …

I have a 1993 Bronco with a 351W & a E4OD and we're at 276K miles. Recently the passenger side exhaust manifold cracked in half. Needless to say this created a huge exhaust leak and the heat burned up a couple of plug wires.

So I thought, great time to bolt on some headers and rebuild the entire exhaust (which was way overdue) … This is my daily driver BTW. So I bought Hooker full length headers and all the other components needed thinking this was going to be a quick and easy fix and upgrade to boot.


The passenger side manifold was a wreck, not only was in broke in half, but it had 2 other large cracks and the EGR tube was also broke in half. I guess no big deal at this point but I was concerned about exhaust valve damage. Both manifolds came old fairly easy except one rather large issue. Each cylinder head has a broken off exhaust manifold bolt in it. From the looks of it these have be broken off for years.

All that being said, I'd have to pull the heads to remove the broken bolts. Mind you, this engine has never been opened up. I wasn't looking for a rebuild project right now and I'm not sure what can of worms I'd be opening up by removing the heads on such a high milage engine. I've thought maybe I could have the heads reworked or replace them with aftermarket, but is that a really bad idea w/out rebuilding the engine too?

This is where I am stuck. Because I've done little to the truck since I bought it 8 years ago. There are cleaner Broncos out there to start with for a project vehicle, of course I'd have to turn this one around and buy another when this one was paid for the day I bought it. And there's the tranny that has the same amount of milage. Is it not a good idea to just do the heads and move on for now?

Anyway, any advice is welcome. Thanks.
Since you don't want another project, I'd go at the minimum. It's a high mileage engine that's running fine, so one can appriciate that fixing some issues like a valve job may create new issues such as pulling oil past the rings, and/or increasing blow by. So it's important to be conservative in what you do to keep from causing new problems. your obsevation about the tranny is valid, if you restore compression which will increase power output, the tranny could well suffer under the additional load and fail simply because up to this point they are aging gracefully together.

I'd pull the heads trying to get as little coolant into the engine as possible. First remove the push rods and identify each of them as where they go so as to keep wear matched parts of lifter at one end and rocker at the other together. The same goes for rocker arms ID each, then inspect them for wear, replace only if needed.

I'd clean gasket surfaces but not the entire head any more than needed for decent part handling. Then center punch the bolts to be removed then drill them out and touch up the threads. Then clean all threads a air blast closed holes to be sure no debris is trapped in them.

Keep plenty of rags on hand to keep debris out of the cylinder bores and anyplace else such as ports, the less trash that gets into these areas the better the chances that some unseen piece of grit, coolant, or solvent won't end up somewhere to do damage when the engine is restated.

Change oil and filter before starting the engine.

Done carefully this should be an event that goes unnoticed by the mechanicals.

I wouldn't ignor parts worn or damaged to where it just doesn't make sense to put it back together with them, valve stem seals for example or a rocker riding on the spring retainer, but at the same time I wouldn't be hunting for wholesale parts improvement either and that includes a valve job. Keep in mind that simply removing the valves can do more harm than good as often the stem tip is mushroomed so it won't pass through the guide, driving it ou will ruin the guide, the stem tip edges need to be dressed so the stem will slip through the guide in these cases. Check compresson before starting, if the cylinders meet the minimum spec continue on. At the same time if it has a burnt valve replace it. Just use good judgement, if you have fix too much you might as well starting hunting for a replacement engine and transmission.

1 - 1 of 17 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.