Exhaust leak - how urgent to repair?

[LeoZelig]

Hey folks, can I ask for your expertise on an exhaust leak problem?

I have an exhaust leak at the front of the manifold on the passenger side.

I'm in triage mode on my new 69 F100, and need to know how urgent this repair is in the grand scheme of things.

I understand that carbon monoxide is a concern. Are there any other issues with running like this for a while? Am I making a repair more difficult? Doing some kind of damage? Any other implications I'm not anticipating?

For now I'm only planning to ride around the neighborhood, 10-15 minute drives max. Longer drives after I've brought all the systems better up to snuff.

Thanks in advance for your advice!

[JoshT]

Assuming that you aren't running an aftermarket efi system, you can run thatehaust leak as long as your ears can stand it.

Carbon Monoxide is more of an issue if running in an enclosed space like the garage, in which case it won't matter if it's coming from a manifold leak our out the tailpipe. Outside and driving down the road they is enough vetelation and air movement that it CO shouldn't be getting trapped in the cab.

The biggest issue of running with the leak is it getting larger. If run with a leak long enough it could affect the sealing surface on the head or manifold, but after 50 years that damage is probably done already.

These engines are prone to exhaust leaks after this much time. Fix it, but expect it to come back if you use gaskets they sell at the local parts store. If you use a good gasket like Remflex and torque properly, it'll work hood and last long time.

[basketcase0302]

The "log" manifolds on the 360/390 are prone to this.
If it were mine I'd plan on a new exhaust manifold or headers down the road, (most the time you'll find them cracked and trash once you pull if off).
if it is a bad leak you stand the chance of burning the exhaust valve seats before their time.

[LeoZelig]

Gents, thank you both for the helpful advice

Assuming that you aren't running an aftermarket efi system

Nope, JoshT, he's bone stock under the hood as best I can tell.

enough vetelation and air movement that it CO shouldn't be getting trapped in the cab.

That's what I'm hoping, too

If run with a leak long enough it could affect the sealing surface on the head or manifold, but after 50 years that damage is probably done already.

That seems reasonable, but it's on my early list of fixes, after making it safe to even take on the roads.

use a good gasket like Remflex and torque properly, it'll work hood and last long time.

Thanks for the advice, JoshT - I don't want to fix this again in the near future

If it were mine I'd plan on a new exhaust manifold or headers down the road, (most the time you'll find them cracked and trash once you pull if off).

Alright Jeff, that sounds like good advice - I'll look up manifolds and see if I can afford to have them ready to swap.

if it is a bad leak you stand the chance of burning the exhaust valve seats before their time.

Ok, I'll definitely keep that in mind and not let this repair linger too long.

[wjwolfe82]

FWIW, I had/have the same problem with a leak at the front right side. I put a Remflex gasket behind the heat shield and so-far-so-good.

[fastEdsel]

The gaskets I use on my stock FE engines are Fel-Pro MS 95000 gasket sets. It's one thing that I have purchased at NAPA that actually worked and worked well. Don't run the leak too long though, get some band aids, penetrating oil, and it usually is a 6 pack job. Keep us informed for your project.

[wjwolfe82]

... get some band aids, penetrating oil, and it usually is a 6 pack job...

Truth.
Plus a few coins in the cussing jar. It's no fun trying to hold that big manifold log down there trying to line up a bolt but surely satisfying once your done and everything's nice & quiet again.

[LeoZelig]

Thanks fastEdsel and wjwolfe82. I keep soaking the manifold bolts with PB Blaster as I fix the more urgent system... brakes! Not to worry, I'm just starting it up weekly to keep the engine exercised - no long term use until I get it fixed.

Two votes for the Remflex gaskets - sounds like a good bet. Felpro sounds like a good choice too. Glad to have options. Thanks for the advice gents!

[fastEdsel]

Sounds like you are focused on your exhaust repair. A technique that has worked for us over the years and perhaps you know of this but make sure your socket is bottomed out on the bolt heads. You don't want to apply pressure on only half the bolt head, well you know the rest. The PB Blaster is a good choice for sure. If the bolt moves at all just rock it till you are sure it will come out, take your time. After the bolts are out I run a thread tap through the bolt holes just real gentle to have a smooth re-assembly. Use new bolts, flat washers and lock washers and an anti seize on the bolts because there may be a time when you may have to do this all over again, yup been there, done that! Keep in touch, let us know how it all works out. Heck you might just enjoy this so much you may want to do the other side too!

[Lee]

When I first installed my headers, I had a heck of a time getting them to seal to the head.

Finally I came accross these:
https://shop.broncograveyard.com/Header ... nfo/10084/

Never had a problem again.

Lee

[jimmy828]

I agree with the Remflex seals. Installed them on my 360 and got rid of that annoying exhaust leak. A leak will sure make a FE sounds like it's falling apart

[LeoZelig]

Hey everybody! It's been a while since I posted. My wife broke her arm so I picked up some of her normal tasks and that left less time for the truck.
Then I took a detour through some other repairs, including rebuilding much of the brake system, and repairing and reupholstering the bench seat (I'll share those in another thread, eventually). I couldn't put off the exhaust leak repair any longer, now that he's ready to drive a bit.

I continued PB Blaster treatments and tried all sorts of the tricks you offered, as well as tricks from YouTube, heat, beat, freeze, oil, you name it. I got the manifold off, but sheared two of the upper bolts in the process. One is sheared practically at the head, the other has about 1/4" meat left on it.

It's clear to me that the head needs to come off, one way or another. Once it's off, I'll see if I can do the weld-nuts-to-the-studs trick, or if I need to take it to a machine shop.

I've never removed the head from an engine, but given some of my other experience and help I've gotten from everyone here, I think I can do it. Time to start reading up!

Thanks again for all the advice! I'm a lot closer than I was, but I have a lot further to go.

[cep62]

I'd try leaving the heads on , taking them off leads to other things.
if you have a wire welder weld a washer to the stub , then weld a nut to the washer and try turning it out.
if you need to drill it get a 90 degree drill and start with a 1/8 bit and work your way up.
if you drill crooked you can always nut and bolt it on an F E engine.

[LeoZelig]

taking them off leads to other things

Yeah, that's definitely weighing on my mind... I'll take your recommendation under serious advisement.

if you have a wire welder weld a washer to the stub , then weld a nut to the washer and try turning it out.

I do have a wire welder, and I tried welding a nut to the shaft once already - but welding uphill and essentially blind proved harder than my meager welding skills But I may give that another try before getting more drastic.

if you drill crooked you can always nut and bolt it on an F E engine.

Well, at least my goose won't be cooked, even if the threads are

Thanks for the advice cep62 - I'm mulling over my next steps now. Good advice like yours has gotten me this far... now to get the rest of the way.

[LeoZelig]

if you need to drill it get a 90 degree drill and start with a 1/8 bit and work your way up.

cep62, I thought long and hard about your advice, and I decided your recommendation made a lot of sense for my situation. My reasoning was this: I'll drill out the bolts and then nut and bolt those two. Some day when I need to remove the head for some other work, I can get those two holes repaired and re-threaded. In the meantime, I can run it with the nut-and-bolt arrangement on those two holes, and this way I don't have to disturb any more of this 52-year-old engine than is necessary right now. My goal right now is to fix the exhaust leak and then move on to other urgent issues - I can refine things later.

Also, I picked up a right-angle drill from Harbor Freight so I could get in there. I realized my little pancake compressor wouldn't keep up, so it was finally time for an upgrade in that department .

The first bolt had sheared off almost at the ear. I was able to use a center-punch to put a dimple in it and start the drilling in the middle. It was really tight quarters, so I had to cut the drill bits down in size to make it fit. I started with a 1/8" drill bit and worked up from there. I have a big enough hole to take a 5/16" bolt - I think that will do for this, for now.

The second bolt had more of the bolt sticking out of both sides of the ear.

second bolt.jpg

I needed as much room as I could get, and I didn't relish trying to keep a longer drill path straight, so I used a cutoff wheel to cut them flush with the ear.

second bolt cutoff.jpg

I tried the center punch again, but no luck. I couldn't make a dent. So I tried starting it as centered as I could - after two off-center failures, it was clear I'd have to do something else. I ground the face flat again and thought about my options. I needed to center the drill without being able to see the face of the shaft.

I used a mirror, and I positioned a nut in the center with tape to act as a guide. That did the trick! I got a perfectly centered hole!

Next steps are to clean the gasket surface, and then mount the new manifold. I'm slowly but surely getting there, thanks to y'all's help!