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Discussion Starter #1
It's been a busy weekend. . .

On my way to Petaluma Friday I got stranded on the freeway. This is the first time since 1998 that I've been stranded anywhere. It's a sad day when I can't say the Mustang has never left me stranded. So I was doing 80 or so on 101 when I heard a boom and saw a big black cloud of smoke in my rearview. The engine died and I coasted to the shoulder. I was just over the crest, if you know the area, probably the lonliest stretch of freeway around these parts. The wouldn't start and run so I called a towtruck and waited 30 min or so for it.

Friday:
I got the car to my buddy's place, where all my tools are, and started diagnosing the problem. I pulled the valve covers, since I thought I may have lost a rocker/stud, and everything looked fine. Then I flushed the rad since I'd just put some stop leak in it because I've had cooling problems lately. Rad looked OK. I pulled the plugs and did a compression test. All cylinders were within 143-150, so no burned valves or blown gasket. I put the carb back on and fired it up. It wouldn't run above 1000rpms. . . So I figured it was an exhaust problem. I'd noticed my Sanderson headers developed pinholes a few months ago and had planned to replace 'em (and had a set of repainted Hedmann's ready to bolt on). So I figured the Sanderson's finally blew out and created a backpressure problem that wouldn't allow the engine to run. But I had to work that night, or I would've continued. . .

Saturday:
Pulled the headers. What a PITA! The flange bolts would've been impossible to loosen if my hands were any bigger. And I had to pull the bolts out of the engine mounts so I could jack the engine up to remove the headers. They were so much easier to install witout the export brace being in. . . So I got 'em out and saw how much more they had blown out. Besides other leaks, on the driver side header, I'd noticed that where the 4 tubes come together before the flange the weld was mostly gone. So I figure that leak created enough backpressure on the #7 and #8 tubes, given that they're the short tudes, for the engine not to run properly. The #7 and #8 plugs were black and wet when I pulled 'em the day before so that theory seems reasonably sound to me: Backpressure was created by the header leak that prevented those cylinders from exhausting. . .

The cracks you see here are on the #4 tube. I didn't get a good pic of where the 4 tubes meet on the drivers side:
http://pic4.picturetrail.com/VOL55/689808/1145806/31531685.jpg


Sunday:
After another night of work I got the new headers on in the morning. Even the hedmann's required jacking the engine up. The good part is that it looks like the exhaust will bolt up to the passenger side OK. But I'll need to do a custom patch job on the drivers side exhaust so I can drive it to an exhaust shop to get it fixed right.

Old and new. I cut the flanges between the tubes and painted the hedmann's with cast blast. Looks good, IMO:
http://pic4.picturetrail.com/VOL55/689808/1145806/31531677.jpg

Monday:
Sorry, but I have to sleep. I trained a new person at the Hotel last night who had no previous experience. Work is so much harder when you have to articulate everything you do. . . So I slept today, drank beer, and caught up on the forum a little since I haven't had time to logon since Friday. . . I'll be fabbing a makeshift exhaust in the morning. . .
 

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I'm not sure what the problem would be but a hole would not cause increased back pressure. Only if the headers actually collapsed would that happen.
-Brian
 

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Weird cracks on the number 4 primary, I have never seen or heard similar mishap.

I also second that the change (actually it might be a drop) in backpressure might not be enough to stop the car from running. I had leaking, rusted headers but the engine kept going.

Have you checked spark in those 7 and 8?
Timing chain jumped a tooth?
Late timing?
Raw fuel burning in the header and creating too much pressure?

Let us know if the engine runs fine with new headers.
 

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I'll go out on a limb and suggest that the headers have absolutely nothing to do with your car dieing, then not being able to run above 1000rpm. What ignition are you running?
 

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Those cracks look similar to what occured on my tri-ys. However, I didn't have stalling and/or runnign problems. The cracks on my headers were near the welds between tubes. I welded the mess up, installed a strap on the pass side header, between cylinders 2 and 3 (1 and 2 y together as well as 3 and 4). Coated the entire mess with POR-20 and I'm still in business...
I am using ARPs header bolts (6 point)...
 

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Perhaps an ignition failure. A cracked header is not going to make the car shut down with lots of black smoke, then allow only 1000rpm.
 

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Discussion Starter #8
Well, it ain't just cracked. . .

I'll see what happens when I start it again.
 

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67 coupe, 69 Sportsroof, 86 hatchback
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I'm pretty sure the cracked headers are a symptom of the main problem, not a cause. Sounds an awful lot like a jumped timing chain or something related to timing.
 

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sounds like a bunged up torque converter to me... those things can freeze up like nobodies business, and when they do, they can really screw up your engine. I had a 90 mustang give me all sorts of fits and once I unbolted the torque conerter adn fired it up the engine ran absolutely perfect, but with the torque converter bolted up, it wouldn't do s it if you know what s it means.

maybe it could be in the transmission. check that as well...
 
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