5.0L Mustang engine issues

Old 04-20-07, 08:32 AM
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Unhappy 5.0L Mustang engine issues

OK....my buddy picked up a standard 89 5.0L mustange/5spd in really nice shape with about 95K on it. The car was sitting in a garage about 6 years before he bought it. The owner who we know stopped driving it because it was really using oil at about Quart every 400 miles....otherwise it ran great....appears these mustangs have the weak oil ring issue!! So we did a very standard rebuild of the motor.......since the bores were in excellant condition with hardly a ridge and no taper we did a basic hone with new cast rings. Also did new bearings, heads refurbed etc. Now here is the problem.....the engine starts and idles great....but once it runs for about 5 minutes the headers (only non-stock item) get super hot and may even start to get red....all 8 pipes!!! The car also starts to "bog" at about 3000 RPM like no power. All the standard spec stuff checks out OK (timing, plugs, EGR) and there are no codes. While the water temp stays normal the dam pips get soooo hot that the plug boots start burning!!!!!!! What can it be? Bad injectors? Bad Timing? Bad catalytics? Need help and insight...making us crazy!!
Old 04-20-07, 09:13 AM
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Sounds like the exhaust is restricted maybe....
Old 04-20-07, 09:40 AM
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Wink Check the injectors

Check the injectors, sounds like it is “dumping fuel”, injectors maybe wrong size or badly warn ( maybe stuck open when they get warm) . The Triumph TR8s did that and the whole exhaust system would glow red.

Just my $.02
Old 04-20-07, 06:19 PM
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No codes or no Check Engine Light?
That vintage EEC-IV can store many trouble codes w/o throwing the CEL

Also-even if you did a check I'm assuming the battery wasn't hooked up and continuously operational for those 6 years until the codes were pulled
There may not be enough run time since the current was restored to get codes
keep checking as you run it...and make sure to do the KOER (Engine Running) codes

Are you sure the headers are the only non-stock item in the system?
Although a common mod, it's usually not the only one
It hasn't been cammed or over-sized injector installed?

Off-hand though, first I'd really look at rust/mice/bees etc blockage in the exhaust
Especially the cats/mufflers

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