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Original FSB.COM Owner
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ok, i am admitingly mechanically challenged, in another post i posted about how my bronco was not staying running in the morning, start it, die, start it die, etc., after it warmed up it would stay running but would idle rough at a stop, like it wanted to die out, so i changed the fuel filter, no help, took it to my mechanic, after having it for a week he changed a transmision modulator that was bad and said it was the fuel pump causing the problem, didnt want to drop the dough on him changing it so me and my brother changed the fuel pump, did not clear up the problem, so i'm still baffled, a co worker knows a garage he said could fix it, big time ford guys with at least 4 different mustangs they drag with, dropped it off there yesterday, he called today and said he checked everything, timing, plugs, fuel pressure, wires, throttle body thing, PCV valve, AGR something another and alot of other things i cant remember now, he said he had narrowed it down to needing a new intake gasket which he said would require taking the top of the motor off at a cost of 350.00 dollars, he said he would start monday morning and have it done tuesday evening, does this price and diagnosis soound right to you guys/gals cause i dont have a clue but i have to have it done
 

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ask him what is wrong with the intake gasket
is it leaking oil/coolant? internally or externally, or is it a vaccuum leak?
the vacuum leak could cause this, but he should have been able to identify that right away as thats a simple hoookup/check.
ask him what the vacuum gauge is reading with the engine all warmed up.
$350 sounds a tad steep, but i think it is a 4. something hour job in the book, so at $70 an hour= about $280, plus a few gaskets... it works out fairly right.

make shure that is the issues. i assume it has a vaccuum leak to cuase your driveability problems, so be shure to ask him how much vaccuum it is pulling before you have him do the job

i have not really heard of the intakes leaking vaccuum as near as much as they do coolant, as the 351's are notorius for poping the intake gasket(coolant to oil, and coolant to outside of block) when they get about 100,000 miles.
 

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Check the compression. sounds like it could be a blown head gasket. that sounds more likely than a intake gasket to me. intake gaskets are more likely to cause a serious oil leak than the symptoms your describing. Do compression checks on all eight cylinders and see if maybe one or two(side by side) have a very low compression isf so it could be
1 a cracked head or block
2. a blown head gasket
3 broken ring ( if it is a broken ring you can tell by pouring a little oil into the cylinder through the spark plug hole and check the compression again. the oil will give a few seconds of good compression if it is a broken ring.


P.S. I am no expert just a shade tree tinkerer but this is what my experiences tell me about the symptom you are describing.
 

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Living in Obscurity
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I'm not as good as these guys at diagnosis, but I know changing the intake gaskets aren't bad at all. The hardest part is torqueing the lower intake back down. But it can be done with some basic tools and some time. I don't know if I would be dropping $350 on it. But that's just me.

MM
 

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southrnpride69 said:
Check the compression. sounds like it could be a blown head gasket. that sounds more likely than a intake gasket to me. intake gaskets are more likely to cause a serious oil leak than the symptoms your describing. Do compression checks on all eight cylinders and see if maybe one or two(side by side) have a very low compression isf so it could be
1 a cracked head or block
2. a blown head gasket
3 broken ring ( if it is a broken ring you can tell by pouring a little oil into the cylinder through the spark plug hole and check the compression again. the oil will give a few seconds of good compression if it is a broken ring.


P.S. I am no expert just a shade tree tinkerer but this is what my experiences tell me about the symptom you are describing.
the oil trick does not always indicate worn rings. it will always jump when you add oil to a dry, COLD cylinder do to no expansion. that is not a very acuarate test

doing a cylinder leakdown test on each cylinder and listening to where the air is coming from is a MUCH better method for finding internal leakage problems.



his symptons sound like it coul d be losing vaccuum, and that will cause the ruff/bad idle, and the lean startup condition.
it only takes 3 minutes to check his manifold vaccuum.
joe, hook a vaccuum guage onto "manifold" vacuum line. anything that is manifold vacuum is bloew the throttle body. finding a spot of the intake is best, and T it in.
it should be about 20 at idle.
it should stay fairly steady with the truck idling. rev it up to about 1500, and recheck. it should drop off for a few seocnds, then rise back up to normal, and stay constant. if it doesnt, then you are having vaccuum issues.
 

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dsotmoon said:
thats what the guy said, that it was vacuum
joe, now you need to eliminate other vacuum sourches for leaks, so start spraying carb cleaner (be carefull, potential fire ,and i know you with fire!!!!) at alot of your vacuum lines, and conections.
most likely you will probably have a bad line, or broken fitting vs the intake gasket.
bad thing is, it could also be a vaccum blader that is leaking badly, and it this case, the vaccum line goign to it will need to be pulled and capped. if your indle gets better you probably found your problem. pulling and capping it may also make your truck want to die more dpeending on what function you end up disabling.
 

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BadassBronco said:
joe, now you need to eliminate other vacuum sourches for leaks, so start spraying carb cleaner
i wish i had a good memory because he mentioned all this to me today, he said he sprayed something around the engine and didnt find any other leaks, the other garage i took it to said he didnt find any vacuum leak at all, just the tranny fluid in one of them from the bad modulater, he did say something about spraying around the throttle body or throttle something or another and it smoothing out, i asked him on several occasions if he was sure that it was the intake gasket and he said yes
 

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dude i paid $150 to get a new Edelbrock manifold & 4bbl on my 351W B4 the 460 went in. you could do the gasket yourself with a torque wrench & basic hand tools. AXE
 
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