What causes this symptom?

[94TURBO5 O]

Rings, Valve seals???
Before pulling off my lower intake I was turning the crank pulley to get the dist to TDC and @ cylinders 5 & 8 there is no compression.
What I mean is while I'm cranking 1/4 turns b/t cylinders going in firing order, when I get to 5 it just glides to 4 and then compression. From 4 to 8 it does it again and then from 8 to 1 there is compression again.

I have stock everything internally except for the hgs, so what's causing this??

 

[AznStanger3v]

bent valves cause no compression

bad rings usually yield some type of results, unless they arent in tact at all

i believe blown HGs yield low numbers, but the numbers are there

valve seals wont kill numbers, those are for oil consumption

 

[94TURBO5 O]

I can still see the rockers and pr's moving up and down. I just hear nothing, no air or pressure at all in those cylinders when I crank through the firing order. I haven't done a leak down or compression check yet.

 

[1TallMF]

Melted/cracked pistons could also cause no compression. What symptoms made you want to do a compression test in the first place? A bit more history and your combo details would help.

 

[Bosko5.0]

did you make sure the plugs were tighened down
and anotherthing you cant hear air or pressure not unless your have special air/pressure hearing powers.

other than that i think your hg may need replacing it may have blew between the cylinders, but it will help to do a leakdown test.

 

[94Cobra69SS396]

Get a compression gauge and do a compression test. Pull all the plugs and test each cylinder. Record the values for each and see how much difference there is. For an example I was having an issue with my Chevelle and when I did a compression test I found that most cylinders were between 210-215 psi except 5 and 7 which were both at 30 psi so I knew I had a blown head gasket.

 

[Adam95GT]

compression test it with in 10% of each other is good

 

[Black95GTS]

http://www.findarticles.com/p/articles/mi_qa3828/is_199909/ai_n8855470

I hope this didn't happen to you.

My cousin's 347 pinged a little after dropping it in, but we stopped driving immediately and after some googling found that this was the cause.

Wierd but true.

Adam

 

[94TURBO5 O]

That was an interesting article.
here's the skinny...I raced it last weekend and it started smoking like a mofo. The smoking was like an oil blow by type of smoke and it's missing like a mofo. I changed the oil and no milk shake. I threw in a new set of plugs and as soon as I started it up started to miss again. I pull the plug wires one by one and 5 & 8 had no change when I lifted them off. I pulld the plugs and 5 & 8 were drenched in oil. I decided to pull the heads to check the valves and that's when I discovered this problem I described in the first post.

I have 2 spare motors sitting here so I'm just gonna yank this one out and see wtf happend.
I'll let you guys know.

 

[BlackVert]

sounds to me like you finally killed it. it's amazing that motor has lasted as long as it has the way you work it so hard.

i bet cracked or burned pistons. there would be at least some compression if you had any rings at all

here's my #8 my ring is shot but i have good compression

oil coming out the spark plug hole

 

[95Vert]

Good luck man. Good to see you have spare motors. lol

 

[nmcgrawj]

Good luck man. Good to see you have spare motors. lol

lol Thats not surprising seeing as JR has spare sets of wheels just sitting around...spare spoilers...spare bumpers....he could probably build another mustang with all the "spare" stuff he has! DAMN im jealous!

Anyway, get that thing outta there and get 'er back running man!

 

[94TURBO5 O]

OUCH! Well R.I.P it was good to me while it lasted. I guess this is why everyone hates these 94-95 pistons.

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[urban96]

hrmm... looks like it got pretty hot

 

[MysteryMachine]

wow you'll have to get polished heads and block now lol jk man . Good Luck getting it fixed up and back the road fast

 

[MattZ281LE]

Just a little melted. I had the exact same problem last week only with the forged slugs.

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<img src="http://i102.photobucket.com/albums/m110/mattz281le/Mustang/th_busted1.jpg"></a>
</center>

 

[wytstang]

You're an animal

 

[1TallMF]

Damn, thats craptastic. Looks like I guessed correctly, do I win a cookie?

j/k that really sucks man. What are your plans for it now? Forged 347 FTW?