Sanity Check Before Tearing This Thing Down

rdharper02 · Nov 27, 2014

So after extensive scientific research (a compression gauge) I found there is no compression on cylinder number 1. I'm still proud of the fact I have 7 with good compression, but really miss the eighth. So far I have pulled the upper intake and valve cover. No apparent binding or spring breakage, and the valves cycle the same as the others. So, as much as I know I am tearing this bad boy down, does anyone have suggestions for diagnosing this thing before full surgery? Oh, happy holidays

mikestang63 · Nov 27, 2014

squirt some oil in the spark plug hole and see if the compression comes up.

CarMichael Angelo · Nov 27, 2014

When you say "no compression", are you talking literally?
If that is in fact a dead cylinder, (little to no compression), then there is a bad valve in the mix.
A burned, bent, or broken valve more likely. Short of a hole in the piston, there is no way else that you can have that much disparity in one cylinder w/o one of the above.

Micheal Nadeau · Nov 27, 2014

No compression on one cylinder would be accompanied with a very noticeable misfire. Can see the retainers still holding the valves in the valve springs? A stuck or bent intake valve would be evident by a backfire into the intake. Did you happen to put a vacuum gauge on the motor?

rdharper02 · Nov 28, 2014

Mike, we are looking at about 15 on that cylinder. I agree and think I'm either having a head redone with new valves or replacing a piston. I even bought one of the nifty Harbor Freight inspection cams hoping I could get a look in the cylinder. By the way, the cam will not fit in a 5/8 spark plug hole. I'm fighting the obvious answers at this point. The beauty about a turbo is that it adds power and acts as a sound reducer for the exhaust note. The bad thing is that if you get sloppy and do not pay attention you get to order more stuff from summit. Hopefully Santa will send me a new sparkling Dart short-block for Christmas.

Michael, no obvious backfire before pulling the intake apart. The turbo may have reduced the noise, but (last I had it running) no general indication. She has been a garage queen the last couple of years, so the lack of tarnish in the intake runners may not be a true indicator of it backing up through the intake. I verified that its still clean all the way to the valve (only area I can actually use the new-fangled inspection cam).

rdharper02 · Nov 28, 2014

Anyone want to take the odds? I've got a dollar on the exhaust valve, but that still leaves an intake valve and a piston for possibilities. I'll post some pics when I tear her down.

CarMichael Angelo · Nov 28, 2014

rdharper02 said:
Anyone want to take the odds? I've got a dollar on the exhaust valve, but that still leaves an intake valve and a piston for possibilities. I'll post some pics when I tear her down.

How could you not notice a cylinder that far down? Running, the motor would've idled like a pig, and the turbo wouldn't have masked that. If you have a compressor, Invest in a leak down tester (or borrow one). It'll tell you in a minute whether its a valve, or a piston. Now that we know that a turbo is in the mix, a HG failure just entered the picture as a possible route for the cylinder pressure to escape.

It really doesn't matter at this point, either way you're pulling that head at least.

jrichker · Nov 28, 2014

See the attachment for a how to build your own blow down compression tester

rdharper02 · Nov 28, 2014

Mike, mainly time, but a myriad of other reasons. She has had about 15 minutes of run time in the last 2 years, with the longest time moving off the trailer into its current home of the garage. The cam is still the old lumpy grind and the computer is a poorly chipped unit out of the old blue mustang. The intent has been to go back through the 8.8 (this guy incorrectly setting the pinion at 14 ftlbs), get to the brake line that's seeping (right between the exhaust manifold and frame rail), and then take it down the hill to get the AEM computer and bugs worked out of it via dyno. None of this has happened due to work and other commitments, so the cylinder was identified (without it running) as I looked for TDC after my 110th time of pulling the distributor to prime the oil pump.

JR, thanks for the schematics.

rdharper02 · Dec 21, 2014

So I finally got to it last night. I did buy a leak down tester, but figured I had the upper intake and valve cover off. So I took the quick route off using my compression tester hose with the valve removed. I backed the intake and exhaust rocker all the way off and pumped the cylinder full of air. The intake was well sealed, but the turbo manifold made it difficult to hear the air moving through it. God knows where my mechanics stethoscope is, so I initially thought it was the exhaust valve. Some additional checking and I found it was leaking through to the breather on the driver side valve cover. Removed it and boom, it starts whistling out the dipstick. So anyone have a rough figure on a 331 Dart short block?

A5literMan · Dec 22, 2014

rdharper02 said:
So I finally got to it last night. I did buy a leak down tester, but figured I had the upper intake and valve cover off. So I took the quick route off using my compression tester hose with the valve removed. I backed the intake and exhaust rocker all the way off and pumped the cylinder full of air. The intake was well sealed, but the turbo manifold made it difficult to hear the air moving through it. God knows where my mechanics stethoscope is, so I initially thought it was the exhaust valve. Some additional checking and I found it was leaking through to the breather on the driver side valve cover. Removed it and boom, it starts whistling out the dipstick. So anyone have a rough figure on a 331 Dart short block?

Around 4500$ for a Dart shortblock. I believe that's what Ford Strokers charges.

rdharper02 · Dec 22, 2014

A5liter, thanks, I checked the site and cringe at the price. Heck with it, it will cost no matter.

Mike, so you do not chastise me for lack of photos:

http://i1117.photobucket.com/albums...in/IMG_20141220_182415779_HDR_zps1c7697ea.jpg

Sanity Check Before Tearing This Thing Down

rdharper02

like kicking myself in the junk

mikestang63

CarMichael Angelo

my rearend will smell so minty fresh,

Micheal Nadeau

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rdharper02

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my rearend will smell so minty fresh,

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At least it is lumpy...

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Sanity Check Before Tearing This Thing Down

like kicking myself in the junk

my rearend will smell so minty fresh,

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my rearend will smell so minty fresh,

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