I did a compression test on my extremely sluggish and loping motor today and discovered the number 4 cylinder has no compression whatsoever. I had a pretty bad exhaust leak awhile back and think it may be a burnt valve.

What options does this leave me? A complete valve job or is there an easier fix?

Also the other cylinders gave me compression readings varying from 100 to 120psi. It this normal for a stock rebuild?

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0 psi? Yikes... If it was an exhaust valve you'd hear it in the tailpipe as a sputtering, or if you put your hand at the tailpipe you would feel uneven pulses.

I believe the FSM states 100psi is minimum compression for engine in good health. I would say 100 on a fresh rebuild seems low... were the cylinders bored or was this just a ring & bearing job?

If you wanted to minimize cost you can pull the head and do only one valve, but after going through the effort you'll probably want to do all of them.

There is definitely sputtering coming from the tailpipe.

The cylinders were bored during the rebuild about 2 years ago.

What does a valve being burnt really mean anyway? I haven't had the motor apart and am trying to visualize the problem.

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http://www.engineproblem.com.au/valve_burnt.htm

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Check the valve adjustment. I had a van come to me with 0 on a cylinder. It was bumping 165 after a valve setting.

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick

Cheapest is find a good used head.

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick

I have a head that is in good shape, and I am close by. PM me for details.

Greg

I took off the valve cover and noticed two push rods disconnected from the rocker arms. Odd thing was that they are intake and not exhaust for the 4th and 6th cylinder. When I pulled one of them out, the lifter came with it as it had been completely punctured by the rod and both parts stuck to one another.

Seems the place that rebuilt the motor installed solid (but hollow!?!) lifters of which two now have failed and have been destroyed by the push rods breaking through the top of them.

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Im no expert, but I think that all early slants used solid lifters. That's why the rockers have adjustments and everybody is always talking about how to adjust them for max power and min clackityness.

I think that the lifter bore might be the same for the v8s- I think the 273 setup might interchange somewhat with the slant. Anyway- it should be easy to find good replacements.

I wonder how this could have happened? Chinese steel? Used parts? Knitting needles accidentally used as pushrods?

Good job finding the problem- and good luck getting back together. You might want to replace all 12 lifters!

Kevin

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madam im adam

Call me ghoulish, but I'd really like to see some photos of this, and one of the remaining "good" lifters.

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

Well, I have the motor running again after replacing all the lifters with new NAPA lifters. The place that rebuilt my motor about two years ago installed 9 new lifters (these cheapo hollow things) and what appears to be 3 of my old lifters or some different ones that were laying around their shop. Here is a pic of the "new" lifter that had a hole punched through the top by the rod:



the piece next to it was the top and became separated when the rod penetrated it. here's another pic:



This happened to two of the lifters. My friend has the other one because he says in all his years of building engines he's never seen this happen. Seems the rod should bend before it's able to punch clean through the top of a lifter. Unless of course the lifter is a hollow piece of s**t.

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What did the cam lobes look like? Putting putting used lifters on any cam lobe other than the one on which they were originally installed is a recipe for cam destrction. New lifters are OK anywhere. I've never seen hollow mechanical lifters, are you certain they didn't stuff in some hydros and just lash them down 'til they quit clattering? Either way the workmanship was shoddy at best.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

I really don't know the condition of the cam although after I installed the new (not used) lifters i was able to set the lash easily and the engine is running smoothly. I'm sure the life of the cam has been shortened somewhat since it's ideal to break in new lifters with a new cam, right? Also at this point I have no idea if the cam was new at the time of rebuild, could be those guys just put my old cam back in. Who knows. Next time I'll tackle the rebuild myself just to be sure there aren't so many frustrating surprises.

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How on earth how this push rods eat thru the lifters?? The lifter plungers is locked in via a internal snap rings.

Cheers, Wizard

If I remember right, didn't the Hemi use hollow mechanical lifters? It may have been in race only applications, but I'm pretty sure some High-horse BB Mopars had hollow lifters. I thought they had quit producing them though.........maybe some "knockoff" company started again????
Yes, your slant six has BB lifters.

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225 Cubic Inches of Iron-Head American Muscle

225 bored .040 /.100 off block, Schneider Cam 224@.050~ .480 lift - Stock valves, blended bowls, Offenhauser intake with 500 Edelbrock carb