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The Mighty Slant 5
https://slantsix.org/forum/viewtopic.php?t=24828		 Page 1 of 1
Author:  caveman [ Fri Sep 07, 2007 8:47 pm ]
Post subject:  The Mighty Slant 5
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?
Author:  Pierre [ Fri Sep 07, 2007 10:00 pm ]
Post subject: 
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.
Author:  caveman [ Fri Sep 07, 2007 10:14 pm ]
Post subject: 
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.
Author:  emsvitil [ Fri Sep 07, 2007 10:35 pm ]
Post subject: 
Quote:
What does a valve being burnt really mean anyway? I haven't had the motor apart and am trying to visualize the problem.

http://www.engineproblem.com.au/valve_burnt.htm
Author:  Rug_Trucker [ Fri Sep 07, 2007 10:57 pm ]
Post subject: 
Check the valve adjustment. I had a van come to me with 0 on a cylinder. It was bumping 165 after a valve setting.
Author:  Rug_Trucker [ Fri Sep 07, 2007 11:04 pm ]
Post subject: 
Cheapest is find a good used head.
Author:  gmader [ Sat Sep 08, 2007 7:26 am ]
Post subject: 
I have a head that is in good shape, and I am close by. PM me for details.

Greg
Author:  caveman [ Mon Sep 17, 2007 2:41 am ]
Post subject: 
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.
Author:  radarsonwheels [ Mon Sep 17, 2007 7:54 am ]
Post subject:  yikes
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
Author:  slantvaliant [ Mon Sep 17, 2007 12:32 pm ]
Post subject: 
Quote:
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.
Call me ghoulish, but I'd really like to see some photos of this, and one of the remaining "good" lifters.
Author:  caveman [ Fri Sep 21, 2007 7:48 pm ]
Post subject: 
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:

Image

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

Image

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.
Author:  dakight [ Sat Sep 22, 2007 6:39 am ]
Post subject: 
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.
Author:  caveman [ Sat Sep 22, 2007 12:29 pm ]
Post subject: 
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.
Author:  Wizard [ Sat Sep 22, 2007 3:15 pm ]
Post subject: 
How on earth how this push rods eat thru the lifters?? The lifter plungers is locked in via a internal snap rings.

Cheers, Wizard
Author:  BigBlockBanjo [ Sun Sep 23, 2007 6:27 pm ]
Post subject: 
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. :shock: I thought they had quit producing them though.........maybe some "knockoff" company started again????
Yes, your slant six has BB lifters. :D
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