NY Texas road trip - bad start.
#79
Rennlist Member
I'm still wondering.
I'm puzzled by the abruptness of the way it failed. I once experienced a very quick, over 5-10 miles on an interstate, progressively surging failure that turned out to be the distributor shaft wearing itself to eccentricity. Also, I once had a broken distributor shaft, that was as if I'd turned off the key.
But how to reconcile the abrupt failure with these posts below. How did it rotate when it got down to the shortblock?
I don't think it's diagnosed yet. Cam nose?
I'm puzzled by the abruptness of the way it failed. I once experienced a very quick, over 5-10 miles on an interstate, progressively surging failure that turned out to be the distributor shaft wearing itself to eccentricity. Also, I once had a broken distributor shaft, that was as if I'd turned off the key.
... Here's what I saw leading up to the failure: ... Car ran great up to about 15-20 minutes before failure. At that point, she started barely surging - like a fuel delivery problem - but just barely surging enough that I could feel it. ... Then she gave out. It was like I turned off the ignition ...
#80
Captain Obvious
Super User
Super User
Take the rings off the pistons you've pulled and lay them down on a white piece of paper. If they are worn down so much that compression is hardly there. You will easily see the wear on the ring thickness.
#81
Rennlist Member
Sorry to hear about this failure.
It seems from the distance that the wear shown is "adhesive" and not "abrasive" (due to contaminants).
If there are some (heat) discoloration signs at the piston, it is likely adhesive.
If so, it leads me to think that there was either poor lubrication (and agree with previous comments that just the oil type change would likely not cause it) or higher than normal temperature.
As the oil analysis does not indicate fuel in oil, which was one of my suspects, I would think either an oil passage (or some check valve) was blocked somewhere, oil volume was low (not likely) or an overheating caused it.
Crank main bearings are under huge stress, so poor lubrication would have affected them as well, I believe.
It seems from the distance that the wear shown is "adhesive" and not "abrasive" (due to contaminants).
If there are some (heat) discoloration signs at the piston, it is likely adhesive.
If so, it leads me to think that there was either poor lubrication (and agree with previous comments that just the oil type change would likely not cause it) or higher than normal temperature.
As the oil analysis does not indicate fuel in oil, which was one of my suspects, I would think either an oil passage (or some check valve) was blocked somewhere, oil volume was low (not likely) or an overheating caused it.
Crank main bearings are under huge stress, so poor lubrication would have affected them as well, I believe.
#82
Rennlist Member
One more thing that might help. I looked into the literature about overheating failures and found this too. This is however related to diesel engines (I work in a large diesel engine manufacturer co) , but will work here as well. So, if you get to the valves at some point, you can inspect them for this.
"High Temperature
Valves for engines that operate in an overheated system will typically have a narrow band of oil coking near the bottom area of the valve guides' travel. Mild adhesive and/or abrasive wear may be present. Valves in overheated systems may have deposits of oil coking on the remainder of the valve head and associated parts.
The following items are sometimes associated with high temperatures.
Temper colors.
Adhesive wear
Oil coking
Piston contact"
"High Temperature
Valves for engines that operate in an overheated system will typically have a narrow band of oil coking near the bottom area of the valve guides' travel. Mild adhesive and/or abrasive wear may be present. Valves in overheated systems may have deposits of oil coking on the remainder of the valve head and associated parts.
The following items are sometimes associated with high temperatures.
Temper colors.
Adhesive wear
Oil coking
Piston contact"
#83
Rennlist Member
Thread Starter
Today, I checked a few more things.
The crank spins nicely in its journals. Nothing odd there. Haven't broken the griddle apart yet.
I measured the top piston ring gaps for #1 and #5.
Squared up the ring with a piston top.
Then measured the gap.
Got 0.024 and 0.025" on #1 and #5.
So that's 0.6096 and 0.635mm
Spec is 0.2 - .4mm from what I can tell in the WSM.
Not good.
I also checked the crank end play (axial play in WSM?).
I got 0.007" (0.1778mm) with a dial indicator.
Spec is 0.11 - 0.31, so I don't see any problem there.
The crank spins nicely in its journals. Nothing odd there. Haven't broken the griddle apart yet.
I measured the top piston ring gaps for #1 and #5.
Squared up the ring with a piston top.
Then measured the gap.
Got 0.024 and 0.025" on #1 and #5.
So that's 0.6096 and 0.635mm
Spec is 0.2 - .4mm from what I can tell in the WSM.
Not good.
I also checked the crank end play (axial play in WSM?).
I got 0.007" (0.1778mm) with a dial indicator.
Spec is 0.11 - 0.31, so I don't see any problem there.
#84
Shameful Thread Killer
Rennlist Member
Rennlist Member
That ring end gap is not what made your engine stop. Continental ran an aviation engine without any compression rings at all and it still made book HP numbers at redline.
So far, you don't have a 'smoking gun' on this deal at all.
So far, you don't have a 'smoking gun' on this deal at all.
#85
Rennlist Member
Thread Starter
The block is an M28/03. 77-79 4.5L 5 speed.
The ring gaps are just a bit tighter half way down the hole.
I guess the out of spec gap wouldn't do much for leak down results, but you'd think they'd build enough compression to fire.
I need to drop off the heads at the machine shop and see what they say.
Still don't know why the engine was dragging so much. Maybe it is the starter, and it really isn't any harder to spin than usual. Maybe I just think it is harder?
Maybe the rings were dragging on the cylinder walls?
The ring gaps are just a bit tighter half way down the hole.
I guess the out of spec gap wouldn't do much for leak down results, but you'd think they'd build enough compression to fire.
I need to drop off the heads at the machine shop and see what they say.
Still don't know why the engine was dragging so much. Maybe it is the starter, and it really isn't any harder to spin than usual. Maybe I just think it is harder?
Maybe the rings were dragging on the cylinder walls?
#86
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Join Date: Dec 2004
Location: Guelph, Ontario, Canada
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The block is an M28/03. 77-79 4.5L 5 speed.
The ring gaps are just a bit tighter half way down the hole.
I guess the out of spec gap wouldn't do much for leak down results, but you'd think they'd build enough compression to fire.
I need to drop off the heads at the machine shop and see what they say.
Still don't know why the engine was dragging so much. Maybe it is the starter, and it really isn't any harder to spin than usual. Maybe I just think it is harder?
Maybe the rings were dragging on the cylinder walls?
The ring gaps are just a bit tighter half way down the hole.
I guess the out of spec gap wouldn't do much for leak down results, but you'd think they'd build enough compression to fire.
I need to drop off the heads at the machine shop and see what they say.
Still don't know why the engine was dragging so much. Maybe it is the starter, and it really isn't any harder to spin than usual. Maybe I just think it is harder?
Maybe the rings were dragging on the cylinder walls?
Wish there was a leak down test as it would have told you EXACTLY where the compression was going.... do I sound like a broken record? ;-)
The reality is there is something else going on that caused your problem. I for one am going to guess the head. Pull the cams and flip it upside down and put alcohol in the combustion chambers. NONE should leak out into the intake or exhaust ports.
#87
Rennlist Member
Thread Starter
I tried your trick of filling the cc's with alcohol.
Maybe a tiny bit of seepage on exhaust #8. No other signs in other cylinders.
Cams all look good. Spin fine. No broken anything there.
Distributor gear seems fine with the cam spinning.
I am able to compress 5 lifters by hand slightly. That seemed unusual.
#88
Captain Obvious
Super User
Super User
You can compress 5 litres fairly easily if you go slow.
As for running an engine without any compression ring is a bit hard to swallow. How the hell did they get it to fire let alone to re to redline?
As for running an engine without any compression ring is a bit hard to swallow. How the hell did they get it to fire let alone to re to redline?
#89
Rennlist Member
Thread Starter
Couple "last" pictures.
The oil pump surface on the block is in pretty bad shape. Don't know if this is new or if this was the way when I put it in, probably the former.
Also, the water pump block surface isn't great.
Time to write this off and rebuild. Move on.
The oil pump surface on the block is in pretty bad shape. Don't know if this is new or if this was the way when I put it in, probably the former.
Also, the water pump block surface isn't great.
Time to write this off and rebuild. Move on.