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| A Final Thought On My Old Engine [message #73772] |
Sat, 13 February 2010 22:43  |
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WD0AFQ
Messages: 7111
Registered: November 2004
Location: Dexter, Mo.
Karma: 207
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Senior Member |
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When we bought our coach, 09-04, the engine had 4,000 miles on it. When I got it home I changed the oil. Within 300-400 miles the oil was very dark. I have always changed the oil every 3,000 miles. Everytime it is dark in 300 miles. I have used dino, Rotella synthetic, and last of all Mobil 1. Everyone of them was blackened within 3-400 miles. No one could tell me why. Engine was strong and did not smoke out the tail pipe.
The compression ring was gone on number 2 piston and the groove was in bad shape. I am thinking that this ring may very well have been broken when I got the coach and caused it to let the oil get black in a hurry. What do yall think?
Dan
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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| Re: A Final Thought On My Old Engine [message #73773 is a reply to message #73772] |
Sat, 13 February 2010 22:45  |
Ron
Messages: 250
Registered: February 2004
Location: Conifer, Colorado
Karma: 0
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Dan..
That would make sense..
Excessive blow by would contaminate the oil quickly. Not necessarily any other obvious symptoms..
Glad to hear you are gonna be on the road soon..
Ron
now a P.O.
Conifer, CO
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| Re: [GMCnet] A Final Thought On My Old Engine [message #73777 is a reply to message #73772] |
Sat, 13 February 2010 23:19 |
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ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
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I think you and Teri are in for a pleasant surprise when start going
down the road. Your new engine and tranny and Rockwell intake will
perform better than ever!
I fervently hope this is so!
And your suspicion that the cylinder has been bad all along nay be true.
Larry Davick
The Mystery Machine
Ljdavick at comcast.net
On Feb 13, 2010, at 8:43 PM, Dan Gregg <gregg_dan@hotmail.com> wrote:
>
>
> When we bought our coach, 09-04, the engine had 4,000 miles on it.
> When I got it home I changed the oil. Within 300-400 miles the oil
> was very dark. I have always changed the oil every 3,000 miles.
> Everytime it is dark in 300 miles. I have used dino, Rotella
> synthetic, and last of all Mobil 1. Everyone of them was blackened
> within 3-400 miles. No one could tell me why. Engine was strong and
> did not smoke out the tail pipe.
> The compression ring was gone on number 2 piston and the groove was
> in bad shape. I am thinking that this ring may very well have been
> broken when I got the coach and caused it to let the oil get black
> in a hurry. What do yall think?
> Dan
> --
> Dan & Teri Gregg
>
> danandteri.blogspot.com
>
>
>
> ///Halon Automatic Fire Extinguishers
> _______________________________________________
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Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
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| Re: A Final Thought On My Old Engine [message #73780 is a reply to message #73772] |
Sun, 14 February 2010 01:03 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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I had that same thought when I saw your oil on the dipstick in Quartzsite but I did not say anything because I would have only been guessing. I thought it might be a bad oil ring or rings. due to the color of the oil and your high oil consumption rate.
Thinking more about it now, bad compression rings would probably allow more blow by of hot exhaust gases into the crank case.
Did you by any chance pull the other pistons to see what they look like?
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: A Final Thought On My Old Engine [message #73785 is a reply to message #73782] |
Sun, 14 February 2010 03:07 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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I would make my first run locally within 20 miles or so. There always seems to be something you need to go back and tighten, or some leak to fix.
I have been reading your blog. Sounds like you made the best of you time in LA.
I'm still having a problem in my mind with your piston failure after 30,000 miles. I guess we will never know.
I assume the old engine is going back as a core.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: A Final Thought On My Old Engine [message #73786 is a reply to message #73772] |
Sun, 14 February 2010 03:09 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
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| WD0AFQ wrote on Sat, 13 February 2010 20:43 |
... The compression ring was gone on number 2 piston and the groove was in bad shape. I am thinking that this ring may very well have been broken when I got the coach and caused it to let the oil get black in a hurry. ...
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Would oil analysis catch this problem?
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
[Updated on: Sun, 14 February 2010 03:11] Report message to a moderator |
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| Re: [GMCnet] A Final Thought On My Old Engine [message #73792 is a reply to message #73786] |
Sun, 14 February 2010 08:23 |
Steven Ferguson
Messages: 3447
Registered: May 2006
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Mike,
Oil analysis would tell you what is in the oil, not exactly how it
got there.Careful study of the analysis results can often reveal which
parts are wearing faster than they should. One of the tech sessions
at GMCWS, Auburn CA. spring rally will be a presentation from
Blackstone labs.
I would suspect that that ring got broken during installation. If
the ring compressor isn't flush with the cyl deck, a ring can slip out
offering some resistance when trying to install the piston. This is a
signal to the assembler to STOP, and pull the piston back out of the
hole and find out what caused the resistance.
On Sun, Feb 14, 2010 at 2:09 AM, Mike Miller <m000035@gmail.com> wrote:
>
>
> [quote title=WD0AFQ wrote on Sat, 13 February 2010 20:43... The compression ring was gone on number 2 piston and the groove was in bad shape. I am thinking that this ring may very well have been broken when I got the coach and caused it to let the oil get black in a hurry. ...[/quote]
>
> Would oil analysis catch this problem?
> --
> Mike Miller
> `73 26' X Painted D.
> `78 23' Birchaven
> Hillsboro, OR
> _______________________________________________
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--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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| Re: A Final Thought On My Old Engine [message #73798 is a reply to message #73782] |
Sun, 14 February 2010 09:08 |
fred v
Messages: 999
Registered: April 2006
Location: pensacola, fl.
Karma: 0
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| WD0AFQ wrote on Sun, 14 February 2010 01:27 |
Ken, we did not pull the other pistons from the block. It just seems to me that the dark oil may have been caused by this all along. When I bought the coach I did not have any notable oil consumption. I never noticed consumption until after I put the Holley tappet covers on. Never related oil consumption to the valve covers but that may have caused it. Going back with stock covers that have the correct baffles. Life has been great here but we hope to get out of here this week.
Dan
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Dan, i have the same problem of dark oil shortly after changing and high oil consumption. this has been discussed at length here. i hope i don't have your problem but i've tried everything else. i just put on the correct valve covers but haven't driven enough to know if it helped consumption.
wish me luck, i'm leaving Sat on a 1500 mile trip.
Fred V
'77 Royale RB 455
P'cola, Fl
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| Re: A Final Thought On My Old Engine - My take [message #73812 is a reply to message #73772] |
Sun, 14 February 2010 11:13 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| WD0AFQ wrote on Sat, 13 February 2010 23:43 |
When we bought our coach, 09-04, the engine had 4,000 miles on it. When I got it home I changed the oil. Within 300-400 miles the oil was very dark. I have always changed the oil every 3,000 miles. Everytime it is dark in 300 miles. I have used dino, Rotella synthetic, and last of all Mobil 1. Everyone of them was blackened within 3-400 miles. No one could tell me why. Engine was strong and did not smoke out the tail pipe.
The compression ring was gone on number 2 piston and the groove was in bad shape. I am thinking that this ring may very well have been broken when I got the coach and caused it to let the oil get black in a hurry. What do yall think?
Dan
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Dan,
Lube oil can go dark for a number of reasons.
The top two are heating (like being in an application where it is pulling a 12k# house around) and blow-by (closely related to cylinder pressures used for the above task) but also component wear or failure. Only experience with a specific engine in very similar service could provide any evaluation to the visible lube oil condition.
Could the "new" engine have had a broke ring from the get-go? Yes.
Could that be the cause of the lube oil going dark in 300 miles?
Sure, That among the others. Without knowing how and where the coach was driven, there it little hope to know. The fact is that you will be the best case we have. You are not likely to change what you do, and so the next 10k miles will be a significant benchmark.
Would oil analysis have picked it up?
As someone else said, probably not as it can only tell you what is in the lube oil and very little about where it came from.
Now, if the new engine in your service stays clean for 3000 plus miles and at some future time, the lube oil suddenly goes dark, you may have cause for some concern, but diagnosing the cause may be very difficult.
What could have found this failure?
A cylinder leakage probably would have indicated an issue. (Ask Ken Burton - He just did)
If someone had done a cranking compression (what most shops are capable of doing), it still would probably not have discovered the problem until the top ring started to break up (it was all over except for the crying).
As I said with the first pictures, you didn't stand a chance of picking that one out before the failure cascaded.
Catching the loss of lube oil pressure when the pump got damaged was about as good as you could ever hope to do outside of an engine lab.
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: A Final Thought On My Old Engine [message #73825 is a reply to message #73772] |
Sun, 14 February 2010 15:31 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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If the engine has been rebuilt, but during the rebuild the bores were not streightned out, it can have a lot of blow-by. Cylinders usually wear on the thrust sides of the cylinder...90* to the pin. When they wear, they usually wear to an oval shape with the most wear at the thrust sides. During a rebuild, often if the cylinders are less than .003 out of round, some places use a common practice of cutting the upper ring ridge in the bore, honing the cylinders with a medium grit stone, putting in cast rings, and letting the rings wear into the bore. The problem with doing this is that, with out streightening out the bore, it's like putting round rings in a square hole. So, during the break-in period (which could be 10K miles or more depending on the softness of the ring) you get a lot of blow-by. These combustion chamber gasses contaminate the oil right away, turning the oil dark. In addition, as the rings are wearing into the bore, the ring end gap is widening, so you end up with a less than perfect seal because the rings are again excessively worn. Best thing to do if you want to use the original pistons with new rings, is to use a rigid hone to make the cylinder round again. Problem with this is that you are then running the risk of high piston to bore clearances which can lead to piston slap. I've done a lot of Quick and dirty rebuilds for myself and others. I'm convinced now that if you take a motor apart and find more than .001 -.0015 out of round or wear, you best do it right and bore it to .010 and install new pistons. That's what I did on my last rebuild only I went to .030. Now that it is broken in, I can go 3000 miles before I have to add a quart, and I think most of that is leaking out. JMHO
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: [GMCnet] A Final Thought On My Old Engine [message #73828 is a reply to message #73792] |
Sun, 14 February 2010 15:52 |
jw mills
Messages: 199
Registered: September 2006
Karma: -30
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Senior Member |
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A compression test or a leak down test should show if you have a
cylinder that is not holding compression.
--
Jim Mills
Greeley, CO
1973 CanyonLands 260 TZE-063V100731(under renovation)
1973 Glacier 230 TZE-033V101993
On Sun, 2010-02-14 at 07:23 -0700, Steven Ferguson wrote:
> Mike,
> Oil analysis would tell you what is in the oil, not exactly how it
> got there.Careful study of the analysis results can often reveal which
> parts are wearing faster than they should. One of the tech sessions
> at GMCWS, Auburn CA. spring rally will be a presentation from
> Blackstone labs.
> I would suspect that that ring got broken during installation. If
> the ring compressor isn't flush with the cyl deck, a ring can slip out
> offering some resistance when trying to install the piston. This is a
> signal to the assembler to STOP, and pull the piston back out of the
> hole and find out what caused the resistance.
>
> On Sun, Feb 14, 2010 at 2:09 AM, Mike Miller <m000035@gmail.com> wrote:
> >
> >
> > [quote title=WD0AFQ wrote on Sat, 13 February 2010 20:43... The compression ring was gone on number 2 piston and the groove was in bad shape. I am thinking that this ring may very well have been broken when I got the coach and caused it to let the oil get black in a hurry. ...[/quote]
> >
> > Would oil analysis catch this problem?
> > --
> > Mike Miller
> > `73 26' X Painted D.
> > `78 23' Birchaven
> > Hillsboro, OR
> > _______________________________________________
> > GMCnet mailing list
> > List Information and Subscription Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> >
>
>
>
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| Leak down test [message #73860 is a reply to message #73828] |
Sun, 14 February 2010 20:16 |
bukzin
Messages: 840
Registered: April 2004
Location: North California
Karma: 0
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Senior Member |
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Fred,
Have you had a leak-down test done?
Can you post the numbers for us?
Dan,
Did you do a leak-down test at any time
during your ownership?
Also, can someone detail the difference between
a compression test and a leak-down test?
Thanks!
Bukzin
1977 Palm Beach
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| Re: [GMCnet] Leak down test [message #73862 is a reply to message #73860] |
Sun, 14 February 2010 20:54 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Buzkin,
Here's a link to compression testing:
http://www.aa1car.com/library/compression.htm
Here's a link to leak down testing:
http://www.aa1car.com/library/leakdown.htm
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Richard
Sent: Monday, 15 February 2010 1:16 PM
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] Leak down test
Fred,
Have you had a leak-down test done?
Can you post the numbers for us?
Dan,
Did you do a leak-down test at any time
during your ownership?
Also, can someone detail the difference between
a compression test and a leak-down test?
Thanks!
--
Bukzin
1977 Palm Beach
Chico California
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Leak down test [message #73865 is a reply to message #73860] |
Sun, 14 February 2010 21:33 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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A compression test is done by sticking a gauge in the spark plug hole and cranking the engine over. All cylinders are done and then compared to each other. The overall average compression reading will vary due the the condition of the engine, compression ratio, and how fast the starter is spinning. What you are primarily looking for is difference between the cylinders.
A differential compression test or leak down test is done by cranking each cylinder to excatly top dead center and blowing air into the cylinder at a given pressure. The air goes through a restrictor on it's way in so only a certain quantity of air can flow. A second gauge measures the pressure in the chlinder. The closer the pressures of the source and the cylinder the better condition the rings and valves are in.
We do this annually to every cylinder on all airplane engines. The source is usually 80 PSI and anything 60 psi or better in the cylinder is considered good. If there is a leak you can hear it by listening in oil filler to the crankcase, the intake, and the exhaust. This will tell you if the leak is rings, an intake vale, or an exhaust valve.
Here is a picture of the tester.
http://www.aircraft-tool.com/shop/detail.aspx?PRODUCT_ID=2E-14
If you want to borrow one, check any airport. Everybody has one of these. Mine is broken at the moment. I smashed one of the gauges at Bean Station last year.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Leak down test [message #73891 is a reply to message #73860] |
Mon, 15 February 2010 08:51 |
fred v
Messages: 999
Registered: April 2006
Location: pensacola, fl.
Karma: 0
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Senior Member |
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| bukzin wrote on Sun, 14 February 2010 20:16 |
Fred,
Have you had a leak-down test done?
Can you post the numbers for us?
Dan,
Did you do a leak-down test at any time
during your ownership?
Also, can someone detail the difference between
a compression test and a leak-down test?
Thanks!
|
i have not done a leak down test. i did a cranking compression test and all cyl were in the 150 range within 5Lb.
Fred V
'77 Royale RB 455
P'cola, Fl
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| test results [message #73896 is a reply to message #73891] |
Mon, 15 February 2010 10:06 |
bukzin
Messages: 840
Registered: April 2004
Location: North California
Karma: 0
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Senior Member |
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What kind of numbers have the rest of you seen
with a compression test?
I know the cylinders should be not that different
but what percentage is 'normal' for
a well used engine?
Bukzin
1977 Palm Beach
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| Re: [GMCnet] Leak down test [message #73902 is a reply to message #73891] |
Mon, 15 February 2010 10:54 |
zhagrieb
Messages: 676
Registered: August 2009
Location: Portland Oregon
Karma: 0
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Senior Member |
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I'll put my nickels worth in here regarding cylinder leak testing. We do it
on airplanes 'cause we must. The FAA mandates it and it has become a
recognized standard. that said, there's disagreement on how it should be
done and what the minimums are (Continental has one procedure, Lycoming
another). Every mechanic has his own technique as well. To do the test the
cylinder must be at absolute top dead center or the air pressure will just
push it down. You'll need someone on a (long) breaker bar (carefully)
holding the crank, Then you'll find that rotating the shaft a few degrees
will change the reading. Sometimes drastically. So, if you pump 80 pounds
in (the standard used in aviation) and get 70 out at top dead center, rotate
the crank a few degrees (holding tightly to the bar) and get 55, what does
it mean? Not much. If you get a really low reading then you have a
cylinder in trouble but a compression test will tell you that also and it's
a heck of a lot easier to do.
Glenn Giere
On Mon, Feb 15, 2010 at 6:51 AM, fred veenschoten <fredntoni@cox.net> wrote:
>
>
> bukzin wrote on Sun, 14 February 2010 20:16
> > Fred,
> >
> > Have you had a leak-down test done?
> > Can you post the numbers for us?
> >
> >
> >
> > Dan,
> >
> > Did you do a leak-down test at any time
> > during your ownership?
> >
> >
> >
> > Also, can someone detail the difference between
> > a compression test and a leak-down test?
> >
> >
> > Thanks!
>
> i have not done a leak down test. i did a cranking compression test and all
> cyl were in the 150 range within 5Lb.
>
> --
> Fred V
> '77 Royale RB 455
> P'cola, Fl
> _______________________________________________
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Glenn Giere, Portland OR, K7GAG
'73 "Moby the Motorhome" 26'
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| Re: [GMCnet] Leak down test [message #73907 is a reply to message #73860] |
Mon, 15 February 2010 12:48 |
jw mills
Messages: 199
Registered: September 2006
Karma: -30
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Senior Member |
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A compression test uses a pressure gauge with an adapter which screws
into the spark plug hole.
Remove all spark plugs, screw the tester into one cylinder and using the
starter turn the engine over for about 15 seconds (engine must turn over
at normal cranking speed). IIRC a gas engine should show between 100PSI
and about 200psi - mostly you are looking for a balance between
cylinders.
A leak down test uses the same adapter but puts compressed air into the
cylinder to find out where the leaks are.
Screw the adapter into the spark plug hole for a cylinder. Position
that cylinder at Top Dead Center (a socket and breaker bar on the
harmonic balancer bolt works to hold the crank from turning).
Commercial testers have a regulator for incoming air (to see if the
cylinder can maintain any pressure). Listen at the carburetor, oil fill
cap and exhaust to see if escaping air can be heard. Bad valve seats
will blow through the intake or exhaust, rings/pistons leak into the
crankcase.
--
Jim Mills
Greeley, CO
1973 CanyonLands 260 TZE-063V100731(under renovation)
1973 Glacier 230 TZE-033V101993
On Sun, 2010-02-14 at 20:16 -0600, Richard wrote:
>
> Fred,
>
> Have you had a leak-down test done?
> Can you post the numbers for us?
>
>
>
> Dan,
>
> Did you do a leak-down test at any time
> during your ownership?
>
>
>
> Also, can someone detail the difference between
> a compression test and a leak-down test?
>
>
> Thanks!
>
>
>
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