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#67919 - 01/09/10 11:12 AM Compression test finally
grandprix38 Offline
Member
Registered: 03/06/09
Posts: 133
Loc: Seattle Wa
I ran my 97 grand prix w/3800 series 2 engine for 5 - 10 min to get it to operating temperture,
Did compression test 3x on each cylinder and here are the results
#1: 155 -150 - 150psi
#2: 150 - 150 - 150psi
#3: 80 - 80 - 80psi (sh@t-f%ck)
#4: 160 - 160 - 160psi
#5: 170 - 170 - 170psi
#6: 180 - 175 - 175psi
If the compression on # 3 is that low and it was due to a ring, wouldn't there be blue smoke, cause I don't see any.
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#67920 - 01/09/10 11:51 AM Re: Compression test finally
Richard Candelario Offline
Member
Registered: 12/15/05
Posts: 5286
bad valve train. gasket leaks.

If it were the rings, you would indeed see smoke. valves wouldnt produce any smoke. gaskets would make a NASTY mess outta the top/sides of your engine and of the engine bay.
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WizAire CAI w/9" K&N & HV3, 2.5" d/p w/h/f cat, Cobra CB, PowerSlot slots w/Hawk HPS, GR-2s, GMPP handling kit, NextLevel STBs, Pilot Sport A/S Plus tires.

98 L36/MM5
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#67921 - 01/09/10 12:32 PM Re: Compression test finally
grandprix38 Offline
Member
Registered: 03/06/09
Posts: 133
Loc: Seattle Wa
By sight I could, only see a leak between lim and head, there is a little water in oil, I think,
funny thing is water never seperated from oil, and it sat for at least a month, before I checked again,thought it looked like white bubbles on oil dipstick last month, so maybe its not water in oil, just my bad eysight..
And another thing is scanner was saying p0303 twice, or whatever code for misfire is cylinder #3 is, would a hg leak in that area throw that code?
Oh and I know the terminal on the coil for #3 plug was rusty collored, so I know coil was bad, just hoping that was the preset p0303 code and a loose #3 spark plug causesd the new p0303 code.
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Thanks for editing my sig Blackarrow98gp great Job!
Now to get this babe back together!


1997 Grand Prix SE 3800 series 2
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#67922 - 01/09/10 01:33 PM Re: Compression test finally
ifitwasnt4u Offline
Member
Registered: 12/27/05
Posts: 2898
Loc: Phoenix, AZ
Bubbles in the oil... either Blown head gasket or bad rings...
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#67923 - 01/09/10 05:49 PM Re: Compression test finally
HercMan(Rob) Offline
Member
Registered: 09/12/03
Posts: 14035
Loc: Fort Worth, Texas
I think the head gaskets are fine. Reason being either cyl 1 or 5 would also be low.

Ok so now we know there is a compression issue on #3. Poor some oil into the cylinder and re check the compression. If the compression rises then it's a ring/cylinder issue. If the pressure stays the same it's a valve issue.
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#67924 - 01/09/10 07:06 PM Re: Compression test finally
Richard Candelario Offline
Member
Registered: 12/15/05
Posts: 5286
Quote:
Originally posted by HercMan:
Pour some oil into the cylinder and re check the compression.
ummm, what? please explain this because it sure sounds like a recipe for disaster to me.
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WizAire CAI w/9" K&N & HV3, 2.5" d/p w/h/f cat, Cobra CB, PowerSlot slots w/Hawk HPS, GR-2s, GMPP handling kit, NextLevel STBs, Pilot Sport A/S Plus tires.

98 L36/MM5
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#67925 - 01/09/10 08:01 PM Re: Compression test finally
nyjets91 Offline
Member
Registered: 04/24/09
Posts: 469
Loc: Wallingford/Hartford, CT
Quote:
Originally posted by Richard Candelario:
Quote:
Originally posted by HercMan:
[b] Pour some oil into the cylinder and re check the compression.
ummm, what? please explain this because it sure sounds like a recipe for disaster to me. [/b]
It's a wet-compression test. You just squirt a little oil into the cylinder, not a lot, and check it again. It will help the rings seal better, so if the psi goes up you'll know it's the rings. It won't help the valves seal better, so if the psi stays the same, it's a valve issue
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#67926 - 01/09/10 09:15 PM Re: Compression test finally
Richard Candelario Offline
Member
Registered: 12/15/05
Posts: 5286
AAH! man, at first it sounded like Bob wanted us to FILL the cylinder! Thanks for explaining it to me. I now feel a LOT less retarded.
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WizAire CAI w/9" K&N & HV3, 2.5" d/p w/h/f cat, Cobra CB, PowerSlot slots w/Hawk HPS, GR-2s, GMPP handling kit, NextLevel STBs, Pilot Sport A/S Plus tires.

98 L36/MM5
RaC
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#67927 - 01/09/10 09:44 PM Re: Compression test finally
nyjets91 Offline
Member
Registered: 04/24/09
Posts: 469
Loc: Wallingford/Hartford, CT
LMAO. Trying to compress oil in the cylinder would have indeed been bad. I wonder what would break first...
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#67928 - 01/10/10 02:23 PM Re: Compression test finally
ordonez1307 Offline
Member
Registered: 04/18/05
Posts: 8901
Loc: Bradenton, FL
Quote:
Originally posted by nyjets91:
LMAO. Trying to compress oil in the cylinder would have indeed been bad. I wonder what would break first...
Our bottom ends are pretty strong, but I would guess the rod.
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#67929 - 01/10/10 06:18 PM Re: Compression test finally
jorgs_7 Offline
Member
Registered: 11/08/08
Posts: 2689
Loc: Eagan,MN
Quote:
Originally posted by nyjets91:
LMAO. Trying to compress oil in the cylinder would have indeed been bad. I wonder what would break first...
You'd hydro lock the engine and rape a connecting rod
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#67930 - 01/10/10 10:01 PM Re: Compression test finally
00grandprixgt Offline
Member
Registered: 02/20/08
Posts: 2647
Loc: Wall Lake Iowa
Quote:
Originally posted by jorgs_7:
Quote:
Originally posted by nyjets91:
[b] LMAO. Trying to compress oil in the cylinder would have indeed been bad. I wonder what would break first...
You'd hydro lock the engine and rape a connecting rod [/b]
nicely put wink
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soon to come: projectors,exhaust work, 3.4 setup.
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#67931 - 01/12/10 01:54 PM Re: Compression test finally
amcsocold Offline
Member
Registered: 03/07/09
Posts: 355
Loc: Topeka, KS
So what's an ideal psi reading?
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#67932 - 01/12/10 02:25 PM Re: Compression test finally
HercMan(Rob) Offline
Member
Registered: 09/12/03
Posts: 14035
Loc: Fort Worth, Texas
iirc over 150.

But you'd prefer a balance across all the cylinders. If all were 180 and one was 150 you'd want to get that taken care of.

The book will have the accurate limits and variation limits
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#67933 - 01/12/10 07:56 PM Re: Compression test finally
grandprix38 Offline
Member
Registered: 03/06/09
Posts: 133
Loc: Seattle Wa
Quote:
Originally posted by HercMan:
iirc over 150.

But you'd prefer a balance across all the cylinders. If all were 180 and one was 150 you'd want to get that taken care of.

The book will have the accurate limits and variation limits
Quote:
Originally posted by grandprix38:
I ran my 97 grand prix w/3800 series 2 engine for 5 - 10 min to get it to operating temperture,
Did compression test 3x on each cylinder and here are the results
#1: 155 -150 - 150psi
#2: 150 - 150 - 150psi
#3: 80 - 80 - 80psi (sh@t-f%ck)
#4: 160 - 160 - 160psi
#5: 170 - 170 - 170psi
#6: 180 - 175 - 175psi
If the compression on # 3 is that low and it was due to a ring, wouldn't there be blue smoke, cause I don't see any.
So what about these readings, hope and pray it is just the valves, the car did overheat and shut down on the freeway and been down for a few months now, are the rest of the readings other then #3 ok, or probobly something to do with valves also.
And I would have to remove head anyway to fix wouldn't I?
_________________________

Thanks for editing my sig Blackarrow98gp great Job!
Now to get this babe back together!


1997 Grand Prix SE 3800 series 2
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