horsehauler
Bone Stock
Posts:3
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| 02/23/2005 9:14 AM |
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| just bought a new 2005 chevy w/duramax diesel. Is it normal for the oil pressure to fluctuate when letting of the gas?[:X] |
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webby4x4
Forum Admin, Magazine Editor
Rock Star
Posts:2375
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| 02/23/2005 9:39 AM |
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How much is it fluctuating?
And, is it bouncing, or just lowering a bit when the RPM's come down?
Rick |
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Rick Webster
Editor, 4X4REVIEW.COM - A Tork Media, Inc. Publication
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'74 FJ40 Land Cruiser
"Measure once, cut twice" |
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horsehauler
Bone Stock
Posts:3
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| 02/23/2005 9:52 AM |
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quote:
Originally posted by webby4x4
How much is it fluctuating?
And, is it bouncing, or just lowering a bit when the RPM's come down?
Rick
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horsehauler
Bone Stock
Posts:3
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| 02/23/2005 9:53 AM |
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| lowering a bit when the rpm's come down |
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webby4x4
Forum Admin, Magazine Editor
Rock Star
Posts:2375
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| 02/23/2005 1:38 PM |
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This is pretty normal, as long as it's not dropping a lot.
If it drops a lot, you're truck will be [dead3] |
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Rick Webster
Editor, 4X4REVIEW.COM - A Tork Media, Inc. Publication
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'74 FJ40 Land Cruiser
"Measure once, cut twice" |
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anthon9283
Bone Stock
Posts:7
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| 11/20/2006 6:43 PM |
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Hello,
I know this thread is old but I have a similar problem with my 2005 GMC 2500HD. At idle speed or letting go of the gas the oil pressure drops around 15-20 psi. It seems that about the same time my mileage went down considerably. Anyone have any idea if it is a problem and how to fix it? Thanks for your help.
Anthony |
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SnoMan
Lift & Lockers
Posts:943
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| 11/21/2006 7:07 AM |
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quote:
Originally posted by anthon9283
Hello,
I know this thread is old but I have a similar problem with my 2005 GMC 2500HD. At idle speed or letting go of the gas the oil pressure drops around 15-20 psi. It seems that about the same time my mileage went down considerably. Anyone have any idea if it is a problem and how to fix it? Thanks for your help.
Anthony
Start will a fresh oil change. GM has had problems with leaky injectors in the past and when they do it delute crankcase oil and reduce pressure and MPG will drop too because of wasted fuel. If a fresh change restores pressure, you might want to get injectors check out but do change the oil now in mean time. I commend you for actually monitoring your gauges as many do not :} |
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webby4x4
Forum Admin, Magazine Editor
Rock Star
Posts:2375
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| 11/21/2006 10:09 AM |
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quote:
Originally posted by SnoMan
...I commend you for actually monitoring your gauges as many do not :}
Probably why they're called idiot lights. :) |
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Rick Webster
Editor, 4X4REVIEW.COM - A Tork Media, Inc. Publication
- - - - - - - - - - - - - - - - - - - - -
'74 FJ40 Land Cruiser
"Measure once, cut twice" |
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anthon9283
Bone Stock
Posts:7
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| 11/21/2006 4:27 PM |
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quote:
Originally posted by SnoMan
quote:
Originally posted by anthon9283
Hello,
I know this thread is old but I have a similar problem with my 2005 GMC 2500HD. At idle speed or letting go of the gas the oil pressure drops around 15-20 psi. It seems that about the same time my mileage went down considerably. Anyone have any idea if it is a problem and how to fix it? Thanks for your help.
Anthony
Start will a fresh oil change. GM has had problems with leaky injectors in the past and when they do it delute crankcase oil and reduce pressure and MPG will drop too because of wasted fuel. If a fresh change restores pressure, you might want to get injectors check out but do change the oil now in mean time. I commend you for actually monitoring your gauges as many do not :}
It happens with a fresh oil change as well. Another thing I noticed was that driving at say 55 mph and I let off the gas, the oil pressure drops down to 15-20 psi as well. I've had the dealership look at it and they said they replaced the sensor but still no luck. I'm not sure if it helps any but it is a 6.6L turbo diesel. |
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SnoMan
Lift & Lockers
Posts:943
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| 11/24/2006 8:51 AM |
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| I would install a manual gage and verify oil pressure readings. If they are that low there is a problem that should be covered by 100K mile engine waranty. Any chance that someone put the wrong oil in it? If they used 5w30 instead of 15w40 there would be noticably lower oil pressure in a warm engine. |
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primetimek5
Lift & Lockers
Posts:537
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| 11/25/2006 6:27 AM |
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| its normal.
look at a forum called www.diesel place.com they have all the d.max info |
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rick p. |
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SnoMan
Lift & Lockers
Posts:943
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| 11/25/2006 4:36 PM |
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quote:
Originally posted by primetimek5
its normal.
look at a forum called www.diesel place.com they have all the d.max info
I seriously question that it is "normal" |
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webby4x4
Forum Admin, Magazine Editor
Rock Star
Posts:2375
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| 11/25/2006 5:03 PM |
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| I drive an '05 Chevy 2500 HD with the DMax and I only get a 5-10 p.s.i. drop (estimated). 20 p.s.i. is pretty substantial. |
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Rick Webster
Editor, 4X4REVIEW.COM - A Tork Media, Inc. Publication
- - - - - - - - - - - - - - - - - - - - -
'74 FJ40 Land Cruiser
"Measure once, cut twice" |
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anthon9283
Bone Stock
Posts:7
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| 11/25/2006 11:49 PM |
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I asked the members at diesel place and the two responses said it was normal. Still don't know if its normal or not. lol
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SnoMan
Lift & Lockers
Posts:943
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| 11/26/2006 4:31 AM |
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quote:
Originally posted by anthon9283
I asked the members at diesel place and the two responses said it was normal. Still don't know if its normal or not. lol
It may be a "normally" occuring problem but it is not "normal" to have pressure drop that much. Some of those members in that forum are so strung out on diesel hormones they think a lot of things are normal that really are not. |
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webby4x4
Forum Admin, Magazine Editor
Rock Star
Posts:2375
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| 11/26/2006 2:37 PM |
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quote:
Originally posted by SnoMan
[quote]Originally posted by anthon9283
...Some of those members in that forum are so strung out on diesel hormones they think a lot of things are normal that really are not.
Now THAT was some funny sh1t! Funny, but sometimes very true. It's a bit of a cult-like thing. I think they may even have secret hand shakes. |
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Rick Webster
Editor, 4X4REVIEW.COM - A Tork Media, Inc. Publication
- - - - - - - - - - - - - - - - - - - - -
'74 FJ40 Land Cruiser
"Measure once, cut twice" |
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anthon9283
Bone Stock
Posts:7
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SnoMan
Lift & Lockers
Posts:943
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| 11/26/2006 5:47 PM |
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| Okay in my "official" GM service manual it say that the minimum acceptable oil pressure at a hot idle (680 RPMs) is 14 PSI (minimum, not normal) Minimum oil prseeure at 1800 RPM hot engine is 42 PSI and pressure relief valve starts to open at 64 PSI. If it is below these level GM considers it in need of repair but I consider 15 PSI to low for a diesel at a hot idle. |
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anthon9283
Bone Stock
Posts:7
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| 11/27/2006 4:44 PM |
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| Is it possible for the relief valve to be stuck open? Or maybe some kind of malfunction with it? |
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webby4x4
Forum Admin, Magazine Editor
Rock Star
Posts:2375
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| 11/28/2006 6:48 PM |
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| If it was stuck open, I would think that you'd have consistently low oil pressure...
SnoMan - what do you think? |
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Rick Webster
Editor, 4X4REVIEW.COM - A Tork Media, Inc. Publication
- - - - - - - - - - - - - - - - - - - - -
'74 FJ40 Land Cruiser
"Measure once, cut twice" |
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SnoMan
Lift & Lockers
Posts:943
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| 11/29/2006 4:07 AM |
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quote:
Originally posted by webby4x4
If it was stuck open, I would think that you'd have consistently low oil pressure...
SnoMan - what do you think?
I agree but it would likely be a lot less then 15 PSI at a idle if stuck open. There is another "valve" that controls spray for piston skirt areas, it opens at 29 PSI and allow oil spray above the main line pressure. If it was stuck open it could cause lower pressure too at a idle. I had a 2000 Dmax powered loaner van yesterday for a while and it idled at 25 PSI hot and it was 55 to 60 PSI cruising. It had no tach so I can provide no RPM data with pressures. |
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anthon9283
Bone Stock
Posts:7
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| 12/02/2006 3:17 AM |
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hmm, I wish the dealer would have fixed this problem the first time I took it in. Think they were just giving me the run around.
This is what one of the diesel place guys posted:
"This is from a GM PI.
Condition/Concern:
The Engine Oil Pressure reading is low or near the red zone when coming to a idle.
Recommendation/Instructions:
Complete the current SI diagnostics for any trouble codes or symptoms found. If the customer concern is only the oil pressure gauge reading low, and they are comparing the reading to a older model diesel engine, compare the gauge reading to another 2004-2005 LLY diesel engine equipped vehicle. It is normal to see the oil pressure gauge near the red zone after running the engine and coming back to idle.
If the low oil pressure warning message/chime is on, follow the current SI diagnostics for Oil Pressure Diagnosis and Testing and/or the Engine Oil Pressure Gage Inaccurate or Inoperative. Complete necessary repairs using SI information.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed."
Also another person added that he changed the oil to Mobil 1 because of low oil pressure and that seemed to raise it. |
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SnoMan
Lift & Lockers
Posts:943
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| 12/02/2006 8:24 AM |
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| The problem is is that SI (I have it) says 14 PSI at a idle is acceptable.(likely to limit warranty claim on production tolerance issues) |
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anthon9283
Bone Stock
Posts:7
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| 12/03/2006 12:19 AM |
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I agree with you there SnoMan.
I think I'll try a different oil and see what happens, if not it seems like its back to the dealer. |
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