Home » Public Forums » GMCnet » [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed.
| Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. [message #336529 is a reply to message #336528] |
Thu, 30 August 2018 07:37   |
GMC.LES
Messages: 505
Registered: April 2014
Karma:
|
Senior Member |
|
|
If you are concerned that your oil pressure is low, the first thing to do would be to physically verify your engine oil pressure with an accurate mechanical gauge. If that test confirms slightly low oil pressure, you can do as Bob Dunahugh suggested at the beginning of this discussion. Try using a thicker oil such as 20w50. This is normally considered a bandaid to a bigger problem, but if it prolongs having to do a costly engine removal and repair, you are generally ahead.
Les Burt
Montreal
'75 Eleganza 26'
> On Aug 30, 2018, at 12:50 AM, John Phillips wrote:
>
> What does changing the oil weight do the oil pressure? I feel my oil
> pressure is low. Would like to have a real gauge. Coach has 117k miles. OP
> said it was reabuilt at 100k.
>
>
>> On Wed, Aug 29, 2018 at 12:26 PM James Hupy wrote:
>>
>> My engine has had frequent oil changes and proper maintenance throughout
>> its service life. It suffers the same problems as many of the motorhomes.
>> Long periods of inactivity. That is a definite no - no. Better to take
>> short warmup drives of 20 miles or so every couple of weeks. Keeps
>> everything lubed, and brakes and all systems operating.
>> Jim Hupy
>>
>>> On Wed, Aug 29, 2018, 12:13 PM Les Burt wrote:
>>>
>>> Thicker oil generally means a thicker oil film on the cylinder walls. It
>>> is my belief that the thicker oil film can overload worn or stuck oil
>>> rings, increasing consumption.
>>>
>>> I’ve actually seen a few engines where a thinner oil helped reduce oil
>>> consumption. Didn’t get to pull them apart for a proper diagnosis, so I
>>> can’t say if it was the guides/seals, or rings that were worn.
>>>
>>> Thicker oil can also overwhelm the pcv system on engines with excessive
>>> blowby. Seen this happen a few times on some worn out engines.
>>>
>>> Les Burt
>>> Montreal
>>> '75 Eleganza 26'
>>>
>>>
>>>> On Aug 29, 2018, at 2:22 PM, James Hupy wrote:
>>>>
>>>> My 403 when I first got it, had 87,000+ miles on the clock. P.O. had
>> been
>>>> using 10w - 30 dino oil in the engine. Consumption was 800 or so miles
>>> per
>>>> quart, which I thought was a bit high. My mechanical fuel pump gasket
>> was
>>>> leaking a bit of oil, so I fixed that and cleaned up all the surplus
>>> stuff
>>>> on the outside of the block. Ran long enough to tell that oil
>> consumption
>>>> didn't change much. Darn. So, I decided to change to Valvoline 20w -
>> 50.
>>>> Oil consumption changed to a quart every 1200 to 1500 miles. That is
>>> where
>>>> it is today with over 125,000 miles on the engine. Compression is
>>>> consistent at 150 psi across the board. So, the old girl is going to be
>>>> driven like she is, until something changes dramatically. Factory says
>>> that
>>>> a qt per 500 miles is acceptable. I think that borders on excessive
>>>> consumption, while the factory is covering their butt on warranty
>> claims.
>>>> Jim Hupy
>>>> Salem, Or
>>>> 78 GMC ROYALE 403
>>>>
>>>> > On Wed, Aug 29, 2018, 10:41 AM Bob Dunahugh
>>> wrote:
>>>> >
>>>> > Sully. Don't know when most of the oil consumption would occur. Never
>>> even
>>>> > saw a hint of oil smoke ever. Thought that the 50 might help some. It
>>> did.
>>>> > Bob Dunahugh
>>>> >
>>>> >
>>>> > ________________________________
>>>> > From: Bob Dunahugh
>>>> > Sent: Monday, August 27, 2018 9:53 PM
>>>> > To: gmclist@list.gmcnet.org
>>>> > Subject: Tid Bits: Oil consumption. It's all in how/where it's
>> consumed.
>>>> >
>>>> >
>>>> > 6 years ago. I knew someone that got very upset that their engine
>>>> > consumed one qt every 300 miles. So we looked at the spark plugs. All
>>> the
>>>> > spark plugs showed about the same as to discoloration/deposits. The
>>>> > compression test came in at reasonable numbers. At 115 to 123 psi. Not
>>>> > great. But not bad. Inspection camera showed oil washing around the
>>> edges
>>>> > of the pistons. All washing on all pistons was about the same width.
>>> Again.
>>>> > Not a great sign. But not bad. Just expected. Put a dial indicating
>>>> > micromotor to the top of each rocker arm. Just looking for consistency
>>>> > between all the intake. Then all the exhaust. Looked good. But that
>> test
>>>> > doesn't show how much the lifters are dished. Or how much of the cam
>>> lobes
>>>> > are gone. Again used the inspection camera to check the cam
>> gear/chain.
>>> Had
>>>> > been changed at some past point. Warm oil pressures were13psi at
>> idle.
>>>> > 21psi at speed. This is a candidate for a high volume oil pump. But
>> the
>>>> > pump could over load the piston oil control rings. That are already
>>> over
>>>> > loaded. Thus it could up oil consumption. I suggested running it as
>> is.
>>> And
>>>> > run a heavier oil. He's been using 20W50 oil. Still running well. Oil
>>>> > consumption has been at about 400 miles per qt. If the engine had all
>>> the
>>>> > oil consumption issues in just one or two cylinders. That's time for a
>>>> > rebuild. As for what's best for you. Not my monkeys. Not my circus.
>> Bob
>>>> > Dunahugh
>>>> > _______________________________________________
>>>> > GMCnet mailing list
>>>> > Unsubscribe or Change List Options:
>>>> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>>> >
>>>> _______________________________________________
>>>> GMCnet mailing list
>>>> Unsubscribe or Change List Options:
>>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
> --
>
> *John Phillips*
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
|
|
|
|
Current Time: Fri Jun 28 20:28:45 CDT 2024
Total time taken to generate the page: 0.00504 seconds
|
GMCforum
Search
Help
Register
Login
Home
