Cm870 low oil pressure
07-21-2020, (Subject: Cm870 low oil pressure ) 
Post: #1
Cm870 low oil pressure
Have a 2006 cm870 w/ 647,xxx miles. It’s been showing a steady 5psi lower than average on the gauge, having trouble figuring it out. Truck seems to be running with a little less power too

At idle it’s about 10-12 psi, going down the road it never gets over 25-27psi. I run delo w/ sta lube in it and have for years. Pressure has always been good up until 6-8 weeks ago

-Changed the oil pressure sensor
-cut filter open to see if there were shavings from worn rods/mains; hardly any metal in it
-did an oil sample ~4,000 miles after changing and the sample showed minimal/normal wear
-updated oil pressure relief valve but no change

Any suggestions as far as what we should look into next? Could Oil pump be on it’s way out?
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07-21-2020, (Subject: Cm870 low oil pressure ) 
Post: #2
RE: Cm870 low oil pressure
something is hemorrhaging oil pretty badly internally if it is that low. -- or the pump is worn out.

pull the engine cover and look for a spun cam bearing. - Leave cover loose and crank it up.. see if there is some place in top end oil is flowing too rapidly than it should be somewhere.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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 Thanks given by: berrytrucking94
07-22-2020, (Subject: Cm870 low oil pressure ) 
Post: #3
RE: Cm870 low oil pressure
(07-21-2020 )Rawze Wrote:  something is hemorrhaging oil pretty badly internally if it is that low. -- or the pump is worn out.

pull the engine cover and look for a spun cam bearing. - Leave cover loose and crank it up.. see if there is some place in top end oil is flowing too rapidly than it should be somewhere.


We just found 2 spun cam bearings..I don’t know why we didn’t check these earlier but thank you for bringing that to our attention. One is almost all the way out

   
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 Thanks given by: Rawze , SquareOne
07-23-2020, (Subject: Cm870 low oil pressure ) 
Post: #4
RE: Cm870 low oil pressure
We’ll be starting to disassemble it today/ tmrw, I’m concerned that it might need a new head if the journals are worn from the bad bearings

In a situation like this w/ 2 spun bearings on a 650k never touched motor, what're the odds it’ll be a can of worms once we pull the cams...?
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07-23-2020, (Subject: Cm870 low oil pressure ) 
Post: #5
RE: Cm870 low oil pressure
Its inframe time, cut the counterbores, new head, the whole shebang. Once the head has to be removed from an isx with more than about 450k miles, it shouldn't be put back on, it's junk throw it away.


User's Signature: Warranty??? Yeah right, I am the warranty!!!
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 Thanks given by: Waterloo , Rawze
07-23-2020, (Subject: Cm870 low oil pressure ) 
Post: #6
RE: Cm870 low oil pressure
yup.... inframe. Do it right, do it up all the way, new OE head, all new OE parts, couter-bore and raise liners to to 0.014" height,.. etc.etc.etc. and take better care of the engine next time.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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07-23-2020, (Subject: Cm870 low oil pressure ) 
Post: #7
RE: Cm870 low oil pressure
I figured that would be the common answer here.

I’m stumped trying to figure where I went wrong with this, since I bought it with 380k miles 4yrs ago I’ve been the only driver and always tried to keep a close eye on the way it ran. Tuned by a member here, 10k oil changes, nothing but fleet guard filters w/ delo and sta lube added

Overhead run once a year..At one point I had fuel pump issues for a bit that wasn’t corrected right away. Also had a slowly sticking vg vein a while ago that may have been causing some over fueling? Could this hav affected it?

We haul 100k gross all day, could it be that? Did I go wrong somewhere with maintenance? Just plain bad luck?

If I can avoid this happening as fast in the future any advice is great
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07-23-2020, (Subject: Cm870 low oil pressure ) 
Post: #8
RE: Cm870 low oil pressure
The damage was probably done in the first 300k miles from previouse owner neglect just took this long for the damage to become a problemb or there was a defect from factory that finally let loose.


User's Signature: 2010 Lonestar - CM871 - 13sp - 3.70s, 2016 T680 - cm2350 - 13sp - 3.36s - skateboarder
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07-23-2020, (Subject: Cm870 low oil pressure ) 
Post: #9
RE: Cm870 low oil pressure
(07-23-2020 )berrytrucking94 Wrote:  I figured that would be the common answer here.

I’m stumped trying to figure where I went wrong with this, since I bought it with 380k miles 4yrs ago I’ve been the only driver and always tried to keep a close eye on the way it ran. Tuned by a member here, 10k oil changes, nothing but fleet guard filters w/ delo and sta lube added

Overhead run once a year..At one point I had fuel pump issues for a bit that wasn’t corrected right away. Also had a slowly sticking vg vein a while ago that may have been causing some over fueling? Could this hav affected it?

We haul 100k gross all day, could it be that? Did I go wrong somewhere with maintenance? Just plain bad luck?

If I can avoid this happening as fast in the future any advice is great

I would have suspected overhead not done every 2 years or so, but you said you did it every year. Would be interested in seeing how much wear there was on the rest of the bearings in the top end. It is kinda odd you lost 2 of them, I know they likely did not go at the same time. - It ever had a history of low oil pressure issues? - Overhead cam ever been replaced?

sounds like you went out of your way to take care of it fairly well according to your post, would be curious if you had other excess wear in that engine.

Have you ever let it overheat (coolant above 225F)? oil above 240f? - Would be curious what the ecm history reports for high coolant or high oil temps were.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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