I think change the filter, drain back valve MAY be the issue.

 

filter is upside down, how can it drain back into the pan? Anyways, good thought but i have yet to see any changes in PSI when doing filter changes.

 

I am really hooked on the idea of a stuck oil pump relief valve stuck open. Just need more info on symptoms or specs if that's the case.

This suburban has amazing power since the AFM delete job, more response and HP. I always have people asking whats under the hood when giving them a ride. Even when idling at 10 psi... jump on it and it launches. Easy instant starts too.. I am baffled : (

 

https://www.pgfilters.com/blog/funct...ve-oil-filter/

 

ok so I have come to terms with removing the front cover & dropping the pan (again) for another oring replacement and a NEW Melling oil pump along with oil pressure release valve thingy which i could be wrong but thought it was a purge for the oil filled collapsible lifters on AFM engines??.. Anyways, my 5.3 was AFM deleted... solid v8... basically a 2007 Hummer 5.3 engine after the delete with new cam.
Big QUESTION is.. which Melling pump do I get???? stock suburban models are for AFM engines. So is that a high pressure or low pressure pump. Do I want stock even with AFM delete or go Hi FLow? I did see they come with 2 springs for option 10 xtra psi boost.

Help please.

Ron

 

CHANGE of Plans....... I will be doing a double motor flush before opening her up for possible repairs.

I do notice a slow loss of coolant... not on the ground nor puffing smoke. But when changing oil, the filler cap has a good amount of white greasy build up from moisture. It is possible that when the AFM Delete repair was done that the heads did not seat correctly and is leaking small amounts of coolant into the engine oil area causing this build up.

I suspect its gumming up the pick-up tube. Any slight tap of the accelerator will instantly boost the pressure quite a bit. Even if its just from a 600rpm idle to 1000rpm.

I will post results when I get around to it..... too cold out this week!

 

Normal to see white on the oil cap in cold weather. It's condensation.

 

well its worth a try... minimal time/investment, compared to my original repair thought, my last 2 suburbans never had condensation build up and they both made it well over 175k. This current one is at 170k and has plenty condensation.

 

Condensation = clear water. Water in the oil looks like a yellow to grayish gel on the bottom side of the cap. Since you said your coolant level is dropping and not on the ground then it's either getting in to the combustion chamber and will show up as whitish smoke/water vapor or leaking into the oil. With that kind of mileage, the first thing I'd do is put a bottle of Bar's Stop Leak in. I've had excellent results using it on older, hi-mileage vehicles that my kids drove early on.

 

Here is an update on my not 1, but back to back double engine flushes from last week!

poured the engine flush in with current 70% spent oil and ran it for 10-12 min. Drained and replaced filter with a basic fram.... added fresh cheap vavoline oil and another can of engine flush..... 12 min later flushed and added a Hi-Performance racing Fram filter and 10w-30 Hi Mileage Castrol oil.... the higher overall idle oil pressure tends to hang longer before settling at a lower level. May be simply because of the new oil. The biggest change was the instant response in pressure when stepping on the gas and also a slightly higher pressure level too when hitting the high RPMs. Also I developed a ticking rocker the last few months but that seems to be gone after about 2 hrs of engine use after its double flushing.

As far as the slowly disappearing coolant..... I do think its making its way into the engine oil. I was always told to not add radiator leak additives into my coolant as it can do more clogging then needed???? This true? I am thinking about trying it unless someone here threatens my membership if I do... lol


thanks for all the input so far

Ron