Motorcraft 5w30, 1995 F150 5.8L

[billman]

I recently had an oil analysis done and the Si level came up around 65ppm (only about 650 miles on the oil). I have been trying to solve a slightly shaky idle and rich exhaust smell. When I sprayed some carb cleaner near the top of the EGR, the idle changed.

Do you think that the EGR has a small hole in it? If so, would it be enough to lead to the above symptoms?

[ May 06, 2003, 06:16 AM: Message edited by: Patman ]

 

[MolaKule]

Maybe this should have been asked in "Mechanical Tips?"


Some Questions:

1. How many engine miles and what type of engine? Some silicon can come from the casting process if the block is cast iron or sleeved with steel liners.
2. Some silicon can eminate from gasket sealing material.
3. Some silicon can be from intake leakage problems such as fresh air intake, PCV grommets, bad sealing in valve covers, broken vacuum hoses, bad TBI sealing, etc.

I don't understand the spraying of the EGR. It's a valve that allows exhaust gasses to enter the intake. If the valve is stuck wide open or partially open on idle, then the idle could be rough. The EGR on most vehicles is only supposed to operate at higher RPM and higher temperatures, and controlled by the ECU.

 

[billman]

Mechanical tips- probably, but here is everything on the analysis:


EQUIPMENT MAKE: 1995 F-150
EQUIPMENT MODEL: 5.8L 351 CI V-8
FUEL TYPE: Gasoline (Unleaded)
OIL USE INTERVAL: 636
TOTAL VEHICLE MILES: 80,045
OIL TYPE & GRADE: Motorcraft 5W/30 (Gas)
MAKE-UP OIL ADDED: None
FILTER: Motorcraft FL-820S

ALUMINUM 2
CHROMIUM 1
IRON 19
COPPER 8
LEAD 4
TIN 1
MOLYBDENUM 2
NICKEL 0
MANGANESE 0
SILVER 0
TITANIUM 0
POTASSIUM 0
BORON 0
SILICON 66
SODIUM 6
CALCIUM 2060
MAGNESIUM 23
PHOSPHORUS 751
ZINC 992
BARIUM 12
INSOLUBLES .5
FUEL WATER 0
ANTIFREEZE 0
TBN 5.5
FLASHPOINT 380
SUS @210 60.1

An oil pan gasket was replaced at the end of this interval- about 100 miles of it. I just got this truck and the owner had the oil changed at the dealer while he was having some warranty work done to it. That is why it is such a short interval.

The idle is not "rough" per se, rather it is "slightly shaky" and the exhaust smells rich. I have not pulled the EGR yet to check if it holds vacuum or if it is carboned up, I just noticed that when I sprayed on top of it, the idle changed. If the EGR pintle is fully seated at idle it will not let the exhaust gases by, but if the diaphragm has a hole, maybe the air could get through to the throttle body???

Thanks for your input,

Bill C.

[ April 21, 2003, 07:53 PM: Message edited by: billman ]

 

[YZF150]

The pan gasket replacement--that's the source of the silicone. It's in the sealant.

 

[hannaco]

Is the Fe a little high? It works out to 29 per 1000 miles.

 

[Spector]

Normally with the gasket replacement I would say that is the source of the silicon however, I believe when you see iron coupled with silicon it is an indication that the silicon is dirt. Especially when you get 19 ppm of iron with only 650 miles on the oil.

Guess there could be other reasons for iron but perhaps I would consider a shorter drain interval the next time around, say 3000 miles?

 

[YZF150]

Something else is going on here. From the specs for the Motorcraft 5w-30 on their website, compared to this analysis:

* the viscosity is down by 8% in these 636 miles
* the TBN is down by 18%
* the flashpoint is down 7%

This oil appears to be diluted, although the fuel % is low. I'm still leaning toward the RTV as the silicone source. The oil seems to be funky somehow, though.

Bill, change that oil and try it again. Use a full synthetic and test it at 3000.

 

[billman]

When I get it back out of the shop (having the MC and MAP replaced under warranty), I plan on changing out the oil and starting a 500 mi Auto-RX. Then I will go for a regular interval with conventional and see how that analysis looks, change to synthetic and see how that analysis looks.

Thanks for all the input. I am still trying to solve a slightly shaky idle and rich smelling exhaust- that is also why I took a sample early to see if I could pinpoint anything.