This UOA was on a blend of 1 qrt. Supertech 5w-20, 1 qrt. 15w-40 Castrol HDEO and the remaining oil fill was 5w-30 (older API SL or SM). Sorry about this unique "Botique" but I was using up some loose end quarts and hadn't planned on the UOA.
This engine has never overheated or blown coolant out of the expansion tank, however I am finding some very small bubbles coming into the expansion tank. I have to take off the overflow cap to look inside to find them because they are not big, or violent, enough to notice through the partial discolored tank side wall. The bubbles are not always consistent but can show up for a few seconds and then nothing for a few seconds - but they are always to be found if you spend a moment to really look and wait for them.
I did a complete timing belt service 1/2 way through this oil cycle and when I was checking over everything that is when I first noticed the bubbles. That has been 4 months and 3,500 miles ago and never an overheating, overflowing coolant, or engine problem during this time.
The cylinder compression test is even across the cylinders with no visible coolant on spark plugs or in the cylinders. The cooling system is holding 12 psi when pressure tested, and the system was under this pressure when doing the cylinder compression test with no changes noted. I also installed a new Toyota radiator cap and it has made no difference.
Still, I don't think any on-going bubbles appearing in the reserve tank is a good thing
so I did the UOA and below is the report. Note that they are reporting negative for glycol, but we do have Potassium showing up.
Code:
Lab comments:
* Wear Levels Appear Normal.
* Silicon Level is high (Possibly dirt as silica).
Aluminum: 10
Chromium: 2
Iron: 25
Copper: 6
Lead: 15
Tin: 0
Moly: 24
Nickel 1
Silver: 0
Titanium: 0
Boron: 31
Silicon: 36 (I think could be from the Silicone grease I used on all the oil seals replaced)
Sodium: 493 ?
Potassium 19 ?
Calcium: 2904
Magnesium 99
Phosphorus:1119
Zinc: 1263
Barium: 0
cSt Viscosity
@ 100°C: 10.74
Glycol: Negative
Water%)
Oxidation 19.05
Nitration 8.82
Does this all seem to be pointing to a "pin hole" type head gasket leak?
Regardless, I think it is ok to continue driving for now, while watching for any changes, or more definitive symptoms to show up. Do you agree?
This engine has never overheated or blown coolant out of the expansion tank, however I am finding some very small bubbles coming into the expansion tank. I have to take off the overflow cap to look inside to find them because they are not big, or violent, enough to notice through the partial discolored tank side wall. The bubbles are not always consistent but can show up for a few seconds and then nothing for a few seconds - but they are always to be found if you spend a moment to really look and wait for them.
I did a complete timing belt service 1/2 way through this oil cycle and when I was checking over everything that is when I first noticed the bubbles. That has been 4 months and 3,500 miles ago and never an overheating, overflowing coolant, or engine problem during this time.
The cylinder compression test is even across the cylinders with no visible coolant on spark plugs or in the cylinders. The cooling system is holding 12 psi when pressure tested, and the system was under this pressure when doing the cylinder compression test with no changes noted. I also installed a new Toyota radiator cap and it has made no difference.
Still, I don't think any on-going bubbles appearing in the reserve tank is a good thing
Code:
Lab comments:
* Wear Levels Appear Normal.
* Silicon Level is high (Possibly dirt as silica).
Aluminum: 10
Chromium: 2
Iron: 25
Copper: 6
Lead: 15
Tin: 0
Moly: 24
Nickel 1
Silver: 0
Titanium: 0
Boron: 31
Silicon: 36 (I think could be from the Silicone grease I used on all the oil seals replaced)
Sodium: 493 ?
Potassium 19 ?
Calcium: 2904
Magnesium 99
Phosphorus:1119
Zinc: 1263
Barium: 0
cSt Viscosity
@ 100°C: 10.74
Glycol: Negative
Water%)
Oxidation 19.05
Nitration 8.82
Does this all seem to be pointing to a "pin hole" type head gasket leak?
Regardless, I think it is ok to continue driving for now, while watching for any changes, or more definitive symptoms to show up. Do you agree?
Last edited: