Headgasket checkup - questions arise.

[JoeS]

Back in May I replaced my failed headgasket. There was coolant in the oil and oil in the cooling system. What a mess and a real bitch to clean up.

So tonight, i decided to check the banjo bolts and check the torque on the headbolts.
1) banjo bolts loose - no surprise.
2) Question - when retorque-ing the head bolts I set the my torque wrench at 65 lbs ( 58 per the bentley + 7lbs for 5 degrees). The engine was cold. All the bolts with the exception of two were okay the back top one near the firewall needed to be tightened up about 3/4 of a turn and the #3 bolt ( per the bentley) needed to be to tightened up about 3/4 of a turn. Do I have any thing to be concerned about?

3) Question - I am running 20W-50 Valoline Synthetic oil. (this was the only 20w-50 syn at the store at the time) I was checking oil with the car cold. I noticed that everytime i pulled out the dipped stick i would see 8 -10 tiny bubbles on the dipstick in the oil. The oil does not smell like gas. I changed to oil filter and sniffed it like a hound and no gas smell. so i do not think fuel is causing these little bubbles. Oh - when i poured out the oil out of the old oil filter there were litte bubbles in it. The oil looked good - dark carmel color and still felt very slick. So.... could this be caused form some residue coolant let over from may OR does synthetic oil have bubbles.

Tomorrow (today) i am going change the coolant again ( and drain the Block) to see if there is still any residual oil in the cooling system. when i check the coolant level in the resevior there still was some oil gooo. Very little, but now I am paranoid.

[Hector]

$17.50. I just sent him a money order for a second kit. Forgot to clean sprayer bar when head was installed so I'm going to either clean it this time or buy another sprayer bar. His kit works great and is simple to installed.

[Derek A.]

Oil does get aerated at times. In some cases if the crankcase if overfilled it can happen. Oil foaming is more common on power steering systems when they are overfilled. When coolant mixes with oil it gets muddy - I don't think you have anything to worry about.

[George M]

ditto to what Hector suggested...purchase Don's banjo bolt kit...but why didn't you adhere to Bentley's 3 stage procedure for tightening the head bolts in the first place?....two torque stages followed by a 35 deg. angle set? There is no OK when checking head bolts for torque because after the 3rd angle set the bolts can't be measured for torque for two reasons...the head gasket compresses and if torqued properly or above the 2nd stage torque of 58 ft-lbs...as they should have been angle set...the bolts are in the elastic zone and measuring torque is not a precise assessment of uniform clamping force on your head gasket. Retorquing the bolts after the fact is a bad idea but if you didn't follow the spec to begin with...just adding more uncertainty. All said, you don't necessarily have a problem but if you did not adhere to the spec for torquing the big six gasket down as your post suggests, you didn't give yourself the best opportunity for success.
Good Luck Joe,
George

[JoeS]

i did follow the rules first time around. I was just guessing at what 58lbs + degress would be so i arrived at 66 lbs. All bolts, but two cracked, the torque wrench at 66lbs with no movement on the bolts... so I would guess they are in there with 66 lbs or more. But the other two moved - What I thought seemed an alarming amount to get to 66 lbs.

So - if you are giving your head a checkup.... how does one verify that the head is snug on all twelve bolts and that one or some botls have not backed out or lost some elasticity?

[George M]

there really isn't a precise method Joe for rechecking the bolts....it is not recommended. Some recheck bolts after 10 years or so and find the back two bolts a bit lower in torque relative to the rest and even speculate this may cause premature gasket failure....if you believe a 10 year run is premature :-) Some actually use a higher no. than 66 lbs...more like 80 ft-lbs. Each isn't a good barometer of uniform headgasket clamping force because the head bolts are TTY. If you adhered precisely to the procedure going in and then you retorqued a couple of bolts...you run the risk of either failing the bolts or point loading the gasket and head. I don't think at 66 ft-lbs you should be concerned however. If you fully cranked each bolt 35 degrees after step two of 58 ft-lbs...the bolts will be very tight...mine were. I am surprised your torque wrench would move two of your bolts at 66 ft-lbs...but there are many factors that contribute to torque variability.
Did you adhere to the right torquing sequence as well? After performing your head gasket change based upon the torquing spec, you simply do not recheck the bolts. There is even a pitfall with starting over with fresh bolts...as now the headgasket is compacted. The headgasket by design is supposed to compress as you torque the bolts. Will reinforce that you may not have a problem at all. Rechecking the headgasket should only be considered if you have any evidence of co-mingling of oil and coolant and/or lost compression or performance if you choose to perform a compression test.
The way I would approach it is...don't sweat any of this stuff unless there are signs of a real problem. Common for residual crud to remain in the cooling system after a failed gasket...just flush it again. Last thing is...I wouldn't run 20-50W. You should be OK because it is synthetic. Don't know your climate but would run something like 5-30/40 in a warm climate and 0/5-30 or even 0-40W in a cold climate.
HTH,
George

[mjfeeney4]

Have an oil leak on the exhaust side of #6 cylinder on my 91 M50. Will be replacing the 5 yr old vlave cover gasket(s) which might be the source of leak. In the previous posts Goerge mentioned that some people will re-tighten the head bolts ( he recommends against it). Do not want to replace the head gasket (major job) and was looking for recommendations. Should I retorque the head bolts according to the sequence and torque specified in Bently's.

[DanH]

If your head gasket is leaking, you'll need to replace it not re-torque it!

But I would be sure it is not coming from somewhere else before doing that. Other people here likely know more about the M50, and can provide insight to common oil leak locations.