Volvo Maintenance Hints for 7xx/9xx - Bill Garland's Nuclear ...

position. (Probably want to practice this without the o-ring and gasket before actually doing it.) It
sets in the block against a square lip, which you can feel with your finger, and it needs to be
square and snug against this lip. And after the installation, use an inspection mirror and strong
light to check to make sure that it went in properly.
Turbo Oil Return Bolts. [Inquiry:] I removed the turbo oil return tube the other day to replace
gasket & seal. Got the parts, went to install them, now it seems the bolts that go into the turbo
are too long, they bottom out. [Response: Paul Kane] The bolts in that area LOOK the same -
but they ain't. Just a 1 or 2 thread difference can cause a 'bottom out' . You may have swapped
1 or 2 and didn't realize it.
Quick and Cheap Silicone Fix:
If you can't get the pipe out (since some previous grease monkey stripped the socket on one of
the cap screws on the turbo end), then you can always seal up the leak like I did. I completely
cleaned the area around where the pipe goes into the block. I used a strong degreaser to clean
the pipe and the surrounding area. I even used Q-tips soaked in degreaser to get inside where
the pipe goes into the block. I then used lacquer thinner to prepare the surface. Once everything
was surgically clean, I dried the area with a warm heat gun. I split the new washer so that it
could be placed around the pipe. The washer was coated with Permatex Ultra Blue silicone
sealant, and some of the sealant was also injected into where the pipe enters the block. The
coated washer was then pushed into this space and sealed into place with even more sealant. It
is a bit of a patch job, but it is working just fine. No leaks in the year since I did the job and it is
cheaper that screwing up the turbo. Before I fixed this leak, I was loosing a quart of oil in less
than 500 miles. Since the repair, I am estimating over 5000 miles per quart. Hard to tell for sure
since I change oil at 3000 mile intervals. Those are the leaks I am familiar with on the B230FT
engines. [Randy Starkie] I cleaned the joint at the oil return line and the block with lacquer
thinner, then sealed it with silicone sealant. It has lasted three years with no leaks.
Clean or Replace the Oil Return Line?
[Inquiry] One thing I haven't done to my car is clean the oil supply lines to the turbo. What is
the best thing to shove into the lines in order to really clean them well. [Response: Dick Riess] If
your turbo is under warranty, the warrantor will insist on a new supply line. Reason: coke can
chip off and destroy your bearings in the turbo. I really believe in buying a new supply line.
[Response: Hermann of Cherry Turbos] The chemicals, time and elbow grease needed to clean
the line out are no guarantee that all the coke inside the line is gone. Because the coke is so
brittle, it can crack and release just from a heat cycle. Ultrasound would actually be the only
"safe" way to clean the coke out. Buy yourself some peace of mind and order the new line.
Extended Boost and Oil Consumption
[Report from JMars] My 89 745 TIC has had catastrophic oil losses twice. Both times happened
when the cruise control caused a downshift from OD and full boost for a time at 4000rpm± on a
long mountain upgrade. At neither time did the plugs foul - this is a key since the non fouling of
plugs told me that the oil lost did not pass thru the combustion chambers. It is impossible to burn
that much oil without fouling the plugs!!! Hence it was not a case of a bad head gasket, valve