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

B23X Engines. Clean off the area around the gasket as best you can. Remove all the manifold bolts and pull it
back enough to replace the gasket. There will also be a couple of air tubes that have to be loosened or
removed, but you'll see what is necessary as you pull the manifold away from the head. It needs only about an
inch and a quarter of movement to clear the studs.You may also want to disconnect the throttle and
transmission cables at the pulley wheel (write down how they are routed) so you don't bend them. The surfaces
should be clean and the old gasket was installed dry, so you do not normally need to scrape the area. Do not
use any sealer or RTV. Retorque to 15 ft-lbs (20 Nm) for a B230 F/T, B234 or B6304 engine; to 7-11 ft lbs (10-
15 Nm) for a B280F.
B6304 Engines. [Doug Young] To my amazement replacing my 960's intake manifold gasket wasn't as difficult
as I had expected! I removed all the air intake tubing to the throttle body, then the throttle linkage assemblies
along with the fuel rail and injectors. You may want to spray some non-silicone-based lubricant around the
rubber couplings for the intake plenum and manifold so they'll slip out easier when loosened. At first I was
concerned about the metal clamps that secure these rubber couplings. I decided that replacing them with
plastic tie-straps would work just as well. You will need a universal jointl for your ratchet to get to some of the
bolts. Be very careful removing them because those bolts love to fall and disappear into the bowels of hell. I
grabbed hold of the plenum then pulled and wiggled it away from the manifold.When I pulled the manifold off, I
found the intake gasket broken in about 10 separate pieces. The new gasket was around $16. I put everything
back together and erased all stored codes. Turned the key and it made the sweetest sound without any stumble
at all.
Vacuum Leak Diagnosis. See the FAQ section on diagnosing vacuum leaks in the intake system.
Headgasket Failure: Diagnostics .
Basics of Headgasket Failure:
[Tip from Import Car Magazine, Oct 2001, Gary Goms] When diagnosing a leaking head gasket, it’s important
to remember that bi-metal engines with cast-iron blocks and aluminum cylinder heads will eventually wear out
the head gasket due to the different expansion coefficients of cast iron and aluminum. Each time the engine
goes through a warm-up cycle, the aluminum head slips a few thousandths of an inch across the head gasket.
Although current head gasket technology drastically reduces gasket wear, head gasket replacement is still the
most common major engine repair. [Tip from Motor Service Magazine, Feb 2002, Greg McConiga] Two major
causes of head gasket failure are overheating and detonation. Don't forget to check for the root cause of the
failure, especially if it's a car with a history of problems. Cooling fan and water pump operation, radiator cap,
thermostat, radiator flow, engine timing and EGR function are just a few of the things you need to check.
Diagnosis of Headgasket Problems:
Symptoms of a blown head gasket include a continually increasing consumption of coolant, a milky
accumulation found under the engine oil cap after extended engine runs at operating temperature, a very
obvious thickening or sludging of the crankcase oil, gas bubbles exiting through the radiator cap,or inexplicable
oil consumption. There are several diagnoses that can be done on the car that will nearly pinpoint the trouble
spot and tell you if it is indeed a head gasket or something else.
1. The first test that should be completed is a coolant system pressure test Test your system for leaks with
12 psi (85 kPa) for 1984-86 cars and 22 psi for 1987+ cars with B2XX engines. It should not show any
noticeable pressure loss within 3 minutes.
2. The second is a block test, also known as a combustion leak test, performed on the coolant in the
radiator/expansion reservoir to determine if you have exhaust gases in your cooling system. A
combustion test kit can be found on the web or at your local NAPA,Snap-On, or auto parts store. The
part number is NAPA 700-1006 ($50) or Snap-On GDCT16 "Combustion Leak Tester ". The homemade
version is in Special Tools. Exhaust gases in your cooling system can suggest a head gasket leak, a
cracked block, or a warped head, etc. To do the test, add the blue detector fluid to the block-tester plastic