BPB
NAXJA Forum User
- Location
- Battle Ground, Washington
how difficult, and how many parts will i have to replace when i change the head gasket on my 88 chevy scottsdale with a efi 350. thanks for the help.
headgasket on 88 chevy 350
- Thread starter BPB
- Start date
Matthew Currie
NAXJA Member #760
- Location
- Vermont, land of big clay
In theory you should not have to replace that many parts, but in practice, you can expect to need to replace at least a few due to rust and seizure, especially in the exhaust. I have not done this, but did have to replace the oil pan on my 88, which involved removing the headpipes, and let's just say you most likely will have to replace the studs in the exhaust manifold. That shouldn't be too hard with the head off anyway. It's a total [sorry, family forum here! use your imagination. ] to do on the vehicle.
Here, from the 88 truck FSM, is what you'll need to do:
Remove or disconnect: Battery negative cable; drain cooling system; remove intake manifold and exhaust manifold (both discussed previously in book); ground strap at rear of head;
If it's the right head remove AIR pump bolt and spacer, nut and stud attaching a/c compressor to head, and fuel pipe,plug wire and wiring harness brackets at rear of head.
If it's left head remove nut and stud attaching main accessory bracket to head (and probably loosen the bracket's other bolts to clear head for removal), coolant sensor wire and spark plug wire brackets.
Take off rocker arm cover, plugs, pushrods, head bolts, head, head gasket.
Now backing up, we go to the intake manifold:
You need to take off a whole lot for this: The air cleaner, battery negative cable (you do this for everything!), heater pipes and hoses, generator rear brace, vacuum hoses, TBI unit, EGR valve, all accelerator, cruise and Tranny cables, the distributor, a/c compressor rear bracket, brake booster vacuum pipe, coil wires, emission control sensors and bracket on right side, fuel line bracket at rear of manifold (push fuel lines aside), bracket at rear of belt idler, TBI unit if necessary, ...whew... then undo the bolts, and take the manifold off, and remove gaskets and clips if there are any clips.
Pause for deep breath. Don't you just love V-8s!
There's less to take off for the exhaust manifolds: The battery negative cable (of course! They probably include that for replacing a window crank!) comes first. Then you are to raise the vehicle and put it on stands, and support it of course safely, and then remove the exhaust pipe at the manifold.
Interjection here: Expect to shear off the studs, and have to drill them out, and buy new studs. The new studs are ridiculously overpriced.
Now back to the book....We can now lower the vehicle, and take off the oxygen sensor wire if it's the left, but don't bother with the sensor itself, the AIR hose at the check valve, the heat stove pipe if it's the right side, the power steering pump bracket at the manifold if it's the left, the dipstick tube bracket if it's the right....then out come the manifold bolts, washers and tab washers, and off comes the manifold itself. It appears the exhaust manifolds are mounted without gaskets.
So there it is: You'll need, almost certainly, new manifold/headpipe studs, that's a set of 6, new intake manifold gaskets, new valve cover gasket, and of course the head gasket. Everything else is just labor unless you break something. If they're rusty, you may have to get new tab washers for the exhaust manifold bolts.
edit add: The exhaust studs also have springs, and they will probably need replacing too. I forget whether or not there's a graphite sealing ring between headpipe and manifold, but you might need those too.
When you replace the intake manifold, in addition to the gaskets, you'll also need to seal it where it mates to the block at both ends with RTV. The book calls for a 5 mm. bead on the mating surfaces, extended about a half inch under the ends of the gaskets, to seal and retain them.
Torques: Manifold bolts = 48 Nm (35 ft. lb) The sequence for these is from the center out. I can't put the graphic here, so simply draw a rectangular figure with two parallel rows of six holes each. The rectangle is on its side, and left = front. The holes are numbered thus: top, 12,11,4,1,5,6; bottom, 10,9,3,2,7,8.
Exhaust manifolds: tighten the two center bolts to 36 Nm (26 ft. lb) and the outside ones to 28 Nm (20 ft lb). Retain them by bending the tab washers against the heads.
The heads are torqued in stages, to a final 90 Nm (65 ft lb). For the pattern, draw another rectangle. In this one, the top row will have nine holes, in a sort of sawtooth pattern, up-down-up-down etc, both beginning and ending down, and the bottom will have 8 in a straight line. The top row is numbered 17,13,9,5,1,2,6,10,14. The bottom row 16,12,8,4,3,7,11,15. A perpendicular from hole one is directly centered midway between 4 and 3, and each other upper hole is midway between a pair of lower holes. Because this pattern is completely symmetrical between left and right, it shouldn't matter which is front and which rear, so the same pattern can be used on either side.
I hope that helps some. Obviously, since I do have the complete 88 service manual, feel free to ask for more detail if you need it. It's a huge, multi-volume manual.
Good luck.
Here, from the 88 truck FSM, is what you'll need to do:
Remove or disconnect: Battery negative cable; drain cooling system; remove intake manifold and exhaust manifold (both discussed previously in book); ground strap at rear of head;
If it's the right head remove AIR pump bolt and spacer, nut and stud attaching a/c compressor to head, and fuel pipe,plug wire and wiring harness brackets at rear of head.
If it's left head remove nut and stud attaching main accessory bracket to head (and probably loosen the bracket's other bolts to clear head for removal), coolant sensor wire and spark plug wire brackets.
Take off rocker arm cover, plugs, pushrods, head bolts, head, head gasket.
Now backing up, we go to the intake manifold:
You need to take off a whole lot for this: The air cleaner, battery negative cable (you do this for everything!), heater pipes and hoses, generator rear brace, vacuum hoses, TBI unit, EGR valve, all accelerator, cruise and Tranny cables, the distributor, a/c compressor rear bracket, brake booster vacuum pipe, coil wires, emission control sensors and bracket on right side, fuel line bracket at rear of manifold (push fuel lines aside), bracket at rear of belt idler, TBI unit if necessary, ...whew... then undo the bolts, and take the manifold off, and remove gaskets and clips if there are any clips.
Pause for deep breath. Don't you just love V-8s!
There's less to take off for the exhaust manifolds: The battery negative cable (of course! They probably include that for replacing a window crank!) comes first. Then you are to raise the vehicle and put it on stands, and support it of course safely, and then remove the exhaust pipe at the manifold.
Interjection here: Expect to shear off the studs, and have to drill them out, and buy new studs. The new studs are ridiculously overpriced.
Now back to the book....We can now lower the vehicle, and take off the oxygen sensor wire if it's the left, but don't bother with the sensor itself, the AIR hose at the check valve, the heat stove pipe if it's the right side, the power steering pump bracket at the manifold if it's the left, the dipstick tube bracket if it's the right....then out come the manifold bolts, washers and tab washers, and off comes the manifold itself. It appears the exhaust manifolds are mounted without gaskets.
So there it is: You'll need, almost certainly, new manifold/headpipe studs, that's a set of 6, new intake manifold gaskets, new valve cover gasket, and of course the head gasket. Everything else is just labor unless you break something. If they're rusty, you may have to get new tab washers for the exhaust manifold bolts.
edit add: The exhaust studs also have springs, and they will probably need replacing too. I forget whether or not there's a graphite sealing ring between headpipe and manifold, but you might need those too.
When you replace the intake manifold, in addition to the gaskets, you'll also need to seal it where it mates to the block at both ends with RTV. The book calls for a 5 mm. bead on the mating surfaces, extended about a half inch under the ends of the gaskets, to seal and retain them.
Torques: Manifold bolts = 48 Nm (35 ft. lb) The sequence for these is from the center out. I can't put the graphic here, so simply draw a rectangular figure with two parallel rows of six holes each. The rectangle is on its side, and left = front. The holes are numbered thus: top, 12,11,4,1,5,6; bottom, 10,9,3,2,7,8.
Exhaust manifolds: tighten the two center bolts to 36 Nm (26 ft. lb) and the outside ones to 28 Nm (20 ft lb). Retain them by bending the tab washers against the heads.
The heads are torqued in stages, to a final 90 Nm (65 ft lb). For the pattern, draw another rectangle. In this one, the top row will have nine holes, in a sort of sawtooth pattern, up-down-up-down etc, both beginning and ending down, and the bottom will have 8 in a straight line. The top row is numbered 17,13,9,5,1,2,6,10,14. The bottom row 16,12,8,4,3,7,11,15. A perpendicular from hole one is directly centered midway between 4 and 3, and each other upper hole is midway between a pair of lower holes. Because this pattern is completely symmetrical between left and right, it shouldn't matter which is front and which rear, so the same pattern can be used on either side.
I hope that helps some. Obviously, since I do have the complete 88 service manual, feel free to ask for more detail if you need it. It's a huge, multi-volume manual.
Good luck.
Last edited:
Similar threads
