Just replaced exhaust manifold on a 1989 B350 Dodge 360 (5.9L) engine. All threaded fittigs were replaced wih new ones and new washers were used in the same locations as what were taken out. My question revolves around the use of conical washers. I replaced the old ones where they were located when I took off the old manifold. That manifold had obviously been removed since it had a gasket. Factory instalation are without gaskets. The conical washers were only on the water jacket penetrating studs which are the first and last or front and rear of the manifold. So that is what I replaced. I now have learned that conical washers for that engine are used on BOTH the threaded shaft AND the screw of the front and rear exhaust ports. Having used only one at each port am I looking to expect future problems. By the way, with this new manifold, I dertimined it completely flat on the mating surface with the head and did not use a gasket.
alloro
10-16-2008, 08:38 PM
A conical washer is the equivalent of a super tense lock washer. Due to the concave shape of the washer, it is actually compressed as you tighten the nut/bolt. All the while the washer is trying to regain it's original shape, it is keeping a degree of spring tension on the bolt/nut/stud assembly.
Chump
10-17-2008, 02:24 AM
I see 8 conical washers and they go on the studs/long screws. I would install the other 4 washers as soon as you get a chance. This info is from the factory parts book...
2121223 QTY-4 WASHER, Exhaust Manifold Stud Y2121223 Y2121223
0115729 QTY-4 NUT, Exhaust Manifold End Stud Y0115729 Y0115729
6025991 QTY-4 STUD, Exhaust Manifold End Y 6025991 Y 6025991
6031857 QTY-AR SCREW, Exhaust Manifold Y6031857 Y6031857
6033613 QTY-1 Lt. (1989) N Y6033613
QTY-4 Long (5/16x2-1/8-Hex) N9421360 N9421360
QTY-4 WASHER, Exhaust Manifold Long Screw N2121223 N2121223
chaingang
10-17-2008, 01:41 PM
Your post is exactly what I was looking for. You've convinced me that NO substitute would be adaquate. Previous installations used only one conical washer on each of the outermost exhaust ports, and substituted regular washers for the other side of the outermost ports. That created an imbalance that resulted in warped ends of the removed manifold. I now know that the manufacture reccomendation IS conical washers on both sides of the front and rear ports. Thanks again
B-300
10-17-2008, 03:15 PM
Actually the fact that the studs at have fine pitch threads and the bolts are coarse thread causes more clamping force to be applied when they are torqued to the same torque.... I would replace the studs with coarse threads on both ends.
Latter (Magnums) have blind holes in all positions and use bolts.. studs were used on pre-magnum engines since they go into coolant passages, they don't on magnum engines.
