Copper washers on main bolts

(Art Ford) #1

I found copper washers on the main bearing cap bolts. 7E engine is probably series 1 1/2. It would seem like this would be a torque problem. The ID and OD are both about right but the thickness is a bit less. That would allow a bit less compression. Is there anyway this could have been correct? I wonder if these 5 might have been misdirected from the brass plugs on the side.

(Rob Reilly) #2

My opinion is, yes, it would allow for inconsistent torque. Copper is soft but work hardens with compression, which is why it works well for sealing leaks, but is best not to use twice if you can find new ones.
I’ve never seen anything but steel fold tabs on XK main bearings.
Copper washers on the side plugs.

(Art Ford) #3

I think the lock tabs under the bolts were not on 4.2s. Not sure about 3.8s. Flat washers are probably the norm for all 4.2s but I certainly have some doubts about those copper ones.

(Roger King) #4

None of the engines I have ever worked on have featured soft metal washers on main or big end fasteners. I can’t imagine Jaguar used them, but I haven’t got that far yet.

(Mike Spoelker) #5

Absolutely no way, no how should you ever install copper washers under a critical fastener. Copper will suffer from plastic flow under compression and the bolt can lose tension and loosen. If you need a washer for some reason, use parallel ground hardened steel from ARP or similar.

1 Like
(Art Ford) #6

Yes. I had my doubts from the beginning. That’s why I wrote. The
answer mostly comes from a few tab washers used on the main brg
caps in place of the round steel ones. With that, the numbers now
add up. Thanks.

(Jim XK140 FHC) #7

Are the tab washers on the main bearing caps hardened ?

(Robin O'Connor) #8

Wouldn’t think they are hardened as they have to be upset against the nuts once torqued down, if they were they would snap.

(Rob Reilly) #9

No, just plain soft low carbon cold rolled sheet steel.

(Mike Spoelker) #10

No, they are not. Soft iron. I wouldn’t use them, either. I’ve found too many broken ones in crankcases and rear axles.

(Rob Reilly) #11

Yes, kind of like split cotter pins; they’re fine for one initial use, but unbend and rebend them 3 or 4 or 5 times and you’re asking for trouble.

1 Like