I’ve had everything off our 3.4 Mk 2 motor in order to hopefully cure oil leaks and, upon reassembly, I’ve got a couple of these special bolts and no idea where they should go. Likely candidates, indeed hard to see where else they could fit, would be oil filter housing, water pump and the timing chain cover. 3/8" dia, 1 3/4" long excl head, 9/16ths AF spanner fits them.
Be grateful if anyone can tell me where they go. Note shakeproof washer, presumably indicating it’s not fastened to an alloy casting, or it would be copper ?
The shakeproof washer indicates it is not in a sealed application such as oil filter head.
The lack of threads on the tip indicates it is for entering and securing some part that rotates or slides into position and then is held.
Maybe you put a regular one in its place?
Too large for distributor shaft.
Some feature of the later XK engines but not found on my XK120.
Hydraulic timing chain tensioner? Rotor oil pump?
Mmm, thanks Rob. Yes, I expect you’re right and I have put regular ones in their place.
I took off the head and sump and fitted new rings and big end shells, otherwise the engine hasn’t been touched internally - only big end caps, so nothing like those bolts. Timing chain tensioner bolts are, I think, considerably smaller and weren’t touched anyway.
Don’t think the 120 engine is much different so it’s always possible, I suppose, that they’re not original and someone’s fitted the wrong ones somewhere along the line.
Just had a thought - as I have the motor out, could they be from somewhere else altogether ? The slight corrosion might support this. Wondered about the slave cylinder as that has two fasteners, but these are studs. I’ll press on with the assembly, fitting gearbox , starter, etc. - hopefully it will become apparent !
Is it a 3/8" UNF bolt? If so,it looks like the front cover bolt from the lower left side?
The end is relieved of thread, some early ones were like this I seem to recall? It was to avoid collision with the one shorter sump bolt.
I have two of those in my “Special fasteners” box. The heads are drilled iirc. I haven’t taken my timing cover or water pump off, or split the transmission from the GB.
All I did was disassemble the rest of the car… completely.
According to my notes they are from the top radiator mounts.
No need for “sorry”. It is a bit odd that the end is shaped that way - body fasteners are often pointed, but that barrel section is unusual. The bolt does have to go through quite a few other bits, but I fail to see how that barrel section is better than a plain point. If I’m right it’s item 6 in the plate below.
Your right about most body bolts being pointed at the end. I do recall though, that some of them were like the ones you have.
Think it may relate to the way the end of the bolt sits in the rad side panel?
Best Regards
Nigel
Many thanks indeed, everyone, we have it ! You’re right, Andrew and Nigel, they’re the radiator mounting bolts - right number, right shape per the picture. So I can stop worrying that I’ve put the engine together incorrectly !
As always, the forum comes up with the answer - thanks again.
Funny how the eyes deceive. I would swear that the thread is not UNF.
Holding calipers on the photo, the diameter transfers to approx 1 1/8
thread length.There are approx 18 threads visible.
3/8 UNF-24 TPI, 3/8 BSF 20 TPI 3/8 UNC-18 TPI and 10 mm@:1 1/2mm pitch
approx 17 TPI. Have the holding threads been retapped?
Peter.
Andrew
I am not suggesting that the bolt has been re-cut, but the captive nut that the bolt screws into. These.captive nuts are not NYLOC. The NYLOC nuts are for the bottom fixing. We are talking MK11 here I presume.
Placing a caliper on the shank of the bolt, which we know is 3/8, and then moving the caliper along the thread suggests a thread length of 11/8" and as I have stated 18 threads are visible…
My comment is based on the photo, a bolt in the hand, of course, is worth two in the ether…
I will try to upload some photos that show where I start with a MK1/11.
Peter.
Coincidentally, the other screw I happened to remove from a Chevy van today.
It holds in the latch mechanism in the door.
The inside door handles have them too.
Chevy calls these a pilot screw.
I think the idea is that it saves about 1 second on the line assembler’s time over a conventional screw.
Multiply by 18 screws per van and I guess after a million vans the time savings adds up to some real money.
Yes Rob .
Lesson learned! Not to view a photo as accurate… unless the item is shown
with a measuring device, Scale it, perhaps you will see why I made the comment.
Apologies to all for a lot of words re a small problem…
No one died.
Peter.
