My neighborhood buddy and I changed our S-Type's IMT O-rings this morning. Took us about two hours. My hands were just too big to be able to remove and re-install the lower IMT valve in that limited space but I insisted on doing it myself. I finally did it, but I slowed us down quite a bit.

Only a tablespoon or two of pooled oil dripped out when I pulled the lower valve. I was expecting a gusher but it never happened. So I sprayed a rag with throttle body cleaner and wiped up the lower chamber as best I could, but my rag came back almost completely clean. Not much to clean up.

After getting both O-rings changed and both IMT valves firmly seated and bolted back in their chamber holes, we buttoned everything back up and took the car for a 10-mile test-drive. It performed normally. Once we came back home, I took a clean white napkin and wiped the bottom of the lower IMT valve's black plastic casing like I've been doing since early October. To my surprise, the napkin came back with some oil on it. I hope it is simply some of the pooled oil that ran out of the chamber when the lower valve was removed. Maybe it spread around that area of the manifold and it will take some time to burn off. Sure hope the new green O-rings aren't leaking like the old yellow ones do. I know the new O-rings are seated correctly, and I know I cranked the four 8mm bolts that hold the two IMT valves in place down tight. I cranked 'em down as tight as I could using an 8mm box wrench.

So I'll keep wiping that lower IMT valve casing with a clean napkin over the next few days and see if the oil spotting does indeed disappear after a while. Sure hope so - I don't want to have to do this job again....

 

Er.... I'm a bit worried about possible over-tightening

 

Congrats Jon, job well done! I'll bet its residual oil and not the new O-rings.
Thats the problem going the "short" route, impossible to torque the tuner valve bolts.

 

My second napkin wipe a few minutes ago came out much, much cleaner. I think it's residual oil as well, Rick. The next few days will tell the tale....

So you guys think that I may have over-torqued those four 8mm bolts? They were pretty damn tight from the factory, and since I'm the one who unbolted them this morning, I tried to put them back on as tight as they were before I removed them....

Hey Brutal, do you think that if they're slightly tighter now than they were originally, they may leak a little bit? Or do you think I'm just continuing to wipe up residual oil?

 

I use a calibrated elbow

 

I'm assuming that's a joke? Sure hope it is, anyway. Maybe there really is such a tool as a calibrated elbow....

 

He might mean there is such a tool but I reckon he means the "feel" all good mechanics (and home guys) tend to get. You just kinda know when something's the right tightness. (Not claiming I have it.)

 

If I recall the proper torque is 10nm. When I did mine last Friday for the "hell" of it, they too were pretty damn tight after torquing them the first time around.

 

Yeah, but that's the breaking-them-free torque now that they've seized/rusted or whatever. It's far more than the torque the threads/nut/whatever is applying to keep it from undoing (at the time that the rust etc wasn't there). I'm sure all these things have names, but sorry I just don't know them!

For an unlubed nut (such as jag lug nuts) there's dry torque. The lubed one is wet torque IIRC. I always want to put copperslip on lug nuts but apparently you're not supposed to.

Lots of small things are about 10Nm, just a bit hand tight for those of us with small hands. For Jon that's breathe on it or just use finger n thumb LOL

 

are you kidding, you cannot "torque to spec" everything with a torque wrench. That can be saved for other things. Connecting rods, mains, heads, Subframes, wheels etc....Anything with a oring does NOT seal by tightening the bolt. Thats to hold the part in place. The oring does the sealing. Rookie mechanics always want to go in an tighten on oringed parts so it doesnt leak, wrong. Like trans, IMTs, AC etc that why bolts get stripped. When youve spent enough time on the business end of a torque wrench and other wrenches day in and day out, you develope a feel. Just like things at your job or life you can now do in your sleep. I have been torquing bolts to spec and could feel them streach before they reached torque. The mistake is to say "na, alittle more and itll be there" that little more then snaps the bolt.
I guess youde be scaired to watch me take off bolts and nuts like cam covers bolts with a 1/2" impact and adapters( no I dont put them on that way) its good trigger control.

 

I agree with Brutal, you will find a factory torque spec for everything but in the real world the trained elbow is 95% effective.

 

As Brutal says, the O ring does the sealing and the (small) torque is plenty to hold it together. Too much torque would eventually strip the threads (or maybe snap the bolt). Before that you probably crush the O ring or put kinks in it so it will not seal!

This is true of the sump plug when doing an oil change. Tighten just enough and no more. Similarly with the oil filter and let's face it most fastenings. (hmm, water pump are ones you may well do; have a look at the bolts if you do and think about their design)

I look up torque figures when I can just in case one's much more or less than I would expect. Hub (bearing) torques are so high I actually can't do them unless I buy a tool lol

Have a good long look at the sump plug on many cars and any washer/O ring with it. Why's the plug made of the particular metal and what's that washer/O ring for?

A lot of the plugs are soft metal to try to protect the sump from those who overtighten the plug. People often say they're not reusable. They sure aren't if overtightened. The washer is often a crush washer designed to be slightly crushed (emphasis on slightly). As you can't get it back in the identical position it was in, you have to (as in: should) replace it. The S-Type's an O ring but similar thinking applies.

Proper techs like Brutal know all this but probably don't normally think about it, just like everyone doesn't think about their breathing most of the time. You just do it.

 

I definetly believe that a professional who repairs stuff, cars, semi's, washer and dryers etc... knows the "feel" of a "trained elbow". Just like in the day where a "trained ear" knew how a motor was running. But if one who has to read up on a certain procedure i.e. IMT O-Ring replacement and torques are given, I will use the torque specs. I believe the engineer that developed that part knows what they are talking about.

 

Most people will over tighten nuts and bolts, just in case it comes loose etc. The actual torque required isn't very much at all especially if you've got a spring washer. You really must be careful with aluminium castings as the threads will strip so easily.

 

I didn't strip any threads or break any bolts. What I did was to crank those four 8mm IMT valve bolts down to "pretty damn tight" status using a small 8mm box wrench, at least in my way of thinking. And yes, I'm a big, strong guy with huge hands even at the advanced age of 56....

So Brutal, do I need to go back in there and back those bolts off by a quarter-turn or so? I dread having to do that, but you're the expert, you tell me....

 

No jon your fine, leave it. The oring on the imt doesnt tighten or crush. It just slips in and out of the manifold opening. The only thing you do tightening it as i said earlier is tightening the imt which is plastic. Another thing parts engineers do it put a metal sleeve on plastic parts like that to protect from the over zealous wrench

 

Thanks for the confirmation. I agree, the metal sleeve in those plastic casings offers a measure of protection from too-tight bolts. I thought about that as I cranked those bolts down as tight as I could get 'em....

 

My daily white napkin wipes of the underside of the lower IMT valve casing are now coming back completely oil-free. Whew, that's a relief. The new green-colored O-rings appear to be doing their job as predicted....

Also, I created a much better cowl fastener system than the eight black plastic push-pull pins supplied by the factory. Found some black plastic fasteners at Pep Boys which use small nylon Phillips screws instead of push-pull pins. Removed the nylon screws and replaced them with larger-diameter stainless Phillips screws to spread the fastener prongs further apart and therefore provide extra grabbing power once the fasteners are inserted in their holes. These should last a lot longer than the factory push-pull pins, and I did all eight for less than what three factory push-pull pins from the Jaguar parts department would have cost me....

 

Any pics of those fasteners - or a part # or brand?
I think I need to do the IMT rings too, and have been tuning in, but worry about the cowl plastic fasteners.

Thanks in advance,

George

 

Sorry, but I've already thrown away the packaging that my new fasteners came in.

Just take one of your factory cowl fasteners into the auto parts store with you, and spend some time perusing their stock of various generic fasteners. Different stores carry different stock so your area probably has a completely different set of products than my area does. Compare your fastener with those for sale that are of similar size and shape. Look for fasteners that are held in place by turning a nylon screw. You can go bigger, but you shouldn't go smaller. If you go smaller, you won't get enough "bite" from the new fastener. After you find an appropriate set of new fasteners, take them to the hardware store and fit them with larger-diameter screws so you get a wider "bite" when they are screwed down in place. I like Phillips head screws because everyone has a Phillips screwdriver or two.

Easy to do. Just go check out the selection of fasteners and use your imagination....